Okay, I'm about to flush out the coolant on my car. It's low mileage and has been done before, but hard to tell how long ago.

Between the numerous threads, my 1986 Service Manual, the Haynes Manual, and Ogre's cave, there are some conflicting instructions out there.

Here is what I'd appreciate clarification on:

1. Drain procedure: I get that I need to drain from the cooling pipes and the radiator. Is it necessary to do the block plugs? If so, does anyone have a picture on the V6? I can't find pics anywhere

2. Fill procedure: Fill through the thermostat housing with radiator cap off until radiator full. Then cap radiator and fill up the rest of way at housing. Add to overflow tank at that point or wait until later?

3. If I use the technique of running the car for 30 seconds and then topping off at thermostat housing -- doing that multiple times till it stays full -- do I leave thermostat out or put in each time? Ogre says put it in to avoid air in the heater core, but no one else does ...

4. Flush: Gonna fill and drain with distilled water a few times to "flush" out. During this, I want to heat up the car to full operating temperature each time and run the heat, right? Given it has to cool between drains, that would make this an all day affair.

5. No "flush agent" should be used, right? I don't want to pull the heater core, so I don't want that agent stuck in the parts of the system where water will remain. Perhaps if only used the first time and then flushed with only water a couple times after?

Thanks for the help.

I've used the following procedure with half a dozen different Fieros (running a 195° thermostat) and never had an overheating issue...

quote Originally posted by Patrick: * Begin procedure with a cold engine. * Make sure rad cap is the proper one for Fiero use. The catalogs are wrong! You want a non-vented one, * Check that the coolant reservoir and the small hose to the rad are both in good shape. Otherwise air gets sucked in. * Ensure that coolant level in coolant reservoir is at the "Cold" level. * Position rear end of Fiero higher than the front. * Remove thermostat housing cap and thermostat. * Remove radiator cap. If coolant runs out, put rad cap back on. If coolant doesn't run out, leave it off. * Add coolant to thermostat housing. If rad cap is still removed, continue to fill until coolant runs out the top of the radiator. * Re-install rad cap. * Continue again to add coolant at the thermostat housing until you see the level come up to where the thermostat normally sits. * Put thermostat cap on (without the thermostat) and turn just barely enough to hold cap on. * Start engine and run for about 30 seconds. * Remove thermostat cap and check coolant level. * Repeat last four steps until coolant level no longer drops. * Re-install thermostat and thermostat housing cap. As long as there are no blockages anywhere in the cooling system and the water pump is circulating coolant, you should be good to go. * After several heat cycles of the engine/cooling system, double-check coolant reservoir level... just in case there's a coolant leak somewhere.

[This message has been edited by Patrick (edited 08-06-2022).]

Coolant circulates through the heater core no matter what position the temperature lever is in.

Procedure 2 works well, with modification......Fill thru stat housing until coolant is visible at cap, but not overflowing. Continue filling using the large discharge port on stat housing until coolant is level with radiator cap. Reinstall cap. Continue filling thru stat housing until block and stat housing are full.
Cap stat housing and allow to warm up, monitoring temp gage. Allow to cool.
Install stat and top off overflow tank. Monitor tank and maintain level.

The system is designed to burp itself.

The overflow tank should be filled to the HOT mark during initial warmup.

[This message has been edited by olejoedad (edited 03-31-2017).]

Whenever I have to service my cooling system I use the recommended method but I do the refill a bit differently. I refill at the radiator till the radiator is full - I can avoid overflowing this way and making a mess with spilling coolant. I will leave the car for about five minutes and the coolant will equalize in the system so I have to add a bit more at the radiator to fill it. Then I cap the radiator, go to the engine bay and finish filing at the thermostat neck. System is filled without spilling or overflowing at either end.

if you really want to flush and clean the system, drain the system, pour in 1/2 lt of central heating system descaler / cleaner fill with clean water, leave the thermostat out,this will ensure maximum flow through the radiator, leave in the car for a month or two, drain then flush with clean water, before filling with antifreeze mix. central heating system cleaner will not harm alloy or iorn

I do want to flush it, but I am not comfortable using any additive that will certainly be left in the heater core and other areas.

What about the block drain points -- worth the effort?

