TIFU

After 400k, I decided it was time to rebuild the 4.0 in my XJ. Pulled everything and sent the engine off to the machine shop. Surprisingly, after that many miles, the engine was still in pretty good shape. One of the rod journals was .001" out and the bore was not too bad and only needed a .020" punch out to get back in spec.

I started the build about a week ago, but somehow I got mixed up with which end was the front (hint, its not the end attached to the engine stand) and ended up having the #5 & #6 pistons in the engine backwards. I left those and installed and finished the other four slugs and figured I'd just swap the #5 & #6 slugs when I got time. I got around to doing that today. Well, I'm not sure if it was a mix of summit fever or what, but I pulled both #5 & #6 at the same time (1st mistake) and decided to install both before I put the caps on (2nd & worse mistake).

Well, here is part of the story that I regret. I couldn't find my good spring compressor, so I was using a rather terrible one. I got #6 piston in the cylinder, but I didn't bother to turn the crank to drop the journal on #5. So, when I put #5 in the rod bolt slammed into my freshly turned crank. I also managed to get the oil ring to pop out and bent the crap out of it as well. So, I need another set of rings at the minimum. However, I'm not sure if should polish the crank or pull it and send it back to the shop to get reground (I'm guessing that the latter will be the response).



Full size pic.

I can't believe I was this stupid.

I hate to say it but it is grinding time.

I don't see that coming out without regrinding. Round is a good thing.

Were you drunk?

So, you didn't stamp your caps.........you didn't cap your rod bolts...........you don't know aft to fore...........jesus christ............

Now you have at least one odd crank journal.......odd bearing..........


and get a stand.


Engine building is not your thing.

Jeep Driver said:

Were you drunk?

So, you didn't stamp your caps.........you didn't cap your rod bolts...........you don't know aft to fore...........jesus christ............

Now you have at least one odd crank journal.......odd bearing..........


and get a stand.


Engine building is not your thing.

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Yeah, That was helpful!

Coach Bruce said:

Yeah, That was helpful!

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Count the number of blows on the journal, 7.


What kind of help did you expect?

Jeep Driver said:

Were you drunk?

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No, but I was coming off 4 nightshifts.

So, you didn't stamp your caps.........

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Caps were stamped, not sure how you come to that conclusion as they weren't even in the picture.

you didn't cap your rod bolts...........

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I did, but caps are not intended to protect from a wooden mallet being applied to the piston.

you don't know aft to fore...........jesus christ............

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Yeah, I just got backwards on it for some reason, probably the lack of sleep. I only managed to get two in backwards before I realized my mistake. Granted it was a deliberate screwup, so I take full credit for that one.

Now you have at least one odd crank journal.......odd bearing..........


and get a stand.

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Engine is on a stand in the picture, but not sure how you could guess that either.

Engine building is not your thing.

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This is probably my 30th engine I've built, and the first I've ever managed to screw up.

Couple of those are so deep they may not even grind out.


Yeah, I gave you a hard time, this really is inexusable. But, it's you that has to pay for that.

So, couple of quick questions.

1: I've got a spare crank that is pretty good, but has about 175K on it. It mic'd in good, so use it with a new set of STD rod and main bearings?

2: Has anyone built up a ding like this with a welder? I've hardfaced auger tips before, but not sure if it would the same thing. Also, has anyone had anything like this reground when its has be built up?

Jeep Driver said:

Couple of those are so deep they may not even grind out.

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Do you have to fill the gouges and regrind, or is it okay to just smooth it out so it doesn't tear up the bearing face? It's not much surface area and it's near the edges. I'd worry that hardfacing wouldn't wear the same as the crank and you'd end up with a high spot after a while.

I could pretty easily smooth it myself with some emory cloth. There really aren't any high spots, regardless of how bad it looks. There is a lot of assembly lube on that journal which makes it look a lot worse than it its.

I say use your spare shaft. Depending on how much it is worn, you can get bearings a touch tighter, off the shelf.

nblanton said:

I could pretty easily smooth it myself with some emory cloth. There really aren't any high spots, regardless of how bad it looks. There is a lot of assembly lube on that journal which makes it look a lot worse than it its.

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Just take the crank to the machine shop have it regound (hopefully welding isnt required) and get a new set of bearings.
The bottom end of a motor is not where you want to cut costs.

If the spare crank measures good, I'd go that route.