Question on radiator thermostat

[bikemikey]

When I first bought my 89 Reatta, I noticed that the temperature gauge would hit at around 233 degrees at a stop light, in this hot Texas summer heat. From what I understand the radiator fans don't kick in until they reach that temperature of 233 degrees. I've also heard that at that temperature it is of no way in danger of hurting the engine, it would have to go a lot higher than that to cause harm. Since then I changed out the water pump and did a flush and also a new thermostat. I noticed yesterday the gauge hit around 228 at a stop light, it was about 90 degrees outside. I understand some of you have installed a 180 degree thermostat, I was thinking about doing that myself. I went to Autozone today and they only showed a 195 degree thermostat for this car. He also told me that even though my fans might work, they might not be running at their full capacity because of a weak relay or worn out fan motors, but I don't think that's the case. I was wondering where some of you have bought the 180 degree for the 3.8 , or should I not worry about it. I get a little worried when I see those high temps. Thanks,

Mike

[Guest Corvanti]

here's a 180 thermo: http://thereattastore.com/stant-13848-thermostat-180-degrees-fahrenheit/

i've found that the 180F thermo helps mainly in stop & go traffic. also a coolant flush & fill should be done if it hasn't in the last couple of years - or if you don't know when a P.O. did so.

about the fans, you might want to use the "search forum" feature to find where some of the folks have lowered the temp the fan(s) come on. i never found it necessary.

[Ronnie]

Changing to a 180* thermostat will keep the engine cooler as long as you're moving so there is some airflow through the radiator but it won't make much difference sitting still in traffic on a hot day. The thermostat only controls minimum operating temperature of the engine... NOT the maximum temperature. The fans have to be reprogrammed to come on at a lower temperature if you want to control the maximum temperature the engine will get at a stop light. I doubt your problem is a weak relay or worn fan motors if they are coming on.

Edited April 27, 2015 by Ronnie (see edit history)

[Guest Corvanti]

Ronnie & bikemikey. the main reason the 180F helps is when you are "going", the 195F will start to close when the coolant temp gets below 195F. when stopped this additional 15F will help keep the temp down. driving my Reatta was usually in city stop & go traffic. while going, the coolant temp would normally go to the upper 170's, and stopped would rarely go up into the low 200's.

i actually put 160F thermostats in my '63 Avanti and '80 Corvette. but they didn't have any electronics that may need a little higher temp to perform correctly. (i think the 170's).

i'd certainly make sure the fans were working as they should, have new coolant, a clean radiatorwith good air flow and cooling system (no rust, etc.) and the water pump was working properly before going to the thermostat. in mine, the thermo was gunked up with rust - thus the change to 180 - from prior experience and others here on the forum going to one in warm weather climates.

[redreattaruss]

When I first bought my 89 Reatta, I noticed that the temperature gauge would hit at around 233 degrees at a stop light, in this hot Texas summer heat. From what I understand the radiator fans don't kick in until they reach that temperature of 233 degrees. I've also heard that at that temperature it is of no way in danger of hurting the engine, it would have to go a lot higher than that to cause harm. Since then I changed out the water pump and did a flush and also a new thermostat. I noticed yesterday the gauge hit around 228 at a stop light, it was about 90 degrees outside. I understand some of you have installed a 180 degree thermostat, I was thinking about doing that myself. I went to Autozone today and they only showed a 195 degree thermostat for this car. He also told me that even though my fans might work, they might not be running at their full capacity because of a weak relay or worn out fan motors, but I don't think that's the case. I was wondering where some of you have bought the 180 degree for the 3.8 , or should I not worry about it. I get a little worried when I see those high temps. Thanks,

Mike

Seems that the first fan should come on at 210 degrees, which will lower the temperature. So, that should never let the temperature rise to 233 degrees. Or, run the AC, which will run at least one fan and cool down those high temperatures.

The fans can be turned on from the dash screen by entering the BCM test. It should be easy to hear the fans running with the engine off.

I have had the same problem with my Corsica. 195 degree thermostat and an electric fan that doesn't turn on until 228 degrees. The OBD1 scanner does show the fan going on at 228 degrees and off at 208 degrees. Car overheated in stopped traffic because the radiator cap wouldn't hold pressure, so coolant boiled out at 212 degrees, well below the 228 degree fan on temperature. A real great design General Motors.

