Strange issues with my 87 turbos cooling system

TheBlueSupra

New Member
Nov 16, 2011
82
0
0
Idaho
Hey everybody, so I am having a few most likely related issues with the cooling system on my car.

First off is a regular exchange of coolant between my overflow and my radiator. One drive the radiator will be full and the overflow empty, the next and the radiator will be low and the overflow full. If I try to add coolant to them in either situation it simply burps back out and on to the road next time the car warms up.

Next issue is my temperature gauge seems to wander around randomly after the car warms up. It will go almost to the red and stay there for a minute or two then come back down. The car does not seem to show any normal symptoms of overheating in these situations, like boiling in the radiator, blowing coolant lines etc, and it will do it at both idle and normal driving.

Third issue is I only get intermittent heat when the car is warmed up, it will blow hot for a bit, then fade to cold, then eventually back to hot again. Typically it stays cold more than hot.

Things I have checked: I have checked for system leaves, and have not found any. I am not burning coolant or loosing any coolant beyond what it burps out when I top it off. My heater core des not leak. My vsv controlling the coolant to the heater core actuates correctly and is receiving appropriate vacuum. My fan clutch appears to be in working order. And all my temperature valves and sensors seem to be working.

Things that change prior to the issues: I replaced the coolant elbow at the back of the head and the elbow from the water pump to the rail on the exhaust side of the engine. I also replaced several cracked vacuum hoses on the intake, all routed correctly as per the tsrm. My charcoal canister intake hose crumbled to dust so I capped the vacuum line off the goes to it.

Any help is much appreciated, thanks!
 
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TheBlueSupra

New Member
Nov 16, 2011
82
0
0
Idaho
Have not replaced it yet, I would think a stuck thermostat would cause either a direct overheat if closed or a delayed warmup if open, thus I ruled it out as neither of these is the issue. Is there another way a thermostat could affect the cooling system?
 

super51fan

New Member
Jul 28, 2010
497
0
0
Indianapolis
Yes, running almost till red for a minute or two then be normal. It is a bi metal spring and it can start to fail just like you said before either stuck closed or open. Always start with basic wear items before going to complex thinking. Trying raising the front end of car and use spill free funnel to bleed cooling system. IMO good luck.
 

TheBlueSupra

New Member
Nov 16, 2011
82
0
0
Idaho
I will most likely change the thermostat, but why I feel it is not the issue is that it would fail one way or the other causing that specific issue on every drive. My car has no issues warming up and does not appear to have a true or consistent overheating issue, as it returns to normal temp on the gauge without any changes. As far as I understand the principles of a bimetallic valve, it will only fail open or closed, not somewhere randomly wandering in between.
 

RobbieRob

New Member
Jun 22, 2014
1
0
0
Dallas, Texas, United States
You likely have a small head gasket leak. The combustion pressure leaks into the water jacket, forcing the coolant into the overflow and leaving air in the system. The air in the cooling system causes your wandering temp gauge and intermittent heat.

This can be tested with a "head gasket test kit", which is a clear tube that mounts on the radiator neck and gets filled with a reactive liquid. If combustion gasses are in fact leaking into the cooling system, the liquid will change color.
 

TheBlueSupra

New Member
Nov 16, 2011
82
0
0
Idaho
RobbieRob;2029662 said:
You likely have a small head gasket leak. The combustion pressure leaks into the water jacket, forcing the coolant into the overflow and leaving air in the system. The air in the cooling system causes your wandering temp gauge and intermittent heat.

This can be tested with a "head gasket test kit", which is a clear tube that mounts on the radiator neck and gets filled with a reactive liquid. If combustion gasses are in fact leaking into the cooling system, the liquid will change color.

Will definitely see about testing this. I am planning on rebuilding the engine as it has 162000 miles on it, but if the headgasket is going then I will get my truck running again and park the car until I can.
 

KKZ SupraMan

New Member
Jun 2, 2013
163
0
0
ohio
Put the nose in the air on a big hill and let it run if it don't burp all air out you definitely got combustion to water best wishes to you there
 

Grandavi

Active Member
Sep 25, 2008
2,663
5
38
Calgary, Alberta, Canada
I wouldn't personally be running an engine I wanted to keep if you suspect a BHG. Simply because of the corrosive ability of the exhaust/cooalant mix. The test is pretty cheap (I bought the kit from amazon for 65.00) and can be used 100's of times really. If you like your block, find out if you have the issue first. Just my opinion.
 

mk3racer

New Member
Mar 5, 2009
19
2
3
Northern Virginia
^^^agree. It appears to be minor BHG, but test it to confirm. I picked up a lot from NAPA, but doesn't matter where you get it as long as you get it done. Then as others mentioned don't run it if it tests positive.


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