Bri-Guy-GA Posted October 20, 2006 Report Share Posted October 20, 2006 I was driving home tonight and about a mile or so from home I notice the temp gauge in the red area almost at 260. It drops suddenly to 3/4's on the gauge then goes back up and beyond the max the rest of the way home. Car ran fine with no knocking or anything though. I have had the car a week and it has not gone more than slightly beyond the mid point even in traffic. What could be the prob? BTW my car is a 95 GP with the 3.1. New GM crate motor with under 10K. Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted October 20, 2006 Report Share Posted October 20, 2006 There's a temp sender just for the gauge and that could be going bad. Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted October 20, 2006 Author Report Share Posted October 20, 2006 One thing I did notice a few days ago after getting to work was a gurgling sound. I looked under the hood ant coolant was bubbling into the overflow bottle. I figured this was normal, but now I am not so sure. Thermostat? Quote Link to comment Share on other sites More sharing options...
SigEpCutlass Posted October 20, 2006 Report Share Posted October 20, 2006 Are you sure you don't have air in your coolant system, since you heard gurgling? If so, you need to bleed it, and the air in the system alone could potentially cause your car to run hot. A few other things come to mind when the car runs hot: CTS (Coolant Temp) near thermostat...small plug screws into engine Thermostat Coolant Fans irradically working or not at all Start with that stuff, and chances are you'll find your culprit. Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted October 20, 2006 Author Report Share Posted October 20, 2006 Would an air bubble all of a sudden show up like that? How do you bleed this system? Never had to do that before. If fans are out, would car overheat even if moving? Thanks for the suggestions. I will give those items a look this weekend. Good thing I haven't sold old car yet. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted October 20, 2006 Report Share Posted October 20, 2006 oh geeze, well even if you suspect that its a messed up temp sender DO NOT drive it when the gauge is registering that high, if indeed it is overheating driving it that hot can lead to blown headgaskets, cracked heads and more fun. these cars have simple, yet fickle cooling systems. first off does your cooling system hold pressure, IE the upper radiator hose, is it hard when the car is up to opeating temp? since you say that it overheats while driving, i'd mabie look to the waterpump, only about $20 for the part and not bad to install. mabie a overly cloged up radiator as well. since you say that the coolant bubbles in the resivor thats unfortunately a sign of a failed headgasket, but sometimes not, that would be the last resort for me. when the car is warm and running there is a screw on the top of the thermostat housing loosen that up and air should come out then once the air is out coolant will freely flow out as well. then it is bled. Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted October 21, 2006 Author Report Share Posted October 21, 2006 oh geeze, well even if you suspect that its a messed up temp sender DO NOT drive it when the gauge is registering that high, if indeed it is overheating driving it that hot can lead to blown headgaskets, cracked heads and more fun. these cars have simple, yet fickle cooling systems. first off does your cooling system hold pressure, IE the upper radiator hose, is it hard when the car is up to opeating temp? since you say that it overheats while driving, i'd mabie look to the waterpump, only about $20 for the part and not bad to install. mabie a overly cloged up radiator as well. since you say that the coolant bubbles in the resivor thats unfortunately a sign of a failed headgasket, but sometimes not, that would be the last resort for me. when the car is warm and running there is a screw on the top of the thermostat housing loosen that up and air should come out then once the air is out coolant will freely flow out as well. then it is bled. I am not driving it till the temp gets back to normal. What are the odds of a head gasket going bad on a new crate motor? Right now it has a low coolant level. Was full when I picked it up, in fact the radiator was serviced before I bought it and the coolant was a nice bright green and worked perfect till last night. I am fairly confident it isnt the radiator. What would cause the coolant to disappear without any visible signs of leakage? Am going to fill with water and see once its up and running where the leak might be and check tail for white smoke. I am hoping for thermostat or coolant temp gauge, but will find out and report back. Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted October 21, 2006 Report Share Posted October 21, 2006 Bubbling coolant in the recovery tank is not always the sign of a blown headgasket. My GP would just heat way up on a long highway trip and the coolant would be bubbling away in the tank after I'd stop for gas or something. Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted October 21, 2006 Author Report Share Posted October 21, 2006 Bubbling coolant in the recovery tank is not always the sign of a blown headgasket. My GP would just heat way up on a long highway trip and the coolant would be bubbling away in the tank after I'd stop for gas or something. So that could just be an odd W both thing? Quote Link to comment Share on other sites More sharing options...
