Strange engine noise - Page 4 - PeachParts Mercedes-Benz Forum

vwnate1 · #46 04-17-2020, 02:30 PM

As long as you're not driving it 200 miles from home run it until it lets go then figure out of you want to install a good used engkne fron a rusty junker or simply let it go .

A sad day when one has to let them go but not everyone wants to or has the $ to fix a failed engine .

fireman1073 · #47 04-21-2020, 09:10 AM

another engine knock post with video i never figured mine out. im still driving it

yuke · #48 04-22-2020, 12:39 PM

A fter giving this much thought and talking to a lot of mechanics I really believe I have a collasped lifter or faulty spring in one of my lifters because the noise started after the car down shifted on its own and rpms rose to about 4,000 traveling 65-70 mph. I really would like to try to pinpoint the noise to a certain cyl. by running with valve cover off and some cover to contain the oil fling while listening with stethoscope. Really thinking coming from 3rd cyl. If I can narrow noise down to certain cyl. how can I remove that lifter for cleaning and inspection or should I just put back together and run some marvel mystery oil through it and hope that fixs my lifter problem if that indeed is what I have? I'm thinking one of my lifters either has a broken spring in it or it is starved for oil and cannot reprime itself for some reason.

Usaguy · #49 04-22-2020, 12:49 PM

Quote:

Originally Posted by yuke

A fter giving this much thought and talking to a lot of mechanics I really believe I have a collasped lifter or faulty spring in one of my lifters

But you have the OM617 so there are no lifters

yuke · #50 04-22-2020, 02:20 PM

Oh guess I was watching a vidio for a later engine so I have no collasped hydraulic lifter so do I have solid lifters in my 617? Just trying to figure out what is causeing my noise from my valve area? There are spings on top is this this what returns the valve to closed position after it is open? Will still try to run it with valve cover off to pinpoint noise better Then button it back up and hope the marvel oil will clean out and lube whatever is causing the tapping noise. Forgive me as I have never worked on the internals of these 617 motors.

Usaguy · #51 04-22-2020, 02:31 PM

Quote:

Originally Posted by yuke

so do I have solid lifters in my 617?

Yes, if you can call them "lifters"

you're supposed to do a valve adjustment every 15k miles

tdoublenastywitit · #52 04-22-2020, 02:46 PM

My only 2 cents is to stop defaulting back to, doing a diesel purge, or marvel mystery oil, or any type of additives. Those don't fix things, they are a maintenance item.

My other advice is just start wrenching, start popping off nuts and bolts and figure it out as u go. You will learn a lot on the way

MB140300SD · #53 04-22-2020, 07:37 PM

Having been working on these 617 engines for over 2 decades, you have a rod knocking.

ROLLGUY · #54 04-22-2020, 07:44 PM

Quote:

Originally Posted by MB140300SD

Having been working on these 617 engines for over 2 decades, you have a rod knocking.

Totally agree......Rich

yuke · #55 04-23-2020, 11:22 AM

Thanks so much 300 SD n Rollguy then I have 2 options run it till it stops or pull the engine put doner in and fix the rod knock. I wonder if I run it like is how many more miles could I get out of it ??

BWhitmore · #56 04-23-2020, 12:27 PM

Predicting the number of miles left in an engine with a rod knock would be a wild guess at best.

Usaguy · #57 04-23-2020, 12:51 PM

Quote:

Originally Posted by yuke

I have 2 options run it till it stops or pull the engine put doner in

other than a roadside breakdown you don't have much to lose (unless you want to pull it apart and replace the crank and put new bearings in)

and remember there's always a chance that it's something else. Engines can make all kinds of noises.

BWhitmore · #58 04-23-2020, 12:57 PM

If the rod comes through the side of the block a lot of oil will be dumped on the road which could cause a skid for you and/or other drivers.

vwnate1 · #59 04-23-2020, 02:01 PM

As I said before :

Look at how and where you drive it then decide .

I worked with a guy in the mid 1980's who had a 1951 Chevy pickup with the non pressurized rod bearings (216CID) , it had a rod knock and he only drove it a few miles, to work and back and the park on weekends .

He drove it this way for two decades, he knew it could have a catastrophic failure so he never lugged nor over speeded the engine...

Me, I'd be looking for another engine, give it a deep servicing , re seal it then plop it in the car .

Do a valve adjust and compression test before paying more than $100 for any used engine .

ROLLGUY · #60 04-23-2020, 09:28 PM

My first 'Benz had that same sound. I drove it till it made so much noise, that I knew it was done. I doubt yours will throw a rod through the block. The engine would have to be turning high RPM's for that to happen. The clearance between the top of the piston and the head is so small, that a little slop in the con rod bearing will cause the piston to hit the head. When you pull it apart, you will probably see evidence of that. I'd say put another engine in it if you need a car, and maybe the noisy engine can be repaired (done it before). The #2 rod bearing (barely accessible without removing the upper pan) was bad, so I sanded down (on a piece of sandpaper glued to a piece of granite) the mating surface of the rod cap, and used plasti-gauge to know the clearance. A couple times of sanding, and I got it within spec. A new bearing, and the engine was good to go. If the crank is too far gone, there is no way to repair it without removing and disassembling the engine.....Rich