I replaced the radiator cap and replaced the new 195 degree thermostat with a 180 degree. This gives another 15 degrees leeway before the fan turns on. I may remove the memcal from the ECM and have it programmed for $60 to turn on the fan at a more reasonable 195 degrees, like an automotive cooling system should be.

Now, I don't think I'm smarter than all the enginerers at GM that design the cars. But a 195 degree thermostat should regulate the cooling system temperature to...195 degrees. Turning on the fan at 228 is stupid, stupid, stupid.

And that's my experience with GM FWD cars with electric fans. Gimme a rear drive car with a mechanical cooling fan attached to the water pump any day.

[Ronnie]

I guess I misunderstood the original post. I was replying to him saying: "I noticed yesterday the gauge hit around 228 at a stop light". I don't think changing from a 195 to a 180 is going to help that.

[bikemikey]

I might be wrong about the fans coming on at 233 degrees, I thought I read that from a past thread. I think what I will do, is check the BCM to make sure the fans are working. I'll also install a 180 thermostat to see if that helps out. if not, I'll probably have to change the temperature settings on the fans. The car usually runs about 214 degrees when the outside temp is under 85, no problems. It's just this hot Texas heat which is around the corner.

Thanks everyone for your replies.

[bikemikey]

I guess I misunderstood the original post. I was replying to him saying: "I noticed yesterday the gauge hit around 228 at a stop light". I don't think changing from a 195 to a 180 is going to help that.

Ronnie, I just saw your post after I just posted mine. Yes, it does get up to 228 at a stop light, but once I get moving it starts going down.

[redreattaruss]

Ronnie, I just saw your post after I just posted mine. Yes, it does get up to 228 at a stop light, but once I get moving it starts going down.

Yes, once moving at 40 MPH, the temperature should settle around 195 degrees. But if you're in stop and go traffic, the sky's the limit until the fan goes on. Best to turn on the AC if in traffic. The cool air feels good, too.

[Barney Eaton]

Padgett has done considerable work on understanding the cooling system and fans. Hopefully he will jump in and share his wisdom.

I will share what I know and all that is in the service manual. The fans are controlled by the Engine Control Module (ECM) which gets input from several sources.

Neither fan works until the engine warms to a predetermined temp (Padgett has these temp memorized)

This help the engine get to operating temp quickly. Then the puller fan kicks in.

The front (pusher) fan kicks in as the temp gets sligthtly above the temp of the thermostat.... so the pusher seldom is on when you are running down the road with air being forced thru the radiator. The second condition that turns on the pusher is turning on the A/C.

At this point both the pusher and puller are running (lets say around 210 degrees F) however they are running at 1/2 speed.....the relay arrangement causes them to be in series so they are sharing 12V. That condition continues until the temp sensor get to something line 230, at that point the ECM energizes different relays that send a full 12V to each fan, intending to bring them to their full speed.

Several Reatta owners have made modification to cause this full fan speed to happen at a lower temp. Some have spliced in aftermarket adjustable fan temp sensors.

I had my ECM controller chip reprogrammed to lower the kick in temp and avoid the temp creeping up in traffic.

The downside to this is higher electrical consumption, possible shortening the fan life, and they make more noise when running at full speed.

One other thing to consider if you live in a hot climate (like Texas) is adding a auxiliary transmission cooler. In my mind this has multiple benefits... (1) it help preserve the transmission by lowering the fluid temperature. (2) If the transmission fluid is at a lower temp, the radiator has less hot transmission fluid coming to it and that make the radiator more efficient in cooling the engine. I have one vehicle that the radiator has no part in cooling the transmission fluid.... using a fairly large transmission cooler, I bypassed the radiator...... NOTE this is only acceptable in areas of the country that little below freezing ambient temperatures. In cold climates, the radiator help bring the transmission fluid to temp quicker.

Edited April 28, 2015 by Barney Eaton (see edit history)

[bikemikey]

Padgett has done considerable work on understanding the cooling system and fans. Hopefully he will jump in and share his wisdom.

