The Craftmans Shop > PowerSports
1954 Ford 850 Tractor w/blown Head Gasket (at the very least)
vtsteam:
Thanks Manxmodder! :beer: Good to hear you use the glue method for washers. It's a real handy thing to have in the arsenal!
I didn't use a magnetic base DTI to measure the lift, thought that's a great idea! kinda didn't want to know! I just wanted to see that one valve lift (exhaust #1 cylinder) to make sure there wasn't a broken lobe or stuck lifter, but more than that -- well this isn't a restoration, but a working tractor/bckhoe. It will probably see under 100 hours of use a year. But if it runs it will certainly pay its purchase cost back quickly -- machine time around here is about $150/hr. So for now, I just want t get it running.
This morning I cleaned the head and rocker arm assembly in kerosene (paraffin), and chased all the holes in the block and head, preparatory to re-,mounting. Then I scraped the deck and cleaned the cylinders as best I could. I'd squirt a little 30 weight around the pistons, and turn the crank by hand, then wipe the cylinders out again. i did that 5 times, and the oil came out clean.
When everything looked ready I set the head down on the deck and stopped to take a picture -- always a nice turning point to be adding things again, rather than taking them off.
Then I set the new head gasket in place
vtsteam:
I decided to try the valve rocker assembly before actually torquing the head down in case there was a problem with cam or tappets in #1. I didn't want to squish the gasket in case I had to remove the head again. I wanted to turn the engine by hand and watch the valve openings.
I fastened the head down lightly, and bolted the rocker towers in. Number one cylinder valves appeared to work properly when i tried them, as did the rest of the valves. But I noticed that the #1 exhaust valve rocker arm was out of alignment with the new valve rotator cap:
vtsteam:
I pushed it over toward the aluminum bracket, and it lined up properly then. There was a spring and a washer that kept it away from that bracket. This didn't seem right. Checking the other end of the rocker shaft, I saw that there were 2 washers on the end with the spring trapped between them -- that seemed to make more sense.
vtsteam:
So it became apparent that someone during the life of this tractor had disassembled the rocker shaft, and then replaced the spring and washer in the wrong place. I verified this in the Ford Service manual.
But not only that, this particular rocker arm and pushrod was the pair that had varnish on the ball and socket joint -- they weren't shiny like the others in the assembly. I'm going to guess that this misalignment along with one other factor had caused the loss of that rocker cap long ago. The loss of the cap probably loosened caused a great deal of valve lash, and probably a very short exhaust timing.
That other factor was the fitting of the caps themselves, which was badly out of spec..
vtsteam:
I removed the rocker arm assembly, pulled the cotter pin and rearranged the spring and washer in their proper locations.
With everything looking correct, it was time to fit the valve rotator caps. I assumed the three I had from the tractor originally were all correct -- I just needed to figure out which one went where. Wrong!! :bang:
Well, there was first a pause while I figured out just how I was going to be able to ensure the .002-.004" clearance they each had above the valve stems. I tried a few methods -- including Manxmodder's earlier suggestion of using a magnetic based indicator. But nothing I tried worked well enough to give me a consistent reading. The main problem was that the valve stem was recessed in the spring and there was nothing to compare its height to. Finally I realized that I could use a small 1/4" drive socket to serve as a spacer on top of the valve retainer. I could set my caliper end on top of that and measure the depth from the top of the socket to the valve stem, then subtract the socket height (.850") to get the height of the stem above the retainer. The depth of the caps needed to be .003" more than this height.
I got consistent readings using the socket and caliper method and started sizing the caps. Well surprise, surprise, they were WAY off! :(
None of these caps had been fitted properly to the valve stems. They varied from 20 to 50 thou too long. So with a fair amount of work grinding and checking many times with the calipers and finally when getting close, hand stoning them. I ground them all to .003" clearance for their respective valves.
I think that some prior owner had simply placed aftermarket caps on the valves, without fitting them. This in combination with the misaligned rocker arm may have spelled the loss of that #1 exhaust cap. I wouldn't be surprised if it (or pieces of it) are located in the oil pan.
Or perhaps the owner had simply lost the cap. I did wonder for a moment whether the warped head had been the result of the lack of a manual and/or torque wrench by this particular mechanic.
Well, no matter, that job done, it was time to torque down the head. The manual gave 65-70 foot pounds as the figure, and I followed the bolt torquing sequence in 3 stages. The I reattached the rocker arm assembly with the oil lines this time, and torqued it down to 45-50 ft/pounds,per the manual.
I blast cleaned the spark plugs, set the gaps, and screwed them into the head. It was beginning to look like a functioning engine:
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version