Thermostat Replacement

[JBC]

In the process of replacing a thermostat on an 1983 NA. I have been having issues with the temp going to the third line while stationary. The old thermostat looks like an aftermarket non branded unit. I have the Whaler 83 degree thermo from Pelican. The old one had the correct steel washer and the larger rubber gasket. So, it was installed correctly. The new Whaler seems to have a firmer spring action. The old thermo was easy to depress. Any thoughts? No temperature ratings on the old thermo. The new one is labeled 83 degrees.

[M. Murphy]

Are you sure it's the thermostat causing the rise in temp? Are the cooling fans coming on? If not, it's not that bad of a job changing just remove the fan assembly.

[Bradical]

I had this same problem- the new thermostat was much firmer than the old, just as you describe. I did the replacement and it did nothing to improve my temp. Turns out I had an almost undetectable leak around my water pump shaft seal. I replaced the pump and now it never leaves the center of the gauge.

If you really think think its the thermostat, change it out and add a bottle of water-wetter once you have the coolant system bled and see were that gets you before getting too crazy.

The third line should be 200degF I believe, a little warm

[M. Murphy]

Sorry, in my previous response I meant to mention the thermo switch in the radiator. In my 83 that switch failing caused just about the same issue except mine kept going up in temp.

[nynor]

i had this issue with my '83. turned out that one of the fans wouldn't turn and it would blow the fuse. check your fuses, too.

[JBC]

All,
Thanks for the posts. The new Whaler thermostat did not change a thing. I put the old thermostat into the hot water test. The old thermostat started to open at 160 degrees F or 71 degrees C. It was fully open at around 198 degrees F or 92 degrees C. So, the old thermostat was fine.

When stationary in my driveway, I did notice that my fans only engage at 102 degrees C. I never see one fan engage. Only two simultaneously at 102 degrees C. Shouldn't I see one fan engage first? If yes, what temperature should the one fan engage? The only time I have seen one fan engage is after shutdown and then one fan will run for a minute or less and then shut down. Is this a symptom of a bad Thermoswitch on the radiator? Additionally, at highway speeds when I get on the RPMs, the temp gauge just sticks right to the third line. So, even with good airflow, I stay at the third line.

I will also see if the local auto parts store has a heat sensor. I need to see the real measured temperature as the car seems to run just fine with good power, etc.

As far as fuses are concerned, I only have one issue, the overhead light between the sun visors and radio fuse always blows when the overhead light is installed. I think the contacts on the top of the light might be touching the metal roof and blowing the fuse. I have a new light on order as the current light will not stay in place. The side opposite the switch on the overhead light has lost its fitting to hold the light in place.

[JBC]

Originally Posted by Bradical

I had this same problem- the new thermostat was much firmer than the old, just as you describe. I did the replacement and it did nothing to improve my temp. Turns out I had an almost undetectable leak around my water pump shaft seal. I replaced the pump and now it never leaves the center of the gauge.

If you really think think its the thermostat, change it out and add a bottle of water-wetter once you have the coolant system bled and see were that gets you before getting too crazy.

The third line should be 200degF I believe, a little warm

I am starting to suspect the pump also. However, I might replace the Temp gauge sensor first as I have had a jumpy gauge in the past.

[M. Murphy]

The temp on the thermostat and the thermo switch should be the same. How long since the cooling system has been flushed? If there is a build up of aluminum oxide sludge somewhere in the system it could result in these symptoms. Happened to me years ago with a GTI.

[JBC]

Originally Posted by M. Murphy

The temp on the thermostat and the thermo switch should be the same. How long since the cooling system has been flushed? If there is a build up of aluminum oxide sludge somewhere in the system it could result in these symptoms. Happened to me years ago with a GTI.

Murphy, the thermo fan switch reads 92 - 102 C. The Whaler thermostat has an 83 degree stamped on it. I assume that means 83 degrees C. So, operation would cause the thermostat to start to open at 83 degrees C and coolant to flow through the radiator at this time. at 92 degrees C, the fans get in. I only see both fans kick in at 102 degrees C. I do not see a fan kick in at 92 degrees. So, maybe the thermo fan switch is toast. The part that bothers me is that at speed, I do not see the temp drop back to the middle of the gauge. Like most issues, I may have multiple pieces to the system either bad or starting to go bad and giving me these symptoms.

I drained and refilled the system yesterday but I did not do a flush. The fluid actually looked clean and good. The heater core looks good and the heater works efficiently and well. Nonetheless, because of what I am experiencing, I will now fully flush and electrically check all switches, sensors and gauges now.

If I do have to replace the water pump, any recommendations on which one to use? Pelican has the GEBA at a significantly higher cost. I think they are $532 or something and the rebuilds are $238 or somthing. Are the rebuilds as good or acceptable?

