I don't know if all compression testers do this, but mine holds the pressure in the cylindar that you create after doing the test until you press in a pin (kinda like a tires pin to let air out). Do all compression testers do this?

I'm asking because after a little research on what a leakdown tester does, does my compression tester effectively tell me if my cylindars are holding compression? In other words my head gasket couldn't be blown, at least in the cylindars because I'm holding my compression numbers solid?

Just curious is all.....

 

I have a similar compression tester. When my headgasket was blown, I did a compression test and got 200+ across the board(D16Y8), and yet when I boosted, the coolant in my radiator would get displaced and fill my reservoir tank. I didn't do a leakdown test, but I was certain it was the headgasket, so I changed it, and no more displaced coolant, no more overheating

 

So strange, I'm praying my coolant bubbling issue is not the head gasket, its happend 3-4 times so far in the past 2 months, doesn't happen all the time, its almost random.

I never overheated once though, ever... but those times I checked under the hood after driving and sure enough, you could head and feel the coolant bubbling, every time I let her idle to get them out for a good 10-15 mins... rev it up a little and no coolant sprays out on me or anything, strange.

 

Is your coolant displacing into your reservoir at all?

 

yah my car got pretty hot once or twice and my coolant resivior was boiling or bubbling or something......what could this be besides my head gasket???? my car still runs great......but this has happened a few times! thanks

 

Might be a small leak in the headgasket. Mine only seemed to leak under boost.

 

When it bubbles, it did this a little bit... but I always seem to catch it when it does this and bleed the system.

 

what were the characteristics? like, was your car not able to hold boost @ all or did the boost spike and then drop/hold constant @ a lower level?

 

What do you mean? If my headgasket was leaking boos tout the cylinders, it wouldn't reflect at all on the boost gauge readings. My manifold pressure was exactly the same as when the headgasket wasn't leaking. The reason I knew it was leaking was because when I would drive around on light-throttle with little or no boosting, my coolant wouldn't get displaced into the reservoir, but if I boosted, enough coolant would get dispolaced to the point where it would overflow out of the reservoir If that went on long enough, I would overheat. After letting the car cool down, I would check the level in the radiator, and it would be pretty low. Before I got around to changing the headgasket, I would just drive around boosting as little as I could, and when I would get home, I would let the engine cool, and then I would pour the coolant that had displaced into my reservoir back into the radiator. Most of the time the coolant level in the reservoir would start out at the MIN line, then after a day of driving, it would be near the top of the reservoir. After the engine cooled, I would pour the coolant back into the radiator, and the level in the reservoir would be around the MIN line again.