91 R32 GTR overheating

[Jjtxaz24]

What's going on guys? I have a 1991 GTR and just got it. Its currently overheating and when it does the oil temps get up there too.

I tried to search but didn't see the issue i was having. I have a theory on what it might be but I'm going to wait and chime in when you gurus reply.

Hint: thinking its the water pump because oil temp and coolant temp go up at the same time, meaning its not circulating as it should. Gets so hot it starts to boil.

[ToroGTS]

An overheat related to head gasket will usually occur within a couple minutes (or moments) of starting the car. The hot combustion gasses in this case are going directly into the water jacket, so bubbles or "boiling" in the radiator overflow tank will be immediate when the engine is started.

If your car heats up normally but then continues to heat up until it's over heating, I would first suspect the thermostat has stuck closed, secondly a total water pump failure (broken impeller or seized , very rare).

If your car seems to overheat just at the light and will cool a little once you start driving again, this is usually a failed radiator fan clutch, or failed electric rad fan (or fan control/water temp sensor), or possible a failing water pump.

Water pumps on RB's usually "fail" in the sense that they leak coolant where the silicone (no gasket) has failed, or the bearing behind pulley begins to seize or develop play. The OEM water pump has an alloy impeller and is fairly robust.

In your case, it's likely just a stuck thermostat.

[Jjtxaz24]

An overheat related to head gasket will usually occur within a couple minutes (or moments) of starting the car. The hot combustion gasses in this case are going directly into the water jacket, so bubbles or "boiling" in the radiator overflow tank will be immediate when the engine is started.

If your car heats up normally but then continues to heat up until it's over heating, I would first suspect the thermostat has stuck closed, secondly a total water pump failure (broken impeller or seized , very rare).

If your car seems to overheat just at the light and will cool a little once you start driving again, this is usually a failed radiator fan clutch, or failed electric rad fan (or fan control/water temp sensor), or possible a failing water pump.

Water pumps on RB's usually "fail" in the sense that they leak coolant where the silicone (no gasket) has failed, or the bearing behind pulley begins to seize or develop play. The OEM water pump has an alloy impeller and is fairly robust.

In your case, it's likely just a stuck thermostat.

Awesome. Gonna go around my parts store and grab a 300zx thermostat. I was reading those are direct fit for the R32s

I appreciate the help and hope this fixes it so I can get back.

another question. Do you think I need to do a full bleed out of the old fluid. I really don't wanna take off the turbo and order those gaskets because i had to remove the block drain plug.

[Jjtxaz24]

Appreciate the help guys.
Pulled out the thermostat and tested it. It appeared to be working, found a replacement at a parts store off a 95 300zx so minus well change that out since I was already in there.
Next up is the clutch fan. I remember spinning it but it didn't seem to put up much resistance, trying to find one locally (I'm located in Texas) I looked around and read a 1991 Pathfinder clutch fan works. Do we know if this is accurate?

[GTR-Dad]

Wouldn't hurt to bleed the coolant system before spending more time and money. If my memory is right, there's a bleed valve on a coolant line above the intake plenum. There's probably a DIY on how to do this, but I think I've had success by just cracking it loose immediately after a cold start. If any air bubbles come out just keep bleeding until they stop.
GL!

[Jjtxaz24]

Good news guys, I was able to locate a 1995 300zx thermostat. Although it is a bit shorter from the top the rest of it is identical to the stock nissan one.



When I pulled the old one out, it read Nissan on the top. So it may have never been changed, either way I needed a new one.

Cleaned up the clutch fan as well with some WD-40 on the little coil part and a wire brush. That gave it back some resistance when I spin it. Used this video as a reference:

https://youtu.be/9qSsKzS2_L0

Anywho, used the manual and refilled the coolant, and topped it off. Drove around for about 40 minutes with some spirited driving,*freeway, and put myself in some stop and go. Temp stayed at halfway and my oil temp was good too. Im pretty sure its fixed.

[Jjtxaz24]

Alright, update time.

Went out and bought a fan clutch for a 1991 Z32, it was the same as the one for the infiniti Q45. Flushed the system and replaced the coolant by undoing both upper and lower hose and removed the radiator and cleaned it out with water from the fill and it trickled all the way to the lower.

I used this to flush the coolant and refill it I did NOT remove the block drain plug. (See below)


I did notice that part of the refill procedure for the coolant there is a step that says to check the lower radiator hose to see if warm coolant is passing through. When my upper hose is warm, the coolant in the lower hose is not.

It also states for you to check the thermostat injection valve (step 7, on the service manual screen shot in the thread above). What is that? The thermostat?

I also check my grounding point cleaned it up and bolted it down. Voltage and flickering on the gauges is gone gauge reads at the 14 volt mark and the Alternator is new, pushing out the required volts.

Also, I went out and got some fresh oil in the car. Read up everywhere and saw it takes 4.5 quarts of oil but not to be afraid to use 5. I used 5, 10w30 full synthetic Mobile 1.

Drove the car around again, coolant temp is good half way but once my oil temp gets to the halfway mark that's when my coolant temp just starts climbing.

Waiting on payday, last thing I can think of that I haven't replaced is my radiator, after the radiator swap I'm out of options on what it is if that doesn't fix it.

Also, thinking the thermostat may have gone bad even though i literally replaced it about a week ago.

Any ideas...