[JBC]

All,

Just did some reading from other post and I think I might have improved my understanding of the coolant system operation.

Thanks to Rasta Monsta, he explained that the thermo switch only turns on the single fan when the ignition switch is in the off position. This is exactly how my 83 works. I only see the two fan operation with the engine running and this is how it is to work. However, the fans should kick in at 92 degrees and my 83 is hit or miss on this one. My fans kick in at 102 degrees almost 90% of the time. I think I have seen them kick in once or twice at 92 degrees. So, I'm going to replace that thermo fan switch on the radiator next. I still think I could have a pump issue due to not seeing good temps while moving down the highway.

[v2rocket_aka944]

I have both low-temp fan switch and low-temp thermostat, a result of overheating years past, and combined with my monster Volvo fan never ever get over the first hash mark if it's under 100 degrees outside.

I would suspect your fan switch.

[JBC]

I just went for another drive and the temperature gauge reached the third line and the fan came on but the lower radiator hose was cool near the bottom of the radiator. I just put in a brand new thermostat. I need to remove it and test it. Plus, could the pump be bad?

[JonA]

Does your heater work? Maybe not all air out of system after you replaced the t-stat.
My expeience is that thermostats are fairly reliable and pumps fail by leaking but seldom lose the ability to circulate the liquid. the impeller in most is metal and not does not often fail.
Older radiators will remove less and less heat as they slowly plug up inside and out. Also, the fins corrode and fall off resulting in loss of surface area. I would be taking a hard look at the radiator

Jon

[nynor]

not to be insulting, but did you install the thermostat oriented properly?

is there still air in the system?

do you get heat inside the car?

[JBC]

nynor, no worries. Actually, it is a good question. I am sure I did, but, it if my Temperature Gauge (Combination gauge to be exact) and Temperature Gauge Sensor check out good, then I will go back and confirm. What I remember is looking closely at the Whaler and orienting it correctly but when I laid down under the car to install, I could have created my own "helmet fire" and installed it wrong.

Today, I started to check all my grounding points. Even if they looked great (and all did), I removed, wire brushed, put on conductive grease and tightened back down. Still have the under dash and an inside firewalls to do and could not get to the top of the bell housing ground. Need to think about pulling stuff out of the way to get that one done. But again, it looks clean but that might not be the true story, so, I need to clean it.

I did another short test drive today with the outside air temperature at 34 degrees F. I have a 92 to 87 degree C radiator temp switch (strange that it is labeled that way and not 87 to 92 but anyway...) and an 83 degree C Whaler thermostat. The car comes up to temperature nicely. The car feels and sounds like it is running great. When the temp reached the middle mark I stopped at a gas station. I sat at idle and rev'd the engine until the temp gauge reached the 3rd line. I opened up the hood and checked the engine. The Thermostat had just opened and the radiator was starting to warm up. I deduced this by the lower radiator hose starting to warm up and the radiator starting to warm up. Also, I think I can hear the pump turning. So, I don't think I have a bad water pump. So, the car is behaving like the Temperature Gauge should be between the 1st line (80 degrees C) and the middle line (89 degrees C) as the thermostat opened but the fans did not kick in. I know the fans work as they do kick in when the outside air temp is hotter. So, I don't think the radiator reached 87 degrees.

For the fans, when they come on, it is always two simultaneously. The only time one fan comes on is when I turn off the ignition. I read on one thread that for Early cars this is the correct operation. For Late cars, you should have one fan and then two. I need to read up on the factory manuals but the thread also noted that the manual are not clear. If anyone can confirm this operation, that would be great.

JBC

[JBC]

Originally Posted by nynor

not to be insulting, but did you install the thermostat oriented properly?

is there still air in the system?

do you get heat inside the car?

I think I have done a good job of bleeding the coolant system.
I do have good heat in the car.

[nynor]

then it may be as simple as a bad temp sender. i've had it happen before on two other vehicles.

[M. Murphy]

I'm sure you probably already know this but drilling a small 1.5-2 mm hole through the thermostat helps greatly in burping the cooling system. It sure helped me. Make sure to de burr the hole.

[JonA]

Does turning on the heat full blast bring down the temp to the proper range or closer to it (let it run for a few minutes to stabilize)? If so the radiator may be too old and too comprimised to dissipate the heat produced. Try this before you start throwing parts at it.

Jon

[Rasta Monsta]

Yep, the aging wiring and especially grounds in your car aren't doing the gauge accuracy any favors. I would shoot the thermostat housing, upper radiator tank, and cylinder head with a laser pyrometer before you cause yourself too much stress.

Also, if while stationary, the temp rises to mark 3, then fans come on and pull it down to mark two, this is normal operation. Drive and enjoy.