I have owned my 85 SE V6 since new- I have only flushed it maybe 3-4 times; Drain it at the radiator and the tube plugs...Never have done the block drains. When I refill, I fill at the radiator cap, then cap it and fill the rest at the thermo housing...I try to squeeze the hose coming off the Thermo housing a few times to blow the air bubbles out, then cap it(Without the thermostat) and run it for a while- get it warm but watch the temp...Fill again at the thermo cap- do this until it doesn't gain air after you run it, then re-install the thermostat.

I fear saying this......I still have the original radiator(I did replace the heater core once)....I know I have now jinxed myself......

quote Originally posted by USMUCL: I do want to flush it, but I am not comfortable using any additive that will certainly be left in the heater core and other areas. What about the block drain points -- worth the effort?

Don't worry about the tiny amount of water left in the block. When you add the correct amount of coolant it will all get mixed up properly. There really isn't a whole lot of fluid to worry about in the heater core either. Once finished with the water drain/refill procedure everything left in the system will be water.

If you want to flush it just drain and refill with water 4 or 5 times. You will flush out the old coolant before replacing with new coolant.

If you want to clean/descale it then that is a different animal. That involves either a cleaning solution like Prestone Super Flush (or a homebrew vinegar solution). Follow the instructions for the product as always. Afterwards there will only be water in the system.

Good info, thanks. The car only has 10k miles on it, but I suspect it has been a few years since new coolant was put in . . . and I would bet it was never really "flushed."

I'd like to get any residual corrosion out, but don't want to mess with the heater core. You got me thinking that doing one flush with something like the Prestone Super Flush, then two more times within only distilled water, would be okay. Then refill with the coolant.

Any concerns with small amounts of the Super Flush being left in the system, you think?

quote Originally posted by Hudini: Don't worry about the tiny amount of water left in the block. When you add the correct amount of coolant it will all get mixed up properly. There really isn't a whole lot of fluid to worry about in the heater core either. Once finished with the water drain/refill procedure everything left in the system will be water. If you want to flush it just drain and refill with water 4 or 5 times. You will flush out the old coolant before replacing with new coolant. If you want to clean/descale it then that is a different animal. That involves either a cleaning solution like Prestone Super Flush (or a homebrew vinegar solution). Follow the instructions for the product as always. Afterwards there will only be water in the system.

With only 10,000 miles, and a sealed system, the antifreeze in your car is as good as the day it was poured into the car. No corrosion or sludging.

No mileage = no need to replace, and certainly no need for a chemical cleaning.

As I said in another thread - Don't fix what isn't broken.

As for your question on the 'block drain ports' (and for that matter the coolant tube bolts) I wouldn't mess with them. When I flushed mine I did the cap and thermostat removal, opened the radiator cap and ran a garden hose thru the system until it overflowed from the radiator cap for an extended period. I then disconnected the top and bottom hose from the radiator and flushed it independently and did the same with the heater core (at very low pressure. I also disconnected the entry / exit hose from the coolant pipes and flushed those. I inspected and replaced the hoses that had not been replaced by the prior owner. System was filled with distilled water and the good green stuff with the rear end jacked up until it ran from the top of the radiator, cap was reinstalled, addition coolant was added slowly until it 'topped up' at the housing and a fresh thermostat was added. Keep an eye on the overflow bottle as the system burps for the first couple of hundred miles. Oh, whom ever the engineer was on the 2.8 that designed the hose that attaches to the bottom central area of the block should be shot, buried, dug up after a week or two, and shot again.

quote Originally posted by olejoedad: With only 10,000 miles, and a sealed system, the antifreeze in your car is as good as the day it was poured into the car. No corrosion or sludging. No mileage = no need to replace, and certainly no need for a chemical cleaning. As I said in another thread - Don't fix what isn't broken.

I'm surprised to read that, but I don't discount it. I would assume a "garage queen" car would experience as much corrosion of the coolant as any. After all, the coolants don't list just a mileage limit for their life, but also a time period, i.e. 2 years or 36k miles.

Edit: According to Prestone, time breaks down the corrosive prohibitors . . . so I might not have corrosion or sludge, as much as time takes away the coolant's ability to protect against such corrosion/sludge.

[This message has been edited by USMUCL (edited 04-03-2017).]

Heat and thermocycling breaks down the corrosion inhibitors.
If your car has only 10k, it hasn't aged.

