I am doing a mod to my hood, to put a vent in it to allow the hot air to excape. I have a set of sunbird turbo vents on it now, but am working on the new scoop idea. I noticed a few folks here have done a similar mod, and some have bought a cut/drop in fiberglass scoop (archie, angle vent, etc... ) but my question is what have you all done with the radiator overflow tank. When searching the net, I found this about overflow tanks:

The true overflow tank is an add on item used with a conventional cooling system. The conventional cooling system uses a radiator, which has an attached filler neck to which a pressure cap is attached. The system is filled though the filler neck on the radiator and should be filled to about ½” to 1” below the bottom of the filler neck. If the system is filled any higher, it will be over full and the excess coolant will be vented from the system. This happens when the heat builds up within the coolant, it expands, increasing the system pressure above the pressure holding capability of the pressure cap (listed on the cap in pounds per square inch or PSI) causing the excess coolant to be vented out through the overflow vent which is exposed when the cap sealing plate is forced upwards. The excess coolant is then vented to either the atmosphere or into an overflow tank, which functions as a catchment basin. The overflow tank is under atmospheric pressure while the cooling system is under atmospheric pressure plus the pressure generated by the heat expansion of the cooling medium. As the cooling system begins to cool down, the internal system pressure drops until it allows the pressure cap spring to overcome the system pressure and the cap then forms a seal again on the bottom of the filler neck. This takes place when the internal system pressure drops to lower than the rated pressure of the radiator pressure cap. Thus, the cooling system pressure will always be above the atmospheric pressure of the overflow tank until the pressure cap again seals and the entire system is completely cool. At that time, both the cooling system and the overflow tank will be at atmospheric pressure. As can be easily seen, the flow of excess cooling can be in one direction only—out of the cooling system and into the overflow tank. The coolant in the overflow tank cannot flow back into the cooling system because a liquid cannot flow from a lower pressure to a higher pressure. Thus, an overflow tank serves strictly as a catchment basin, not as some form of extra coolant reservoir.

This leads me to believe that I can put the tank anywhere, but close to the radiator cap. But I have always thought that the tank had to be higher than the radiator cap. Can I mount it in a location that is below the radiator cap?

Have you swapped them out for a differant tank. If so, what have your used. I checked ebay and they just all look like crap.

Where is the best place to relocated it, can you located inside the "sealed front trunk" or does it have to be outside of it in case it overflows.

finally, when it comes to the tank, does the top of the tank have to be higher than the radiator cap, will it work if its located lower on the body.

Pictures too if you have them

Thanks

Rob

[This message has been edited by qwikgta (edited 03-29-2011).]

It is just a overflow bottle. You can use a soda bottle if you want.
It does not have to be above the rad opening.
It works off a vacume. When the raditor get low on water, it should suck some of the overflow water back in the rad. or push it out when too hot and passes the cap pressure.

So mount whatever you use to hold/catch the water, wherever you need to place it. inside or outside the trunk.
I would make it a short run to be on the safer side. closer to the headlight and a smaller bottle sounds like what you need. ( Look at the aftermarket stuff for a small bottle.)

Quikgta: Could you post up what you decide to do, please? I will need to do something similar, as my headlight mod hits the bottle and I'd like to clean it up a bit.

Revin: thanks for the info...

Bob

You could always go with something like this.

I guess there is a diff between an expansion tank, and an overflow tank. The big diff is the pressure. I still feel that I have read that the overflow tank has to have the cap higher than the radiator, but I can't confirm it.

I don't want to do something cheap, and most of the tanks are cheap. Has anyone reloacted their tank? If so, what did you do/use and how did it work?

Khw, the issue with that one is size. It will not fit and function in the space up front. I am looking at a smaller, square/round one that I can mount inside the truck area.


//

This is the early stages, I plan to cut out the area and then cut the lines, then bend down the two sides. Its still early, and my main goal is to not cut the front of the trunk.





Rob

[This message has been edited by qwikgta (edited 03-28-2011).]

quote Originally posted by qwikgta: After all the reading on the net, I feel safe that I can buy this tank and install it just off center and lower near the radiator. http://www.jegs.com/i/JEGS+...s/555/51137/10002/-1 I'll let you all know if it works. Rob

That looks decent. I was mostly suggesting looking for one that was longer and round that could be moved to the side more out of the way, not the specific one I posted a picture of.

quote Originally posted by Khw: That looks decent. I was mostly suggesting looking for one that was longer and round that could be moved to the side more out of the way, not the specific one I posted a picture of.