I will share what I know and all that is in the service manual. The fans are controlled by the Engine Control Module (ECM) which gets input from several sources.

Neither fan works until the engine warms to a predetermined temp (Padgett has these temp memorized)

This help the engine get to operating temp quickly. Then the puller fan kicks in.

The front (pusher) fan kicks in as the temp gets sligthtly above the temp of the thermostat.... so the pusher seldom is on when you are running down the road with air being forced thru the radiator. The second condition that turns on the pusher is turning on the A/C.

At this point both the pusher and puller are running (lets say around 210 degrees F) however they are running at 1/2 speed.....the relay arrangement causes them to be in series so they are sharing 12V. That condition continues until the temp sensor get to something line 230, at that point the ECM energizes different relays that send a full 12V to each fan, intending to bring them to their full speed.

Several Reatta owners have made modification to cause this full fan speed to happen at a lower temp. Some have spliced in aftermarket adjustable fan temp sensors.

I had my ECM controller chip reprogrammed to lower the kick in temp and avoid the temp creeping up in traffic.

The downside to this is higher electrical consumption, possible shortening the fan life, and they make more noise when running at full speed.

One other thing to consider if you live in a hot climate (like Texas) is adding a auxiliary transmission cooler. In my mind this has multiple benefits... (1) it help preserve the transmission by lowering the fluid temperature. (2) If the transmission fluid is at a lower temp, the radiator has less hot transmission fluid coming to it and that make the radiator more efficient in cooling the engine. I have one vehicle that the radiator has no part in cooling the transmission fluid.... using a fairly large transmission cooler, I bypassed the radiator...... NOTE this is only acceptable in areas of the country that little below freezing ambient temperatures. In cold climates, the radiator help bring the transmission fluid to temp quicker.

Barney, that's some good information. That's a good point on that transmission cooler, I'll look into getting one. Anything would help to get the temperature down. I don't use this car that much, other than an occasional Sunday ride with my girlfriend to get some BBQ, but I would still like to use the car year round without having to worry about overheating the engine. I put about a 100 miles on the car yesterday, that's a lot of miles for this Reatta.

Thank You

[Barney Eaton]

If you visit Pick-n-pulls, some Riviera have factory auxiliary coolers. They are a nice size and if you take the time to pull the lines, you have everything you need.

Rear wheel drive V8 Cadillacs ofter have them and look in the truck area, most trucks with the towing package had an auxiliary cooler.

Where are you in TX?

[bikemikey]

If you visit Pick-n-pulls, some Riviera have factory auxiliary coolers. They are a nice size and if you take the time to pull the lines, you have everything you need.

Rear wheel drive V8 Cadillacs ofter have them and look in the truck area, most trucks with the towing package had an auxiliary cooler.

Where are you in TX?

I'm way out west of San Antonio. I know of a few junk yards, I'll give them a call when I get a chance. Somewhere on ebay I came across a cooler, it was a new different style. It was round and long and would not block the radiator as much as a conventional one. I'll check into that one as well.

Mike

[TexasJohn55]

Has anyone with widely ranging cooling temps replaced the radiator to restore cooling capabilities?

[Barney Eaton]

bikemikey.... there is a pick-n-pull south of 410 off 16.

Way out West of SA.... I was in a KMart in Uvalde once and the blue light special was announced in Spanish (only) that was back when my Aggie daughter was a park ranger at Garner State Park.

[wws944]

I would also suggest using the built-in diagnostics to make sure the fans are operating correctly. You may find that a relay or a fan motor is bad. Locally, Kitskaboodle had a problem with his car. Via the diagnostics, we tracked down a bad relay - which partially fixed the problem. The other thing turned out to be a big dent in the lower portion of his radiator. Looked like a previous owner had placed a jack under the sheet metal below the radiator and dented it. Kit had a thread about it on here a while back.

It is always good to fix the problem and not the symptom.

[bikemikey]

bikemikey.... there is a pick-n-pull south of 410 off 16.

Way out West of SA.... I was in a KMart in Uvalde once and the blue light special was announced in Spanish (only) that was back when my Aggie daughter was a park ranger at Garner State Park.

