Engine temps all over the place (Page 5/9)
Spoon NOV 23, 07:32 PM
Cliff, some coolant loss will not leave any evidence such as puddles under car, clouds of steam, etc, but a working temperature gauge will indicate something is not normal. I've experienced such events myself. One turned out to be a bad head gasket. I'd have to add coolant once a month. I discovered the problem by accident while working on a running engine with the back of my hand near the cylinder head and exhaust manifold. The head gasket was leaking but the vapor leak was invisible to the eye. The car was a 67 GTO with less than 30k miles.

Another event was a Ford Econoline kept loosing coolant with no puddle evidence left behind. About once a month I would add coolant. No odd smells at the exhaust or extra clean spark plugs indicating a problem. Another accidental discovery found the problem. I was removing some air intake ducting and saw a fine crack on top of the radiator which is the plastic area. I tried a product called K-Seal that worked for months until I got around to having the radiator professionally repaired and flushed.

My advice would be go to Orges Cave and find out the proper radiator cap & T-Stat for your Fiero. Also any cracks in your coolant recovery bottle can cause a problem as well as some of the issues mentioned on this topic by others.

https://www.kseal.com/products/k-seal

Spoon


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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

Cliff Pennock NOV 24, 03:14 AM

quote
Originally posted by Mike in Sydney:

Where from? How much? Any strange puddles under the car? Like I said in a previous post, I had low coolant levels and I saw problems similar to what you are describing. I was able to identify the leak because of a big puddle of coolant.

Does your oil look like a chocolate milk shake? Got any sweet smelling exhaust (if you have antifreeze, anyway.)? What do your plugs look like? Do you have any that are really, really clean?





I don't see it leaking anywhere. No puddles under my car. Oil looks normal, no weird smelling exhaust (or white smoke). Haven't checked the plugs (they haven't been removed for over 20 years, I'm afraid they will break off).

The water pump has a metal impeller.
Cliff Pennock NOV 24, 03:20 AM

quote
Originally posted by Spoon:

Cliff, some coolant loss will not leave any evidence such as puddles under car, clouds of steam, etc, but a working temperature gauge will indicate something is not normal. I've experienced such events myself. One turned out to be a bad head gasket. I'd have to add coolant once a month. I discovered the problem by accident while working on a running engine with the back of my hand near the cylinder head and exhaust manifold. The head gasket was leaking but the vapor leak was invisible to the eye. The car was a 67 GTO with less than 30k miles.



Well, I know one (maybe both) of the the exhaust manifolds has a leaking gasket.

My problem is that I don't have a garage to work on the car in. All work needs to be done at the side of the road, so I can't do any repairs that might take longer than an afternoon to finish. Also, anything left "open" will collect water and sand (I live a few hundred yards from the beach).
theogre NOV 24, 10:10 AM
If loosing coolant and can't find the leak(s)...

see https://www.fiero.nl/forum/Forum2/HTML/145505.html Coolant Pressure Testing for Fiero.

Many repair and part shops have a tester but not T-stat adapter to test Fiero w/o taking other things apart to clear the radiator neck.
Part shops can have "loaner tools" to rent or loan w/ deposit you get back.

This way can pressurize the system when cold, on a lift, etc, looking under the car or other places.

Other Example: http://www.fiero.nl/forum/Forum2/HTML/146198.html Hidden Fuel and Coolant Leaks...
Cliff Pennock DEC 20, 12:16 PM
Ok, I know it's leaking coolant, and I still don't know where but for now that's a secondary problem. I'll try to explain why.

Like the subject says: Engine temps are all over the place. I honestly think it's losing coolant because of this. And not the other way around; that the temps are all over the place because it's losing coolant. Reason being that even when I refill the coolant, and making sure there's is no air in the system and the overflow tank is filled, engine temps are still all over the place.

I refilled coolant yesterday. Did the thing where I parked the car on an incline, opened both the thermostat housing and radiator, removed the thermostat, topped of coolant (at the thermostat housing) until coolant flowed out of radiator, closed caps, run engine for a few minutes - repeat. Run the car until it's hot, filled overflow bottle, removed thermostat cap, open radiator cap to let air out, refill if necessary at thermostat cap.

Sorry for the Cliff's Notes, but I did all I can to make sure coolant system is filled and no air is trapped. So I drive it for 10 minutes and it overheats. Few minutes later temperature drops to normal, only to rise again after a few minutes. This repeats itself for about 20 minutes, after which the temperature settles at normal (below 90 degrees) temperatures. After driving it for a while, if I check level at thermostat housing, it's at the top. If I open radiator cap, no air escapes - it starts spewing coolant immediately. Overflow bottle is still filled.

Odd thing I have noticed: if I do a sharp turn to the left, it overheats. Sharp turn to the right and temperature drops again.

So the only thing I can think of is that the thermostat is the problem. But I've recently replaced it and that did not help. Could still mean the thermostat is at fault because it's either junk or I got another faulty one.
ArthurPeale DEC 20, 04:03 PM
remove the thermostat completely and run it. If it overheats again, I'd say not the thermostat.
Cliff Pennock DEC 20, 06:25 PM
Yes I did that. Never overheated. In fact, never got up to temperature. It stayed at around 140F...
Patrick DEC 20, 06:55 PM

With the Stant SuperStat apparently no longer available, maybe it's time to re-investigate the merits of an old trick - thermostat modification

I'm sure The Ogre will have an opinion on this.
Cliff Pennock DEC 25, 08:07 AM
Ok, I drilled a 1/8" hole in the thermostat:





I need to make a small trip this afternoon so I'll let you know if it made a difference.
Cliff Pennock DEC 25, 02:39 PM
Yeah, so that didn´t make much difference...