Do what you want, I'm just being Captain Obvious here, trying to save you time and money, and maybe a bit of aggravation......

I respect what you have to say. I will think on it further . . . .

quote Originally posted by USMUCL: According to Prestone, time breaks down the corrosive prohibitors . . . so I might not have corrosion or sludge, as much as time takes away the coolant's ability to protect against such corrosion/sludge.

Yes, Any coolant system can have corrosion.
More so w/
car w/ 3 year coolant and now been in there for many years.
car not running to keep coolant mix and parked for months or years.
cars w/ weak coolant cause by owners filling wrong etc.

Ignore other methods and follow directions in my cave.
System will "burp" itself IF overflow tank and tube are good.
"flushing" chemicals often won't help but waste money and wrongs ones can damage Aluminum and other parts so Read The Label.
drain pipes and radiator and leave water in the engine and H core and use only full strength coolant.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

So, it is your opinion that old coolant, but with low miles, should be changed -- I think I'm reading? I have 10k miles. I doubt my coolant is 31 years old, but I also doubt it has been changed in the last 5 years. It is the standard green stuff.

By the way, the biggest difference I see in the instructions in your cave is that you believe the thermostat should be installed during the top off procedures, as opposed to leaving out until the system is burped and full?

quote Originally posted by theogre: [QUOTE]Originally posted by USMUCL: According to Prestone, time breaks down the corrosive prohibitors . . . so I might not have corrosion or sludge, as much as time takes away the coolant's ability to protect against such corrosion/sludge.

Yes, Any coolant system can have corrosion.
More so w/
car w/ 3 year coolant and now been in there for many years.
car not running to keep coolant mix and parked for months or years.
cars w/ weak coolant cause by owners filling wrong etc.

Ignore other methods and follow directions in my cave.
System will "burp" itself IF overflow tank and tube are good.
"flushing" chemicals often won't help but waste money and wrongs ones can damage Aluminum and other parts so Read The Label.
drain pipes and radiator and leave water in the engine and H core and use only full strength coolant.


[/QUOTE]

[This message has been edited by USMUCL (edited 04-03-2017).]

Coolant and water will not separate after mixing.
The corrosion inhibitors are used up, they don't 'go bad over time'.
Heating and thermocycling of the metal parts in the engine leads to corrosive products entering the cooling system, these corrosive products 'use up' the corrosion inhibitors.
There is no shelf life for antifreeze, it is good for pretty much forever in a closed container or unused closed system.
When recycling antifreeze, the ethylene or propylene glycol content is reused, the corrosion inhibitors are removed and replaced......

Then why, with every type of antifreeze, is the life measure in miles OR time, whichever comes first (as opposed to mileage only)?

And don't say cause they want us to buy more antifreeze -- most people would hit the mileage first anyway, so that would not be an effective money maker.

quote Originally posted by olejoedad: Coolant and water will not separate after mixing. The corrosion inhibitors are used up, they don't 'go bad over time'. Heating and thermocycling of the metal parts in the engine leads to corrosive products entering the cooling system, these corrosive products 'use up' the corrosion inhibitors. There is no shelf life for antifreeze, it is good for pretty much forever in a closed container or unused closed system. When recycling antifreeze, the ethylene or propylene glycol content is reused, the corrosion inhibitors are removed and replaced......

OK, I won't say that....

I have a bit of experience with chemicals, having spent 35+ years in the industry.....

Do what you want, just trying to answer some of your concerns.

[This message has been edited by olejoedad (edited 04-03-2017).]

Hold on, Joe. I'm just trying to learn. When I question you (and others) as sort of a counterpoint, it is not to tell you that you're wrong . . . . I want to hear why I'm wrong.

quote Originally posted by olejoedad: OK, I won't say that.... I have a bit of experience with chemicals, having spent 35+ years in the industry..... Do what you want, just trying to answer some of your concerns.

No attitude here, we're good.

My input is based on knowledge and experience, if I say something that you want to go ahead and look into with detail, feel free to spend the time.

I understand your desire to make sure your car is as good as it can be, and I'm happy you have that outlook on maintenance.

If you do decide to replace the coolant, please be sure to recycle it.

