Heat & Fan issues for my 95 164LS

1672 Views 10 Replies 7 Participants Last post by Mistalava, Aug 18, 2007

Renaldo

Discussion Starter · Aug 16, 2007

I've done a search through the threads here on the 164/168 and haven't found exactly what I want to address here.

A couple of things going on here. First my fan doesn't come on till my temp gage reads around 220 - 225. Mechanics have said that the gage is off by 20 degrees...when gage in cabin reads 220, a temp reading at the radiator (via laser temp gauge) reports back ~200 degrees. Ummmm, well I'd like to believe this is true, but then why when I'm running the car on the freeway in 80 degree weather at 70-75 mph, or on a main arterial @ 40-45 mph w/out stop n go traffic, the cabin gage is reading 195-200, which would seem like what the normal operating temperature should be. If the 20 degree thing is true, then the car, at normal highway or road speeds is running @ 175 degrees. Could that possibly be true??? For a while I had the fan jumpered to remain constantly on when the ignition is hot. Under those conditions the temp gage always read around the 195 mark, straight up @ noon.

Secondly, the thermo switch has been tested...I've had it out of the car and put in the pot of water, and found continuity on the pins around the 200 degree mark +/- 5-10 degrees. Radiator fluid is @ fresh 50/50 concentrate.

I removed the fan jumper, and had the system checked. I'm being told that it is running correctly, even though interior gage is showing 225 -235 in any stop and go situation. It is literally freaking me out! I pop the hood, and while it's hot in the engine bay, it doesn't appear to be extremely so. I don't hear the ping, ping of expanding/contracting metal. No evidence of steam or bubbling radiator fluid anywhere.

So I guess perhaps the physical measurements taken with the laser tool might hold true. At the same time I'd like to have my temp gage be more reflective of the actual temperature...seeing the gage go that high, really grabs my attention and makes me tense. I find it hard to snooze at the wheel, along with the rest of my fellow drivers on the road. Does anyone else have this discrepancy between actual and reported temps? I've also been told that the 24Vs, especially the 95's run hotter for better emissions.

I'd hate to install a manual fan switch for peace of mind, but baring some sort of sage advice here on the BB, that might be my only other choice.

PS The thermostat was changed out at 5K-7K ago, with the water pump when belts were done.

Thanks for any advice on this.

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andrewg

· #2 · Aug 16, 2007

I have a 12V, so here is what I have from my experience. Living in Houston is it hot for much longer period of the year and we almost always run with the AC on. The car under normal driving conditions regardless of out side temp runs at 200 plus or minus the width of the needle. With the hot days in Houston, if I run into normal rush hour traffic the needle moves to the 225 mark. With really bad traffic ( happens a lot in Houston ) the needle with floats between the 225 and half the distance to 250 mark ( around 238-240 ). I have noticed that when the outside temp is 90 or less, the temp does not move as much in traffic.

This makes me nervous as the GTV6/Milano's I have had in the past would be going super nova at this point. I run a lower temp fan switch with the low speed resistor bypassed during the summer months. The fan works properly, the 164 just runs at these hotter temps for emissions purposes. The 164 has never overheated or even puked coolant out at these temps. Even at these high temps the overheat has not come on.

At the AROC time trials, I noticed after 3'ish laps temp would climb to the same 238-240 mark and stay there, even after running 3 or 4 more laps.

The water pump is new, thermostat is new, low temp fan switch is new and everything works according to the book. 50/50 mix of distilled water and antifreeze with a bottle of redline water wetter.

Since we are almost finished with the heat of summer this year, I will wait till next spring to improve upon this situation - for peace of mind. I will most likely replace the radiator as it is the original one that came with the car.

Your temp experience seems very similar to mine, so I do not think you really have a problem.

Maybe Jason will have some feedback.

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gt601

· #3 · Aug 16, 2007

I switched the sensor in the radiator to a VW sensor. It turns the fan on at a lower temp. I can't remember what the part # is but a good parts place should be able to tell you. The VW sensor comes in several temp ranges. I would try a late 80's golf/rabbit rad sensor. I think that is the model I picked mine from. It is 3 wire.

Paul

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Alfisto Steve

· #4 · Aug 16, 2007 (Edited)

First off on your 95LS it should have the OEM radiator thermal switch with the long wire connector with 3 wires as switch is mounted in right side tank of radiator above lower return hose.

