Compression check when cold

[gottadiesel]

Can anyone tell me what I should expect to get when trying to read compression with the engine cold, as compared to operation temp.

So you ask why? Well I already have numerous items removed, including turbo and ex manifold. Yeah I know I should have checked plugs 1st, but anyway so I pull the plugs there were two issues, one is a certainly have an issue with both valve cover gaskets, but also the No3 Cyl head cover issue, which I know what I want to do to solve that issue, so there was oil on the top of the plugs and on the threads from that issue, but I the plugs are also wet in the chamber, not all but 2 or 3 of them had a film on them, so now I want to know why... so now I need to check compression to see if I am getting some blow by or what...

Unless I am perhaps missing something and the oil over time could actually make it through the plugs threads...but I assume not or another way that oil could make it on the plugs...

Any thoughts would be appreciated.

[spudz29212MKIII]

Did you read this first?

So it says check the gaskets and the No. 3 cylinder head bolts. Thats for the oil ontop of the plugs. Also torque is very important on the 7M, if somone over torqued anything on the head most important the valve covers which are very fragile, they could warp and not get a good seal on the gasket so that could be possible too.

As for blow by causing it, I doubt it. That would have to be a hell of alot of oil blow by. You would never have to change your oil again, your car would simply do it for you every 4 days. I bet (guess) it might be the opposite. The pooling oil in the galley may be leaking down into the combustion chamber, which puts me back at torque while im talking about it. The plugs need a certain torque also.

Ive only done a compression test on normal temp so I dont know the numbers cold. Before hand take the oil cap off and smell it. If it smells like gas you may have shot rings. Another thing if your plugs are fouled on the bottom it might be other things too. Have you used any Carb/throttle body cleaner lately or used too much fuel additive for too little gas in the tank?

Anywho just some ideas im no pro, But if your plugs are fouled and you have oil in the galley its prolly fouled the wires too. You need to replace both plugs and wires to be certain you dont get mis-firing thats bad, anti-seize on the plug threads and a little di-electric grease on the contact points is good.

[gottadiesel]

Thanks for the thoughts - yes I did read and print off all 30 something pages of that post...

I have not owned the car long, so one of the reasons I am going through everything, so in regards to the fuel additives and such, no idea. I literally have only put 100 miles on the car since I bought it a couple of weeks ago, that was mainly to get it home.

Yeah, I have new plug wires on the list to replace along with the plugs themselves.

I might just have to replace other items first and put all back together then see what happens. Even if I have an issue, probably will not be yanking motor at this time anyway, so I might as well just run it till something major happens.... put before I started pulling anything apart, the engine ran smooth, no mis-fires, pre-ignition, no smoke blow by etc... although it felt weak, but I also found more than one vacuum line disconnected, boost lines kinked and cracks in the boost intake line along with connections at throttle body, on top of FOD damage to the turbo.... so if it ran that good with all of that, it should run much better once I get those issues resolved...

Eitherway I appreciate the thoughts, many heads are always better than one...

Thanks

[tsupranami]

I see you found the oil leak. Valve covers dripping down back and front and into the plug galleys. ITYS!

Compression when cold should be above 120-125psi. The absolute value is not as critical as the differences between cylinders. Any more than 10% difference warrants further investigation( ie. wet test and leakdown).

Oil on the plugs after finding oil in the galleys is what the 7M engines are all about! lol! It's usually just the residue around the sparkplug gasket area that drains into the hole and onto the plug-end as soon as the seal is broken upon removal.

But...playing devils advocate here...in the worst case scenario given the info so far...

FOD to the turbo could have damaged the seals, which would cause increased blowby. Especially if it has run that way for a while; the imbalance will screw-up the seals quickly. Valve stem seals get hard and also contribute to blowby. Rings hardly ever wear on these motors unless abused or well over 200k mi., as well as valve guides, so not likely suspects.

So probably not a big deal motorwise. If the compression is good and even across all 6, just fix the turbo and the valve covers, and if there's no smoke out the tailpipe, you're good to go. Just watch the boost on that stock HG.

I went through mine several times, from the cheapest (and quickest) fix to currently one of the most expensive (full rebuild).

First I tried just replacing valve cover gaskets. That kept the oil in the engine, kind of, but I kept painting my rear bumper with oil from the blowby in the exhaust.

Next was a simple disassembly of the head. I had an exhaust stud hole welded and repaired, the head surfaced, and valve stem seals replaced for $200, including assembly. Just a cleaning and surface shouldn't run you more than $100, if you assemble the head and fix any messed-up studs yourself. An OEM headgasket set is around $160, aftermarket under $100.
Toss or sell the fiber-style HG that comes with the kit. I'd use the box the gaskets came in before I'd use another stock-type HG!

I installed a Titan 1.5mm MHG w/ARP head bolts for about $250. Oil painting the rear bumper was drastically reduced, but not eliminated entirely. That lasted for over a year 'till I had the turbo rebuilt and upgraded ($850). That was the final step in eliminating oil consumption and a greasy back bumper. A few hard runs at over 16psi had the coolant shooting out of the reservoir, though. I only cleaned the block (no machine work), so it was no big surprise.

I lived with that mildly blow head gasket for 2 more years (~30k mi.), and as long as I kept it under 14psi (or only breifly exceeded), it wouldn't overpressurize the coolant system. I drove it to Vegas in September and Montana in early October with no problems. It pulled 300rwhp/292rwtq on the dyno and ran 13.98@105mph (@14psi) in the 1/4mi. just days before I pulled it for a rebuild last October (crank-pulley keyway was chewed to hell).

All of this was done with the block still in the car for a little over $500 (not incl. turbo upgrade).

With a little careful shopping, you could do it for less. With a block in better condition than mine, it should last longer, too. Mine was pretty FUBAR. I really shouldn't have gotten as far as I did!

Good luck!