If you want to know if your coolant is still good: Drain a small amount out from one of the pipe plugs under the car (6-8 ounces is all you need, so it's a quick unscrew of one of the plugs pull it out for a moment then screw it back in). Now smell the coolant. If it smells like bananas it is time to replace. Fresh coolant has a sweet smell, but very little odor. When coolant (the green ethylene glycol based antifreeze) needs replacing it always smells like bananas to me.

quote Originally posted by olejoedad: Coolant and water will not separate after mixing. The corrosion inhibitors are used up, they don't 'go bad over time'. Heating and thermocycling of the metal parts in the engine leads to corrosive products entering the cooling system, these corrosive products 'use up' the corrosion inhibitors. There is no shelf life for antifreeze, it is good for pretty much forever in a closed container or unused closed system. When recycling antifreeze, the ethylene or propylene glycol content is reused, the corrosion inhibitors are removed and replaced......

OK, question for you.

If the inhibitors don't break down over time then why do I have pitting and corrosion in my thermostat housing at the lowest point where the thermostat seal is? Seems to me thats from sitting still for so long without the coolant being changed or moving. I believe my coolant was 30 years old

30 years and all you have is pitting? I'd say job well done. Imagine bare metal sitting 30 plus years in plain water?

Unless the OE coolant is in the system... You have No Clue what coolant was used. Green coolant have different formulas and some are better then others. Worse, Many twits fill a flush car w/ premix coolant and run the car w/ very weak mix that looks ok but won't protect WP seal etc.

You leave Tstat in the system to force coolant thru the heat loop to push out air. You may not have air in the heat loop but no way to know. See my Cave, Heater

quote Originally posted by olejoedad: Coolant and water will not separate after mixing. The corrosion inhibitors are used up, they don't 'go bad over time'. Heating and thermocycling of the metal parts in the engine leads to corrosive products entering the cooling system, these corrosive products 'use up' the corrosion inhibitors. There is no shelf life for antifreeze, it is good for pretty much forever in a closed container or unused closed system. When recycling antifreeze, the ethylene or propylene glycol content is reused, the corrosion inhibitors are removed and replaced......

Many markers say Wrong.
Most new packages have a shelf life. Stores have enough turn over that's not a problems but many have seal bottles at home sitting for many years even decades. Some additives can go thru the plastic bottle over time.
Now ignore that... Goes into a car and run @ 50/50 mix then have whatever the product is made ± X months because of many reasons. Yes Base EG/PG doesn't go bad but many additives do after X time. Green coolant can be 1 to 5 years for additive packages like Prestone Green Prime only rated to 1 year but Prestone yellow bottle is 5 year/150,000 miles and been so for a decade or more but only when you follow their directions.

Coolant Systems for Most vehicles are not closed/sealed as many people think. Some additives can work around or go thru gaskets/seals over time to escape the system. Then add most Overflow Tanks do not seal out air and dirt to let additive "fumes" escape or react w/ air, ozone and other pollution. Fiero and Many others Overflow Tanks and the caps are only to keep out major crap and keep in most coolant driving on bumpy roads.
Pollution getting into the system via Overflow tank is part of problems w/ Dex-cool. (Dex-cool is EG base coolant but way different corrosion additives.)

Depending on product Coolant and additives does separate over time and why many WP goes bad when parked for a long time. You might drive the car but hard WP seal can fail in a day to several months.

quote Originally posted by olejoedad: Coolant and water will not separate after mixing. The corrosion inhibitors are used up, they don't 'go bad over time'. Heating and thermocycling of the metal parts in the engine leads to corrosive products entering the cooling system, these corrosive products 'use up' the corrosion inhibitors. There is no shelf life for antifreeze, it is good for pretty much forever in a closed container or unused closed system. When recycling antifreeze, the ethylene or propylene glycol content is reused, the corrosion inhibitors are removed and replaced......

Yup.. My 86SS has sat in garage since 2002 with new green and distilled water mix.. it still test as good as it did the day it was put in and car warmed up.. and stuffed in garage.. and it's ph is the same..

[This message has been edited by E.Furgal (edited 04-04-2017).]

This should really get a couple heads exploding . . . if I do change the coolant, might as well change out the 3 temp sensors (ECM, fan, gauge) to new ACDelco's while there is no coolant to spill out, right?

quote Originally posted by USMUCL: This should really get a couple heads exploding . . . if I do change the coolant, might as well change out the 3 temp sensors (ECM, fan, gauge) to new ACDelco's while there is no coolant to spill out, right?

