Originally posted by fierobear: 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.
Sorry, dude, I messed up. The link I gave you was for my OBD2 scanner for my Escalade. I use an AutoXRay OBD1 scanner for Fieros. They don’t make them any more, the company looks like it went out of business. I recommend getting a real time/live data scanner. Just this morning, I got another long dead Fiero running, and when I got it running well I put my scanner on it and it showed the coolant temp sensor is reporting to the ECM a temperature of -37 dF, which will cause all sorts of running issues. I now know to replace that sensor. Scanners are highly recommended .
Been driving around just to see what it does and it is kind of more civilized now I guess. Only shoots up some above 220 and then goes down quickly even without hitting the throttle. Then it still kind of oscillates but it looks a lot better. Also there's no rad cap hissing so I guess that was indeed the overflow hose sucking in air. Maybe _now_ it's just time until it burps itself?
Got a multimeter with a thermocouple and measured the temperature where the gauge sensor goes into the block and it pretty much confirms what the gauge says. It's not as fast as the gauge but it settles at what the gauge says. On hot shutdown it soaks to about 220 which is what the gauge shows when after shutdown I turn on the ignition. Hot engine running seconds before shutdown it was at the second mark. Couldn't really get to measure it where it was shooting up days before due to traffic and the gauge not pegging that high anymore... for now at least.
No reservoir overflowing, level changes hot/cold good so the hose is flowing. No rad cap hissing. However I noticed after shutdown my thermostat cap now is hissing a little bit... Is that normal? Or should I replace it? It has been opened up and closed a lot of times this past month so I guess it can wear down.
EDIT: I did mention before that my thermostat was loose in the housing. The Stant new one is snug so I guess the Gates one was a little less in gasket diameter.
[This message has been edited by cebix (edited 11-26-2019).]
I noticed after shutdown my thermostat cap now is hissing a little bit... Is that normal?
Originally posted by Patrick:
The top of the thermostat housing can get bent from improper removal of the cap (ie using a big honkin' pipe wrench to remove it), so you need to make sure it's flat. I've used sandpaper on a flat surface (when the housing was off the engine) to see where the high points were, but something similar can probably be done while the housing is still on the engine. You want the top edge of the housing to eventually be corrosion free and flat, otherwise even a new cap won't be able to seal. And when the cap is put on, push down while turning to make sure it's turned all the way (past the first click and to the end).
[This message has been edited by Patrick (edited 11-26-2019).]
Still fighting with it, driving around, no change. Made a rubber gasket to seal the thermostat cap. Now the thermostat housing is leaking where it attaches to the block... Guess now it's a leak hunt.
Anyways another question - how much should the reservoir tank level move? It's at "ADD" level at cold and goes up about half an inch maybe when hot. Should it go all the way up to "FULL"? That's about a 3 inch difference I guess. I'm wondering if my leaks are excessive pressure related since they weren't there before and if my rad cap is actually opening or has the little hose clogged itself... Many thanks.
EDIT: Then again I think because of a leak there might never be enough pressure to push the rad cap open? I guess I'll post again when I get rid of the leak(s).
[This message has been edited by cebix (edited 12-04-2019).]
Looking for leaks and found this too. This is the hose that connects to the passenger side coolant tube in the rear (under the water pump).
Looking for a side of the road fix - I don't have the means to flush the coolant again right now since it's a pretty low point in the system. Is there a way to fix this without taking the hose off? Maybe just try to tighten the clamp, maybe move it further a little or is there no point in doing that? The same thing is on the water pump outlet... Many thanks.
Since my reservoir tank level stopped moving much if at all I guessed anything goes at this point and decided to check the reservoir hose for flow and the rad cap "hole" that goes to that hose.
The hose was clogged. Some weird shaped rubber stuff, maybe the hose is disintegrating from inside... I guess that's where the leaks came from, shouldn't have fixed them before checking out the reservoir tank issue. Hope I didn't blew anything like a head gasket but I didn't see any leaks.
Anyhow, first drive after the fix. I filled the cold tank to the halfway point between "ADD" and "FULL". Drove about 3 miles, checked the level with the engine running at temperature and it was about a half inch higher so I guess that's good(?).
However - the second I shut the engine off there was a loud "whale" sound from the radiator for about 3 seconds and in those 3 seconds the reservoir tank filled itself to the "FULL" mark. Does that sound like a clue to you guys? I guess that's not normal? Does that indicate something? Many thanks for your help, I wouldn't have gone to this level without this forum and hope to finally nail my cooling issues down.
EDIT: This was what clogged the hose, I have no idea what this stuff is on second thought... It's about 7mm in diameter. EDIT2: Checked level 2 hours after driving - the level dropped nicely and noticeably from full to about an inch lower so I guess the hose flows good again and the rad cap is good.
[This message has been edited by cebix (edited 12-11-2019).]
However - the second I shut the engine off there was a loud "whale" sound from the radiator for about 3 seconds and in those 3 seconds the reservoir tank filled itself to the "FULL" mark. Does that sound like a clue to you guys? I guess that's not normal?
Geez, how big is your reservoir tank?
Even though I live only about a mile from the ocean, I have never heard a whale sound while in proximity to my Fiero(s).
I really have no idea what the hell that is but it's rubber.
Rubber? Are you sure? Judging from the size and shape of it and the "sealant" you found in your reservoir, I'd hazard to guess it's possibly a not fully dissolved Bar's Leak (or something similar) pellet.
I suspect your cooling system is still partially plugged up somewhere with this stuff.
Originally posted by cebix:
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.
[This message has been edited by Patrick (edited 12-11-2019).]
I searched for Bar's Leak pellets and thought that those are inside the bottle in the link you posted. If you're saying those look like stop leaks then it's highly probable that's it - I've never seen one personally.
