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New issue, low to no oil pressure!

As others have already stated. Put a mechanical gauge on it to confirm pressure.
 
Pressure was verified with a mech gauge when I replaced the sensor!
 
I finally got a return call from Basko Engines. Ray has been doing my machining/balancing work for me for over 40yrs. He said the 4.0 is notorious for eating cam bearings. That's the type of info I was trying to find out!
 
And somebody was steering you wrong here?

Anyway I've not run across too many threads where cam bearings were bad so often they are notorious. At least not on the non stroker engines. Hell 300k is common for these OEM motors. Finding a JY engine with less than 150k is a challenge.
However a rebuilder probably sees more serious failures then jeep hobbiest.

IMO everyone offered helpful advice on a vaguely described issue any number of things can cause.
It could be simple or more complex. If it's the cam bearings it has to be pulled to be replaced. Everything else I think can be done in vehicle.

Nobody was BSing or hiding the real cause. Following the KISS rule usually works out for the best. You still could have another cause other than cam. But with low pressure it may have done enough damage it doesn't matter.






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No bad info here, but sidetracked! I thought I was clear in my original post that I knew the cause of the problem and was looking for the "most likely" damage that had occurred.

As of this morning with another oil change but to 20/50, it seems to be holding its own.

That will "hopefully" buy me some time to get a good game plan together!
 
20/50 holding its own...
I wonder if it's just sludge on the oil pick up.

Or the pump.

Far as damage goes it's had to tell. Cam bearing means it comes out, the rest could be done with the pan off. I've seen plenty of motors where the cam bearing killed the oil pressure, on the 4.0 it might not be dead yet.

If you've got the guy to rebuild it maybe just nursing it is the best solution.


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Green Mesa XJ said:
If you've got the guy to rebuild it maybe just nursing it is the best solution.
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Click to expand...

I am the guy that will rebuild it, that's what's so scary! I'm envisioning 5K to do it my way! Already been thinking about a stroker, but I would want a "long rod" version which most likely mean custom pistons!
 
OMG !!

I just p/u a new pump today, it's got to be the poorest design I've ever run across! I was thinking this weekend about what one would look like and how would I go about "blueprinting" it! It very easily could be the "heart" of the issue.
 
I'm pulling the valve cover today (to clean in there) along with installing my new injectors. If time allows I will replace the oil pump
 
RCP Phx said:
I had a extreme cooling system failure not to long back. To keep it short, I'm curios as to what bearing failure would be the first affected. At this time my thoughts are leaning toward the rods?
Click to expand...

What exactly are the oil pressures? What oil are you running?

I installed a high flow oil pump on mine 12 years ago and switched to 20W50 oil. Solved the gasoline in oil dilution issue caused by 2 fouling spark plugs, among other ongoing issues, even used Restore and Lucas oil additive to thicken the oil, and put 60,000 miles on it since. Currently runs about 30-50 psi except on the hottest summer days when the lowest pressure after a good hour of heavy driving is about 22 psi.

I was hitting about 15 psi before I solved the miss firing, oil fired plugs from leaking valve steam seals on 2 cyclinders issue. ( need need new valve guides on those as the seals only lasted about 8000 miles). It was hitting about 12 psi before I located and fixed the exhaust leak blowing on the oil pan. And about 9 pis before the new high flow oil pump and new crank bearings.
 
The oil pressure is still holding about the same, maybe a little better(didn't do the pump today)! I didn't notice any performance gains, but I'll have to wait for the computer to fully reset and check the mileage!
 
I had an engine that wiped all the bearings. Zero oil pressure cold or hot.

I dropped the pan and replaced the crank and the rod bearings and it still had no pressure. Cam bearings in a 4.0 are critical to the oil pressure.

I wouldn't bother spending a ton of money on the rod and the crank only to end up pulling it out anyways.
 
Well yesterday I got a #2 mis-fire code for cyl #2. It appears I have a bad injector. They are alreadt sending a replacement set so I have to go thru this again, luckily it's easy on my 2000!
 
$5k on a 4.0? Yikes, I've built a few motors, never spent that much unless I was using ALL new parts...even the block. I could see spending that kind of money for someone else to do it I guess.
 
JohnX said:
$5k on a 4.0? Yikes, I've built a few motors, never spent that much unless I was using ALL new parts...even the block. I could see spending that kind of money for someone else to do it I guess.
Click to expand...

I don't build "ordinary" motors, it would be the best 4.0 possible. Things like custom pistons and Scat rods at a minimum. Add in headwork, crankwork, polishing/balancing...........it never ends!
 
RCP Phx said:
I don't build "ordinary" motors, it would be the best 4.0 possible. Things like custom pistons and Scat rods at a minimum. Add in headwork, crankwork, polishing/balancing...........it never ends!
Click to expand...

I'd love to see some dyno sheets when you finish...be interesting to see if doubling the $$ adds any power?
 
I doubt much HP would be gained, I would classify this build as a "Utimate Mileage" (mpg/lifetime) motor instead of building for max HP. Years ago I did one for "Crackerbox" boat racing, a Chevy six with 2 3-barrel Side-draft Weber carbs and that thing screamed!
 
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