• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Nearly destroyed my rebuilt 4 liter... help. (long post)

mellowvision

NAXJA Forum User
Location
Brooklyn NY
So, last year, you all helped me figure out some details of rebuilding a 4L for my 89. It had been running pretty strong since october, and this summer has seen a lot of long drives.

On friday night, I drove up to boston from ny on 95, and made REALLY good time. I was having a ton of fun, pushing it. It felt good. When I got to MA, it was idling a bit rough, but not out of control.

In the morning I noticed a puddle of oil under it, and that the drivers side of the truck was soaked with oil under there. I was heading to my mechanic's hosue, so I didn't get overly concerned. When I got to the end of the block and steped on the gas, I looked down to watch the oil pressure gauge drop to zero.

When lightly accelerating or idling, the pressure was ok, 20-40 range. At steep acceleration, 0. I drove less than a quarter of a mile to the mobil station and she took 5 quarts of oil. Was smoking out the dipstick and valve cover.

I drove it to my buddies place, it kept the oil and drove ok. A little rough in the idle.. I did an oil and filter change, no problems. Looked in the air box for kicks, and the k&n is soaked with oil, the box looks like it had been full and emptied, and under the box is totally soaked. the breather line is soaked at the joints.

So, problem one seems to be loosing oil from the dipstick, breather and valve cap.

We check compression. 150-175 across the first 5, but the rear most cylindar gets less than 75psi. We button it back up and start it, pull that plug, no noticable difference.

At this point, I still needed to drive a little bit, and drove it probably 2 more 40 minute drives, trying not to abuse it. By the time I left it at the shop, it had developed a knocking that sounded like my old hydrolocked motor that this one replaced. Not as loud, not all the time, but usually present at idle and light acceleration.

My buddy brought it by another local shop where the machinist is a jeep fanatic, and he thought it sounded like I spun a bearing due to lack of lubrication.



so, at this point, I figure, I have problems with the breather, a clog somewhere that is forcing the oil out, either a slipt bearing, or a problem with a valve or something, potentially blown rings, and who knows what else.




How do I go about finding and curing the original problem, and what should I be looking for? We haven't had the chance to take the pan off for an inspection, but I'm still curious to hear opinions on potential causes, problems to look for, and what I should be considering for repairs at this point.

sorry bout the long post, I had to get it off my chest.
 
Last edited:
Me too. Don't see how a spun bearing would cause a drop in compression. My guess is that it overheated due to low oil pressure and partially melted the #6 piston. Stroker? What are you running for injectors? If it's running lean, that would also contribute.
 
I third, fourth, and fifth CheapXJ's opinion because that is exactly what I did to my old block. around 200,000 miles I stepped on it from Fort Collins, Colorado to Atlanta, GA. In Kansas I stopped for gas and there was a fine coat of oil all along the drivers side of the car. It was coming from a pool in the airbox. Limped it to Georgia (love these motors) putting a quart of oil in everytime I filled the tank with gas to find that #6 was done.

Needless to say I was prepared and was driving back to put a new Jasper longblock in with a buddy of mine but that is the EXACT same experience.
 
The motor was set up stock, and the injectors were the ones off the old block. In fact, we never had a chance to take apart the fuel rail, it came off the old and onto the new.

I think the spun bearing was probably a result, not a cause of all of this, if it even happened at all.



so, you think I blew the rings or something before loosing the oil, and the oil escaped that way? ugh. How much of a mess you think my block is going to be? I don't know if it's going to be able t come out this time around...
 
mellowvision said:
The motor was set up stock, and the injectors were the ones off the old block. In fact, we never had a chance to take apart the fuel rail, it came off the old and onto the new.

I think the spun bearing was probably a result, not a cause of all of this, if it even happened at all.


so, you think I blew the rings or something before loosing the oil, and the oil escaped that way? ugh. How much of a mess you think my block is going to be? I don't know if it's going to be able t come out this time around...

You're most likely right about the spun bearing being the result and not the cause.

As for your last question:

Best case scenerio: You didn't ruin the crank or the block or the piston and a cylinder honing, new rings, crank polishing and new bearings will put you back on the road. Considering how far you've driven it, probably isn't likely unless you're incredibly lucky.

Worst case scenerio: The piston is collapsed, the cylinder walls are scored beyond safe boring limits and the journal of the crank looks like an old Edison tube record, which is probably way before your time and you have no idea what I'm talking about.

Really all of this is conjecture and until YOU take it apart and see what has happened, the damage will be unknown. I'm hoping it's the former though that you find so you can be back on the trails soon.
 
Back
Top