OT - Connecting rod bearings (jeep)

TBprnaa · Sep 16, 2010

'96 Cherokee, 4.0L 6 cyl.

Starting to get a knock like noise and garage thinks it is a rod bearing. 145,000 miles. Anybody have similar issue? How long did it go until it threw a rod? Not thrilled with engine rebuild costs, etc. Maybe heavier oil and live with it until it lets go? Thanks.

El Toro · Sep 16, 2010

It may cost you more down the road if a rod goes out through the engine block. You should drop the oil pan and take look at those rod and main bearings. Hal

TBprnaa · Sep 16, 2010

Thanks. Replacing bearings cheaper than blowing a hole in engine block. Engine has been great so far. Time to shop around for repair costs.

dhermesc · Sep 16, 2010

I'd check the cost of a salvage engine. There are a lot of those 4.0s out there as many Jeeps of that vintage died from unsolved electrical problems. A decent low mileage engine will probably run a lot less than an overhaul. Given the age of the body may not last nearly as long as the freshly overhauled engine.

If the salvage engine can be found for a decent price drive it till she blows.

JDemaris · Sep 16, 2010

You need to ascertain if the knock is from something loose, or from lack of oil pressure. And if you've got low oil pressure, things will get loose pretty quick, anyway.

RN · Sep 16, 2010

If you can drop pan and wiggle rods, you have room to plastigage the rods and mains, look for scratches. This may take a couple hours shop labor time but you"ll have a idea of what needs to be done. I had rear main seal replaced during clutch job of my 4.0- wasn"t that much more $ and labor since it was up anyway. Wasn"t cheap to start with compared to clutch on older dodge pickup but crank got a quick visual and rods were test wiggled, oil pump pickup checked and wiped, pan wiped. Knocks can vary- could be wrist pin, could be electrical- Ford van last week was a spark plug with way burned electrode that sort of sounded like rod knock. Number one sparkplug under bracketing may have been skipped during tuneup couple years back-check your electrics, etc before scrapping old Jeep-- you should have another 50,000 mle or better. RN

TonyIN · Sep 16, 2010

Got the same thing going on here in an '01 with the 4.0
Been knocking for at least a year, which for me is around 40,000 miles. I know it needs work, but that's not in the cards right now.
I'll probably go for the short block when it's time. I have 236,000 on it now and really don't see me getting rid of it anytime soon. Can't find anything similar that has the room BEHIND the back seat. Besides, it will go anywhere in any conditions.
I did try some Rislone - no change
Tried Lucas Oil with a bit better results. Not as noisy, but still there.
Tried also Sea Foam. No change in noise but "felt" like it ran smoother.
Not sure what a short block goes for so I may look for the slightly used when the time comes.
Good luck and post back/email if you find something that's working
Tony

Anonymous-0 · Sep 16, 2010

Get a proper diagnosis of the problem. If necessary, I'd go with a salvage engine like others have suggested. Last year was 2004 for the 4.0 I6 engine.

You're about to get into some costly end-of-life issues with that Jeep. I have 197,5xx miles on my 1997 with a clean, solid, quiet engine. Oil, filter, and lube have been done every 3,000-4,000 miles.

On the other hand, I have replaced the exhaust manifold, coils, ECM, the fuel pump and the water pump and had the rear end rebuilt. It needs an antilock brake unit, a transfer case, and a catalytic converter.

It's still cheaper than payments on a newer vehicle with that kind of capability.

Dblair · Sep 16, 2010

pull the plug wire on the cylinders one at a time and see if the noise goes away . if so it's probably a rod , but the jeep is famous for a wrist pin.

Mike M · Sep 16, 2010

I had to put new bearings in a 1979 jeep way back when it had low miles. the frt main was makeing it knock.

TBprnaa · Sep 17, 2010

Thank you for all the great ideas and info. I'm going to check out a few areas myself this weekend. I've seen on some sites that a cracked flexplate (it's 4x4 with auto) and or loose bolts on torque coverter can also make knock. Will try removing one plug wire at a time also. If no luck, drop pan and see what things look like. Has been such a reliable vehicle for the 6 years I've owned it. Hate to see it croak.

TBprnaa · Sep 17, 2010

I've done oil/filter changes at 3-4K too. Trans., diff. also. Have had to replace water pump, power steering pump, front axle seals and front axle joints. A fair ammount of $, but like you say, cheaper than new payments and at least we know what we have and what it can do. Thank you for your input. Hope your Jeep keeps on running for years to come.

OT - Connecting rod bearings (jeep)

TBprnaa

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El Toro

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TBprnaa

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dhermesc

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JDemaris

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RN

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TonyIN

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Anonymous-0

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Dblair

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Mike M

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TBprnaa

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TBprnaa

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