Mystery Leak from Block. Freeze Plugs??? (Page 1/1)
sultan86GT MAY 04, 11:08 PM
Recently I left my mostly-stock 86 gt running to recharge the battery (stupidly) unattended, and a small coolant leak I forgot about over the winter meant most of the coolant was spewing out under the hood causing a major overheating situation. I fortunately seem to have caught it just in time to avoid severe engine damage on the sub-30k mile engine.

However, coolant is absolutely pouring from somewhere on the passenger side of the block. Doesnt seem to be coming directly from the water pump but I could be wrong. Any ideas on how to figure this out? I heard that freeze plugs can be blown out by overheating and thought that might be possible, but I cant find any diagrams with their locations to start looking.

Thanks for reading!
Patrick MAY 04, 11:26 PM

quote
Originally posted by sultan86GT:

However, coolant is absolutely pouring from somewhere on the passenger side of the block. Doesnt seem to be coming directly from the water pump but I could be wrong.



I had a similar problem ten years ago, trying to find where the leak was... Where the heck is this coolant leaking from?


quote
Originally posted by Patrick Here:

Okay, I got a bunch of stuff out of the way (including the water pump pulley) so I could see better, and by using a mirror from the top I can see moisture that has come out the weep hole. I'm quite surprised that this didn't result in the backside of the pulley getting wet, but it appeared to stay dry which threw me off the trail. Coolant came out of the weep hole, ran along the underside of the impeller hub towards the timing cover, and then ran straight down behind the harmonic balancer and out at the bottom.



Not saying that this is necessarily where your leak is located, but make sure to look.
1985 Fiero GT MAY 05, 08:02 AM
I don't know where the factory block heater is on the engine, but if you is equipped with that, trace the wire and see if that fell out, my dad's 89 Cutlass Ciera has the retaining mechanism for the block heater (similar to a drywall anchor) rot away, so it just fell out 20 minutes from home (thankfully it was -40 out, and by taking it easy we had a successful air cooled engine haha) that will give you a very big leak, and can be hard to spot (I've been under my Fiero hundreds of times and still don't know where the block heater plug goes to)
Jason88Notchie MAY 05, 11:36 AM

quote
Originally posted by 1985 Fiero GT:

I don't know where the factory block heater is on the engine, but if you is equipped with that, trace the wire and see if that fell out, my dad's 89 Cutlass Ciera has the retaining mechanism for the block heater (similar to a drywall anchor) rot away, so it just fell out 20 minutes from home (thankfully it was -40 out, and by taking it easy we had a successful air cooled engine haha) that will give you a very big leak, and can be hard to spot (I've been under my Fiero hundreds of times and still don't know where the block heater plug goes to)



I don't believe Fieros came with block heaters. You may have some aftermarket thing installed?
Jason88Notchie MAY 05, 11:41 AM
Check t-stat housing base. Coolant coming from there due to failed gasket?
1985 Fiero GT MAY 05, 12:18 PM

quote
Originally posted by Jason88Notchie:


I don't believe Fieros came with block heaters. You may have some aftermarket thing installed?



It was an option, very rare down in the warm US, more common up here in frozen Canada haha, as far as I know, every gm car from the era could be optioned with a block heater, option code KO5 is the Fiero block heater option.
sultan86GT MAY 05, 06:40 PM
UPDATE:

I filled up the coolant again today to try to find the leak, and the strangest thing happened: it didnt leak! I started the car up and there was no/minimal dripping from the original spot. After turning the car off though, coolant suddenly seemed to drain from the original location very rapidly.

Has anyone ever seen a similar situation or have any idea whats going on here? Im totally stumped
Patrick MAY 05, 06:48 PM

That's normal behavior with a coolant leak. When the coolant heats up, there's more pressure in the system, and this pressure then forces the coolant through the opening.

In regards to that second (unnecessary) thread you started, you can't delete it. Only Cliff Pennock can do so.
82-T/A [At Work] MAY 05, 07:00 PM

quote
Originally posted by 1985 Fiero GT:

It was an option, very rare down in the warm US, more common up here in frozen Canada haha, as far as I know, every gm car from the era could be optioned with a block heater, option code KO5 is the Fiero block heater option.



My 1984 Fiero 2m4 SE had one down here in South Florida... but it's because the lady I bought it from came from Michigan and moved to SoFla. I only discovered it had it because I was poking around the trunk area and found a long "extension cord" that only had one end. I followed it along to where it literally just plugged into the block, and I put two and two together and assumed it was some kind of heating element for when the car is cold. Haha...
theogre MAY 06, 12:39 PM
Yes, sometimes coolant & other leaks are intermittent. Yes is a huge pain in the ass & leak worse again w/o warning.
Some times heat, pressure or both changes causing a leak then not.
Other times the leaking part "seals" for a while as dirt etc plugs a small leak.

You can get a pressure tester from loaner tools @ AZ etc but need adapter in https://www.fiero.nl/forum/Forum2/HTML/145505.html Coolant Pressure Testing for Fiero.

Or if buying a test kit maybe see https://www.fiero.nl/forum/Forum2/HTML/147652.html but hasn't say works or not as of this post.

------------------
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