W124 non turbo 300d loosing power

[Fergal1975]

Went on a long trip 70mile there n 70 back on way there car lost power and pulled in cut out started again went ok on return lost power a few times got gradually worse smell of a hill would slow right back got it home eventually with a struggle. Tried it this morning and seems fine ? Was a petrol 230e converted to diesel ?

 

[Doug1234]

Change fuel filter.. common symptoms are lurching at higher revs but back off throttle slightly a few hundred revs and its ok and obviously going up hills requires more revs /fuel hence losing power.
On a w124 e300 diesel you have a primary filter and main filter and also a tank strainer.
Your main filter most likely needs changing replace pre filter as well, pre filter will always have a small air bubble in it most of the time and this is normal.

 

[Fergal1975]

Not long since I did a full service oil feul and air . Didn't change the pre filter or strainer so could be there . Car was lying up for a good time and as I say was previously petrol. S many tank strainer is the prob. Maby best change all three filters . Would I need to clean tank ?

 

[Doug1234]

Should not need to clean tank if it was previously petrol but check the pre filter for black lumps as these could be small bits of rubber fuel hose as it breaks up after many years and maybe the diesel has helped it along and that will block pre filter up.
Other than that check no air in fuel lines when engines running ,could have a weak lift pump maybe but I doubt it.
Not much stops these its either fuel or it cannot get enough air or somethings blocking exhaust .
Check the stop lever on pump is not getting pulled down when engines running, put an elastic band on it to hold it up and go for a drive and see if its better.

 

[Fergal1975]

Sound will check that . When you mention exaust there is some liquid comes out of exaust

 

[Doug1234]

Thats most likely just condensation from the cold weather, but check the engine water level and keep an eye on it.

 

[Fergal1975]

Thanks i will keep an eye on that happy xmas!

 

[mattkh]

Not much stops these its either fuel or it cannot get enough air

I know a 1959 190Db owner who use to put a blanket over the engine in winter. A mate borrowed the car and came back after 100 yards complaining of lack of power. The blanket was still on the engine, so not enough air going in.

 

[Doug1234]

Its occurred to me that Im presuming its an om603 engine , so if it is the om606 the usual suspect will be the pre filter which sits beside the main filter most likely having a bad seal letting some air get but you normally get starting problems when this is the case.

 

[Fergal1975]

Do e a bit today tank full of rust n the pre filter clogged with small black bits . Have a spotless tank from Donner going to install it . There's a unit which the pre filter goes into what does it do ?

 

[Doug1234]

Its just part of the filter housing … so you have the om606 engine.
You could fit an inline filter at the bulkhead where the underbody steel line from tank joins the rubber hose and this would catch the bulk of any junk and let you drive until you get around to swapping tank.

 

[Fergal1975]

What I'm talking about is a small steel unit with 4 pipes . There is a clear plastic in line filter then goes into this unit up to the top of engine then back to main filter and in to the pump. This unit is about the size of a salt cellar . Going to clean the in line filter n put it back in till I get the proper one . I'll take a picture n send it

 

[Doug1234]

When you remove that pre filter(10mm bolt and a small steel clamp ) it obviously pulls out , now it has a thin o ring on it .. I always found it a good idea to fit another o ring on it and roll it up above where the original one sits … it makes it harder to push back in but it stops any air leaks getting in as this is the highest point in the fuel delivery system and any air getting in here lets fuel drain back to the tank and causes hard or no start

 

[Fergal1975]

Is this pre filter I center of photo ?

 

[Doug1234]

om606 pre filter - Google Search

 

[Fergal1975]

Nearly sure my engine is a om603 as my pre filter is an inline type . And the unit I'm looking at I think is the fuel heater . Thanks again I swapped out the tank and cleaned the pre filter now it seems to be running good . Had a bit of slippage in 2nd to 3rd but I adjusted the vacume via castle nut. How will I know when its good ?