No I understand. I was just saying it that specific one its more of an expansion tank vs. overflow tank. That one in the picture has a radiator cap top (not vented). I knew you were talking about the aftermarket type of tanks.

Rob

You can push the vent down quite a bit before it will make contact with the overflow tank. If you would like I can take a measurement for the actual depth from the top side of the hood.

You should be able to find plastic overflow bottles in the auto parts store. They're usually about half the size of the stock Fiero unit, which should give you the extra space you need. And they only cost around $10 or so.

That said, I decided to use one of the Moroso canteen-style aluminum tanks. Of course, it cost more than one of the plastic ones. But I don't have to worry about it splitting open. I mounted it in the same area as the stock Fiero tank, but a couple inches lower, to give some room for the hood vent. It's been like that for years, and has worked just fine.

quote Originally posted by fieroguru: You can push the vent down quite a bit before it will make contact with the overflow tank. If you would like I can take a measurement for the actual depth from the top side of the hood.

Guru, that is the exact look im aiming for. Yes, please if you could, the measurements for: A: distance from the lip of the hood to the horizonal cut. B: the distance of the vertical cut in from the hood line, and C: lenght of the vertiacl cut. I had been using a measurement of: A= 9 1/2", B= 3 3/8" and C= 9" Also, how much of the hood did you cut before you laid it back (down). I want the same look, the only diff is that I plan to put some of the honey comb material over the cut so you don't "see" down into the opening.

Also, did you have to cut your trunk front to get that to lay down that much? If so, how much.

My idea was to copy that look, but instead of one large scoop, i'd have two smaller ones. I just wanted it to be differant. We have a member who has the "one big opening" in the club.

Thanks

Rob

[This message has been edited by qwikgta (edited 03-29-2011).]

I bought a Billet Specialties tank and mounted it to the fan shroud. My hood vent is so big I had to cut out the bulkhead and use remote reservoirs for the brake booster as well. You can see the overflow tank through the vent, I kinda like it like that. The tank was kind of expensive, but is nicely made from polished aluminum.

I'm pretty sure it's this one http://www.summitracing.com/parts/BSP-77113/

Edit for pics

[This message has been edited by SCCA FIERO (edited 03-29-2011).]

quote Originally posted by qwikgta: yea, but with the $$$ I spent on the LS3 and all the other mods, I don't want to go cheap on a overflow tank.

The Moroso aluminum overflow tanks are not cheap, neither in price nor build quality.

Only a couple of years before the fiero expansion tanks were not even a standard item. eg: my 86 model bmw 318i didn't have one standard. If you check the water regularly you could get away not even having one my pontiac doesnt even use water or get hot anymore since i installed a GM commodore/GTO fan. In the last 5 years after i first overheated and replaced my fan i have never topped up my coolant / water (but have flushed it 2x) I did overheat a lot with the stock fan and the relay was half the blame the other half was the fan itself. What i found is it spun and looked fast with stock fan butwhen i replaced it my hair would blow about when standing near the open hood and that never happened with the standard fan.

[This message has been edited by Australian (edited 03-30-2011).]

my trans am currently uses an old anti freeze bottle for its over flow etc...so...yeah...

quote Originally posted by qwikgta: Guru, that is the exact look im aiming for. Yes, please if you could, the measurements for: A: distance from the lip of the hood to the horizonal cut. B: the distance of the vertical cut in from the hood line, and C: lenght of the vertiacl cut. I had been using a measurement of: A= 9 1/2", B= 3 3/8" and C= 9" Also, how much of the hood did you cut before you laid it back (down). I want the same look, the only diff is that I plan to put some of the honey comb material over the cut so you don't "see" down into the opening. Also, did you have to cut your trunk front to get that to lay down that much? If so, how much. My idea was to copy that look, but instead of one large scoop, i'd have two smaller ones. I just wanted it to be differant. We have a member who has the "one big opening" in the club. Thanks Rob

Most of the dimensions and pictures are in the build thread here, but I did end up taking another 2" (or 1 1/2") off the bottom pressed down portion:
https://www.fiero.nl/forum/A...090907-2-084040.html

The front bulkhead seal surface remains stock

I bought a kit of 3 catchcans, they were pretty cheap (made) but good enough for the job. Used one as a coolant overflow tank,


I modified one of the supplied mounting strips and painted it, I was able to lower the tank for clearance to the hoodvent

quote Originally posted by Blacktree: The Moroso aluminum overflow tanks are not cheap, neither in price nor build quality.

