Mullins_j

Hi all.

It's been awhile since I've posted. I have a quick question for everyone.
Recently my 1994 Jeep 4.0l motor went bad. I don't blame it having close to 300k on it.

So I decided to buy a re-manufactured motor. I do not what to post the name of the company as we are in the middle of a pi$$ing match over the following:

I put the "new to me" motor in, ran a good break-in with zinc rich oil. All ran very good. I actually put 600 miles on the "new to me" motor.

I went and did an oil change at the 600 mile mark. All seemed good. On my way back from a 40 mile drive, the jeep back fired and stopped. Long story short, the distributor gear was stripped out.

Blah, blah.

I then dropped the oil pan, and oil pump and took a good look at the cam gear, and the bearings. See attached photos. The gear looks good, but the bearings are melted and squeezing out the side.

I sent these photos to the company. They think that this was my fault and asked me to send the motor back so that they can look it over and see what the cause is.

Has anyone seen this, and does anyone know that cause?

I'm just trying to arm myself ahead of time, since this company will have to send me another completely re built "new to me" motor at their cost. I'm guessing they are going to come up with some reason to make this my fault.

Any advice would be great.

Thanks,
J

KD4315

I've seen the stripped dist on an old AMC 304. Have you checked the timing gear to see if the oil hole is plugged, misaligned or the hole in the block is plugged by flashing? Did you supply the dist? Was it a cheap one from eBay?
I'm at a loss over melted bearings. That's a first for me.

Mullins_j

I'm pulling the "new to me" motor out in the morning. I'll have more info and photos then.

The distributor was one from the local auto-zone.

The three reasons I know that would cause this is:

The cam journals are not aligned.
The smoothness on the cam journals were not smooth for the heat transfer to the block.
Bearing oil holes not aligned with the blocks.

Like I said, I'm just making sure that this company can not turn this around on me. I have rebuilt a few motors in my time, and am by no means new to jeeps.

This motor only has 600 miles on it, and the bearings already look like this. Seems very strange to me.

Mind you this jeep was a 2wd when I bought it 5 years ago. It is now a 4wd, with a Ford 9" and a Dana 44HP sitting on 35's. I think I know a thing or two about jeeps.

I'm not to concerned about the dizzy gear as I am the cam bearings.
I plan on sending this motor back Monday. Tomorrow I'll pull it, and pull the timing cover off and take a look at the front.

Thanks,
J

bubbarules1958

Distributor still turns freely? Oil pump lock up? Never seen this type of damage before.

Mullins_j

The oil pump does spin freely.

I have an old dizzy that I took the gear off of so that I could prime the engine before starting it. I installed this dizzy and put a drill on it and it spun fine.

I even took the oil filter off and spun the dizzy to see the oil flow. Which was very strong.

I have no idea why this would happen. Do you guys think the cam bearings and the dizzy gear are related failures?

Thanks,
J

bubbarules1958

Was it all the bearings? Or just the one next to the distributor?

bubbarules1958

Is this hole plugged?

Mullins_j

All bearings that I can see are melted.

Which hole? the round one in the middle of the photo?

Thanks,
J

Edit: I see the hole you are talking about. I'll be pulling the timing cover of tomorrow. I'll be able to see that then.
The company thinks that I did not install the spring and button that goes in between the timing cover and the end of the cam, and that allowed the cam to walk forward. But that does not explain the cam bearings.

bubbarules1958

Make a video when you pull it off. Just to show them that you installed it. I always run the break in oil for a thousand miles. What was the engine providers recommendation? Been through a lot of engines and have never seen this before.

golfmiser

Definitely an oil problem. Could be a lack of oil to the bearings. Could be that the cam and bearings never got coated with zinc. When you changed the oil it not having the zinc caused premature failure.

Mullins_j

I do plan on doing this in the morning.
Thank for the suggestion.

Thanks,
J

Mullins_j

Engine manufacturer recommended 500 miles of normal driving conditions with zinc. Then full oil change. After 1000 more normal miles with regular oil, change again, and should be good to start normal oil change schedule.

I didn't think that the zinc did anything for the bearings. I thought that the zinc was more for the hardening of the cam lobes during the 20 - 30 minutes break in period after first starting.

I did speak to them about this, and they told me that if I had been driving if for 600 miles and all has been fine, then the break-in went as planned. I would have known right away if the break-in did not go good.

Thanks,
J

bubbarules1958

Keep us posted. I'm interested in what would cause something like this.

Mullins_j

Will do. Not sure how long this will take for them to figure it out. But once I find out, I'll come back and post the company and what they said.

Thanks,
J

bubbarules1958

Awesome. Going through a top end break in on my first 4.0 assembly. Any information related to a break in failure is good.