'75 280Z - Starts and Runs, Shuts Off after 30-60 minutes

[chaseincats]

Just now, Zed Head said:

2nd edit, actually a post...just curious.  I wonder if people could pop their caps and see if they have rubber on there.  To CO's last post's point.  Just one of those curiosities.

TBH I didn't know there was supposed to be a gasket there either.  The gasket seems to be NLA though...

[Captain Obvious]

I have one on my cap. It's a black washer and if you poke at it with a screwdriver tip you can see that it's not quite as hard as the plastic cap, but it's pretty hard. Maybe 1/16 inch thick? ID is a snug fit on the threads, and the OD is about the same size as the raised boss on the valve cover?

I don't know how compliant they were when new so I don't know if it was always that hard, but I suspect it was slightly more compliant years ago. Every Z I've messed with has had one. I think you might just be not realizing it's there. It's really easy to mistake it for "part of the cap".

I'll take a pic tomorrow if someone doesn't beat me to it.

[Zed Head]

4 minutes ago, Captain Obvious said:

I think you might just be not realizing it's there.

Nope.  I looked closely because I thought that there should be one.  Then I thought "what a fine piece of engineering and manufacturing".  The reality is that they didn't need one there, as shown by my leak-free cap.

[Bigz Zee]

I saw this image before and looked at my cap. Mine looks like one piece. I thought about poking it with a screwdriver. I need to take another looks at it. I see a little oil around the cap, and was thinking about getting a more pliable seal.

The seal on my 240Z is more obvious.

[Dave WM]

I got one, thought it was part of the cap, pretty hard, but it def is a separate piece. the drawing make it look wider than it is.

 

Edited June 17, 2020 by Dave WM

[Captain Obvious]

Right. It's easy to mistake it for part of the cap. Here's some pics.

Cap, as it's normally seen:

Close up of the seal in-situ. Looks like all one piece:

But in fact, it's not. Used a thin blade to get a little separation and get things started, and the seal comes off. Note the step on the seal and the recess on the cap. Speculation on my part, but I bet the earlier seals (with the different part number) didn't have that feature:

And here's a close-up of the cap with the seal removed. You can see the recessed area for the step.

[Zed Head]

Could be I missed it.  I sold the car so can't check.  How does it seal without the rubber piece?  Did you try it?

[Bigz Zee]

Mine looks like the last pic, with the seal remove.

[w3wilkes]

The seal on mine is in the valve cover. Car is 12/70 date.

[Mark Maras]

 

46 minutes ago, w3wilkes said:

The seal on mine is in the valve cover. Car is 12/70 date.

 Ditto, 10/70 build date.

[Dave WM]

now I have to check the valve cover.

[Captain Obvious]

9 hours ago, Bigz Zee said:

Mine looks like the last pic, with the seal remove.

Yeah, then yours probably petrified and fell off some time in the past.

And for the guys with the O-ring style built into the valve cover, I guess that's the older style. according to the documentation, they changed over to the newer style in 71.