No you misunderstood, I was talking "Cheap" for the plactic bottle ones. NOT the Moroso ones. I know they are not cheap.

Rob

I relocated mine to the engine compartment. (Actually bought a kit at the parts store. One of the "cheap" ones.)
It required a fill adapter in the thermostat hose. The fill adapter also has a hose barb for an overflow hose.
I put a 20 lb. cap on the radiator, and a 16(?) lb cap on the fill adapter.
The added benefits are that it's now at the highest point in the system, and it's never a bad idea to have a "full sized" fill point at the engine, anyway.

FWIW, Summit has fill adapters that will also adapt different diameters of hoses. Was very useful for my application.

Not really a good pic, but you get the idea.


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Raydar
88 4.9 Formula IMSA Fastback

Read Nealz Nuze! Praise the Lowered!

[This message has been edited by Raydar (edited 03-30-2011).]

quote Originally posted by qwikgta: Has anyone reloacted their tank? If so, what did you do/use and how did it work? Rob

I bought one several years back for #020 from Watson's Street works.

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"Friends don't let their friends drive stock."

quote Originally posted by Fie Ro: I bought a kit of 3 catchcans, they were pretty cheap (made) but good enough for the job. Used one as a coolant overflow tank, I modified one of the supplied mounting strips and painted it, I was able to lower the tank for clearance to the hoodvent

I have seen this style on Ebay, but I have a concern about the plastic/glass tube. Not sure I want to invite leaks and a possible weak spot (in case it takes a rock or something)
SCCA, Aus, Hockaday, Raydar, Madcurl, thanks for the input.

Rob

Raydar, question concerning your setup. Anyone chime in....

I like your idea, I guess I never concidered not having the catch up front. My question then is this..With my engine swap, I added a Grand am style fill bottle in the back. It is at the highest point and continuosly recirculates the coolant. Do I really even need the front bottle?

Bob

quote Originally posted by RCR: Raydar, question concerning your setup. Anyone chime in.... I like your idea, I guess I never concidered not having the catch up front. My question then is this..With my engine swap, I added a Grand am style fill bottle in the back. It is at the highest point and continuosly recirculates the coolant. Do I really even need the front bottle? Bob

I'm not sure what you mean by a Grand Am style fill bottle.

Is it under pressure?
You say the coolant circulates through it...
If it's under pressure, I'd still be inclined to have an overflow bottle of some sort.

I don't much care for the front location because if anything happens to the cooling system, it can allow half of the coolant to drain out onto the ground.
I had a situation with my 4.9 system where a bit of dirt got caught under the little flat valve on the bottom of the radiator cap. When I opened the flush attachment at the rear (my previous fill/burp location) it allowed the water to slowly leak out into the overflow bottle since it was lower than the fill point.
Of course, in a perfect world, there would have been no crud in my cooling system and it wouldn't have leaked.
Since the overflow is now at the back, nothing at all ever comes out of the front. By design or by accident.

OK, that makes sence..The overflow needs to be on the otherside of the pressure cap, so my rear fill tank won't work unless I have an additional outlet on the cap (which it doesn't). The "Grand Am style" tank I was refering to is similar to the Corvette tanks used on several Northstar swaps. I felt this one fit better and there are tons available. I'll post a pic later.

thanx...

Bob

edit for pic:

[This message has been edited by RCR (edited 04-01-2011).]

Thanks again for the reply's. I walked the yard the other day, looked at 100's of cars and found a few bottles that I thought would work, but in the end they were all too small or too big. And I could not find a good (best) place to put the damn thing other than the spot it is in. I was looking at moving it to under the passenger headlight in the dead space, but would need to cut a chunk of the sheetmetal out and fab up a bracket or two, similar to a few folks putting a battery there.

I guess i'll keep bumping this up until someone see's it and has a differant idea.

Rob

quote Originally posted by qwikgta: I guess i'll keep bumping this up until someone see's it and has a differant idea.

If you want to come over this way, this weekend, we can start stripping my 85, and look for better places to mount an overflow tank, without the body/headlights in the way. If you have any you'd like to try and use, we can see where they fit.

quote Originally posted by dobey: If you want to come over this way, this weekend, we can start stripping my 85, and look for better places to mount an overflow tank, without the body/headlights in the way. If you have any you'd like to try and use, we can see where they fit.

ooo, taking apart Fieros is fun. I just may have to help you. I'll chat with you later in the week.

Rob