Wonder how long was that stuff in the system and what else is in there. I've had the car since I registered here and this problem only showed up about two years ago I guess(?) and persisted through the engine rebuild. But I already flushed the system once fully and it was supposedly flushed during the rebuild too so I don't know how much can I get it flushed... Guess will have to watch out for that hose clogging up if anything else will unclog itself and find its way there.
[This message has been edited by cebix (edited 12-11-2019).]
So the overflow hose clogged again. Didn't find any major evidence this time, just noticed the reservoir level stopped moving again and some crap in the tank. Decided to take the tank out again the next day after no driving.
So I leave the car for the night and in the morning there was a puddle of coolant on the passenger floor... Bypassing that is going to be probably the next thing to do until a new core arrives. So flushed the tank, was ready to start burping to see if I can see the heater core leak, pulled the tstat and its gasket looked like this:
Could too much pressure in the system have blown this? And the heater core probably too and who knows what else...
A question about burping... say the system's a little low on coolant. Will it ever fill itself up just through the overflow tank after some heat cycles and just filling that tank up will do the job or will the overall level never change and coolant has to be added to the system internally through the rad or thermostat openings anyway?
Patrick, I haven't done anything yet to the radiator other than the full system flush about a month ago with the radiator connected but it seems there is still crap circulating. So yeah, probably it's finally time to get the radiator on the bench and flush it properly or just get a new one.
fierosound, I did a flush like you described about a month ago but I didn't take out the radiator.
About the heater core - I have AC and I see two variants available, a $25 aluminum Spectra one and a $35 APDI copper one. Which one do you guys recommend? Thanks
[This message has been edited by cebix (edited 12-15-2019).]
About the heater core - I have AC and I see two variants available, a $25 aluminum Spectra one and a $35 APDI copper one. Which one do you guys recommend?
I'm unfamiliar with the new copper ones, but the new aluminum heater cores are dimensionally a bit smaller in size. It's not really an issue, but just be aware that they don't fit as snugly as the original cores.
When you temporarily bypass the leaking heater core, do not restrict the coolant flow through the heater hoses. If you do, there's a chance the thermostat "arms" will collapse due to the added pressure (as reported Here)... and once they've been bent and straightened, they're never as strong.
[This message has been edited by Patrick (edited 12-16-2019).]
So took the heater core out, made a bypass tube from a copper fitting.
Ran a test drive, no leaks, all hoses hot.
...and the temperature doesn't now fluctuate so much, pretty much just a steady overheating condition, and giving it gas doesn't help much anymore in terms of cooling. The fan even came on when the gauge was showing a little above 220 when it wouldn't engage before until heat soaked engine start and it did it while driving steadily at 30 mph.
Also the reservoir level didn't move one bit, just a slight "burble" after engine shutoff so I know the hose is flowing because I could see the coolant in the reservoir bubble up a little when this happened.
I know, I haven't taken out the radiator yet but wondering if this gives any clues to anyone... Why wouldn't the reservoir level change?
The fan even came on when the gauge was showing a little above 220 when it wouldn't engage before until heat soaked engine start and it did it while driving steadily at 30 mph.
I don't know what's going on with your reservoir, but there's obviously still a serious cooling system issue for your rad fan to be coming on "while driving steadily at 30 mph"... especially in December!
It's just weird that this came up after bypassing the heater core. There was some "rust" crap in the core so there's definitely some stuff circulating. Maybe there's an air pocket after removing the heater core. Going to drive around for a bit like this and see where it goes.
EDIT: The coolant level in the tank dropped overnight from half full to just below add. Filled it up to half full. Drove to work today and NO overheating whatsoever. And the hot level got up to almost full so maybe, just maybe it was the heater core all this time? Maybe now it's just a matter of burping itself?
[This message has been edited by cebix (edited 12-18-2019).]
So maybe it's a little early to be certain but I think it's solved.
It was a clogged heater core.
No overheating whatsoever with the core bypassed.
Unless the added coolant pressure, due to a plugged heater core, was somehow preventing the thermostat from opening (I don't know if that's possible), the heater core has little to no bearing on coolant temperature. I suspect you're going to have continued problems until you properly deal with the radiator. It no doubt has the same crap in it as the heater core had... probably a lot more of it.
You're probably right. I'm also now doubtful of flushing since it looks like it's not easy to get right and I doubt a shop will do any better and probably charge me more than a new radiator is worth.
Are there any specifics in the new Fiero radiators? I have an '85 2.5 automatic with AC. Do they all come with transmission coolers? My only real option because of shipping costs is a Spectra Premium CU828 from Rockauto which seems to say it's a universal fit but I would like to ask you guys for an opinion first. Thanks.
Thanks. Going back to your pressure buildup thinking - I think that might explain the sudden overflow of the reservoir after engine shutoff. And the pressure probably was what blew the heater core finally.
All right... Installed a new heater core and radiator. Flushed the system, burped it per Patrick's instructions... And it ran like a dream! Like a new car should. Steady gauge, all that. Sure enough I was happy it's solved.
That was yesterday. After cooling overnight I noticed the reservoir level didn't drop. So I took the rad cap off (maybe shouldn't have done that?) to see if the hose is flowing. It is. I'm wondering if I might have messed up the burping by removing the rad cap and introducing air back to the system. Is that possible? Looking for probable cause as a rad cap failure at exactly this time seems not that likely to me.
Also the "old" symptoms started creeping in back today, gauge starting to fluctuate at a standstill but not even reaching 220. Would go down rather quick after revving up and staying firm at highway speeds at the second mark.
[This message has been edited by cebix (edited 01-12-2020).]