New Jeeper, New Knock, Dirty Oil, Need advice

[Ctknorr]

I have a '74 CJ5 with a 258, which now has a new knock in the engine.

About three hundred miles back I changed the oil and checked all the fluids on my 'new' purchase.

This past friday (3-4) night while tooling home the engine started to lose a little power and started knocking with a new knock.

Pulled over, let it cool and restarted. Knock still there. Shut off towed home.

As it sat on the side of the road friday night I noticed lots of oil on the ground in places it has not leaked before. Front end of the valve cover was leaking like never before. Outside of engine down the right side was coated with oil.

I wiped down what I could reach it looks like the oil was all on the outside. no new puddle in my driveway.

Last Wednesday, oil was still looking clean and new. Oil is Quaker State 10W30 High mileage oil.

Friday night oil was low and dirty as all get out looking like it had 10K miles on it.

Where do I start looking for solutions to the knock? And what makes the oil turn so fast?

CK

 

[PistolDave]

The oil getting dirty in an engine is mostly from combustion byproducts and unburned fuel contamination. The more worn out an engine is, i.e. leaky rings, worn cylinders, worn valve guides, etc. the faster the oil gets contaminated. Carbed engines are the worst especially if you are somewhat out of tune, this generates a lot of contamination for the oil compared to say a modern fuel injected motor that mostly runs a lean or stoichiometric air fuel ratio.

As to the sudden loss of power and sudden increase in oil leaks, it sounds like something might have pressurized your crank case, could be as simple as a malfunctioning PCV or something more serious like a failed compression ring or badly worn valve and guide. I am sure there are some other possibilities that some of the more knowledgeable troubleshooters will chime in with.

You might run a quick compression test to see if one of the cylinders is weak.

 

[HackFabrication]

Curious if it's an upper engine knock or a lower engine knock???

Probably time to pull the engine and have a look-see internally.

 

[Torxhead]

If you are not ready to do an overhaul, I would suggest a heavier oil like a 20w-50. One of the thick oil additives like rislone or stp could quiet things down. Start researching just where the oil leaks are coming from and just where the noise is also. Like is it a bad rod bearing or just a sticky lifter.

 

[mtnwhlr]

The 258 is known for spinning the #6 rod bearing. I bought a CJ cheap with a rod knock and that was the problem.

 

[gert]

put a mechanical oil pressure gauge on the motor you want at least 7-10 psi at idle and for it to max out around 60 psi at max at high rpm. no oil pressure at idle could mean a spun bearing and that would be the cause of your knocking noise

 

[Ctknorr]

Curious if it's an upper engine knock or a lower engine knock???

Probably time to pull the engine and have a look-see internally.

At first I thought it was coming from the water pump. But not sure. I defiantly think its coming from the front end of the block.

 

[HackFabrication]

Can you post up a video with sound? If you can't post pics, PM me for my email address, and I will for you.

 

[Lumpy Grits]

How many miles on this engine?
X2 on a recording of the sound.
Does it get worst as the rpm goes up?
Have you checked the spark plugs?
How much wobble do you have in the fan blade?
LG

 

[Ctknorr]

Here are two sound files. The Video is to large to upload.

The Knock file I ran the recorder from front to back and back to front in about 36 seconds. you can here the knock go faint and back loud as I hover over the #1 cyl.

 

[Ctknorr]

How many miles on this engine?
X2 on a recording of the sound.
Does it get worst as the rpm goes up?
Have you checked the spark plugs?
How much wobble do you have in the fan blade?
LG

ITs unknown how many miles are on the engine. I estimate 200 plus if it's the original. Are there Identifying marks on the block that would confirm build date and CI? I believe it's a 258 CI.

Knock matches the RPM.

Fan Blade is solid tight and no visible wobble or other movement when running?

Plugs prior to this were clean and not fouled. Have not checked them since. Getting tools needed for compression check.

I've been sick so Have not been able to do as much of this testing as I would have liked. This weekend is another story tho. I may pull the pan off and see if I have a bad rod problem.

 

[Lumpy Grits]

Get well fast.
Drop'n the pan on our 6's is a bit of a PITA as you have to remove an engine mount to do so.
What was the engine oil level when the knock started?
LG

 

[Ctknorr]

The oil was down maybe 1/2 quart. Which I think was all during this trip. Been sitting in my driveway for over a week now and it's stopped dripping.

It was full and clean two days before the knock started. It had been on the road steady highway speed about 20 miles when it happened.

 

[Lumpy Grits]

Front and rear main seal leaks are common on our 6's.
Both of mine have dripped for decades.
LG

 

[Torxhead]

Front and rear main seal leaks are common on our 6's.
Both of mine have dripped for decades.
LG

and the valve cover.

 

[Belizean]

Front and rear main seal leaks are common on our 6's.
Both of mine have dripped for decades.
LG

Yeah You Right!

 

[Lumpy Grits]

and the valve cover.

Yup-Have resealed mine 6 times, in 32 yrs.
Keep an eye on your PCV valve to be sure it's kinda clean and works 'rite'.
LG

 

[mtnwhlr]

I'm still betting on the #6 rod bearing.

 

[scramcraz]

Could be anything from a rod knocking , piston slap, or a collapsed lifter. Usually a rod knock will be more pronounced when the engine is gunned. Have you tried pulling plug wires to find a missing cylinder? If you have an automatic tranny, set the e brake and put it in drive to load the engine. Then pull plug wires one by one. Good cylinders will drop RPM when cut out; a dead one will have no change.

Good Hunting!

Bob

 

[HackFabrication]

Finally got one of your videos to upload to photobucket:



I'll work on the other one today...