Overheating but not really? Air in system or other problem? Need help diagnosing (Page 8/14)
Patrick NOV 16, 03:13 PM

quote
Originally posted by cebix:

I also guess your gauge is pretty steady and moving fluidly and not going into the red just to fall down with a blip of throttle down to 220 and less?



That would be a correct guess.


quote
Originally posted by cebix:

Haven't tried to flush the heater yet. Can't get those hoses off anyway, and would probably have to cut them.



My experience has been that even if the last inch or so of a heater hose needs to be cut off in order to remove it, the hose is still plenty long enough to reattach it.
Gall757 NOV 16, 09:36 PM

quote
Originally posted by cebix:

I also guess your gauge is pretty steady and moving fluidly and not going into the red just to fall down with a blip of throttle down to 220 and less?



My gauge moves up and down quite a bit....but not like that. That sounds more like an electrical problem.
cebix NOV 17, 02:45 AM
I'm going to try to shoot a video of the gauge while driving if I find a safe way to do so, so maybe it'll become clearer how it behaves. Don't really have the means to flush the heater right now so I guess I'll drive around for a few days and see where it goes from there.
cebix NOV 20, 10:27 AM
Not really sure how to shoot a video durig my commute showing the dash all the time. Might have to fabricate some kind of phone holder.

I've been commuting a few miles these past few days and no driving besides that. It's 40F here. The car still goes to red on first heatup after about 3 minutes from dead cold and wants to go up there all the time unless I give it some throttle. However it does become civilized after about say 15 minutes of driving and idles forever with the needle on the second mark. Guess it's burping itself? This would not be a symptom if it's clogged somewhere? Unless it unclogs after some heating up and clogs itself when cold? I'm going to flush the system this weekend and try to flush the radiator and heater core and see what I get.
Patrick NOV 20, 03:12 PM

quote
Originally posted by cebix:

Guess it's burping itself?



No, there's something else going on.
cebix NOV 20, 03:30 PM
Man, that's a shame, thought that would indicate something. Could it still be clogged? Guess I'll find out in the next few days.

EDIT: So I guess the current bet is an at least partially clogged heater core. Hope I find out soon.

[This message has been edited by cebix (edited 11-20-2019).]

cebix NOV 22, 03:50 PM
All right, been flushing the heater core and it flows all right I guess. Some rust particles came out but not so much to clog it I guess. Going to leave it overnight filled with vinegar to see what comes out tomorrow.



However! This is what I found at the bottom of the overflow tank:



Looks like sealant? No idea how much of that is in the system. The overflow hose also looks fishy and wasn't as tight as I would like at the rad fitting so going to replace it. Going to try to flush the radiator but have a feeling that the hoses under the car may be clogged with this stuff inside. Are they stainless steel? Is it safe to use NaOH to clean them inside? The radiator is aluminum so that's out of the question. Anyway looks like I have to overhaul the whole cooling system.
fierobear NOV 22, 05:02 PM

quote
Originally posted by cebix:

Not really sure how to shoot a video durig my commute showing the dash all the time. Might have to fabricate some kind of phone holder.

I've been commuting a few miles these past few days and no driving besides that. It's 40F here. The car still goes to red on first heatup after about 3 minutes from dead cold and wants to go up there all the time unless I give it some throttle. However it does become civilized after about say 15 minutes of driving and idles forever with the needle on the second mark. Guess it's burping itself? This would not be a symptom if it's clogged somewhere? Unless it unclogs after some heating up and clogs itself when cold? I'm going to flush the system this weekend and try to flush the radiator and heater core and see what I get.




The gauges, especially at their age now, are notoriously inaccurate. I’ve changed senders and temperature gauges in my 88GT more than once and it still goes nuts. The way I test the real temperature in the system is I put a scanner on the ALDL and see what the ECM is seeing. Do you know anyone with a real time data scanner?

Edit, remove scanner link.

Any time I’m reviving a long dead car or I need to be sure everything is working properly, I put the scanner on and see what the ECM is seeing.

[This message has been edited by fierobear (edited 11-23-2019).]

Patrick NOV 22, 07:59 PM

quote
Originally posted by cebix:

All right, been flushing the heater core and it flows all right I guess.



You need to flush more than just the actual heater core. You also need to flush the heater core supply hoses (both ways).


quote
Originally posted by cebix:

Looks like sealant? No idea how much of that is in the system.



Looks like the garage that supposedly did the "flush" did a crap job.

I've heard of people having huge problems with their cooling systems after way too much of that "stop-leak" has been added.

You'll probably need the radiator to be boiled out... or replaced.

[This message has been edited by Patrick (edited 11-22-2019).]

cebix NOV 23, 01:28 PM
Flushed the whole system, radiator, heater core. No signs of blockage and pretty much no crap came out. Got a feeling I got lucky with the reservoir crap as it probably was added to that tank and never got sucked into the system. Cleaned the reservoir tank, replaced the hose from the rad cap, burped the system per Patrick's recommendation... and no change, nothing. I installed that fitting you guys told me not to... I cut the heater hose a little short and it served as a good connection. So I used it as a bleeder valve and it worked good, let out a lot of air but the symptoms are the same. Might look at that IR gun though, they're not that expensive and may come in handy for other things.

Maybe indeed there's an electrical issue with the sender or the gauge itself? Or I did a crap job at flushing the system or there's still air. Got to say, there's no sign of overheating other than the gauge reading. Might try to get an ECM scanner but that $190 is a little too expensive for me. Or I'll try to install an external temperature sensor for reference.

[This message has been edited by cebix (edited 11-23-2019).]