Quick Cooling system question? 3.1L
05-27-2010, 10:19 PM
#1
Quick Cooling system question? 3.1L this is in a 92 RS I sold through my dealership a few weeks ago anyways shes been having a few problems I was wondering if some of you guys could chime in..
anyways the car is really kept up has 254k on the clock, new waterpump and all kinds of other stuff I drove it around 400-500 miles while i had it and determined it was good to go anyways I sold a guy the car and the same day the thermo gets stuck open top radiator hose hard.. no biggie replaced it.. let it idle for 30 minutes to 40 with the cap off and 30 with it on it was all good..
anyways he drove it around was fine then he went and had it flushed few days later same hose hard again put another thermo (failsafe one this time with a hole in it) was good for alittle bit now its doing the same thing again the hose gets hard then soft it goes from right where its suppose to be (right over half to red and back and forth and so on.. i was thinking H/G but no water/oil either way and no smoke no noises..
my next thing was to try bleeding it (Dunno if it was done properly) was going to jack it up on the front with cap off, put a good cap off something else on it, pressure test cooling system then compression test but i have a feeling something else real stupid is going on
anyways the car is really kept up has 254k on the clock, new waterpump and all kinds of other stuff I drove it around 400-500 miles while i had it and determined it was good to go anyways I sold a guy the car and the same day the thermo gets stuck open top radiator hose hard.. no biggie replaced it.. let it idle for 30 minutes to 40 with the cap off and 30 with it on it was all good..
anyways he drove it around was fine then he went and had it flushed few days later same hose hard again put another thermo (failsafe one this time with a hole in it) was good for alittle bit now its doing the same thing again the hose gets hard then soft it goes from right where its suppose to be (right over half to red and back and forth and so on.. i was thinking H/G but no water/oil either way and no smoke no noises..
my next thing was to try bleeding it (Dunno if it was done properly) was going to jack it up on the front with cap off, put a good cap off something else on it, pressure test cooling system then compression test but i have a feeling something else real stupid is going on
05-30-2010, 12:58 PM
#2
pressure tested holds at 10-15 and 20 put a new cap on.. only starts over heating when driving
no oil in water and water in oil.. all fluids are at spec
jacked front of the car up and bled it for a hour with heater running
im thinking bad WP at this point
no oil in water and water in oil.. all fluids are at spec
jacked front of the car up and bled it for a hour with heater running
im thinking bad WP at this point
05-31-2010, 03:09 AM
#4
i believe it does still have the air splitter at the bottom although it doesnt have the stock intake anymore its behind the headlights on the passenger side... so its sucking hotter air in
took off the waterpump earlier no play or anything in it going to flush the whole block tomorrow.. my buddy said it might be the CAT but i would think it would puff alittle bit but like i said idling is not the issue its when your driving
took off the waterpump earlier no play or anything in it going to flush the whole block tomorrow.. my buddy said it might be the CAT but i would think it would puff alittle bit but like i said idling is not the issue its when your driving
05-31-2010, 12:26 PM
#5
It sounds like bad head gaskets or clogged radiator. And as far as not seeing oil and water mix, headgaskets are alot more likely to just leak compression into the cooling jackets and cause cooling issues than they are to allow coolant into the oil. It does happen yes but you can have a blown headgasket with no signs of coolant/oil mixing.
I would let the car cool down then run it and feel the radiator it should start to warm up at the upper hose entrance to the radiator first and then shortly after the entire radiator should become warm then hot. If you run it for about a half hour and there are cold spots on the radiator especially the lower end then most likely it is clogged. I would drive it and make sure its fully warmed up then check the radiator. Try it on another vehicle that does not have an issue you will notice the radiator is evenly hot. When its just starting to warm up it will be cold at first until the coolant circulates so dont get thrown off by checking it too early.
You said the hoses are hard, or the upper you said anyway, both hoses should be hard, cooling system is holding in 16 psi. If only the upper is under pressure that could also possibly be the radiator being stopped up since the pressure should go right through it to the lower hose and it should be equal.
FWIW generally these rules apply to cooling systems:
-Overheating while driving is lack of water flow or lack of water, and can rarely but can be caused by too much flow, as when people take out the t-stat and the water flows too fast through the radiator to be cooled down while in it. A bad headgasket will introduce air into the system and disturb water circulation and a lot of times cause over pressurizing of the system resulting in boiling over or busted hoses etc...
-Overheating while at a stop is usually lack of airflow due to fan/fans not working.
I have put head gaskets on many 3.1L GM motors but pretty much only on ones that had been overheated due to another issue, and with that kind of mileage I would be highly suspecting the radiator. There is a fluid that NAPA sells that detects Hydrocarbons in the cooling system that you put in a little sampling tube and draw air through the fluid from above the radiator cap, it works really well and if the fluid changes colors you know that without a doubt you have a bad head gasket. If you hold the sample tube near the exhaust and pump the bulb that draws in air the fluid changes from blue to green/yellow really quick. Its pretty neat stuff. I believe NAPA calls it Block Test Fluid, you will need the kit with the tube and suction bulb.
I would let the car cool down then run it and feel the radiator it should start to warm up at the upper hose entrance to the radiator first and then shortly after the entire radiator should become warm then hot. If you run it for about a half hour and there are cold spots on the radiator especially the lower end then most likely it is clogged. I would drive it and make sure its fully warmed up then check the radiator. Try it on another vehicle that does not have an issue you will notice the radiator is evenly hot. When its just starting to warm up it will be cold at first until the coolant circulates so dont get thrown off by checking it too early.
You said the hoses are hard, or the upper you said anyway, both hoses should be hard, cooling system is holding in 16 psi. If only the upper is under pressure that could also possibly be the radiator being stopped up since the pressure should go right through it to the lower hose and it should be equal.
FWIW generally these rules apply to cooling systems:
-Overheating while driving is lack of water flow or lack of water, and can rarely but can be caused by too much flow, as when people take out the t-stat and the water flows too fast through the radiator to be cooled down while in it. A bad headgasket will introduce air into the system and disturb water circulation and a lot of times cause over pressurizing of the system resulting in boiling over or busted hoses etc...
-Overheating while at a stop is usually lack of airflow due to fan/fans not working.
I have put head gaskets on many 3.1L GM motors but pretty much only on ones that had been overheated due to another issue, and with that kind of mileage I would be highly suspecting the radiator. There is a fluid that NAPA sells that detects Hydrocarbons in the cooling system that you put in a little sampling tube and draw air through the fluid from above the radiator cap, it works really well and if the fluid changes colors you know that without a doubt you have a bad head gasket. If you hold the sample tube near the exhaust and pump the bulb that draws in air the fluid changes from blue to green/yellow really quick. Its pretty neat stuff. I believe NAPA calls it Block Test Fluid, you will need the kit with the tube and suction bulb.
