Complete Misfire on Three Cylinders

[Captain Obvious]

LOL.

So today I officially turned a corner and started on the reassembly. Here's the first two valves back in the head. Woot!! :

Everything went great. But this process does bring up a question for today... I'm using the Sealer Power valve seals. ST-2034:

The seals went on great using the little condom that came in the box, but after installation, they don't seam very tight against the valve stem. I'm no engine rebuild expert, but in my limited experience the other valve seals I've messed with on other cars seemed to have a tighter grip on the valve stem. Anyone have any input about this?

Just for a point of reference... The weight of the valve itself is enough to pull the valve down even with the seal installed. My previous experience with other seals is that the grip of the seal on the stem would keep the valve in place against gravity. Of course, it would slide if you pushed it, but gravity alone wasn't enough.

Have I got an old dead box of seals, or is that normal?

[Dave WM]

can you check the ID of the seal? I have some OE ones new in the bag I will check against those. Just to compare the resting diameter.

did you oil the seal before installing? Somewhere I read you should with reg engine oil.

Edited July 24, 2019 by Dave WM

[dutchzcarguy]

4 hours ago, Captain Obvious said:

The weight of the valve itself is enough to pull the valve down even with the seal installed.

Ow... Don't think thats normal.. maybe after a few years of wear.. not with fresh installed ones.. but.. what do i know.. last time i installed (Original nissan ones)  is 12 years ago.. ?

[grannyknot]

7 hours ago, Captain Obvious said:

Have I got an old dead box of seals, or is that normal?

That's not normal, as you said, the seal should be able to hold the weight of the valve.

[Captain Obvious]

Crap. Well maybe I'll check one more valve to see if it's my imagination. If it's not imagination, I guess I'll stop with the reassembly and get a different brand of seals on order.

11 hours ago, Dave WM said:

can you check the ID of the seal? did you oil the seal before installing?

Dave, Checking the ID of the seal is pretty much impossible since it's bendable rubber. Can't get an accurate measurement. IMHO, the best way would be to place them on a gradually tapered dowel rod and see where they stop and then measure the diameter of the rod there. I don't think a direct measurement with calipers or something like that would work.

And yes, I used a little drop of motor oil on the seals.

[Captain Obvious]

6 hours ago, dutchzcarguy said:

Ow... Don't think thats normal.. maybe after a few years of wear.. not with fresh installed ones

Yeah, that's what first struck me as odd. The brand new ones didn't feel any tighter than the old ones I pulled out.

OK... So probably a little step backwards today. Just when I thought I had a day of nothing but progress!    

[Dave WM]

I got a barely perceivable drag at .028 using calipers.

I have a head on the bench right now. Later today I will check it out by installing the OE seal and see how much it takes to move the valve.

Edited July 24, 2019 by Dave WM

[jonathanrussell]

I just took a look at a valve on my N42 head with 56k miles. The original seal allowed the valve to move freely and if I lift to the valve closed position and release the valve slowly moves down.

I then installed a sealed power seal. I think there is a slight bit more drag but the valve still moves freely and if I release the valve from the closed position it will drop down...though maybe a bit more slowly.

Bottom line, both seals allow the valve to move freely without much drag.

This seems consistent with what I remember when I used these seals on my E88 head last summer and that car doesn't burn oil....fyi.

[Captain Obvious]

Thanks guys. I did a few more valves, and I think I've got a non-problem.

There is significant interference between the seal and the valve stem, but the stem is so smooth and with a little Mobil-1 on there, the seal just can't get a grip. jonathanrussell, what I have here behaves exactly as you described.

I messed around a little bit with a valve and seal loose from the head, and I think it's OK. The seal is scraping the stem, but with the oil on there, it's really slippy.

I'm moving ahead. Thanks again guys!

[Dave WM]

still going to post up my made for CO video... coming soon, wait for YT to finish upload and publish.

Edited July 24, 2019 by Dave WM

[Dave WM]

 

[Captain Obvious]

Thanks Dave! I think that's just how mine behave. Maybe just a tiny bit looser. I think my new ones behave like the original OE seal you started with. But they are clearly gripping the stem.

And BTW... I did a little measuring of some valve stems, and they are purposely ground a thousandth or so smaller up at the top end where the retainers install. Maybe the first half inch or so along their length? That would be why your valves drop easier once you get them to that point. The stem is actually a little smaller at that point along their length. So it makes perfect sense that as you push the valve down through the seal, you'll reach a point where you get to that narrower part of the stem and it won't grip as tight.