Flathead thrust bearing
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From: New Braunfels Tx
Flathead thrust bearing
I originally started a thread about replacing a clutch and release bearing on my 1949 239 V8 flathead F1. I figured I’d start a newly titled thread since my original diagnosis was wrong. The problem cropped up after the truck sat for awhile and sounded, to me, like a bad clutch release bearing. Here’s a link to a short youtube video.
The engine has less than 100 miles on it since the supposed rebuild. I purchased the truck from the widow of the previous owner and for what it’s worth he appeared to be fairly discriminating about who he chose to have work on it. She provided his box of receipts though I don’t have the specifics of the machine work and rebuild (yet). The existing clutch, flywheel, and crank bushing looked brand new so I initially replaced only the clutch bearing as it did appear to have more play then it should have. I got it all back together and had the same clattering. Apparently the bearing was just a victim of collateral damage. Today I pulled the transmission and put a dial indicator on the face of the flywheel, first near the perimeter, and then with the clutch off near where the outer edge of where the clutch disk would engage. More video
There’s a little parallax issue with the video but I was working alone so I had to prop my cell phone as best I could. The discrepancy was .010. I was hopeful the “new” flywheel was the issue but no luck. I removed the flywheel and checked the crank end play.
Sigh, it was .014. So I’m guessing at a minimum there’s a thrust bearing or crank issue. For those of you with more flathead experience what is my next best course of action? Pull the motor and get it on a stand or is there more I can or should do in the way of diagnosis with it still in the truck before I get that drastic? Thanks Neil
Fleet Owner
Joined: Jul 2004
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From: NM
Drop the pan and pull the rear main cap. The thrust bearing is the sides of the rear main. You'll be able to see if the bearing is bad or the crank was machined wrong.
What was oil pressure like in the past?
What was oil pressure like in the past?
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From: New Braunfels Tx
The pressure was good, 35 at idle 50+ cruising. I’ve rotated a bearing into place with the crank still in an engine before but never a thrust bearing. It seems like it would be a challenge. The only thing I can think of that may have led to it’s demise is I had some repeated flooding issues awhile back due to a pin hole in the carb float. I changed the oil not long after I pin pointed the cause and it definitely smelled strongly of gas. Perhaps I diluted it enough to drop the pressure though it definitely didn’t run for a prolonged period of time.
Fleet Owner
Joined: Jul 2004
Posts: 27,294
Likes: 1,055
From: NM
You'll want to loosen the front and mid caps to gain a little extra room if you pull the upper. But the condition of the one in the cap will tell you a lot.
I doubt the dilution would cause the thrust surface to wipe, but the oil flows to the rear main first, it could happen. I'd expect the journal part of the bearing would also be wiped in that case. I'd want to check a couple of the rod bearings while in there.
I doubt the dilution would cause the thrust surface to wipe, but the oil flows to the rear main first, it could happen. I'd expect the journal part of the bearing would also be wiped in that case. I'd want to check a couple of the rod bearings while in there.
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