Engine Knock

ChiroKJ · **Posted:** Tue Dec 16, 2008 9:40 am

So over the last few weeks my engine developed a loud knock. I tried searching for previous stuff but it all seems to be cold engine knocking. My on the other hand only happens when the engine warms up. I happens randomly at low RPM but i can sometimes reproduce it when i let off the gas. Happens when i idle it as well. its a 3.7L with 60 000 miles

any ideas?

TAHOE · **Posted:** Tue Dec 16, 2008 1:09 pm

What year is it? Could be some carbon building up on pistons/valves etc. I do remember reading when we first got ours about a lot of people with 05's having burnt valve issues. Worse case could also be oil getting thinner when warm and rod knocks developing when pressure drops at lower rpms.

ChiroKJ · **Posted:** Tue Dec 16, 2008 4:33 pm

its an 02 and i use mobil one 0w-40

Jeepjeepster · **Posted:** Tue Dec 16, 2008 6:56 pm

Maybe you should try using a weight oil that is recommended for the 3.7 and go from there? 0w is a bit thin and 40 is a little too thick.

5w-20 would be the most I would ever go. Personally I use 5w-30 in the winter and 10w-30 in the summer.

LIV42DY · **Posted:** Tue Dec 16, 2008 9:22 pm

Drop some Mobil 1 syn 10-30, my 02 was raised on it 67000 miles with no issues. I run it all year round no matter hoe cold it gets. Try it it may get rid of the knock.

ChiroKJ · **Posted:** Sat Jan 24, 2009 3:53 pm

had the mogil one 5w 30 for a while and the knock is still there especially at idle. it almost sounds like a spring sound with a distinct metal knock......

afornal · **Posted:** Sat Jan 24, 2009 10:29 pm

Sounds kinda Similar to mine. See my Post Under general Discussions #2 Cylinder Misfire. Mine did this after we had an Extreme drop in temprature. Just started her up on a 10 below morning and bam, I got the tinging noise, with a diag code telling me #2 Cycliner is misfiring. Changed all the Plugs, and a NEW Coil Pack for that Clyinder - Same thing, so she was flat bedded off to My Mechanic last tuesday for deeper analysis. I have not heard anything as of yet, but will be posting updates on the problem under my post when i get the final diagnosis and the Bill $$$$$$$$$$$

Good Luck

ChiroKJ · **Posted:** Sun Jan 25, 2009 2:20 am

i changed the plugs a few days ago and no help either

tjkj2002 · **Posted:** Sun Jan 25, 2009 11:18 am

ChiroKJ wrote:

i changed the plugs a few days ago and no help either

You need to pull the valve covers and you will find your problem.

afornal · **Posted:** Mon Jan 26, 2009 8:44 pm

Just heard back today from my local mechanic - My Problem was the rocker arm came loose - They fixed that - perfomed an Oil Change and she be back on the road tomorrow! - Price $100 fix. I'm happy!!!!!!!

trailman · **Posted:** Mon Jan 26, 2009 9:21 pm

100 bucks! Nice!

cfreelv711 · **Posted:** Tue Jan 27, 2009 11:02 pm

Hmmmm...rocker arm..under valve cover?? Any doubt tjkj know his stuff?? Stealership would charge $78 just to tell what the problem is and tjkj does it or free :lol:

ChiroKJ · **Posted:** Tue Mar 31, 2009 6:14 pm

The knock kind of went away ( well it was not constant in the first place) it would only do it once or twice during a 5 mile trip. the weirdest thing is that i got out of the car today and heard it again AFTER the engine was turned OFF... :shock:

Engine Knock

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