still overheating

[87-WE2]

Just in case does dash have to be removed to bypass heater core?

No sir. Under the hood, there's two coolant hoses that look like they go into the fire wall on the passenger side. To bypass the heater core, you connect those two hoses together instead of to what they're currently connected to.

I'd do this only after you get the freaky sounds from the water pump addressed. If the water pump doesn't cure the problem, bypassing would be worth a shot. It's kind of a red-neck band aid (no offense to any red-necks out there - I happen to be one!!)

 

[Jackie grabos]

hey thanks. back at station today, so will test block on thursday and look at a few other things. will not have time to do pump until saturday, hope it fixes problem. also it looks like i have the side pieces for fan shroud, but not bottom piece so will look into possbly ordering one of these also. thanks again

 

[groumoutis]

Trust me on this, a water pump can cause the temp problem. I was having the same problem last summer. I flushed the radiator several times and boiled it out to no avail. I had a clean radiator, new hoses and a new thermostat and still was running hot. The only thing left to do was change the pump. Now I will say this first. The pump was moving coolant through the radiator but not enough. I pulled the old pump off and the impeller was almost gone. I imagine this was the original water pump. I put the new pump on and temps were great. The beginning of this summer the radiator sprung a leak so I put in a f- body radiator and haven't had any problems. I went on the power tour and didn't have any temp issues. With all that said I have a stock intercooler. But I live in Indiana and run a 50/50 mix for coolant/water

This may or may not be your problem but it won't hurt changing it out.

 

[Jackie grabos]

thanks, this is the original pump. was up all night at work so slept most of the day. going to remove some stuff and change it in the morning. how hot was your car getting?

 

[Red C5]

If the water pump is fine, make sure your radiator isn't partially plugged. I've seen that before too.

Peter

 

[chops]

Did you check your thermostat???? Maybe its not opening all the way? I've seen it 100's of times also I've seen the fins on the water pump rot away and break off and cause the cooling passages to get clogged and also if there are no baldes left on the pump its not doing its job especially when driving

 

[Jackie grabos]

well, changed my water pump and bypassed the heater core just in case there was a leak there. took the car out for a drive and heated up to 225. i did the block test and it failed. i guess this means the head gasket has a leak, although the oil and coolant look normal. guess the exhaust gases are leaking into the coolant causing it to overheat? does anyone have a ballpark figure of what the head gasket costs to change? i assume it is expensive. very bummed out, this is what i was afraid of. any advice? thanks for everyones help.

 

[Jackie grabos]

forgot to ask, is there anyting else that should be done when changing the head gasket, timing belt extc?

 

[TurboBuRick]

Don't tear your motor apart yet.

What are you watching the temp on?? Gauge? ECM?

Does your cooling system hold pressure?

RL

 

[Jackie grabos]

i am reading temp on vdo gauge, also have a new temp sensor installed. have not had cooling system pressure checked. i have new radiator, thermostat, fans etc. don't know what else it could be.

 

[BlackBandit]

do you still have the baffle under the car that seals off the area below the radiator so the air entering the grill is forced to run over the radiator instead of just getting forced down and under? I doubt it's your pump.

just a thought.

 

[TurboBuRick]

Do you have a scanmaster? What is ecm coolant sensor reporting?

Check upper or lower radiator hose after a short ride. A firm hose would indicate the system is under pressure. If the hose is easily squeezed, the system is loosing pressure.

RL

 

[Jackie grabos]

when i let it heat up to about 180 after changing the water pump i felt the lower radiator hose and it was easy to squeeze. this is after car was sitting for about 10-15 minutes. does this confirm bad head gasket. i thought the block tester was full proof, if the color changes from blue to yellow then there is internal combustion leak, is this not right?

 

[TurboBuRick]

I would not trust a chemical test alone. Get some hard core data before you go doing drastic engine work.

Does the gauge reading coincide with the ecm coolant temp?

You may be loosing pressure and fluid past the radiator cap. If it was going somewhere else, you would see it.

Just to clarify, are you actually loosing coolant?

To check cap, fill the system and put the cap back on. Pull the small over flow tube off the radiator fill neck. Squeeze upper radiator hose. If fluid comes out, your cap is bad.

 

[chops]

Make sure your not boiling over and that's why you think your losing coolant ! Also make sure you don't have any air pockets that will definitly cause overheating . Was any thing done to the cooling system before you noticed this problem?

 

[BlackBandit]

An air pocket would make it overheat whether he was moving or not. Inadequate flow over the radiator at speed would cause overheating.

Edit: The OP indicated the car only overheats at speed in his first post.

 

[chopped39]

Pull the spark plugs and pressure test coolant system. Then turn engine over by hand and see if any coolant comes out of spark plug holes. do it cold and if nothing do it hot. Or you can do a leak down test and watch for bubbles in radiator. follow directions on leak down kit but also check the cylinders at bottom dead center. I have had cylinders crack an inch below the deck so if piston is at top dead center you wont find it. these tests are easy. How far down was coolant down in radiator during block check test?

 

[86GN-862+2]

Just throwing this out there… I had a GN that would the same thing no matter what I did to the cooling system. Turned out to be the weak link stock transmission and converter. Swapped a rebuilt unit and a restalled D5 and overheating is no more. Good luck. The ticking noise could be the oil is too thin when hot so lifters bleed faster. Just some thoughts. Hope you post up when problem is resolved. I hate unsolved mysteries.

 

[Jackie grabos]

when block test was done was after water pump changed. coolant was about 4 inches below neck of radiator. i could see coolant moving through radiator. i have side pieces of radiator schroud but missing the bottom piece. thanks

 

[TurboDave]

i am reading temp on vdo gauge, also have a new temp sensor installed. have not had cooling system pressure checked. i have new radiator, thermostat, fans etc. don't know what else it could be.

This question has been raised a couple of times and I didn't see your answer.

What is the ECM reporting(on scanmaster) as coolant temp as compared to your gauge???

I also have a VDO temp gauge and if I had to rely on it, I would also be complaining of overheating or consistently running hot.
However, my scanmaster reports more realistic temp values.

I know it's a vdo gauge problem because of its inconsistent readings and many times reading way hotter than what is realistic for the conditions.