Thanks Barney, When I get a chance I'll check it out as well as others. I think Texas John has a good point about the radiator. I don't know for sure but mine might be the original and not operating at full capacity. It might be something as simple as changing out the radiator. I noticed the Reatta Store has a nice one for $111.00. I think it's still a good idea to install a trans cooler

[wws944]

If you do decide to look for an external Riviera tranny cooler, here is what came from the factory on the '90-'93 Rivs:

The bracket on the left side would work perfectly on the Reatta. The Reatta (at least my '90) already has a bolt hole pre-punched in the correct spot for one of the positions, and an indentation waiting to be drilled for the other. To triangulate it on the right side, the Riv has a spot near the headlights for that strap. But the Reatta is different, so something else would be needed.

I would imagine the '90-onwards Toronado has the same arrangement. I know the similar year Eldos and Sevilles had the exact same cooler as well, though with different mounting bracket.

Edited April 28, 2015 by wws944 (see edit history)

[bikemikey]

I would also suggest using the built-in diagnostics to make sure the fans are operating correctly. You may find that a relay or a fan motor is bad. Locally, Kitskaboodle had a problem with his car. Via the diagnostics, we tracked down a bad relay - which partially fixed the problem. The other thing turned out to be a big dent in the lower portion of his radiator. Looked like a previous owner had placed a jack under the sheet metal below the radiator and dented it. Kit had a thread about it on here a while back.

It is always good to fix the problem and not the symptom.

Nice photo. I'm curious, when it was factory installed, did they bypass the radiator , and how did you install yours.

Mike

[wws944]

Nice photo. I'm curious, when it was factory installed, did they bypass the radiator , and how did you install yours.

Mike

The factory did not bypass the radiator. As Barney says, the radiator cooler is useful to get the transmission 'warmed up' quickly, especially in colder climates.

I've not installed the one in the photo yet. Was too lazy to pull the lines in the Riv that day. (Two needed - the upper line between rad and external cooler, and the one between the external cooler and the tranny.) Then never got around to looking for another set. Need to find a 1990, as the part numbers change for '91.

FWIW, I just looked up the part numbers for the 1990 Toronado, and it uses the exact same parts.

Edited April 28, 2015 by wws944 (see edit history)

[bikemikey]

I've been very busy, I just found time to work on my Reatta. I checked my radiator fans yesterday, E010 and E009 and they seemed to be working okay. While looking at the front "pusher" fan, to my surprise, I noticed a transmission cooler. It's a very small one, but at least it is a cooler. I guess one of the previous owners had it installed. I've come to the conclusion I need to change out the radiator. But before I do that I thought about doing a flush. Last year I changed out the water pump and flushed the system with tap water, then filled with 50/50 Prestone. A mechanic friend talked me into not using an additive flush, he said with the mileage on my car it might cause more harm than good. I'm thinking now I probably need to use an additive flush and maybe with some bars stop leak. I've also learned to use distilled water instead of tap water when doing the flush. Do you think this is a good idea.

Thanks  

[handmedownreatta]

i think you are seeing the power steering cooler

 

While looking at the front "pusher" fan, to my surprise, I noticed a transmission cooler. It's a very small one, but at least it is a cooler

[bikemikey]

Okay, I stand corrected. I did not realize the power steering had a cooler. I thought it was a little small for a  transmission cooler.

Thanks

[padgett]

Not sure how I missed this.

 

Ronnie: I prefer the 45848 SuperStat - opens and closes fater than a stock one.

 

Fans: Two choices:

1) Reprogram the ECM PROM to bring the fans in faster. Mine are set at LO: 184 on 181 off and HI 189 on and 185 off. I may see it touch 190F at a long stop light but then comes back down. 

2) Auxilliary switch like this. Can put in parallel.

 

For an 88 you can jumper the big resistor on the fan so puller goes on HI whenever on.

[bikemikey]

I think I'll go ahead and do a flush with an additive. I was worried about the freeze plugs leaking, but if they do I'll just have to fix them.  I'll also try that 180 degree Super Stat thermostat and see how it works. I can always switch back to a 195 degree thermostat. If this doesn't work I'll go down the list I've learned from this thread.  Thanks for all the information, that pretty much sums it up.

Mike