jwillman

trying to get the car put together and the O ring I got seems mighty narrow for the space provided. Should I have this much space? The O ring I removed filled the gap although it was likely flattened a bit.

Ducman82

Mine was like that.

GregBBRD

Two different o-rings, for that application.

I'm not at work to look up the two part numbers, but that is not the right one.

Do not proceed!

Rob Edwards

Greg, is this the pair of o-rings in question?

jwillman

What I have according to the package is PN 999 701 425 40, item # 10 in the parts manual.

It is narrower than the O ring that was on my camshaft - see pic below, Oring on the left is new versus right is what was installed. Of course that does not make it right has my oil pump had no O ring's around the bolts

GregBBRD

Yes, Edwards to the rescue, once again.

Number 10....two different o-rings.

One is 4mm x 52mm and the other is 5mm x 50mm.

You need the 5mm x 50mm version.

You install the 4mm version and you will think your engine was built at Rainbird.

jwillman

So how should I have determined whuch O ring was correct for my car so others may avoid my mistake?

Ducman82

Get both.... :-). Mine was a little lose, but ya, I don't think it was that much.

GregBBRD

There was a specific model/year "split" when this change occurred, but pieces have seen mixed so much by now, one can find either o-ring at random.....sometimes both sizes on one engine.

If someone is in a big hurry, I'd suggest for them to have both sizes available when they take the engine apart.

ROG100

If you look at PET it states that the thinner ring is suitable for M28/1,2,3,4. No reference to VIN/Eng # split. Thickness and diameter changed significantly.
The smaller O ring used at the spacer changed early in 78 (ref: TSB 78-03). No reference in that TSB about the larger O ring. Cam part numbers changed to 155-07 & 156-07.

Found it TSB 78-04 11/1/78 - O ring changed to larger diameter - From Engine number = 5 speed Eng #829 0252 and Auto Eng #829 5131.

ROG100

Jim,
What is your engine number?
Roger

jwillman

829 1078

ROG100

Jim,
You will need the larger O ring.
Roger

ROG100

Cam Shaft O Ring 77 to 78 small 999 701 452 40
999 701 452 40 up to Eng # Manual 828 0081 & Auto 828 9025
Cam Shaft O Ring 78 to 86 small 999 701 592 40
999 701 592 40 from Eng # Manual 828 0082 & Auto 828 9026
Cam Shaft O Ring 78 to 79 large 999 701 425 40
999 701 425 40 up to Eng # Manual 829 0251 & Auto 829 5130
Cam Shaft O Ring 80 to 86 large 999 701 602 40
999 701 602 40 from Eng # Manual 829 0252 & Auto 829 5131

jwillman

Thanks for doing the research Roger!

I will call tomorrow as I need a few other bits as well.