Engine Knock at Idle

[Briuah]

Today I moved the car from the front of my house to my driveway, Ran fine. I then started the car up about 20min later to leave. I have This Very Loud Knock at Idle and only idle(below 1k rpm)42 counts of knock on logger. The knock goes away when brought up higher than 1k Rpm. It is definately not a tap its a knock. I need help trying to figure out what it is.

Thanks, Christian

 

[DSM90AWD]

Can you pinpoint where the knock is coming on the engine? Beltside, front, back top..etc?

The symptoms you mention sound like a lifter(s) not fully "pumping up" due to low oil pressure. When you rev higher than Idle (750RPMs) you increase the oil pressure which may be why the noise stops.

 

[Briuah]

I can hear the knock from about 1 house away. It sounds like its coming from the valve cover to me, But im not 100% positive. I have new revised lifters sitting right here, But I have to wait till i get my new clutch to start it up again. (Tranny out). Is there anything I can check at all? I need some pointers because im stumped.

Thanks, Christian

 

[DSM90AWD]

What kind of oil/filter do you use? When did you change it last? Have you checked that the oil is topped off?

The new lifters should help a ton. My old ones would sound like a team of horses galloping down the road at idle.. but would be fine when I got the oil pressure up.

 

[Briuah]

I use the Mitsubishi filter, Valvoline Durablend 10-30. Changed it after it started knocking, Was about 2k into last change. And the oil is also topped

Thanks, Christian

 

[DSM90AWD]

Don't change a thing with the oil/filter. Some use FRAM which in my own 13yrs DSM experience got more lifter noise.

Did the oil you changed come out clean or look silvery? A spun rod bearing (which would also sound like bad knock) could show up in your oil as silver residue.. but the noise would come from the bottom of the engine (oilpan).

 

[Briuah]

I dont know If the oil had a silver residue. I changed it during the night. I will drain it tommorow again to see if i find anything. If there is, should I drop the oil pan?

 

[klipzedgsx]

check crank pulley

 

[Briuah]

When I look at the crank pulley, what should I be looking for??

 

[vertGST]

Originally posted by klipzedgsx
check crank pulley

i had the same problemand it was the crank pully. turn the car on and watch the pully. if it vibrates at all or looks like its shaking then its bad. i waited and waited until finally it disintegrated and i lost all my accessory belts.

 

[Briuah]

Ahh thanks, I will keep that in mind.

Anything else I should check up on?

 

[Defiant]

My guess is jumped timing.

 

[Briuah]

Timing is fine, The gears line up perfect.

 

[DSM90AWD]

Originally posted by Briuah
Anything else I should check up on?

Have you pulled the tranny yet? Check that all the bolts on the tranny, flywheel and pressure plate are all torked down and loc-tited. Tendancy for said bolts to back out. Also check the condition of your stock Clutch/Flywheel.

Also while checking the crank pulley.. always a good idea to check for excessive play in/out.. though have yet to see a 6-bolt with CW (knock.. knock).

I know alot of suggestions have been made.. but really until you have the car running again and can pinpoint the noise.. gonna be tough to find the problem.

 

[Briuah]

OK, the tranny is out. All bolts were tight there. The flywheel was all torqued. The clutch was roasted, Pressure plate burnt to all heck, with hairline cracks around the edges. Flywheel isnt in such great shape. It was a ACT 2600 kit in there. Throwout bearing was squeaking before I dropped tranny, It barely spins (grinding sound inside of TOB).