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Head gasket/compression test (cold)
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Old 13 Apr 2014, 07:53 PM   #1 (permalink)
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Head gasket/compression test (cold)

Hi people, newbie member here after a little advice from those with more experience!

On Monday last week I picked up a 51 plate, WRX with an oil leak & suspected head gasket problem. Since then I have been having a look over it, (around the other projects!) and I can't seem to find a lot. On driving it back home there was no steam/smoke from the exhaust, no bubbling in the header tank, on the one try I got, still pulled like a bee-atch, sounded like a gorilla raping a wasp & felt solid with no knocks or bangs.

It has definitely been serviced recently, it's obvious from the new parts all over it, from the log book it's been well looked after and only had one keeper from new. After dropping the fluids out, the oil seemed fine, and the coolant had the very odd speck of oil in it.

Just done a cold compression test, had 95, 95, 95, 102. Is this a little low or just from being cold? It has been stood for about a week as I don't want to run it until I know for sure what's wrong.

I have heard various rumours about Subaru dealerships being over cautious with the head gaskets, as well as people changing the fluids after diagnosis from them and not having any further issues. I have also heard that the head gaskets are prone to break between the oil and coolant ports at the bottom of the head.

Anyone got any advice as to where I can go from here, and if there is any other way to test without having to rip the heads off for a closer inspection as it's the DOHC.

Many thanks in advance
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Old 18 Apr 2014, 12:25 PM   #2 (permalink)
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Re: Head gasket/compression test (cold)


Compression Testing

These might be of help to you
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Old 20 Apr 2014, 04:53 PM   #3 (permalink)
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Re: Head gasket/compression test (cold)

Great guide, thank you very much

Well, bearing in mind the motors done nearly 240k, but has been looked after by one owner, here are the results. (Started turbo corner then worked around anti clockwise.., teas nearly do e and haven't time to google locations & firing orders!)

Turbo corner: 149
Power steering revs: 147
Battery corner: 146
Screenwash corner: 143

As previously stated, there were no signs of head gasket failure either from the exhaust, no bubbles in the tank, no sweet smell in exhaust, and no overheating. After the compression test (done dry but after warming up to normal op temp with FOT) im wondering if the usual oil & coolant port has got a slight crack in it? If so, if I bypassed the heater matrix first, could I get away with using some steelfix rather than rip the engine apart as it's only going to be more of a fun plaything/hill climb project?
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