Time to pull the head!

I had a meeting at work this morning, so I didn’t get started until after lunch. Excellent day – 75 deg!

I received my shocks and footman loops earlier this week and I already had my gasket set. I got started by test fitting my shocks to make sure they fit – and of course I had to take a test drive up the driveway and around the field. It was a totally different vehicle on the road and over the bumps (corn rows) in the field – it was controllable at speed. I got back in the shop and took them back off. I hung them up from the ceiling and scuffed them down to get them ready for paint. I used the wire wheel on the footman loops (because they are nickel plated) to get them ready for paint. Three coats on everything with the rattlecan 24087 (OD green), and they will be ready to install tomorrow.

Next up was the engine. I wanted to narrow down (or at least double check) the reason for the low compression in cyl. #2. First, I ran a compression test on all cylinders again. All except #2 checked out again – #2 was even lower than before at 60psi (it was 77psi brfore). The next step was to do a wet compression test on cyl. #2 to see if the rings are bad or a valve. I squirted oil into the spark plug hole and ran the test again – no change, so the rings are good and has to be a valve (if a ring was bad, it would have had a higher compression reading). Next step was to pull the side valve cover off to see if the exhaust valve clearance was too tight, causing the valve to not close. All of the valve were tight, so I set them and put the valve cover back on. Then I pulled the top valve cover off and checked the intake valves – all of them were off too. While I was adjusting them, I was feeling for pressure on the #2 cylinder and there was none! I checked the compression again and had the same 60psi. Time to pull the head and check for a bent, burnt or stuck valve.

It only took me about 20 minutes to tear it down. Nothing really apparent at first except that cyl 2 wasn’t the same color as the rest. The exhaust valve didn’t look burnt, and it appeared to be sitting square in the block. I turned the engine a few times to see if it was sticking – it wasn’t. I rotated it until the #2 valve was open. Then I used a flashlight to check the valve seat – it didn’t look like it was seating right. Then I turned the valve to check to see if it was burnt – it wasn’t burnt, but it was BENT! I guess it wasn’t seating completely, causing the low compression.

I still had a little time to work, so I went ahead and cleaned the head bolts with the wire wheel and scraped the old head gasket off and cleaned it with the wire brush on a drill. I also went ahead and did the thermostat mod (drilling an 1/8″ hole in the thermostat to keep the coolant from surging out of the overflow tube when the thermostat opens). I will pressure wash the head tomorrow to get all the crud out of the water passages and oil and grease off of it.

I’ll have to go borrow a valve spring compressor and lapping tool and paste tomorrow and buy some gasket sealer. The plan is to take one of the exhaust valves out of my spare engine and check it over real good. Also check the valve guide in the current engine to make sure it isn’t worn out. I can scrape the carbon buildup out of the valve seat and then lap the valve to the seat. While I have the head off I will go ahead and check the rest of the exhaust valves and valve guides and lap them in too.

Engine - head off


One response to “Time to pull the head!

  1. Wil, great blog on your resto progress, I got a few parts if your interested in trades?

    working on an M-series myself. thanks t

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