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Low End Knocking ?

H

Hylander

NAXJA Forum User
Location
Texas
Just bought a 97 4.0 Cherokee, 125,000 miles.
Fresh 10-30 oil change.
When I start it up, it has what sounds like a Low end Knock, it gets quiter when bringing the RPM's up.
When engine warms to operating Temp 190-200 degrees the knock goes away.
At start up I have 40lb. + oil pressure, after reaching operating Temp I have 20lb. +- Oil pressure
This morning with the engine cold after setting all night, I removed the Valve cover, started the engine and it took about 15-20 seconds before oil made it to the Rockers, and it does not squirt out of the rods, it just ozz's slowly.
 
Sounds like the same problem I'm having. I tried lucas oil stabilizer and the knock is still there.
 
Rule of thumb you want a minimum of 10 psi per 1000 rpm, so you are Ok.

Just for grins and giggles, what brand of oil filter?

Sounds like you have some buildup in the engine--how does that valve cover look inside?

You could try Seafoam, just follow the directions for flushing the engine.

Or, you could do it slow with Shell Rotella, which will clean the crap out of your engine and it still has ZDDP in it for the flat tappets in the 4.0.
 
joe_peters said:
Rule of thumb you want a minimum of 10 psi per 1000 rpm, so you are Ok.
Just for grins and giggles, what brand of oil filter?
Sounds like you have some buildup in the engine--how does that valve cover look inside?
You could try Seafoam, just follow the directions for flushing the engine.
Or, you could do it slow with Shell Rotella, which will clean the crap out of your engine and it still has ZDDP in it for the flat tappets in the 4.0.
Click to expand...

Fram Filter, but it had another brand before the change and it was the same noise.
No Gunk build up and no Varnish, Valve covers and Rockers and Head
Very clean inside.
 
Hylander said:
Fram Filter, but it had another brand before the change and it was the same noise.
No Gunk build up and no Varnish, Valve covers and Rockers and Head
Very clean inside.
Click to expand...

Then I would change the filter, go with something good like Wix or NAPA Gold.

The opinions on this forum regarding the current productions Fram oil filters run from no problems with them and that it killed their engine. Do a search on fram filters, make up your own mind.
 
Hylander said:
This morning with the engine cold after setting all night, I removed the Valve cover, started the engine and it took about 15-20 seconds before oil made it to the Rockers, and it does not squirt out of the rods, it just ozz's slowly.
Click to expand...

Just as a data point I noticed the same thing in mine, a new rebuild engine. It took the same amount of time for oil to start to ooze out of the pushrods. Perhaps it's normal.

The FSM shows the oil routing from the filter directly to the tappet gallery so you wouldn't think it would take that long for oil to appear out of the pushrods.
 
before your next oil change, warm the engine to operating temp and pour 1/2 quart of ATF in the crankcase. let that idle for about 20-30 minutes and drain it all out. i have fixed more sticky lifters with that trick than i can remember.

zedpapa
 
zedpapa said:
before your next oil change, warm the engine to operating temp and pour 1/2 quart of ATF in the crankcase. let that idle for about 20-30 minutes and drain it all out. i have fixed more sticky lifters with that trick than i can remember.
zedpapa
Click to expand...

I am going to give this a try tomorrow, my Dad tought me that trick with my first 1968 383 Road Runner
 
those lifters will tick and tick but you know what, it keeps chugin right down the road. I've had ticky lifters for almost 2 years now and its still running. the lifters of course are gradually getting louder though. what kind of ATF do you recommend? I'll try anything in this noisy motor.
 
Any atf will have the disolving qualities you want. I recomend the Seafoam over atf only because it is made for doing what you are trying to do, but the atf trick works, just dont overdo it.
 
Well i got my RE lift installed, so I thought I would pull the oil pan and check out the inerds.
Rod bearings are toast and the Crank at #2 Cyl is Scored pretty bad.
Also the engine has had water in it at some point in time and #2 Piston was replaced at some point. Looks like I need a new engine.
What burns me up is the guy that sold me the rig was suppose to be the second owner and said no repairs had ever been made other than a water pump recently.
 
An old trick I was showed and triesd it on my 89 was to drain out all oil, put the drain plug back in and fill it with 2 qts atf and 2 qts amonia and run it for about 15 minutes and drain.

Made my 89 with 200k on the clock almost sound new.

Also it is recomended to drop the oil pan because any carbon build up in the motor will end up in the pan.
 
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