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Got the head off today, here's what I found:
Between cyls. #2 and #3 the head gasket was blown. And I mean "blown," there was a 3/8" wide strip of it missing! The narrowest part, between the cylinders was simply gone.
Did a very rough and quick clean up of a 2" wide strip, the long way, across the head and checked for warpage using a machined aluminum straight edge and a feeler gauge. Warpage was 0.3mm or less at the center. Volvo allows up to 0.5mm. Later on, when I had the time, I cleaned it up much better, and verified. Max long warpage was still under 0.3mm, and across the head, or the short way, it is 0.08mm to 0.1mm. Volvo allows 0.25mm. Boy am I happy. Did not have time today to do the final super immaculate clean up of the head, but I did get even happier when I noticed that there is some crud still lurking at the ends of the head. It is very small, but is certainly holding the ends of the straight edge up a bit. Cleaning it up will further reduce the long axis warpage that I am measuring. Hallelujah!
I checked the measurements of the head bolts too. Mainly since I forgot to order new ones, so I figured that I'd check them and see if it was even worth it to consider saving them. Using a Mitutoyo digital caliper, they all measured between 147.96mm and 148.12mm, a max difference of 0.16mm. Allowing a bit of slop for my non-laboratory measuring technique, I'd say they are all within .15mm or less of each other in length. That's pretty close. I measured the diameter of the middle of the thin section of the bolts too. Every one measured exactly 10.72mm in diameter. There were no visable signs of stretching either. Thus I'm going to figure that since Volvo is a very conservative company, one that errs on the side of caution always, and they say you can reuse head bolts up to 5 times, I can reuse mine. Saves me FedEX air charges on a new set.
Taking the turbo off was more hassle than everything else combined! But getting it out of the way makes it very much easier to do all the other little things that need to be done. Like changing the O-rings on the oil filter/cooler adapter, and maybe the right engine mount.
The valves look very good. In fact my neighbor, who worked his way up to being the general manager of a Toyota dealership, and has restored cars, thought the valves looked so good that he sggested to leave them alone. For what it is worth, the head sat with the galleys around each valve full of oil for 7 days before I removed it, and there was no leakage of oil through the valve seals from the galleys. The valves were fully flooded with oil, covered up all the way nearly to top of the stem, and all 4 galleys stayed at exactly the same level for a full week. So I guess the seals are okay too.
There is little carbon in the cylinders. In fact it is about like onion skin and peeling off of piston #1. It just flakes right off, very thin. The cylinder walls are nearly pristine, mirror smooth, the cross-hatching still visable. It has over 193,000 miles on it.
When I actually lifed the head off some coolant spilled into 3 of the cylinders. I quickly and gently dabbed it up with those blue disposable shop towels. I kept dabbing gently every so often, and left the hood up so the breeze and sun could help dry them out. Is there anything else I should do about it? For overnight, I've left the block covered with saran wrap, weighted down by some 2 X 4's, so nothing gets in it. Hood is down, of course.
Current plan is to take at least until Sunday to finish it up. Spend the next three days cleaning stuff up and making it shine. Then two days to reassemble. Minimum.
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Scott Cook - 1991 745T, 1985 RX-7 GSL-SE, 1986 Toyota Tercel (Don't laugh, it is reliable, faithful AND gets 41 mpg!)
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