Losing power, developing a knock (om617) - PeachParts Mercedes-Benz Forum

tompaah7503 · #1 09-09-2016, 10:56 AM

My 83 300TD non-turbo 617 has lost a bit of power and has developed a knock since about 2 months or 8000 kms.

The engine has about 373.000 km on it and appears normally maintaned, I have owned it for the last 16.000 kms. I have changed all fluids and filters about 1 month ago but the symptoms began earlier than that.

Symptoms:

Rough idle
Smokes more than usual (not water vapor or oil, it's badly combusted fuel)
Has a knock while idling, not all cylinders, maybe just on one
Need to floor the pedal to get car somwehere
Struggling to maintain speed at fifth gear on flat terrain
It starts strong and easy, glows fine

I don't know when it last had it's valves adjusted, I have not done it during the 16000 km's I owned the car.

Could a bad valve adjustment have these symptoms?
Or is this a case of a bad injector nozzle?

What would be a recommended first action?

leathermang · #2 09-09-2016, 11:00 AM

No good news here..
SET the valves carefully and keep your fingers crossed...
check back with the results...

tompaah7503 · #3 09-09-2016, 11:06 AM

Oh, forgot to add.
It doesn't seem to consume any oil, and maintains both normal temperature and oil pressure during drive, even when flooring it for miles and miles.

leathermang · #4 09-09-2016, 11:12 AM

Does not change your path to finding what is wrong.

oldsinner111 · #5 09-09-2016, 11:40 AM

no gasoline in fuel?

tompaah7503 · #6 09-09-2016, 11:46 AM

Not that I know, have fueled multiple times since the problems began.

I'll try the valve adjustment for starters, just need to get my hands on the bent wrenches.

leathermang · #7 09-09-2016, 12:11 PM

Once your valves are set... then you can use the IP system to see if the ' knock' can be pinpointed to one cylinder...

panZZer · #8 09-09-2016, 03:22 PM

Quote:

Originally Posted by tompaah7503

My 83 300TD non-turbo 617 has lost a bit of power and has developed a knock since about 2 months or 8000 kms.

The engine has about 373.000 km on it and appears normally maintaned, I have owned it for the last 16.000 kms. I have changed all fluids and filters about 1 month ago but the symptoms began earlier than that.

Symptoms:

Rough idle
Smokes more than usual (not water vapor or oil, it's badly combusted fuel)
Has a knock while idling, not all cylinders, maybe just on one
Need to floor the pedal to get car somwehere
Struggling to maintain speed at fifth gear on flat terrain
It starts strong and easy, glows fine

I don't know when it last had it's valves adjusted, I have not done it during the 16000 km's I owned the car.

Could a bad valve adjustment have these symptoms?
Or is this a case of a bad injector nozzle?

What would be a recommended first action?

I have one here in Texas ill sell you, its got the m pump on it.
or I got a turbo one ill sell you, and also got a matching tranz

im serious, shipping is easier for me than if you were here in America.
Mangus ships American iron to Sweden from my home town 4 times a yr.

http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/280370-large-300d-300cd-parts-post-12.html

tompaah7503 · #9 09-11-2016, 04:04 PM

Quote:

Originally Posted by panZZer

I have one here in Texas ill sell you, its got the m pump on it.
or I got a turbo one ill sell you, and also got a matching tranz

im serious, shipping is easier for me than if you were here in America.
Mangus ships American iron to Sweden from my home town 4 times a yr.

http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/280370-large-300d-300cd-parts-post-12.html

Interesting proposal, though I'd need a turbo engine with the wagon/sls head. Yours are CD and SD engines right, no SLS pump on them?

panZZer · #10 09-11-2016, 04:34 PM

Quote:

Originally Posted by tompaah7503

Interesting proposal, though I'd need a turbo engine with the wagon/sls head. Yours are CD and SD engines right, no SLS pump on them?

nope plain, you could or would have to deliete -or get some custom pump for the sls

rocky raccoon · #11 09-11-2016, 05:17 PM

Before going to extremes, I would check the injectors. A badly set up injector or two ( pissing instead of spraying) will definitely cause a knock that can sound much more expensive.

Easy and Cheap first before jumping.

dude99 · #12 09-11-2016, 09:51 PM

X2 for checking injectors

Clemson88 · #13 09-13-2016, 08:11 AM

It is my understanding that valves out of adjustment makes the 617 hard to start. No matter, those valves probably should to be adjusted.

I'd loosen the injectors one at a time to see if the knock was caused by an injector. If the injectors are bad and you pull them for replacement or repair it will make adjusting the valves a bit easier. The engine will turn without a fight.

I'm never in a hurry about anything. Everytime I walk toward my car with a wrench it rolls over on its back and begs for mercy.

yuke · #14 09-14-2016, 06:58 AM

Try to determine if the knock or noise if coming from the top or bottom of the engine. I recently had what I would call was a nailing noise which I determined by loosening 1 injector at a time was coming from my 4th cyl. back when I pulled that injector and learned what a good prechamber should look like I realized my prechamber blew the bottom out down into the cyl. had a big loss of power and engine consumed more oil in the last 1,000 miles I ran it. I could not pull the prechamber out I think only way is if I remove the head which I put on hold as I have a good 617 motor that I am currently putting in. Sounds like your noise is a pretty serious problem good luck.