Quote:
Originally Posted by NZScott
1977 280>300D, OM617.912 auto
20W-50, ambient temps about 0-20 *C.
Been a while since I've felt I've had to ask for thoughts on this forum...
Been using the '77 I've had for about a month now as a daily driver. For most of that time, it has had the long wait for oil pressure to build like the oil filter housing is draining out.
I replaced the 2x o-rings on the oil filter lid stem, and it helped a wee bit but didn't help as much as I'd hoped.
She's an old engine but still shouldn't have to fill the filter housing each start (I presume that's the issue).
Oil is literally cheapest I can get my hands on with a Cx rating...it burns a lot as I now do 8.5hr road trips semi-regularly now I've moved house. I realise going to 5w-40 etc will help but it's not the cause of my issue.
So how else is the filter housing draining?
There is no external leak from the lid big o-ring so I doubt air is getting in that way. As an aside on my '78 with turbo conversion I had to put a check valve in my turbo feed line which was tapped off the housing because it was letting air get in backwards via the turbo drain and causing the same delay post-start before pressure came up.
Cheers...
Forgot to mention. Idle oil pressure when at normal temp (85-90) is 1.5bar, same as my '78 (with 10W-40). Goes to 'bout 1-1.2bar when cooling off from 100+*C.
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This is from my notes "
On 617.952s you can substitute a 7mmx11mmx2mm in the upper groove on the Oil Filter Stem instead of the 6mmx10mmx2mm. If you do that you have enough O-rings for 24 O-ring changes. (This was suggested by another member and I did it and it works; since I bought the kit I do this on mine.)"
Inside of the Oil Filter Stem somewhere in the last bottom 1/4 of it is a spring loaded valve. I don't know how you get at that valve but one of our Members did and he said he found some of the cotton from the upper portion of the stock Oil Filter stuck in the valve. (Once the Oil goes past that Valve it goes into the Oil Pan.)
While there is only a tiny hole at the top of the stem tube for Oil to run out of if the Valve was open it would allow Air to go through the little hole and allow the Oil to drain out faster.
So there is 4 ways for the Oil to get out of the Oil Filter Housing. 1- draining back through the Oil Pump, 2- draining past worn Bearings, 3- draining past the 2 stem O-rings and the mentioned valve allowing air to get inside the Oil Filter Housing.
The above presumes there is no cracks in the Oil Filter Housing and the Oil Filter Housing Block to Oil Filter Gasket is good.
I don't know how this could possibly happen but if after you shut the Engine off there was a Vacuum inside of that would cause the Oil to drain out of the Husing faster.
The red circle on the diagram is where the valve is inside of that Oil Filter Stem.
When I added a bypass Oil Filter to my Car I removed the Oil Filter Stem so I could drill out the Oil Filter Cap for a fitting. That stem is just pressed into the Cap. I tapped the jaws of a Vice Grips and then careful not to use more tension on the jaws then was need to grip the tube I pulled on the tube while I turned the tube back and forth.
Once the tube is out if you dry up the oil on it you can stick the bottom of the tube under water and by mouth blow into the tube. If you see a lot of bubbles come out of the tube you know something is keeping the valve open or perhaps there is an issue with the valve spring.
After the Tube was loose I used an air gun and compressed air and blew down through the tube and past the valve. That worked because my Air Gun had a tapered rubber section attached to the air gun nozzle. If I remember correctly the valve displacing and closing made sort of a buzzing sound.