Hello, my 1987 300SDL has NO flow to the oil cooler!
I have 2 of these cars and my problem one has a cold oil cooler.
The lower pipe is hot a few inches from the oil filter housing but the top is hardly warm - probably from just its proximity to the engine.
And the oil cooler is just outside temp anywhere you feel it.
My other car you can easily feel the oil cooler is plenty warm and I know that one is working good.
I've driven the car 20 miles, some high throttle opening and up a few hills to ensure the engine is fully warmed up.
I removed the metal lines and it was easy - and messy - to blow air through the oil cooler.
I can't find any good info on a so called oil filter housing thermostat for the OM603 engine!
Can it be a oil thermostat and check valve issue!
Can I replace these parts inside the oil filter housing? ( removed from the engine )

On my 84 300D The Oil Filter Housing has a thermostat in it. If someone would post a site that has the parts breakdown drawing you could see if your year and model has a thermostat in the oil filter housing.

Having a thermostat also implies that the Oil flow is restricted till the thermostat starts to open mean the Oil has to be hot enough to open it.

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84 300D, 82 Volvo 244Gl Diesel

I contacted the dealer and they told me the oil thermostat is 6031800075 but the fun part is they say its not available anymore. Anyone got a lead on one?

Junkyard, or look for a universal racing unit

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

I believe that Mach 4 did a thorough investigation on the oil cooler thermostat for his OM617 engine, might want to find that thread and read up.

Basically the choices are to re-engineer and find some other way to control oil flow via the cooler, or live with it.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

This car of mine was tampered with before I bought it. I'm really not liking putting in that labor into an unknown junk yard part only to have the same or worse issue. If it was a simple part okay but I want to be extra careful around the oil system.

I did wonder about just making an opening and let the oil flow but I'm sure that is a problem too that I just don't know about that well. Something like technically oil does not fully lubricate its best until its as a correct temperature ability to burn off moisture. But thanks all - keep the ideas coming.

Here's the thread I was thinking of.

http://www.peachparts.com/shopforum/diesel-discussion/370363-oil-cooler-thermostat-replacement.html

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Thank you for that. Now if I can get the oil thermostat part or have to go all in on a complete new housing.

Anyone know if the 617 part is the same for the 603?!

Miltiviscosity Oil should not exhibit the same temp issues. It is supposed to lubricate cold or hot.

I am guessing that when most people add on an oil cooler it is full flow all of the time.

I don't think the thermostat not opening till the Oil is hot is an issue in areas that have mild temps. It is likely more an issue where it gets really cold then it is a benefit not to have the oil going to the cooler.

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84 300D, 82 Volvo 244Gl Diesel