Head Gasket?

checked my compression , cylinder 1, 3, 6, have 120psi. 2 and 4 have 150psi, and 5 is 10psi, I put a Little oil in and shot up to 30psi. theres oil in the water too, So does that sound like a head gasket

I think the engine is certainly worthy of a teardown, with those numbers and the fact that you have oil and water mixed, to determine exactly what happened.

those Numbers are with the engine cold,

You need to do two tests: a cylinder leakdown test and a cooling system pressure test. That kind of compression issue could be bad rings, a chipped piston ... Or ahead gasket leak. Do some more research before you tear it down. Either way I suppose you'll be taking the head off to see what's going on inthere, but it's nice to know as much as you can before you go in...

I did a cooling pressure test, and it was slowly losing pressure, How do I do a leak down test?

A leak down you may need a shop to do for you, but basically you pressurize the cylinder with compressed air. Although in your case the compression test pretty much tells the story. What you may be able to determine from a leakdown test is where the air is escaping, coult be a bad valve seal for example. Also with the pressure test on the cooling system, where was your pressure going? Coolant should be coming out there, wherever there is. It would hopefully make some noise, did you listen with a stethescope (piece of garden hose)?

no but I seen watercoming out the lower intake gasket, how would I know it is the rings? It started has a misfire at WOT

That's an important clue right there. The original LIM gaskets are notorious for warping after years of service, so you definitely need those. The coolant seepage could be the cause for ring failure or worse. If you are lucky it's just a head gasket, the 10PSI number is very alarming to me. You also said there is oil in the water? Do you just see oil under the radiator cap? is there white foam under the oil cap? It's possible for both of those to be caused by a bad LIM gasket, but you will want to figure out where your compression went. It's possible that if coolant was getting into the cylinder it ruined the rings. Do you have any blowby? If you take the oil cap off while the engine is running is there significant pressure coming out of the crankcase? Do you have to add oil frequently?

Again, hopefully it's just the head gasket here, Be careful of the gasket when you take the head off and you should be able to see signs of what was leaking to where. There will be a nice picture drawn out for you from port to port, either on the head, the gasket or on the block itself.

Your misfire certainly can be attributed to no compression... how is that spark plug? If you chipped a piston (worst case scenario) the plug is probably banged up a bit...

I did a leak down test, and it was blowing air threw the intake, so I pulled the head off and found a burnt intake valve. One side of it was flat. I had to order ever thing, but I should be back on the road in 4 days. There was a lot of head gasket medal ever were too.

Good, sounds like you found it! I'd guess the intake valve failed due to the LIM gasket leak...

Do u think so? Heres a dum question how could that cause it to fail?

The coolant flashes into steam and eats at the valve over time. The steam will ruin the valve seat/valve lubrication with rust... one way it could happen.

Derek, Thanks for all ur help, I would'nt of even thought about a leakdown test, That really pin pointed my problem. One more question what should the compression be at?

Compression is different for every motor, and without knowing the specifics of the S1 3800, 120-150 is in an okay range. I haven't seen a high milage motor that didn't have a wide spread. On a new engine they should all be much closer, within +-10 (range of 20) of the average... you'll see different numbers depending on the compression ratio, piston design, combustion chamber shape, how good the cold dry seal is of the rings (hot&oily makes a big difference), what kind of rings you use... stuff like that, but still usually well over 100 for all cylinders.

Glad you found the problem and it's not replacing pistons!!

Yeah me too, replacing pistons would suck, thanks again!

I wish I had the money to do 1.9 rockers, I think that is the next mod I'll do

OK Deekster, great work but you're not done. My Buick is fine but my child's 96 Lumina with the 3.1 has oil in the coolant. It was Grandma's car and has had the LIM gasket replaced before we got it. So how can oil get in the coolant besides the intake manifold? Thanks a lot.

I was looking at the head today and I notice a small crack in between the Intake and Exhaust Valve. Now I'm a little worried about this!!! How bad is this? I'll try to get some pictures

Im thinking I may have to buy a new head

Should I replace 1 or both heads? I found some on ebay. I was thinking that it might be better to do both, since the front is this bad, I would hate to see the back one looks like

those cracks between the valves are pretty common on the pre 97' heads. There are people still running them regardless.

99prixgt wrote:

those cracks between the valves are pretty common on the pre 97' heads. There are people still running them regardless.

This is a S1 engine don't forget.

If I found a crack like that I wouldn't run it. It's hard to tell - but is the valve cracked too? That could be where the compression was going.

anyhow, if it were me I would replace the head. You want to make sure you get another head with the same casting number, or consider replacing both heads together, just to make sure you get the same size cc', or else have the new head's cc checked by a machine shop and compared to your original head. Did you take both heads off?




Steve, how else can oil get in the coolant? Intake manifold gasket, head gasket, timing cover gasket... how much? Could it be leftover from the LIM gasket change? How often do you need to add oil? Is the coolant discolored? Do you get a little brownish-whiteish foam on the inside of the oil cap? (indicates coolant in the oil)

I would start with a coolant flush and see how quickly it comes back.

No I havent took the other one off yet, Im tring to decide if I sould replace both or not

I would take the other one off and take it to a competant machine shop and have them Magnaflux it, this should reveal any cracks.

Concerning the oil in the coolant: no I don't see any indication of coolant in the oil, no foam no chocolate milk colored oil. Just a little bit of oil in the expansion tank. Could be left over from earlier. I'll flush the coolant some time and see what happens. It seems to have normal oil consumption for a 100k car, about a quart in 5k miles so I'm not too worried about it. Thanks for the advice.