Coolant leak - ZR-1 Net Registry Forums

Wigert · 03-15-2018

Hello everyone! I am new to the registry and own a 1990 zr1. I have several issues that need solving including a coolant leak, an oil leak and a very high oil consumption. But lets start with the coolant leak and i will start new threads on the other stuff when i get to those...

The coolant leak seems till be coming from the lowest part of the thermostat housing. I hope it is visible in the picture. I could not really see any coolant running from further up (even though it seems wet). I looked in the factory manual and there does not seem to be a seal in the housing? The bolt seems tight. Any suggestions om what to do would be much appreciated.IMG_20180314_205500.jpg

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Dynomite · 03-15-2018

http://www.jerrysgaskets.com/seal-co...at-90-95-11c1/

Thete are some tricks in removing thermostat.

Thermostats, Fans, Water Pump, and Radiators

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A26B · 03-15-2018

There is a seal around the thermostat flange, inside of the housing.

The lowest part of the thermostat housing is where the leak end up, but may be higher up. You will need to clean the housing & connections, then dry off.

There are 2 heater hose connections on top of the housing that could be leaking, as well as the hose clamp visible in your photo (Have you tried tightening the clamp?).

Once dry, you can try to wrap a narrow band of folded paper towel around the heater hose connections. If they become wet, then you know the leak is in that area.

Once you locate the leak, better help can be provided.

Wigert · 03-15-2018

Hey Dynomite!
Thanks for the reply. I did not realize that the seal that you referenced was also a seal for the housing. I thought that there would be an additional seal just between the mating surfaces. So replacing that seal should help with the leak? It does not seem to complicated to replace it.

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Dynomite · 03-15-2018

Quote:

Originally Posted by Wigert

Hey Dynomite!
Thanks for the reply. I did not realize that the seal that you referenced was also a seal for the housing. I thought that there would be an additional seal just between the mating surfaces. So replacing that seal should help with the leak? It does not seem to complicated to replace it.

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The complicated part is keeping the seal in place as you put the two thermostat housing halves back together as the thermostat wants to spring out just a bit. That is where the putty knife comes into play

Wigert · 03-15-2018

Thanks for the additional input A26B! The hose connected to the radiator seems also to be leaking slightly. I have already done the paper towel test and there was not so much coolant on the paper even though plenty of drops from the bottom of the housing. I will by some hoses from Jerry's gaskets as well.

I also tried tightening the clamp without success...

RussMcB · 03-15-2018

Call your local auto parts stores (chain) and borrow a Stant Cooling System Pressure Tester. It will show you exactly where your leak is. No guessing.

Wigert · 03-15-2018

Quote:

Originally Posted by RussMcB

Call your local auto parts stores (chain) and borrow a Stant Cooling System Pressure Tester. It will show you exactly where your leak is. No guessing.

Thanks for the tip! I will see if the local show has one of those.

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Ccmano · 03-15-2018

Quote:

Originally Posted by RussMcB

Call your local auto parts stores (chain) and borrow a Stant Cooling System Pressure Tester. It will show you exactly where your leak is. No guessing.

Good idea, but not sure they do that in Sweden.
H

RussMcB · 03-16-2018

Quote:

Originally Posted by Ccmano

Good idea, but not sure they do that in Sweden.
H

(forgive me if I've posted this before - I probably have...) I bought mine 20 years ago for < $100 and it has been a great investment. I use it often, and often lend it out. Sometimes you need to buy an adapter if your radiator cap isn't "regular ole American" (like my Miata). On my race car, whenever I've done stuff with the cooling system, I check if it holds pressure, It always tells me if something's not tight. It's great to find problems in the garage rather than away from home.

03-15-2018	#1
Wigert Join Date: Jan 2018 Location: Sweden Posts: 73	Coolant leak Hello everyone! I am new to the registry and own a 1990 zr1. I have several issues that need solving including a coolant leak, an oil leak and a very high oil consumption. But lets start with the coolant leak and i will start new threads on the other stuff when i get to those... The coolant leak seems till be coming from the lowest part of the thermostat housing. I hope it is visible in the picture. I could not really see any coolant running from further up (even though it seems wet). I looked in the factory manual and there does not seem to be a seal in the housing? The bolt seems tight. Any suggestions om what to do would be much appreciated.IMG_20180314_205500.jpg Skickat från min GEM-701L via Tapatalk

03-15-2018	#2
Dynomite Join Date: Aug 2009 Location: South Dakota/California Posts: 3,794	Coolant leak http://www.jerrysgaskets.com/seal-co...at-90-95-11c1/ Thete are some tricks in removing thermostat. Thermostats, Fans, Water Pump, and Radiators Sent from my iPhone using ZR-1 Net Registry __________________ Left Clickable links -Solutions- LT5 Modifications/Rebuild Tricks Low Mileage ZR-1 Restoration 1990 Corvette (L98) Modifications LT5 Eliminated Systems LT5 Added Systems LT5/ZR-1 Fluids 1995 LT5 SPECIFIC TOP END REBUILD TRICKS Last edited by Dynomite; 03-15-2018 at 03:26 PM.

03-15-2018	#3
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,385	Re: Coolant leak There is a seal around the thermostat flange, inside of the housing. The lowest part of the thermostat housing is where the leak end up, but may be higher up. You will need to clean the housing & connections, then dry off. There are 2 heater hose connections on top of the housing that could be leaking, as well as the hose clamp visible in your photo (Have you tried tightening the clamp?). Once dry, you can try to wrap a narrow band of folded paper towel around the heater hose connections. If they become wet, then you know the leak is in that area. Once you locate the leak, better help can be provided. __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1*, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed.

03-15-2018	#4
Wigert Join Date: Jan 2018 Location: Sweden Posts: 73	Re: Coolant leak Hey Dynomite! Thanks for the reply. I did not realize that the seal that you referenced was also a seal for the housing. I thought that there would be an additional seal just between the mating surfaces. So replacing that seal should help with the leak? It does not seem to complicated to replace it. Skickat från min GEM-701L via Tapatalk

03-15-2018	#6
Wigert Join Date: Jan 2018 Location: Sweden Posts: 73	Re: Coolant leak Thanks for the additional input A26B! The hose connected to the radiator seems also to be leaking slightly. I have already done the paper towel test and there was not so much coolant on the paper even though plenty of drops from the bottom of the housing. I will by some hoses from Jerry's gaskets as well. I also tried tightening the clamp without success... Last edited by Wigert; 03-15-2018 at 03:34 PM.

03-15-2018	#7
RussMcB Join Date: Jan 2015 Location: Marietta, GA USA Posts: 1,160	Re: Coolant leak Call your local auto parts stores (chain) and borrow a Stant Cooling System Pressure Tester. It will show you exactly where your leak is. No guessing.