I think I broke my engine

Rods are installed correctly, I stamped them before taking them out so I wouldn't mix them up or reverse them. Good thought, though.

Ross, give me a shout if you are passing through.

 

Chris, if you really want an original fhead pump, I have a fairly complete engine. It is locked up right now, not sure why. If interested, shoot me a PM.

 

Will do Chris

 

Chris, empty your PM box!!!

 

Done.

 

I was going to order new mains and rod bearings from my normal Willys supplier but then I figured I'd run down to the FLAPS (Advance Auto) to see if they could get them quicker -- sometimes they can get things next day. They sell reman cranks that come with all the bearings that will only run about $50-60 more than the bearings themselves. Assuming I need to have the crank turned again (debatable but I won't know until I take it all apart) it seems worth it to go that way because I would have that much in machine shop fees anyway.

F head cranks are balanced, correct? So it shouldn't be a problem to swap in another crank.

As usual, I'm just thinking out loud.

 

Update for those who are interested. Finally tore the motor back down and found some bad things. First, the rod bearings were in horrible shape -- especially considering only around 100 miles on them. The mains were OK although they show signs of scoring. The crankshaft has some scoring marks on it, too. The #4 rod bearings were the worst (those are the ones that are completely worn out and gold colored in the picture.)




The oil pump may very well be the source of the problem. When I took it out, I couldn't even turn it by hand. Come to find out, the main shaft gear was rubbing hard against the housing wall. I know when installed, it would turn freely by hand so something had to happen to it.


Not easy to see in this blurry picture but the housing wall is worn where the gear was rubbing against it.


Everything else looks OK. The camshaft looks good as do the pistons and rings so I will reuse them.

 

What a shame......

From the extent of the damage it would point to lack of lubrication, and that stiff oil pump was no doubt the source.

I keep watching for NOS oil pumps, if one pops up I'll post it....

It's kind of hard to imagine that the oil pump itself would suffer from lack of lubrication, but there must be bushings in there...I suppose anything is possible...

 

Sounds like something got wedged in between the gear, and the housing, or the gear shaft and the housing. Now, the real question is where did this come from??? Was it a piece of crud that was still in the engine during assembly, or was it something that came loose during the process of the engine failure?

An oil pump is not a very sosophisticated piece of work, they rarely go bad in a hundred miles.

 

I'm not sure. Even after I tore the oil pump apart, cleaned it, and put it back together, the gear still rubbed the housing. So it doesn't appear to be crud, it really looks like the gear and the housing do not fit together. The camshaft gear looked perfect so it wasn't rubbing hard enough to put a strain on it. I've heard stories from others on this forum of new oil pumps seizing and stripping the camshaft gear. It's possible I caught mine before that happened. Either way, I'm chalking it up to a defective oil pump and I'll see what happens in the future. (Naturally, I'm cleaning everything good and blowing out the oil passages.)

I ordered an NOS pump on eBay. Funny, it was actually less expensive than a new repop.

 

the minimum oil pressure specs for an F4 are 6 psi at idle and 20 psi at 2000 rpm
what was yours doing prior to the problem
I'm not convinced it's the pump, regardless of the gear rubbing.

 

Well, I don't have a tach so I'm not sure of the RPMs but I was cruising at 45-50 MPH when I started to hear the noise. At first, the noise sounded like it was coming from the transmission (with no top on the Jeep, wind makes it hard to pinpoint) so it took me a little while to glance at the oil pressure gauge. It would typically be around 40 psi if I recall but I noticed it was only about half that -- 20 psi or so. I pulled over and when it went to idle, it dropped to about zero. But it may have been higher than zero so it could have been around 5 or 6. Still much lower than it would typically idle at.

The next day I started it up and it came up to 30 psi at idle but would drop when reving the engine so I knew there was something wrong. The knock was gone, though (or at least I couldn't hear anything.)

I think the #4 bearing was spun because it was very loose when I took it apart. That would explain the dropping oil pressure on revs. Still doesn't explain the root problem, though.

 

"That would explain the dropping oil pressure on revs. Still doesn't explain the root problem, though."

I wonder if the pump relief valve stuck open. At higher rpm the residual oil pressure might be bled off faster by the engine's internal operations. (Just guessing.)