Another engine running warm; maybe - Pontiac GTO Forum
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post #1 of 6 (permalink) Old 06-26-2018, 05:45 AM Thread Starter
 
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Another engine running warm; maybe

This past Sunday, I took my '71 GTO to a car show about 15 miles away. Sunday it was sunny, low humidity and about 75 degrees. Maybe a tad warmer. I have a 180 thermostat in the engine and it took about 8-10 miles before it reached that temp. Pretty much flat road and about 45 mph; 2200 rpm's. I got on the interstate and ran it to 60 mph; about 3000 rpm's. Had to or I would get run over. Temp. rose to about 195. Then hit a steep, long hill of about 3 miles. Temp. rose to slightly less then 210. Got off and went down hill for a distance to the event. Temp. went down to 195. Returned home the same route with the same results. Do these temps. sound about correct for the conditions?? I have a Cold Case aluminum radiator with 2 1" rows of tubes, shroud, 7 blade clutch fan, TH400 trans. with 3.55 gears, water pump divider plate was worked on, engine runs well and seems to be tuned properly with 14 degrees of initial advance timing. This is my fourth GTO and I could never get any of them to run around the thermostat number. Not sure if it's just bad luck or I'm doing something wrong. This engine will take a distance to warm up and will stay at 180 for a brief period of time, until meeting with a demand. It likes the 195 temp. a lot. Doesn't return to 180 too often. I would like it to run around the 180 temp. but not sure this is possible. Once it reaches 195, at about 45-50 mph, it will run all day at that temp., without other circumstances. Also, I know it's a 180 thermostat. If this temp. for the conditions sounds correct, then there is nothing to fix. Just looking for some advice or suggestions. BTW, the engine has never run hot enough to boil over while running. I have returned home with it after a ride and in the morning, I saw it puked out some fluid. I refilled it and this happened a few times until I realized I had too much fluid in it and it was only seeking the level it was happy at. Hasn't happened again. Thanks everyone.

I think I posted this in the wrong section. Sorry. If someone could move this to the proper section, I'd appreciate it. Thanks.
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post #2 of 6 (permalink) Old 06-26-2018, 09:11 AM
 
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Sounds very atypical, 210 max is not bad. Have owned half a dozen 70's and 71's with 400/ 3.23's and 455/3.31 gears and none cruised at 180 degrees in 85-90 degree heat. Of course with 1-1 top gear, the 3.55 gearing exacts the higher rpm on the hwy and this contributes some heat to the cooling temp. From a stoplight your '71 should get up and go, unlike if a set of '71 economy ratio 3.08's were installed. That heat contributing factor wouldn't bother me, did you install a small overflow canister? On such builds, if the '71 was going to be destined to be a bug smasher/rock chip magnet/driven all over the country, a well built & prop installed 200R4 trans would be a good fit. No super steep 1st gear ratio OR hacking up the floorpan for a Tremec. Have contributed on several 200R4 builds in original auto GTO's, & all left big smiles on their owners face.

Again, it all comes down to where the car's Purpose Build fits into the Pontiac Spectrum. My longtime keeper '71 233 HO cars, one is an original M22/3.31 gear car, the other is original T400/3.55 gear car. Neither are being restored to cruise the local roads & streets, that's not what anyone has prev done restoring such cars. Both now have 3.73 gears, as that is the optimum ratio for the purpose build of each car, to compete at Pure Stock Drags & then be loaded back up on the trailers for the long drive home. 3.73's out back would not be comfortable at all if either was a driver.
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post #3 of 6 (permalink) Old 06-26-2018, 09:27 AM
 
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Hi I basically had the same issue and put a 160 degree thermostat in and it cured the problem although mine was running a little hotter than you stated. Its an easy swap and you can always go back to a 180. I don't plan on ever needing the heat so that was not an issue for me. Also how do you like the cold case radiator I am planning on upgrading mine soon. Did you install it ?
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post #4 of 6 (permalink) Old 06-26-2018, 05:07 PM
 
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I have similar temps. And as was mentioned, swapping in a 200R4 cured the interstate cruise temp issue.
However on 90 deg days, sitting at a stoplight, AC running, I get puckered up. Seeing that temp gauge creep into the 220+ range I'll turn the AC off.
Idiot lights come on around 225-30. Never had that happen, never had overflow.
185 thermostat.
Decided to just live with it since it never overflows.
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post #5 of 6 (permalink) Old 06-27-2018, 05:03 AM Thread Starter
 
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Thank you everyone to take the time to respond. I do appreciate it. I'm not sure about the Cold Case radiator. It is a quality radiator and well built, but I don't have anything to really compare it against, over time. The old, stock radiator allowed the motor to run a little hotter, so I replaced it with this one. I didn't keep the old one that long. It runs cooler, so I guess it works as best it can. I bought another all welded aluminum radiator from a different company for my '62 409, costing considerably less then Cold Case did, and the motor runs at 180-185 all day long. I would buy another Cold Case radiator, but would look around first, comparing apples to apples.


Another quick question. Same topic. Does the size of a torque converter have an influence on the motor temp.?? I have one of the smallest torque converters with a non stock stall speed, I have ever seen. It's not something I want. Came with the car. Going to remove it over the Winter. I read that my type of converter makes the engine run hotter. I don't think I understand this, or a lock up vs. non lockup converter. Thanks.

Oops. Forgot. No overflow can yet. Do I really need this?? Will install if I do. Would I want one that allows the engine to draw what was discharged, back into the system??
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post #6 of 6 (permalink) Old 06-27-2018, 11:08 AM
 
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Hi again I believe that anything that slips which is what a stall speed does causes some type of added heat or temp increase. That's why people run trans coolers. Also you might want to investigate which type of cam you have and how your engine is set up before you remove the stall speed. You might lose some performance off the stop lights.As far as the overflow can I don't run one but mine doesn't overflow.With that being said you Can't have spills at the track or car show.
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