Does low speed fan come on after A/C switch on for a bit when freon pressure builds up to about 215 psi? If not have you tested/checked low speed resister in upper corner of radiator cooling fan shroud near air cleaner?
This resister used for both A/C pressure switch and low side of radiator switch.

Did you test both low and high contacts in thermal switch?

I believe in manual override toggle switch inside car for that stop and go traffic and those hot days to help a/c condensor do a better job. I have it wired to energize high speed relay but we wired both my son's L and S models with two position switch so he can run either low or high speed fan. He has VW three wire lower temp switches installed in radiators too.

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Renaldo

Discussion Starter · #5 · Aug 16, 2007

Yes, my car has the OEM 3-wire sensor. When I went to test the pins, the water temp kinda shot past the low point to the high point, so I wasn't really able to test the low temp activation, but when the water was near boiling (with air bubbles forming on bottom of pan) I found continuity on all the prongs....which wasn't there at the lower temps. Car Disc chapter wasn't clear on what prongs are which so I was moving my multimeter around till I found continuity, and then tested the other lead and found it there too. I assumed all pins are activated at the high temp...couldn't catch the senor at the lower setting which is only like 8-12 degrees lower for activation I believe.

On the way home from work this a.m. I'll give the A/C a try. Living here in Seattle, turning the A/C on to troubleshoot something is like the farthest thing from our minds. Good thing I have a ready supply of flanel to don. May have to change out of the Birkenstocks and put the Doc Martins on....

Will let you know the results of that.....

Ciao for now,

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goats

· #6 · Aug 16, 2007

gauge reading

Ron if you search back on this you will find (somewhere) I described the same thing yuo are seeing. I instrumented the car with KJ thermocouples and found that the interior guage would run 195 while the mean temperature in the hot spots that were accessible (top of thermostat housing, top of radiator, etc) all measured about 20 C cooler. I installed a ?27 ? ohm resistor in series with the gage sender and all is now well. Remember that the 94's gauge dial had about a 20C difference in position compared to the 95 dial (in other words, 12 o clock on the dial was about 20 hotter on the 94 was about 20 hotter than 12 o clock on the 95). I wonder if the resistor in the instrument panel was every changed to compensate for the different gauge....

Also check your overflow cap and make sure it is still holding pressure.

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Alfissimo Int.

· #7 · Aug 16, 2007 (Edited)

YES!!!!! This is true.
I temped mine yesterday as a matter of fact.

When The temp gauge read 220˚F the actual temp was 180˚F In-fact it was 179˚F
THATS 40˚F OFF!!!!!!!!

100 Ohm resistor in line on the temp sender usually fixes the problem.

I also went by the fan just to verify! At 180˚F (using my low temp fan switch 180/190, german made switch

)
Slow speed was on at 180 like clockwork. When temp was around 230˚F+ the high speed finally came on, ran for a bit and went off.

No signs of over heating!!! I am running an aluminum radiator as well so i know I am not close to those temps even with an Ambient temp of 108˚F and 15% humidity!
I am running around 190-195˚F but I have alumin. Rad. I ran 220 with OEM.

Not to worry!

Now with OEM radiator, same thing, ran a bit hotter but not much. Make sure you fan is running in slow with A/C, and high when it needs. No splicing or any of that. Keep it stock. The only way to run it, really!

As far as coolant. 60/40 is fine. I run mostly water and about 20% anti-freeze in the summer.
I can run 50/50 now with the new rad. got run but will finish when I get back.

Jason

Renaldo said:
I've done a search through the threads here on the 164/168 and haven't found exactly what I want to address here.

A couple of things going on here. First my fan doesn't come on till my temp gage reads around 220 - 225. Mechanics have said that the gage is off by 20 degrees...when gage in cabin reads 220, a temp reading at the radiator (via laser temp gauge) reports back ~200 degrees. Ummmm, well I'd like to believe this is true, but then why when I'm running the car on the freeway in 80 degree weather at 70-75 mph, or on a main arterial @ 40-45 mph w/out stop n go traffic, the cabin gage is reading 195-200, which would seem like what the normal operating temperature should be. If the 20 degree thing is true, then the car, at normal highway or road speeds is running @ 175 degrees. Could that possibly be true??? For a while I had the fan jumpered to remain constantly on when the ignition is hot. Under those conditions the temp gage always read around the 195 mark, straight up @ noon.

