Tom in Austin

Justr re-reading the WSM instructions for changing chain tensioner pads, and it mentions a 'check valve' on the head side of the J-tube. Wasn't 100% clear, it sounded like maybe the banjo bolt for the head side has a check valve inside it, and the point is to make sure you put the right one in that position?

If that's it, I don't recall noticing that banjo bolt looking any different than the one on the tensioner end of the j-tube. Hopefully, there wasn't a ball that fell out when I worked the J-tube up and out. Actually, I thought I did pretty well to fish out all of the crush rings!

I do recall on my 968 hearing about a check ball in the oil supply mechanism for the chain tensioner, so it rings true that Porsche would have used one in the 928.

So, before I finish all this and seal up the cam cover, does anyone know if there is in fact a check valve or ball associated with the tensioner/j-tube, and if so, where it is exactly?

AO

[slight panic] I don't recall seeing a ball either when I had my heads apart. [/slight panic]

Jerome Craig

You might want to have a look at this: http://members.rennlist.com/v1uhoh/oilcheck.htm

RyanPerrella

nice link, but thats another part of the head then the one the poster is refering too.

I think both the banjo bolts are identical, and ive never seen a check valve either. Maybe a look through the PET is in irder but i dont think there is anything shown their either.

The WSM instructions you were looking at were 944 or 968 WSM pages correct?

blown 87

There were not any in my 87 when I took it apart.

Tom in Austin

Thanks, I feel better hearing the BTDTs. PET shows same numbers for both banjo bolts, and no valve or ball anywhere, so not sure what they were thinking in the WSM text.

It was the 928 WSM BTW ... mentioned removing the cross brace and other 928-specific steps.

RyanPerrella

cross brace?

is this a 16V or 32V?

What's the cross brace? Sounds like something that would be a structural part inside the head but i cant imagine what.

only cross brace i can think of is the one tht goes from just in front of the shock towers, the aluminum tube that ties the inner fenders together.

Big Dave

Yes, one of the bolts does have a valve inside. The other is hollow. I can't remember at the moment which bolt connects to the tensioner and which connects to the cylinder head.

Big Dave

Here it is....#34 is the checkvalve/bolt that fastens the J tube to the chain tensioner. The J tube itself (#36) has the "banjo" fittings attached to either end. #17 is the hollow bolt.

blown 87

I just went out and looked at mine, it looks like just two banjo bolts to me with no seat anywhere for a check valve.

I am not sure if that has been revised or not.

But they were not in mine.

AO

I just looked at the WSM again... they show the removal for a 85/86 head where they refernce the check valve. I wonder if it was deleted in later years? See #6 below.

Big Dave

The diagram for MY87-91 doesn't have the valve.

What year is the 928 in question?

Tom in Austin

yes, step #6 in the WSM page is what made me wonder about this ...

Big Dave

SOOOOOOOOOOO.....what year is your 928?

AO

I think what Big Dave wants to know is what year your car is...