86 coupe, stock
I need help with a problem as I am stuck. Got behind an accident Memorial Day weekend and sat in traffic for over an hour. No problem. Drove home and parked the car. No problem. Next day it wouldn't keep running. Problem.
It's needed new injectors for a while, so I went ahead and replaced them. Also replaced EGR valve at the same time. Now it maintains fuel pressure at 38-40 while running (44psi at startup). Oddly enough, it didn't run much better and I noticed that it was overheating. Replaced the thermostat (went with 160) and that made no difference. Not much water appeared to be moving and a slight squeal could be heard from down low, so new waterpump. No difference, except now it has a better flow. Radiator is 1 year old. Fan comes on at 229 like clockwork. CTW checks out OK. There is no trash blocking radiator/condensor area. Timing is set dead on, but noticed skip in motor and when this happens, you can see the harmonic balancer hesitate with timing light. Idle is at 600rpm. TPS reads 0.54 at idle. Coolant is weak because of loss to overheating. Heater control valve is bypassed and hoses "straight pipe" it directly to heater core (which should help it cool, right?).
Question is: why is this thing overheating? I mean, 5-10 minutesand it's fine, but longer than that or if I try to drive it and it overheats. It sounds like it is boiling when I shut the engine off. Heats up faster on the right side, and then all of a sudden, it starts gurgling very hard and spewing into the reservoir and gurgling out of it through the cap. Considered a head gasket problem, but there is no visible water contamination in the oil or oil in the coolant. There is no steam or odd odor coming from the exhaust. Help me, please! I am at wit's end.

 

During and after warmup is the top hose hard like the system is pressurized or is it soft? Sounds that your cap might not be allowing the system to pressurize, because the gurgling sound is coolant boiling, also you might want to burp the system as well. Any coolant loss other than the reservoir? The 84 I worked on did this exact same thing but there was a split on the side of the radiator that would leak only when the sytem was getting up to temp and pressurizing itself. Hope this helps, just my thoughts.
Bob

 

Are you sure nothings clogged?

You probably don't want to hear this story, but when I blew the head gasket in my daily driver cavalier a few years back- I didn't notice any strange exhaust or any discolored coolant.
I was fighting an overheating problem in it for about 2 months, then just one day boom... and it's spent...

 

If you are not loosing any or loosing very little coolant-
Try the cap thing, probably need a new one anyway if its original. Also I have had this problem due to not being able to get all the air out of the system. I finally parked the car on an incline, with the radiator neck higher than the motor, and burped the system. With it level I didn't see any bubbles in the water, but when I put it on the incline, I got alot of them. There is a specific procedure for doing this as well, as in you have to warm the car up then shut off, then repeat, I just can't remember it right now, maybe someone else will chime in with it.

Also if you ARE loosing coolant but not in the oil or on the ground or in the passenger floor board, check the intake gaskets.

 

Radiator cap is new. Replaced the plenum and runner gaskets when I replaced injectors. Burp the system every time I have to refill (lately every day). But intake to head gasket might be an idea. Great deal of heat on passenger side, most notably around the intake. You can here a hissing sound sometimes. If leak gets mixed through the intake, it could cause the misfire if it wet a plug, right? It might also acount for a vacuum leak that just compounds the whole problem.
OK. Off to check it out. I have trouble hearing leaks, even with the piece of hose used as a stethoscope (hell, even with a double-lumen, power amplified cardiology stethoscope). Think spraying a little starting fluid around the intake mating surfaces would help show this?

 

With all you've changed and it still overheating I would check the cap first and pressure test the system. Also the thermostat may be new but that doesn't mean it couldn't be defective. When the engine warms do you see the temps drop on the gauge as well as feel the upper hose get hot? After that I would be "sniffing" the coolant system looking for exhaust gases.

 

Have your coolant system pressure tested.

 

I'd venture to guess that there's air in the cooling system. Did you 'burp' it yet? I'd do have your mech do a pressure test as well.

 

You have a leak. Rear passenger side is where mine blew. Was making the hissing sound you describe. I do agree with the others though you should have it pressure tested. If you have an air compressor you can just unhook the overflow tube from the radiator and use an air sprayer tool (I have no idea the real name) and stick the nozzle in there.