White93z34 Posted October 21, 2006 Report Share Posted October 21, 2006 Bubbling coolant in the recovery tank is not always the sign of a blown headgasket. My GP would just heat way up on a long highway trip and the coolant would be bubbling away in the tank after I'd stop for gas or something. So that could just be an odd W both thing? i never said it was THE sign, it is just a sign of a blown headgasket, meaning it may or may not be. depending on how bad and how long it was overheated it could have blown the headgasket, but with a new engine i'd imagine it would take a good while of doing that to blow it out. i've never had my car do that in the 3 years i've owned it now, now have heard anyone talking like that was normal. i'd namely look at a thermostat, and if that dosen't solve it, try a waterpump. Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted October 21, 2006 Author Report Share Posted October 21, 2006 K, here is what I found. I filled it back up and let it idle to operating temp (210 on gauge). Turned off and checked levels, added some coolant put cap back on and restarted. It did get to about 3/4 with the low coolant, but that is expected. Ran up to operating temp again and everything seemed ok. Had buko heat, no leaks or sounds of leaks. No thick white smoke or coolant smell from tail. Took for a test drive and ran fine, temp right around 210. I did notice that the fans were working on the initial warm-up but after driving for a few minutes they werent on. I purged out some air from the system and after shutting down the last time I cracked the rad. cap and there was pressure. Hoses are new with engine, felt firm and were warm/hot. I'm thinking Coolant temp sender. Anyone else have suggestions? Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted October 22, 2006 Author Report Share Posted October 22, 2006 I took it out to 6 flags last night (20 minute drive) and it ran fine,temp 210 even in traffic and driving around parking lot. I did notice the same bubbling and some coolant that overflowed the recovery bottle on the ground. Could it be the cap isnt right? What pressure is it supposed to be? Mine is 15lb. I am gonna run for a bit with the cap loose and see if anything weird happens. Can the system be overful? Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted October 22, 2006 Report Share Posted October 22, 2006 15psi is the correct rating on the cap. So, when it's warm, it overflows the resevoir? Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted October 23, 2006 Author Report Share Posted October 23, 2006 15psi is the correct rating on the cap. So, when it's warm, it overflows the resevoir? Exactly. After driving and getting to temp the resevoir gets filled from the rad. From what I saw last night and today it happens when parked and when driving slow. WFT? I do not see the fans turning either even when at temp, but it stays around 210 when driving or when stopped at lights. Never seen anything like it. I have a feeling my overheat was due to coolant getting out of the resevoir and the rad running low on coolant. Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted October 23, 2006 Author Report Share Posted October 23, 2006 This shit it getting annoying now. Driving to work (about 30 miles) everything is fine and dandy, when all of a sudden the temp just spikes to pin the gauge. I mean it happened in seconds. I stop and get ready to shut it down when the temp just drops to normal again all within 10 seconds. Also while this was going on the heat when cold. It was nice and warm then nothing. You would think that running so hot the heat would be oven hot, but nothing. Let it idle a few minutes and head off to work, no more problems. Even the heat came back. Whats going on? Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted October 23, 2006 Report Share Posted October 23, 2006 hmm...could be a sticking thermostat. That's really about all that's left to replace. Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted October 23, 2006 Author Report Share Posted October 23, 2006 hmm...could be a sticking thermostat. That's really about all that's left to replace. I am gonna replace it this weekend, but could it close then open like that? I had driven the car 45 minutes or so before it happened. Do the fans play a part in this or at highway speed they dont do much. Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted October 23, 2006 Report Share Posted October 23, 2006 Yeah, if it's sticking, you could get something like you described. The fan's dont play a part in this. A stock t-stat should open around 195*F. The fans should come on around 220*F (1st fan) and ~230*F (2nd fan). Remember that the gauge cluster uses the single wire sensor on the rear head and the ECM uses the two wire sensor on the lower intake to turn the fans on/off. Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted October 31, 2006 Author Report Share Posted October 31, 2006 I put in a new thermostat (Moto-Rad 195) and it seemed ok, until I was on my way home tonight from school. Car was just getting to temp when it kept going. I pulled over, let it sit a minute and temp dropped right back down. It happened once more and I heard a clunk then what sounded to be fluid rushing into the heater core. Temp then dropped right back to below 210. Is there some valve or something that controls the coolant to the heater core? What is the best way to check for bad head gaskets? Could all this be air in the system? I am still not sure the fans are coming on either. I also replaced the coolant temp sender. Where to go from here? Quote Link to comment Share on other sites More sharing options...
Cueman Posted November 2, 2006 Report Share Posted November 2, 2006 Any update on the overheating situation? I am having a similar problem, and I have replaced the thermostat and the coolant temp sensor, and it has not helped yet. Waterpump is new about 6mo ago. ' I can' t figure out what is causing the temp guage to go up and down so fast. And having the heat turn cold is really annoying. Can anyone help? Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted November 2, 2006 Author Report Share Posted November 2, 2006 Well I am embarassed to say I think I found out what was wrong . When I bypassed the AC compressor I ran the belt over the water pump back down to the crank pulley. In doing that I reversed the rotation of the water pump. I put in a new compressor and put back the original belt and now it everything seems to be working correctly. Will let you know in a day or so if I was lucky today or it was actually that. I stand in shame awaiting your ridicule. Not sure if that helps Cueman, but thought I should update everyone. Quote Link to comment Share on other sites More sharing options...
Regal_GS_1989 Posted November 2, 2006 Report Share Posted November 2, 2006 I'm wanting to say that there is air being forced into the cooling system. Possibly bad head gasket, or even a cracked head. I had a cracked head on my GS, and that sounds exactly like what was happening to mine. My 88 started acting the same way. Although I havent pulled it apart yet to see if the heads are bad, or if the head gasket is on its way out. Quote Link to comment Share on other sites More sharing options...
Bri-Guy-GA Posted November 4, 2006 Author Report Share Posted November 4, 2006 Well I am embarassed to say I think I found out what was wrong . When I bypassed the AC compressor I ran the belt over the water pump back down to the crank pulley. In doing that I reversed the rotation of the water pump. I put in a new compressor and put back the original belt and now it everything seems to be working correctly. Will let you know in a day or so if I was lucky today or it was actually that. I stand in shame awaiting your ridicule. Not sure if that helps Cueman, but thought I should update everyone. Its confirmed I am an ass. With the water pump running the correct direction the car stays at the right temp. Got up a little in traffic, but once the fans kicked in it dropped right down and never over 3/4. Quote Link to comment Share on other sites More sharing options...
GIANT MOTH Posted November 7, 2006 Report Share Posted November 7, 2006 Haha. What a dummy!!! I was going to put my money on the trapped air and thermostat. I hate to laugh but it sounds like your freeze plugs are going to pop off anytime now. Your going to need new heads. Quote Link to comment Share on other sites More sharing options...
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