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| Overheating but not really? Air in system or other problem? Need help diagnosing (Page 2/14) |
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cvxjet
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OCT 31, 06:33 PM
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I want to chime in here with a problem I have not heard of with our Fieros but happened on my '73 mach 1. I rebopped the cooling system- new radiator, hoses, and heater core. The car would do fine but every time I got on the freeway it would overheat.....Finally figured out that the LOWER radiator hose was collapsing under suction- The hose had a spring in it to keep it from collapsing- but this spring was short!
Ended up cracking the Cleveland heads (They are known to be weak) I swapped in a FI 5.0 and AOD trany...
My question here is, do any of the Fiero hoses have anti-collapse springs in them? This is a bizarre set of circumstances- It took me a while to figure it out.
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Spoon
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OCT 31, 08:51 PM
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A lower radiator hose with a spring to prevent collaspe is on the suction side of the water pump. I don't recall the Fiero having one. Nonetheless at idle it is less likely to collaspe than at a higher rpm. Your Fiero is overheating at the lower rpm.
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
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cebix
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NOV 01, 09:35 AM
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Still suspecting it's got air in it. After multiple burpings I can hear now fluid sloshing around in the heater core at startup and some hissing while revving up and down.
Thinking of installing a T fitting to the heater hose to help with burping but for now I want to purge it the way it is.
How should I burp the core? Hot or cold? Engine running or not? Thanks.
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olejoedad
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NOV 01, 09:43 AM
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The core will self burp.
Coolant flows through it constantly when engine is running.
Check undercar lines on passenger side of fuel tank for kinks or crushed area.
(Not very common)
Im thinking you have a small air pocket that will work its way out.
Keep the expansion tank level at the correct level and be sure the hose does not leak.
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Spoon
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NOV 01, 06:00 PM
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I usually fill the system and run it for several miles without the stat. That way coolant will circulate hot or cold. after it cools off I check level in bottle and add if needed. Then I add to t-stat housing if needed and put the t-stat back in. Start engine and let it warm up til fan kicks on and back off. Drive and watch the temp and check for heat at the vents.
Seems to work for me.
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
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fierobear
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NOV 02, 11:47 AM
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All good ideas so far, but one issue hasn’t been raised. What condition are the radiator and thermostat housing caps? Does coolant keep rising in the overflow when you add? That normally means a bad rad cap seal.
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cebix
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NOV 02, 04:22 PM
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Radiator is old, condition unknown. Rad cap is new but isn't hot to touch, just warm when engine is hot. Thermostat cap is new and seals great.
I've been trying to burp the system today a few times and I keep adding coolant to the thermostat housing and it just seems to want more and more. Also today my expansion tank overflowed coolant on the ground a few minutes after the hot engine was shut off. You think the rad cap may be bad? It's new and the correct type and pressure rated, non vented.
After shutting down the hot car I opened the hood and the rad cap was hissing. I watched the overflow tank expand and expand and it overflowed about 3 minutes after shutting down the engine.[This message has been edited by cebix (edited 11-02-2019).]
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theogre
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NOV 03, 09:58 AM
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| quote | Originally posted by cebix:
Radiator is old, condition unknown. Rad cap is new but isn't hot to touch, just warm when engine is hot. Thermostat cap is new and seals great.
I've been trying to burp the system today a few times and I keep adding coolant to the thermostat housing and it just seems to want more and more. Also today my expansion tank overflowed coolant on the ground a few minutes after the hot engine was shut off. You think the rad cap may be bad? It's new and the correct type and pressure rated, non vented.
After shutting down the hot car I opened the hood and the rad cap was hissing. I watched the overflow tank expand and expand and it overflowed about 3 minutes after shutting down the engine. |
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Should be right cap but could be bad or leaking.
Cap can be 100% good but rad neck may be damage and cap and tube can have problems.
If good there then system still has problems which is likely.
Rad cap hot might not mean much. check D side tank and see if is hot or not at same time.
Cheap USB bore scope via amazon etc can look inside of rad tanks and often have mirror tip to look at tubes too. Often w/o taking rad out of car but you must drain the system before using. try to anchor USB end to laptop etc so you can't stress that end and break USB plug or port. Auto Trans rad's maybe hard to find spot to get by trans cooler to look at bottom of D side tank. Either way is easy to stress USB end as you bend/twist the other end.
Check oil.
If engine keeps taking coolant, possible someone F'd the rebuild and leaking coolant in #4 cyl from bad intake gasket then "burning" coolant or in the oil thru iffy head etc.
If you have some shop neerby w/ exhaust tester... See if tester see exhaust in T stat tube. Do not put tester on coolant, just sniff the opening w/ cap off. If tester see exhaust there then have a rebuild w/ big problems. But problem is if you have coolant flow problems too then might not get enough exhaust there to test.
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fierobear
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NOV 03, 11:30 AM
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| quote | Originally posted by cebix:
Radiator is old, condition unknown. Rad cap is new but isn't hot to touch, just warm when engine is hot. Thermostat cap is new and seals great.
I've been trying to burp the system today a few times and I keep adding coolant to the thermostat housing and it just seems to want more and more. Also today my expansion tank overflowed coolant on the ground a few minutes after the hot engine was shut off. You think the rad cap may be bad? It's new and the correct type and pressure rated, non vented.
After shutting down the hot car I opened the hood and the rad cap was hissing. I watched the overflow tank expand and expand and it overflowed about 3 minutes after shutting down the engine.
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It has been my experience that if you keep adding coolant and it keeps going into the overflow tank, it’s the Rad cap. If I recall, parts stores actually list the wrong part for the Fiero. Ogre can probably clear this up.
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theogre
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NOV 03, 03:45 PM
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| quote | Originally posted by fierobear:
It has been my experience that if you keep adding coolant and it keeps going into the overflow tank, it’s the Rad cap. If I recall, parts stores actually list the wrong part for the Fiero. Ogre can probably clear this up. |
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Already did... has New non-vent cap as in cave. He's read my cave.
"Boil over" and most of coolant system is cold to barely warm is blockage somewhere or rebuild engine has big problems like messed up head or intake gasket(s).
4 cyl Intake gaskets are Dry install. standard ones are rubber/plastic over metal and sealer or wrong bolt torque will leak coolant out or far worse leak into #4 runner.
just iffy 1 head bolt and head gasket can leak coolant, cyl pressure or both and can be internal, external, or both.
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