You can but changing after w/o leaking is easy... just drain system to a clean container below the part then return coolant after. Many times you only need to drain 1-2 quarts for changing them in Fiero. Many times can just suck out enough thru Tstat housing on Fiero and some others.

If caps etc are good and done carefully you can change them w/o loosing more then a 1-2 spoon fulls w/o draining w/ engine cold. spin out last few threads then quickly install new unit. I've change senders/sensors in the lower engine block w/o leaking more then that. If needed coat the sender w/ thread sealer before you start.

[This message has been edited by theogre (edited 04-04-2017).]

quote Originally posted by theogre: Green 50/50 mix should test to −34°F(−37°C) and "Pure" coolant in bottle should "peg" most tests because freeze point is too low to read. That's the job for EG part of coolant. (Most "pure" new coolant has a little water 1-5% plus additives.) pH is only a test of acidity and doesn't mean anything to many additives. (New Green Normal pH should be ~10.75 w/ 50/50 mix) Unless you have access to a lab and compare to new product you have in the car can't test most additives. "Dead" and Weak coolant will protect for freezing, even pass the tests above, but not for corrosion and/or wear problems. Once damage is done the system parts are permanently weak. Rust/corrosion happens without heating/cooling the system because Corrosion is a Chemical reaction. Heating or cooling only speed or slow the reaction while silicates etc additives tries to interfere/block the reaction. Hard seals and caps are not a "drying" problem. Weak/dead coolant or worse filled only w/ water can pull plasticizers right out of the "rubber" and plastic and won't lube moving parts. Yes air pollution like Ozone can attack from outside but often is not the root cause of bad WP and other seals. If you have Ground problems in the car then even New coolant install before the problem is found can be weak or dead to prevent corrosion when ground problem is fixed and often still pass tests above.

The mix tested at 0F when put in.. and does 15 years later..
Did you miss the part of the ph test being good, the same as new coolant.. or just brushed it off..
Not only did I test the coolant in the radiator but I did the overflow tank.. and it also past the temp test and the ph test..
And if you really are interested the voltage test..
15 years after it was put in the car it still test as it did the day it was put in..
ODD..
Orge you have a bunch of great tech in your cave.. but My dad and I have cared for collections of vehicles that sit for 10-15-20-25-40 years.. For owners that if it needs it ,it gets it.. coolant doesn't just degrade from sitting..
Though I will admit that all vehicles involved get a good reverse flush and drained completely (block plugs removed and air blown out.. then boiling hot water flushed through them.. drained, and refilled before they go for a nap.. But I doubt with just the reverse flush. and draining of system it not be the same.
Again this is 100% and customer mixed with distilled water.. not the 50/50 mix crap they sell now..
Now todays green is also sold as long term ,high mile coolant.. they might have very well have changed the make up..
We have 1 1/2 full pallets of the real green..

[This message has been edited by E.Furgal (edited 04-04-2017).]

quote Originally posted by E.Furgal: The mix tested at 0F when put in.. and does 15 years later.. Did you miss the part of the ph test being good, the same as new coolant.. or just brushed it off.. Not only did I test the coolant in the radiator but I did the overflow tank.. and it also past the temp test and the ph test.. And if you really are interested the voltage test.. 15 years after it was put in the car it still test as it did the day it was put in.. ODD.. Orge you have a bunch of great tech in your cave.. but My dad and I have cared for collections of vehicles that sit for 10-15-20-25-40 years.. For owners that if it needs it ,it gets it.. coolant doesn't just degrade from sitting.. Though I will admit that all vehicles involved get a good reverse flush and drained completely (block plugs removed and air blown out.. then boiling hot water flushed through them.. drained, and refilled before they go for a nap.. But I doubt with just the reverse flush. and draining of system it not be the same. Again this is 100% and customer mixed with distilled water.. not the 50/50 mix crap they sell now.. Now todays green is also sold as long term ,high mile coolant.. they might have very well have changed the make up.. We have 1 1/2 full pallets of the real green..

No you don't "get it." Test at install = 0°F mean coolant is too week to do any good. (or you did not run the car at all to mix the coolant.)

