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ChevyGuy
User
Nov 3, 2007, 10:30 PM
Post #1 of 6
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help with sunfire
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i have a 1998 sunfire with 2.2 4cyl. when i have the car idleing at a fast speed it pushes the antifreeze out of the tank and when it sits the and idles it doesn't do anything
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 4, 2007, 3:44 AM
Post #2 of 6
(1410 views)
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Re: help with sunfire
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?? Do you mean radiator's end tank or recovery tank? Is the pressure cap on this car on the radiator or the recovery tank? Is the pressure cap any good? Sorry for just questions but need to know,
T
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ChevyGuy
User
Nov 4, 2007, 8:38 AM
Post #3 of 6
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Re: help with sunfire
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its got the recovery tank on the pass side
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 4, 2007, 11:31 AM
Post #4 of 6
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Re: help with sunfire
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Ok: If this does this with a working pressure cap when the engine is still just cool to warm this is tricky problem that might be a head gasket pumping gases into the cooling system. It could still do this with an overheat from another cause which needs to be determined. I still need to know whether the pressure cap is on the radiator or the recovery tank. Either way the radiator must be filled full to about spilling and that can take a few cycles or tricks to get air out of cooling system and then filled at recovery tank which should stay at the ranges marked on that tank.
So for now to diagnose further get the cooling system full at the radiator and tank as mentioned and just make observations while letting it warm up to norm as to the pressure felt in the upper hose and how fast it can pressurize and what happens with coolant as far as transfer to the recovery tank. Leave heater on and it should blow warm/hot air. If it can't there is probably air still in system or it's boiling and the boiling won't make heat for the heater and can blow coolant out. Don't allow that it if all possible as that's territory to wreck a head gasket or more when this could be simple right now to fix. At the moment I think air in the system is the problem and then how it got there is the question too,
T
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ChevyGuy
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Nov 5, 2007, 12:58 PM
Post #5 of 6
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Re: help with sunfire
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the cap is on the recovery tank. i did a radiator test and it stayed at 15lbs for about good 30mins
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Nov 6, 2007, 1:55 AM
Post #6 of 6
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Re: help with sunfire
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Ok, you've done what you should do - the pressure test. This is still likely to be a head gasket or flaw in the head perhaps.
As you said this can behave at idle and hold pressure but when put idle up it blows out to recovery tank. By that I take it that it pushes more than some expected amount - right? If it can go over and spill and it wasn't overfilled there to start with the combustion pressures have exceeded the 15lb pressure cap quickly and gasses are pushing coolant out. It would seem odd that it can hold pressure and that makes it rare but it can happen.
What is needed next is to test for exhaust gas in the recovery tank. There is an exhaust gas detector for that and even I never owned one but would borrow one in the rare event of something like this. I'd hate to see you tearing into this and be wrong.
It makes it tough as this is not steady and many cars don't put much for detectable gasses in exhaust. On an real old six or eight cyl with something like this you could just pull a plug wire and if it quit doing that there was a problem with exhaust gasses getting in and when that cylinder was cancelled it would probably stop doing it. That could work for a four cyl but they can run real lousy vs six or eight. Some you could even smell hydrocarbons.
With the pressure control on the tank there would be some exchange at different RPMs but not out of control watching the level.
All this could happen and it probably is the gasket and not a fracture in a metal part. Coolant must be full at radiator and throughout engine which can be hard if it's been low or empty for any reason to get it there and this could just be a hot spot making steam fast at one little spot but that would quit it if system was properly filled and free or air.
As I'm sure you are not interested in doing a job on this if this could be a normal fluke of filling the system up. Has it been low at the radiator? Can you see bubbles at the recovery tank? Some of the pressure at the recovery tank type systems are hard to get all the air out but again that would be soon after being low for some reason. Once filled and purged of air it stays that way unless there is a problem.
It can happen this way and hold the 15lbs but not more and don't exceed that with a tester. Some of these type things may only misbehave when cold or hot also. Leaks can happen only at low or high pressure but not in the middle which is why many techs are bald!!
Seriously. Ever have a leak in a tire that will get low but not flat or you can't find it when low and it shows up with soapy water at a medium pressure but quits at a higher pressure? That crap happens.
It is true that most things like this would not hold pressure and would put coolant into the exhaust when pressure tested but I seen it happen the way I understand this so far by your description,
T
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