Secondly, the thermo switch has been tested...I've had it out of the car and put in the pot of water, and found continuity on the pins around the 200 degree mark +/- 5-10 degrees. Radiator fluid is @ fresh 50/50 concentrate.

I removed the fan jumper, and had the system checked. I'm being told that it is running correctly, even though interior gage is showing 225 -235 in any stop and go situation. It is literally freaking me out! I pop the hood, and while it's hot in the engine bay, it doesn't appear to be extremely so. I don't hear the ping, ping of expanding/contracting metal. No evidence of steam or bubbling radiator fluid anywhere.

So I guess perhaps the physical measurements taken with the laser tool might hold true. At the same time I'd like to have my temp gage be more reflective of the actual temperature...seeing the gage go that high, really grabs my attention and makes me tense. I find it hard to snooze at the wheel, along with the rest of my fellow drivers on the road. Does anyone else have this discrepancy between actual and reported temps? I've also been told that the 24Vs, especially the 95's run hotter for better emissions.

I'd hate to install a manual fan switch for peace of mind, but baring some sort of sage advice here on the BB, that might be my only other choice.

PS The thermostat was changed out at 5K-7K ago, with the water pump when belts were done.

Thanks for any advice on this.

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Alfisto Steve

· #8 · Aug 16, 2007

Renaldo said:
Yes, my car has the OEM 3-wire sensor. When I went to test the pins, the water temp kinda shot past the low point to the high point, so I wasn't really able to test the low temp activation, but when the water was near boiling (with air bubbles forming on bottom of pan) I found continuity on all the prongs....which wasn't there at the lower temps. Car Disc chapter wasn't clear on what prongs are which so I was moving my multimeter around till I found continuity, and then tested the other lead and found it there too. I assumed all pins are activated at the high temp...couldn't catch the senor at the lower setting which is only like 8-12 degrees lower for activation I believe.

On the way home from work this a.m. I'll give the A/C a try. Living here in Seattle, turning the A/C on to troubleshoot something is like the farthest thing from our minds. Good thing I have a ready supply of flanel to don. May have to change out of the Birkenstocks and put the Doc Martins on....

Will let you know the results of that.....

Ciao for now,

Poor baby, to cold for a/c! Never to cold for a/c even in the winter just adjust temp level.

As for thermal switch wire colors and purpose. On 12v black is ground, white is low temp/speed switch and red is high speed switch. Pretty sure 24v the same colors. red goes to brown-white wire for high speed relay and red goes to brown wire for low speed relay activation.

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Renaldo

Discussion Starter · #9 · Aug 17, 2007 (Edited)

So I do have the fan come on when I activate the A/C. I like the idea of getting the ****pit gage in synch with the real temperature in the engine bay so I will seriously consider putting an inline resistor in the gage wiring. The cap on the overflow tank is good...it hold pressure.

Goats, how did you determin the 27 ohm value? Trial and error or ????

Down the line I will consider going the aluminum radiator route, along with the A/C condenser. First Jason, I need to get that combo for the Verde beast under construction with JJ. Mid August here, and the "hot" weather (everything is relative) is almost over for the moss&mildew crowd up here.

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goats

· #10 · Aug 17, 2007

How did I know?

IIRC--Looked at the temp /resistance curve in the manual, measured my resistance at temp and compared to the manual graph, subtracted graph from mine and got 25-30 ohms (not an exact science by any means), had a 27 ohmer (1/4 watt) in my stash (I restore and modify tube stereo gear as another hobby) and put er in. Instrumented again and its pretty much spot on.

Back when I posted this, someone thought that perhaps the guage was really reading internal engine temp== in other words, did the engineers bias the actual thermostat housing/guage reading high to more truly reflect the internal engine temp? I don't know! Caveat Emptor!

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Mistalava

· #11 · Aug 18, 2007

Jeez Goats..

I thought I was the only one here obsessed with 300B's, EL34's, 12AX7's, 6922's and NOS Amperex, Mullard and the like. I think Alfas, tube gear & vinyl, automatic watches and hot women all go together.

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