No I did not ignore pH... simple fact is the value does not mean much to additives and more so when you see 0°F on a hygrometer etc.
The additives I mean are IN the Coolant product like Silicates for corrosion protection won't protect and product also won't lube/protect seals gaskets etc.

You fill a flush engine w/ "pure" coolant to 1/2 total system volume and rest w/ water to make a final 50/50 mix.
IOW If a system spec is 6-8 quarts then you need 3-4 quarts of pure coolant in the system or there is no point to flush and system will have rust etc soon after.
Fiero needs almost 2 gallon of pure coolant after flushing. To get that in the car you must drain the radiator and both pipes minimum after flushing a 4cyl.

Almost Every coolant maker call for a final 50/50 mix minimum for −34°F for "pure" coolant. 70/30 max for −84°F protection. (70% does add some boil over but not main job.) Just read Prestone Peak and other "full strength" product pages like PEAK® Antifreeze In fact Part of WaterWetter product is to give systems full of water or cars w/ "weak" coolant on purpose to get corrosion protection.

You can use a Pre mix product to "top off" the overflow tank level w/o having to mix a small amount. These are good for many that buy a gallon of coolant once a year because most are adding ~1 quart to a good system.

I just had an epiphany. Or maybe I'm delusional.

Given the potential drama with the drain plugs on the coolant pipes .... If you just drain from the radiator completely and then jack the back of the car up a couple feet, won't that force the remaining fluid out of the pipes and into the radiator where it drains from the peacock?

quote Originally posted by USMUCL: I just had an epiphany. Or maybe I'm delusional. Given the potential drama with the drain plugs on the coolant pipes .... If you just drain from the radiator completely and then jack the back of the car up a couple feet, won't that force the remaining fluid out of the pipes and into the radiator where it drains from the peacock?

If you're truly flushing the system, with clean water, it isn't really going to matter. I live in a hilly city, so I opt to park on a hill for draining and burping my Fieros. Wheel chocks are quicker than jacking the car up anyway.

Were Peacocks an option on fieros?

Yea, pointed down hill or jacked up . . . for argument's sake, I'm just curious whether the pipes would get drained that way as well as they would if the drain plugs are pulled.

Seems gravity would dictate they would. But, as many times as I've read people have stripped out their coolant pipe drain plugs, seems like the 'jack the rear end up' idea would have already been offered as a better alternative if it worked. So, I'm wondering what I'm missing.

So easy, A Kid can do it!

quote Originally posted by USMUCL: I just had an epiphany. Or maybe I'm delusional. Given the potential drama with the drain plugs on the coolant pipes .... If you just drain from the radiator completely and then jack the back of the car up a couple feet, won't that force the remaining fluid out of the pipes and into the radiator where it drains from the peacock?

I removed my plugs when I changed mine. No problems at all. I think you will find that those that have had issues are on high mileage cars with lots of corrosion. I didn't even use any tape or sealant when I put them back in. One leaked a little I just tighted it a bit more and all good.

left side won't drain much like that.
right side maybe more but not all.

both pipes are bent up to clear the front cross member and left hose to top of rad.
Unless replacing hoses, don't touch them.

w/o draining left pipe then likely will have problem filling w/ straight coolant to make a final 50/50 mix.

Dirt Corrosion etc can change size of plug opening for the key. Make sure you remove all dirt and use very tight Allen key. Try SAE and Metric sizes.

I use nondrying Teflon pipe sealer to install plugs. (not Teflon tape.)
Sealer seals w/ less torque and prevents future corrosion issues.

Good info, thanks, all.

quote Originally posted by USMUCL: Good info, thanks. The car only has 10k miles on it, but I suspect it has been a few years since new coolant was put in . . . and I would bet it was never really "flushed."...

Forget the flush, you need a new motor for sure by now.

Just kidding. This is one area I've abused Fieros in. You seem to be very concerned about it and for that reason I would suggest you pull a plug from the block and try to catch the first quart or so of coolant that comes out in a jar and let it sit for a couple of hours and observe the sediment at the bottom of the jar. The engine block catches a lot of debris suspended in the coolant in the lower portion of the block. That should give you a good idea of whether you are heading off a potential problem, or chasing your imagination. I've opened a plug before and had to use a screw driver to poke a hole through substantial debris to allow the coolant to drain. I doubt you'll fine much but a car in that condition is worth the trouble.