White93z34 Posted September 6, 2005 Report Share Posted September 6, 2005 this is about my buddies 97' GTP, we replaced struts today, then took it out on the highway, and after a high speed run or 2 it started overheating to the point that we had to pull over to let it cool down. this is no new problem, ever since we put the engine back in the car, its had overheating / cooling system problems, and after redoing headgaskets and intake gaskets, the coolant leaks were a thing of the past. now when the engine was out it was completely rebuilt. now if we were to do sane driving (read= under 100mph). it will stay normal. and before i go any further, heres some specs on the engine: stage 1x cam diamond coated pistons l32 connecting rods arp studs/mains mls (cometic) head gaskets no balance shaft slp headers 3.4 s/c pulley (10:1:1) final compression, 160 stat drilled new water pump/oil pump/timing cover all said its comeing down the the point where we are keeping track of whats still origional on this car, and the rad is still one of those items, could it be cloged the the point that it won't hold proper pressure, and not let enough coolant to keep the engine cool under hard acceleration. so we are more or less at a loss here as to whats causeing the temps to shoot through the roof after any sorta run like that. anyone got any ideas? Quote Link to comment Share on other sites More sharing options...
cutty Posted September 6, 2005 Report Share Posted September 6, 2005 no idea, my cutlass does the same thing it will run at like 250-260, after it warmed up, so thats why i did the colling fan switch mod. i still have no idea why it does it. maybe if you get some info it will help me fix mine. Quote Link to comment Share on other sites More sharing options...
Brian P Posted September 6, 2005 Report Share Posted September 6, 2005 just for kicks, how is the radiator cap? Quote Link to comment Share on other sites More sharing options...
White93z34 Posted September 6, 2005 Author Report Share Posted September 6, 2005 its brand new, and we know both rad fans are working. Quote Link to comment Share on other sites More sharing options...
slick Posted September 6, 2005 Report Share Posted September 6, 2005 Have you guys tried a radiator flush yet? Might be something to look into. Otherwise, it's very odd that it's running that hot. Does the coolant overflow resivoir seem to fluctuate with engine temperature any? Quote Link to comment Share on other sites More sharing options...
White93z34 Posted September 6, 2005 Author Report Share Posted September 6, 2005 well the coolant has a scant 3000 miles on it since we put the engine back in so i don't think thats the problem. Quote Link to comment Share on other sites More sharing options...
slick Posted September 6, 2005 Report Share Posted September 6, 2005 I was suggesting rad. flush just incase there may be something clogged in the rad, not neccessarily the fluid. Does coolant seem to flow fine through the rad or not? Quote Link to comment Share on other sites More sharing options...
paulo57509 Posted September 6, 2005 Report Share Posted September 6, 2005 Under what conditions does the engine overheat? You mention after high speed runs. Need a bit more detail here. Does it over heat while going down the road at highway speeds or after you get back into town and slow down? Overheat in stop-and-go traffic? Overheat just idleing in the driveway? How many miles are on the radiator? I'm leaning towards a plugged radiator. If this is the case, I'd skip the flush. Hard deposits in the radiator tubes aren't going to be removed by the flushes available at Autozone, etc. For hard deposts, either the tanks need to be removed and the core rodded or a new radiator is the solution. Quote Link to comment Share on other sites More sharing options...
Dannymik Posted September 6, 2005 Report Share Posted September 6, 2005 maybe a bad tstat? Quote Link to comment Share on other sites More sharing options...
DaveFromColorado Posted September 6, 2005 Report Share Posted September 6, 2005 without all the info, it's kinda hard to tell, could be a bad t-stat, could be not enought coolent flow, could be the cam is too retarded, or the ignition is too advanced, or that there's something in the radiator causing this problem ... at high speed only it could be that the contour of the body isn't allowing enough air to pass over the radiator too... --Dave. Quote Link to comment Share on other sites More sharing options...
bartonmd Posted September 6, 2005 Report Share Posted September 6, 2005 What kind of water did you mix the coolant with? If you used tap water, it's probably coated everything with iron and calcium... Seems about the only safe thing is RO or Distilled water... Mike Quote Link to comment Share on other sites More sharing options...
White93z34 Posted September 6, 2005 Author Report Share Posted September 6, 2005 usually it will overheat after slowing down from high speeds to around 65ish, then the temps will rise, and stay more or less in check till after we get off the highway, then they will rise to the point that we gotta pull over. the engine and tranny have around 3000 miles on them wheras the rest of the car, and as far as i know the radiator have 112k. i'm prety convinced its not the thermostat, since when he has the 180 in it it did the same things as it does now with the 160. and i believe he just bought 50/50 mix dexcool when we put it backtogether, so i doubt that should be an issue. however who knows what was run in it before he got the car. Quote Link to comment Share on other sites More sharing options...
paulo57509 Posted September 6, 2005 Report Share Posted September 6, 2005 Chris, from what you describe it sounds like a plugged radiator. Quote Link to comment Share on other sites More sharing options...
lakefxgp96 Posted September 6, 2005 Report Share Posted September 6, 2005 Im thinking it could be a leaky headgasket or at least air inside the lines somewhere. What about the waterpump? bad bearing, bad seal? clogged cover? Quote Link to comment Share on other sites More sharing options...
Dannymik Posted September 6, 2005 Report Share Posted September 6, 2005 and the list goes on... Quote Link to comment Share on other sites More sharing options...
gp90se Posted September 6, 2005 Report Share Posted September 6, 2005 pull the rad and have it pressure tested/cleaned. toss a new 160 t-stat in it and see how many miles are on the waterpump, if the waterpump isnt flowing fluid right, you could be restricting fluid at certain speeds. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted September 6, 2005 Author Report Share Posted September 6, 2005 it initally had leaky headgasket problems, we have resolved those, and we have bled and bled and bled the coolant system, so air in the lines should not be an issue. when the engine was put together it got a new waterpump, and about everything that was 112k old was replaced with brand new, so unless some new part is bad i shoulden't see it being a problem. Quote Link to comment Share on other sites More sharing options...
DaveFromColorado Posted September 7, 2005 Report Share Posted September 7, 2005 I've seen waterpumps come defective... they heat up and the impellers stop spinning... (it's really hard to diagnose that one) I'm thinking a clogged radiator tho. --Dave. Quote Link to comment Share on other sites More sharing options...
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