Might have a blown headgasket
Since the facebook guys don't seem to want to post my issue, I will try here.
Here are the facts: 1. The temp gauge is occasionally rising above normal. 2. After the car cooled after the first time my son noticed this, I checked the coolant level. The radiator wasn't full to the fill neck. I topped it off with a couple of cups of coolant. 3. After topping off the radiator, I drove the car 100 miles up and down hills in northern central PA. The car didn't get hot AT ALL. 4. Fans are working. 5. After a couple of days of driving back and forth to work (20 minutes each way) I saw the temp gauge climb again. Again, the radiator was not full. However, the overflow tank was more full than it was previously. I topped it off again with quite a bit of coolant. It drove home with no overheating. 6. I bought a new radiator cap. When I went to install it, I noticed the radiator was not full again and the overflow tank was full to capacity. 7. I installed the new radiator cap and transferred some coolant from the overflow tank to the radiator. 8. I ran the car at idle until the fans came on. I saw no bubbles in the overflow tank. The temp dropped like a rock when the fans came on. It didn't overheat. 9. I see no oil in the coolant. 10. My mechanic pressurized the cooling system and said it held pressure for 30 minutes and he didn't see any obvious leaks. So, I will see if the radiator cap helps. If not, I suppose the inevitable finally happened. Any other ideas or comments? |
Re: Might have a blown headgasket
Keep an eye on the gauge. If it's overheating you should see bubbling. Has it been hot as hell there like it has been here in Quebec?
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Re: Might have a blown headgasket
Have you recently changed cooling fluid ?
If so then you need to burb the system, normally by jacking up the car (from front or rear - someone else confirm which one). Then while jacked up fill the cooling areas..... I find it interesting that the radiator is low and the overflow is ok ? - is the rubber pipe between them blocked or split, as the overflow should take up the lack of any water in the radiator. |
Re: Might have a blown headgasket
To be honest in my personal experience it does sound like the first signs of a blown head gasket.
The combustion pressure is slipping into the cooling passages (very very slight though at this point) it is displacing the coolant to the overflow tank since its only a very small amount at this point it isn't enough to push it out of the overflow tank yet. and why it passes the pressure test the combustion pressure is pushing from the cylinder to the cooling system and its very high pressures, pressurizing the cooling is (at this time) actually pushing the gasket into place sealing it better. And since the problem is very very slight right now the car won't over heat until enough coolant is removed from the system to be low on fluid. |
Re: Might have a blown headgasket
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Also check the bottom of the reservoir for clogs or debris. I have seen coolant pumped into the reservoir, under pressure, from the radiator when the engine is hot. As the engine cools down, the radiator should draw the fluid back from the reservoir which is normal. however, if there is debris at the bottom of the reservoir, it may keep the fluid from draining back. Repeated cycles just keep the fluid entering the reservoir (and filling it) Easy to remove and check. But I did experience head gasket failure back in 2009 with 122,000 miles. . |
Re: Might have a blown headgasket
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I had a shop use this tool on my Outback with great results. Uses vacuum to exacuate all the air from the cooling system and draw in 100% new coolant without air pockets. https://www.amazon.com/UView-550000-.../dp/B0002SRH5G See the video here of how it works. https://youtu.be/_WCRcuCZI50 |
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And as to the coolant pushing into the overflow then getting sucked back, yes in normal operation that is what happens, however that relies on heated coolant pushing out, and cooling coolant inside the engine contracting creating a vacuum to pull the coolant back. but if the exhaust gas is seeping into the coolant those gases are displacing the coolant, thus no vacuum is occuring. |
Re: Might have a blown headgasket
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I need to decide what to do if it is a blown gasket. It will cost me about $1800 to get it repaired. It is a 96 with no rust at all and runs well otherwise. It has 149K on it so I think I can get another 50K and probably three or four years if I reseal it. That is definitely worth $1800. But I will be driving a car with crappy clear coat and several dings and scratches around for 3-4 years. Not sure I want to spend $1800 to do that. Do I spend an additional $3K and get it repainted too? Then it would look less ghetto. But now I probably need to get at least 5 years out of it to make it worth while. Tranny is original so will I get 5 more years? And, even if I do, will I want to drive it around daily when it is pristine? I suppose I could go all out and turn it into a garage queen and bring it to car shows. Not sure if I am a car show guy though. |
Re: Might have a blown headgasket
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Re: Might have a blown headgasket
This is a how to to find out if the head gasket is leaking combustion gasses into the cooling passages. Disregard the rattly noises, bad bearing in the power steering pump. Here is the Tester I own and use, but any shop will have one, or any of this type will help. The blue fluid when in contact with the carbon-monoxide (I believe is the gas that does it) turns green if just a small amount, or yellow if large leak. https://www.amazon.com/UView-560000-...on+Leak+Tester |
Re: Might have a blown headgasket
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Well, the rad cap is not the problem. New OEM cap and it overheated on the way home yesterday. I will check for a clog like John suggested and order the tester but I suspect it is a gasket. Seems logical to get the engine re-sealed at this point. I just need to decide if paint makes sense. |
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And since the intake manifold is off, the PCV valve too... . |
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Nice. I may pick up one just for the hell of it. Necessary tools for a Subaru owner! |
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