Engine Knock on Cherokee 4.0

We have a UK 1995 Cherokee 4.0 LTD Auto with a genuine 35000 miles, we
noticed a heavy bottom end knock on starting, only a knock or two, the sump
was removed and some wear was found in the big end bearings so they were
replaced, the main bearings were fine, the engine was turned over without
the coil connected to build up oil pressure, but when the engine was started
there was an end noise 10 times worse than before so it was turned off after
a few seconds.

The mechanic who carried out the work has rebuilt bottom ends before, and
has rechecked all the bolts etc on the car and all seems as it should be,
but he admits he is stumped by this, he has now suggested that we start
looking at the top end.

Anyone got any advice or had a similar problem.

John

 

The guy 'repairs' your engine and then it produces even more noise than
before and he blames the top end?.. lol.. he has you fooled for sure.. take
it to somebody that truly knows what they are doing before you pay out
anymore.. it is true that if you repair half of an engine, it can put more
strain on the rest, but it would take more than a few seconds for that to
become apparent.. good luck.. you may get a 0 miles engine out of this if
you continue to let your friend work on it, but it will cost you dear..

 

Did he bore out the cylinders and install new oversize pistons?
Was a torque/honing plate attached to the block when "fitting" the pistons
to their cylinders?
I think you might hear piston slap maybe? Although I think it is heard more
with the engine running.
Or possibly exhaust leak from a cracked exhaust manifold?
Or possibly a cracked driveplate or flexplate?
just some thoughts!
good luck,
dave

 

Ouch!

Sure sounds like buddy screwed up big time.

The last time I 'heard' something like that, I helped the owner take it
apart and fix it right.

The engine had a knock and went for a 'cheap' bottom end rebuild.

He ended up needing a new crank because the bozo that put it together
forgot to put the journal caps back in the right place.

I couldn't believe the noise it was making, so we ran a stethoscope on
it and it appeared to be knocking all over the bottom end.

It was!

Only 3 bearing caps were on right, the rest were mixed up and on
backwards.

I mean crap, all the caps and connecting rods and main bearing caps were
numbered even. The fool couldn't even follow the numbers.

When all else is the same and the noise changes, look at the 'repair',
don't let anyone give you a snow job to cover up incompetent work.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

 

A 4.0 that needed to be taken apart after 35k miles? Almost unheard of.

Was it beaten mercilessly during it's life? Mine has more than 100 thousand
miles more than that and it sounds great.

 

I agree with you Clem, I've owned 5 Cherokees (not counting cj5, cj7, yj and
the cj8 I still have) since they've come out and I've always gotten over a
100K on all of them. That 4.0 and the older 4.2 (258) engines are bullet
proof. (my cj8 has 182,000 on the 258 inline and it ain't slowed down a
bit) Never any problems. Keep the oil changed between 3000 & 4000 miles and
you're good to go.

Ol' Reb

 

Not knowing how loud the sound was or what it sounded like.... could it be
wrist pins?

 

Thats my luck! car has done genuine 35000 miles rest of the car is mint
inside and outside, I saw the wear in the bearings myself.

John

 

First the knock was a loud single or double knock only when the starter
dis-engaged, but following the new bearings it was a sickly loud constant
knocking so bad that my mechanic only let it run for a few seconds before
turning it off.

 

Roughly 12/17/03 01:11, John C's monkeys randomly typed:

That is a bit abnormal to say the least, almost like there was
something wrong right at the beginning. As for luck, you could
look at this as a golden excuse to consider installing a
stroker kit... make a 4.5 or 4.7 out of it.