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Going Through a Beater XJ 4.0.

Re: Going Through a Beater XJ 4.0. Head Cleaned Up.

Got the head scraped off and pressure washed today. Got quite a bit of rust out of the cooling passages in the head. Now it's ready to have the seats cut with a 3 angle valve job. Maybe even back cut the intake valves a bit for more flow.

https://youtu.be/sODYCv7_7Po
 
Re: Going Through a Beater XJ 4.0. Rust Resolved !!

So happy to find out that this rusty bolt problem is not just with my XJ !!!

Here is what happened at the junkyard today !!

Edit: Uploaded corrected video.

https://youtu.be/zNinsI11H5w
 
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Re: Going Through a Beater XJ 4.0. Head Bolt Cleaning With Vinegar.

It turns out that simple cheap white vinegar took the rust right off of the rusty head bolts. Amazing how well it worked. So I tossed in all of the rest of the oily head bolts. After several days, the remaining bolts are nice and clean, especially the threads. Then they were soaked in a water and baking soda solution to neutralize the vinegar. So today I blew them off with compressed air, then coated them asap with wd40. They will be ready come assembly day.

The junkyard head bolts I picked up a while back just went into the water rinse after soaking in the well used white vinegar. There were 1-2 inch diameter flakes of crusty black material floating on top of the vinegar. The vinegar did a great job on the 6 or so junkyard head bolts. So they will be grooved with an angle grinder for thread chasing after they go though the rest of the cleaning process.

Super clean threads allow the torque to go into tightening the bolts, rather than overcoming friction from dirty threads.
 
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Glad you got it figured out.
In the vid you can see the wear on the flex plate also. While it isn't a common problem it is a known problem. Clean them up and some blue Loctite should get it sorted

I hate to be that guy but torque convert bolts were mentioned by a couple people when you first started asking questions.
 
It wasn't because I didn't know about the tc bolts. It's was because I've had massive headaches for some time now. Seriously. Just saw the neurologist today. The day I started this project, I didn't have the strength to rotate the crankshaft with a big ratchet. I was looking right at one of the tc bolts that was tight and said, they will be fine. So I became that guy. At least this engine gets a 3 angle valve job, de-carboned, and inspected.

Just picked up a can of Berryman Chem Dip. Just put a piston in it. Once they are clean, back into the block they go, right after I order bearings for them and the crank.
 
I'm not sure how a flexplate shows wear on the outside ? My inspection cover is mia however.
 
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I have a 92.
Never seen that bolt rusted.
I think your block is cracked. or factory mistake.

That's a water jacket under there. Plus I've seen the rust on 2 renix 4.0's now. I could still be wrong. But since there is no mixing of oil and water anywhere, I'm sure it's fine. Bare minimum it's a factory mistake.
 
Glad you got it figured out.
In the vid you can see the wear on the flex plate also. While it isn't a common problem it is a known problem. Clean them up and some blue Loctite should get it sorted

I hate to be that guy but torque convert bolts were mentioned by a couple people when you first started asking questions.


To answer your questions in the video, I'm inclined to think your problem was loose t/c bolts all along. It's not necessarily that the bolts back out and the heads start hitting anything. It's the flexplate slopping back-n-forth rotationally with respect to the t/c because the bolt holes are larger than the bolt. In more severe cases you even see the holes starting to egg out from the banging and the threads on the bolt start to get mushed. Really loose, I can see the plate flexing and moving up/down the threads.

Plenty of other threads on NAXJA where the knocking was fixed by re-torquing the bolts.

Glad you got it figured out.
I hate to be that guy but torque convert bolts were mentioned by a couple people when you first started asking questions.

I just rewatched the original video and it sounds like t/c bolts to me, including gong away under load or when reved. He even suggested it might be the t/c bolts. Can't say I've never overthought something myself.
 
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To answer your questions in the video, I'm inclined to think your problem was loose t/c bolts all along. It's not necessarily that the bolts back out and the heads start hitting anything. It's the flexplate slopping back-n-forth rotationally with respect to the t/c because the bolt holes are larger than the bolt. In more severe cases you even see the holes starting to egg out from the banging and the threads on the bolt start to get mushed. Really loose, I can see the plate flexing and moving up/down the threads.

Plenty of other threads on NAXJA where the knocking was fixed by re-torquing the bolts.



I just rewatched the original video and it sounds like t/c bolts to me, including gong away under load or when reved. He even suggested it might be the t/c bolts. Can't say I've never overthought something myself.

I had the answer in my hand. I just physically couldn't do anything about it. Lots of other more minor things happily repaired on both XJ's. Turned a corner. Now it's part and gasket ordering time.
 
Got the lower rear most main bearing off to inspect it and replace the rear main seal.

Discovered that AMC did not necessarily use the same size bearings on each rod or main journal. The lower rear main is marked .001. So it's undersized .001". Turns out that the rest of the mains can be a different size, and the top and bottom bearing shells can be different sizes too. Since the rear most main bearing is in decent shape, I won't go any further with them. Just replace the rear main seal and be done with it.

The rod bearings are still in their respective rods and sitting on the bench. So I have to look at all of them to make sure of their size. That way I can get them ordered. Hopefully they are the same size.

As of now, the #1 rod bearing is marked with an X where the under size mark is usually placed. So they are standard, I assume.
 
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