m104 oil non-return valve

[brigadier]

Hi! My m104 engined coupe makes terrible (tappets) sound for a second until oil pressure rises up. I think it might be the one way valve, that keeps the oil in filter for immediate lubrication.
I understand i need these parts 26,29,32,35,110 in diagram bellow?
It's called by-pass valve in epc.

 

[Dieselman]

The bypass valve is what it says, a pressure relief bypass.

 

[brigadier]

Thanks! In that case where is the non-return valve that keeps the oil in the filter?

 

[WDB124066]

Does it do it every time on startup, after standing for a few hours or only after standing overnight or longer......??

 

[brigadier]

Only after staying overnight or longer.

 

[WDB124066]

Ok. My guess is it is the hydraulic tappets, it won't typically be all of them but my feeling is that it is these that are giving the problem. Far more common that a NRV failure on a M104.

How to diagnose for sure I will leave to others........

 

[brigadier]

Might be. Is the NRV in the filter housing? I could only find by-pass valve on epc.

 

[jaymanek]

My 300TE-24 engine does exactly the same, taps away for a few seconds... tried various different oils.

 

[kth286]

Hi! My m104 engined coupe makes terrible (tappets) sound for a second until oil pressure rises up. I think it might be the one way valve, that keeps the oil in filter for immediate lubrication.
I understand i need these parts 26,29,32,35,110 in diagram bellow?
It's called by-pass valve in epc.

By terrible tappets sound, it may not be that, because tappet sounds are not terrible.

What is terrible is timing chain thrash.

That could be the spring weak in tensioner. Used to be able to buy
seperate internal parts for tensioner from merc dealer.

There is also a non return valve in front of block just under tensioner
to help keep oil there when engine off.

 

[brigadier]

Thanks! To replace the chain tensioner non-return valve I need to take off the timing covers, the chain etc. Tensioner spring assembly however would be easier as it screws in from the side. I found this pdf that shows 3 valves in the oil filter housing - non-return valve, by-pass valve and drain valve, that drains oil to sump when element is removed. I guess i could easily test the non-return valve, if I open the cover and see if it holds oil in filter after longer period.

http://w124-zone.com/downloads/MB CD/W124/w124CD1/Program/Engine/104/18-1000.pdf - that's the pdf showing filter housing insides.

 

[jaymanek]

Its pretty difficult to get to if you end of changing that filter housing... I think the intake manifold would have to be removed.

 

[kth286]

Thanks! To replace the chain tensioner non-return valve I need to take off the timing covers, the chain etc. Tensioner spring assembly however would be easier as it screws in from the side. I found this pdf that shows 3 valves in the oil filter housing - non-return valve, by-pass valve and drain valve, that drains oil to sump when element is removed. I guess i could easily test the non-return valve, if I open the cover and see if it holds oil in filter after longer period.

http://w124-zone.com/downloads/MB CD/W124/w124CD1/Program/Engine/104/18-1000.pdf - that's the pdf showing filter housing insides.

NIL record of problems with the oil filter assembly, BUT plenty of records
of tensioner problems.

Record the sound that is causing you concern,and put a link on forum.