The new head gasket came today - an Elring listed for the B20E (and others..?)

As George suggested eariler I applied a light coating of grease to both sides of the gasket before installation.

I took a few minutes to wire-wheel the top of the compression chambers and valve surfaces. This was previously noted as safe for the head and it cleaned up the valve surfaces nicely.

Given the mixed responses and the fact that I couldn't find them, I did not try to change the valve seals.

I carefully installed the head and gradually torqued up the head bolts in the clockwise-from-center pattern recommended in the volvo green book. I hand tightened, then torques to 25, 35, 45, and 55 lb-ft before I halted.

I'm having difficulty getting the engine to start, but I did do a quick compression check on the cylinders. #1 is 155. #2 is 155. #3 is 175, and #4 has 0 compression...

The compression test before the head came off was #1 10-15 and #2, #3, and #4 were an even 180.

I'm very confused now. This makes no sense at all...

What the other guys said +

If the head is off & the engine was previously running, the bore will usually be shiny enough to see the reflection of the top ring + the ring itself to see if it's in one piece. A good bright flashlight helps. If the ring is broken, then in all likelihood, the piston is junk.

Compare the the height of the 1 & 4 cylinders exhaust valves to the cylinders 2 & 3 exhaust valves. The inner pair run hotter because of the siamese exhaust manifold & they will show seat recession faster.

It isn't worth pulling the head apart just to clean the valves & ports out & lapping them in is an outdated procedure. If you take it to a head shop for work, a 30-45-65 3 angle job works well with a 30 degree backcut applied to the inlet valves only. You'll likely need exhaust guides. If you have a head gasket & don't want to shell out for a full VRS kit, a set of cheap Datsun stem seals for an early SOHC head works fine for change out of $10. All the other gaskets are recyclable.

"#3 could a valve problem lower my compression test results to less than 30 psi?"

Yes. Since you had what appeared to be very good compression on the back 3 cylinders, you might want to try this, just takes a few minutes:

With the valve springs still installed, put the head upside-down on the workbench with the intake/exhaust ports facing you, propping the head up to get the machined surface relatively level. Using a fluid with significantly less surface tension than water (e.g. alcohol or lacquer thinner), fill the #1 & #2 combustion chambers. Watch at the ports for seepage or leakage/dripping of the fluid down the valve stems. Really well seated valves will leak zero (or near zero) fluid, even after a prolonged period. A valve that has a moderate leak will seep fluid and get the valve stem damp after a few minutes. A terribly worn/warped/burnt valve (one that would cause the sort of compression readings you saw on #1 cylinder) will probably allow the fluid to actually start dripping. If the valves on #1 cylinder (15 psi) perform as good during this leakage test as the ones on #2 (180 psi), you can be assured the bad compression was due to something other than a leaky valve.

Gary L
--
1971 142E ITB racer, 1973 1800ES, 2002 S60 T5

1) The rubber doohickeys on the B18 are what they used in lieu of a real valve stem seal underneath the springs, on top of the valve guide. I'm not exactly sure how it ever really did much of anything. Certianly not needed if the head hads real valve stem seals, as all B20 heads did. And I think it's rpetty easy to modify a B18 head to use them as well.

2) Well worth the effort to put those on. It's easier to pull the valve spring when the head is off and you can more directly hold the valve up.

3) Most certainly. A burnt valve, or a valve that isn't closing completely will lower compression. Typically, the way to rule out leaking rings vs. something else is to test the comrpession 'dry', then quirt in some oil and test again quickly. the oil will settle in on the top of the piston and make a good temporary seal in place of the rings, so if the numbers go up significantly, it's the rings that werte leaking. If they stay the same, it's 'something else'. Which could be holed piston, cracked block, cracked cylinder head, bad HG, bad valve. To diagnose between those, you need to get a hose fitting and blow compressed air into the cylinder (make sure it's at BDC or it will go there, back off the valve adjustments as needed to ensure both valves are closed on the offending cylinder) and see where it leaks to. Intake manifold, exhaust manifold, crankcase, cooling system. But a valve with enough problems to cause a significant drop in compression shuold either be very, very tight (held open slightly) or have very visibly evident problems when you remove the spring and look at the mating valve/valve seat surfaces.
--
'63 PV544 rat rod, '93 Classic 245 + turbo

#1 No, B20 heads have "for real" seals, the rubber disks aren't needed.

#3 Yep. Valve leak could be doing it. I think Pooch had an experience with that this time last year. I may be going out on a limb, but it seems that when compression is that low, i.e. seemingly worse, it's usually in the head.

Is it too late to put some oil down the cylinder to do a wet test?