Compression numbers??

robmee · Post by **robmee** » Mon Oct 20, 2008 8:04 pm

What is a the target range for compression on the 1.6 NA? I was able to do a Comp test with the harbor freight tester and got:

#1 - tested last, starter caught on fire....whole other issue
#2 - 420 psi
#3 - 460 psi
#4 - 380 psi

I know lower numbers is a bad thing, what is the target range to have?

I am thinking that I have a blown head gasket, if I am going to replace the gasket, is it going to be more cost/time effective in the long run to just overhaul the whole engine? I think it is blown because I have oil that that is pooling at the base of the block between the vac pump and the dip stick (doesn't seem to come from anywhere else ).

Thanks,

tylernt · Post by **tylernt** » Tue Oct 21, 2008 8:39 am

402 is the wear limit as I recall. A newly broken-in engine can get up near 500.

However, plenty of VW diesels are running around with less than 400PSI compression, even as low as 300PSI, and the only downside is they get harder to start in the winter without a block heater or multiple glow cycles.

There is an O-ring on the vac pump that can leak. As it's a 50-cent part that's easy to get to, you might clean the block and replace the ring just to be sure that's not the source.

82vdub · Post by **82vdub** » Tue Oct 21, 2008 8:44 am

I agree with Tylernt. I'd check to verify where the oil is coming from. Could be seeping down from the block to head surface, or coming out of the vacuum pump opening, or possibly even from the valvecover. Identify the source of the oil first, then determine where to go next. If your compression numbers are good and it's seeping from the block/head location, you may be able to extend the service life (assuming the head gasket isn't shot where you're getting combustion gasses in the coolant) by retorqing the head bolts. Just an idea. If you do pull the head off to redo the gasket, buy yourself some head studs and reassemble with studs, not bolts.

VW cat · Post by **VW cat** » Tue Oct 21, 2008 9:00 pm

I'm a little in the dark about using studs on the 1.6. Are they just as effective as the stretch bolts on aluminum heads, in the long term?

I got a set once in Buffalo for my 327 in my Camaro, back in '76. No more worries about wear and tear on the holes in the block. Phil