Hey look, another overheating thread!

[ZenkiOwns]

hey guys I'm having a few issues and need some insight.

I have a SETA that started running a little hot on me (3/4 mark)

Well I replaced the water pump today and the problem persists. I'm getting consistent coolant coming from the bleeder screw and once the car comes to operating temperature I can feel pressure building up in the hoses.

The only thing that concerns me is that the lower radiator hose (one coming from bottom of radiator to the METAL water pipe) stays cold, and until the car gets warm the upper radiator hose stays empty (I'm guessing because the Tstat is closed) The heater works and gets very hot.

The thermostat is new, there is no coolant in the oil, smoke of any sort, etc.

I'm at a loss here.

[the_ps]

Thermostat arrow pointing up?

[Komzorz]

Might sound a little crazy, but your temp gauge in the cluster could just be bad. I've got a cluster that will PEG the temp gauge before the engine is even remotely warm.

Got a new cluster, works perfect.

You could also have a bad sensor.

Or, if it's only getting to the 3/4 mark when stopped in traffic, your fan clutch could be shot.

[E30_Pare]

+1 on fan clutch. If u can spin it with slight/no resistance it's bad

[jeffnhiscars]

Even a new tstat can be bad & if your lower hose stays cool that may be why. Running without it is a good diagnostic suggestion to eliminate it as a cause & while its out I suggest you test it in a pot of water & drill a small hole in the flange (1/16 is fine) to allow it to self bleed.

If the water pump is new, fan clutch is truly good & tstat is confirmed working then I suspect your radiator is the cause.

[ZenkiOwns]

I boiled the new thermostat along with the old one to test the opening temperature. They both opened around 180 degrees.

I also tested the fan clutch and it is good.

Shouldn't all the hoses have water in them at all times even if it is cold,hot,running etc?

I would suspect the temperature gauge, but when bleeding the thermostat the coolant coming out is extremely hot and the gauge stays consistent with that.

Also, the water in the overflow stays cold. It's a weird fact but I figure I'd throw anything out there that may help.

[jeffnhiscars]

If the system is properly bled then, yes of course all the hoses will have water in them. What Ive found though, is that a hose that is not yet circulating may feel empty since it is not pressurized but it does in fact have coolant in it.

When at OT all the coolant should be warm-hot.

I'm not 100 % sure about this but I think the metal wp pipe is on later cars and yours being an SETA is an earlier car. Perhaps something has been retrofit and/or is not connected properly.

[jlevie]

Given what you have done the first step is to make sure the system is fully bled by:

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500rpm for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

Then find out if the engine is actually running hot by checking the head temperature with a contact or IR thermometer. With an 80C thermostat the head should be 80-83C.

If the engine is running hot only at idle, the fan clutch and radiator are suspects. But if it runs hot when being driven at 35mph or more, the radiator becomes the prime suspect.

@jeffnhiscars: The late cooling system with the cross-over pipe was introduced in late 87, thus it will be on an SETA.

[jeffnhiscars]

@jeffnhiscars: The late cooling system with the cross-over pipe was introduced in late 87, thus it will be on an SETA.

Thanks. I wouldn't know an SETA if it ran me over :nice:

[ZenkiOwns]

I continued with it again today with out any luck. That lower hose being cold really bothers me. I checked the radiator again and it flows consistently. Same thing with the water pump, turning over the motor pushed fluid out.

How would I know if a water passage was blocked in the head etc? I may be over thinking it, but I really am getting beat up over this.

[Komzorz]

The lower hose is going to be colder because all that water has just transferred a lot of heat through the radiator. I just went through this a couple months ago, I know that feel.

My advice would be to hook up with someone with a known good cluster and test it real quick. After you get the trim pieces off it only takes like 10 minutes to pull a cluster.

[RobertC]

Radiator

These cooling systems are stupidly simple and bleeding them require nothing special.

If your driving at 40+mph and the car is overheating then your not flowing enough coolant, period. No magic here.

Just because you can ram a garden hose in it and water runs out the other side does not mean its flowing enough volume.

Case in point, customer starts overheating takes it to the shop they change the thermostat, bleed it, never test drive it, its all good they tell her. Continues to overheat on the road, takes it back, change the water pump, bleed it, tell her its all good, drives it again, overheats, cracks the cylinder head.

At this point she refused to go back to that shop for obvious reasons and brought it to me. Built her a new cylinder head and while looking for the source of the problem used a bore scope to look in the radiator, over half the tubes where plugged with build up. It was the original radiator.

Water pump pumps water
Thermostat regulates warm up and maintains operating temperature
Radiator actually cools the water

jlevie writes:

But if it runs hot when being driven at 35mph or more, the radiator becomes the prime suspect.

Exactly. Just saying you might want to replace the radiator as your next step.

[jeffnhiscars]

An infrared gun should show you how evenly the radiator is circulating as well as let you compare temperatures at different spots. A handy tool to keep around.

[ZenkiOwns]

Okay.

I replaced the water pump, removed the thermostat (temporary) replaced the radiator with an e36 m3 mishimoto, and now my clutch fan dies. I picked up a new a few days back but I'm waiting on a hand to knock that clutch fan free. Being 130lbs does really cut it when you're trying to break something free. haha

If that doesn't fix it then I'm lighting it on fire.

[Bretts85E30]

It doesn't take that much effort I'm the same weight and for the initial break just tap the wrench with a hammer and it should break loose just make sure u remember its clockwise to loosen counterclockwise to tighten