3.7 knock?

[jeeptorino68]

Got under last night and hit the exhaust all over with my hands, etc. Couldnt get a similar noise, especially from the pre-cats. Am So I doubt its the exhaust

 

[ltd02]

Let us know what the oil looks like when you change it. Should get a filter cutter. I like mine.

 

[jeeptorino68]

Found this article about cat converters and I am now very sure its my pre cats

https://shop.advanceautoparts.com/r/diagnose-a-broken-catalytic-converter

The noise keeps switching sides, a coupke days ago definitely the lower pass side. Yesterday lower driver. I was able to press my hands on the driver cat to change the sound. And things are consistant with that article. I was smelling the sulfur/rotten egg smell a couple weeks ago at Hwy speed with windows open towing uphill. So I ordered all 4 new oxygen sensors. Nee band clamps, and pacesetter pre cats. We will see

 

[jeeptorino68]

Bringing this one back up.
Changed the cats. Still a knock. Vut the driver side was toast so not a wasted effort...

Now what? Sounds more and more like rod knock...but I'm not experienced with that. So how can I determine/be sure?

What about engine mounts? Common failure?
Torque converter bolts?

I'm at a loss. I've searched everything
Tries pulling the coil plug at each cylinder one at a time. The noise doesnt really change. Going to pull one spark plug at a time tomorrow and then run it and see what the noise does. Then I guess pull the oil filter and cut it open?

 

[John P.]

Hi and good morning, I'm not a fan of additives to oil but maybe as a last ditch troubleshooting move add in a quart of Lucas oil stabilizer with some straight 30wt oil and see if the noise changes. I wouldn't run straight 30wt for regular use. Just something to try since you've explored everything else. I guess on the bright side 3.7 engines are plentiful if it comes down to it.

 

[jeeptorino68]

Hi and good morning, I'm not a fan of additives to oil but maybe as a last ditch troubleshooting move add in a quart of Lucas oil stabilizer with some straight 30wt oil and see if the noise changes. I wouldn't run straight 30wt for regular use. Just something to try since you've explored everything else. I guess on the bright side 3.7 engines are plentiful if it comes down to it.

Thanks for the idea. Forgot to mention I threw in sime of the lucas (I was half a quart low anyways) no change though to the sound. Hence why I'm not so sure it is rod bearings...

 

[lfhoward]

Jeeptorino: I had a 3.7 engine die from a bad rod bearing about 6 years ago, and got a remanufactured engine.

Anyhow, if it is a rod bearing, the sound will be coming from the low end of the engine. It will also be a clacking sound, which gets much worse at high rpms with no or light loads. When pulling up a hill in a low gear, the sound won’t be as bad as when you crest the hill and the engine doesn’t have to work as hard. The slack will make all sorts of noise as the crankshaft turns. Eventually when the bearing completely disintegrates it will sound like someone dumped gravel in your engine...

I hope it’s not actually a rod bearing.

 

[ltd02]

Did you ever cut open an oil filter and see if there is any bearing material in the folds? Look for bits in the drained oil too. Use a paint filter.

I spun a #2 rod bearing around 175k in my 02. Knocked for quite a few months before it went.

 

[lfhoward]

Did you ever cut open an oil filter and see if there is any bearing material in the folds? Look for bits in the drained oil too. Use a paint filter.

I spun a #2 rod bearing around 175k in my 02. Knocked for quite a few months before it went.

No, I never did cut open the filter, but it would have been interesting to see. I did have Blackstone Labs analyze my oil in the months leading up to failure and everything seemed ok, but then again the engine only had 86K on it when it happened. I think it was a factory defect because I was always careful about doing oil changes. If everything else was fine in the engine, one rod bearing may not have been enough to flag anything in the oil analysis. Mine too knocked for quite a while (years actually) before it went. I was told, “Yeah the 3.7 can be a noisy engine.” Now that I have 90K on my remanufactured Jasper engine and it purrs like a kitty, I think, “Nah, knocking noises are not normal.”

 

[jeeptorino68]

I drained the oil opened up the filter. Nothing. No glitter! My next path is the timing chain. Took off the valve covers driver side is tight (timing chain) passenger side is slack!!!
Parts are on the way. This has gotta be it....

 

[jeeptorino68]

Well that *****. Wasnt the timing chain.
If there is no metal flakes The oil or filter then it cant be a bad rod bearing right....??. Or can it?

 

[John P.]

May be a shot in the dark but maybe it's coming from the crankshaft damper?

 

[lfhoward]

Jeeptorino68, can you make a recording of the knock sound and post it in here? I’d really like to hear what you hear and know if it sounds familiar. I know what my rod knock sounded like, so I can maybe confirm or rule out yours.

 

[John P.]

Second that, a recording would be great. I could put on my headset and listen.