Valve stem seal question
 

I am rebuilding my motor with Toyota gaskets and seals and i am curious about my valve stem seals. The new valve stem seals are in two different sizes and I cannot remember if the exhaust valve gets the taller seal or the intake. Can someone please point me in the right direction?

There's a link to FSMs in my signature; it has everything you need for complete & total vehicle repair.

It doesnt say anything about the size of the valve stems. It only said that one will be brown, and both of the ones that came in the Toyota rebuild kit are grey. Attachment 190697

they r same size the ones ive done , got the stem seals from autozone and just put em in and no more oil in exhaust

Can you post a picture from the sealing end of the seal? The seal surface itself is what should have the different colors assuming they are seals from Toyota. Not sure on other brands.

Which motor and year?

I have the same problem, both are brown. So what is the answer?
Short - Intake?
Tall - Exhaust?

Thanks for any replies

Intake(taller, gray colored)
Exhaust(shorter, brown colored)

Page EG2-74 http://personal.utulsa.edu/~nathan-b...68cylinder.pdf

Some places will only have/try to sell you the shorter exhaust valve seals. Which they'll claim are for the intake valves too. Or vice versa(all the taller size). And that they don't have 2 different sizes for this engine(3VZ-E). Some will have 2 different sizes, but all one color(gray, brown, black). Though in reality it's not an issue of sizes, or colors(unless they're OEM).

Because using the exhaust valve seals on the intake valves is not likely to cause any issues. And, in fact, might actually work better. How or why might that be the case?

Answer:

All the seals are most likely identical in size other than height, which makes no difference in terms of fit. Since, the valve guides are all the same size. So the 2 types/sizes of seals must fit all of them universally. The intake and exhaust valve stems themselves differ in diameter only .0002". And allowing for wear tolerances, .0006" for both, they could all be exactly the same diameter and still be acceptable for use/reuse. So, all the seals will probably fit perfectly on any valve stem they're used on regardless of their size, color, or shape.

However, THERE IS A DIFFERENCE BETWEEN THE OEM INTAKE AND EXHAUST VALVE STEM SEALS(that IS NOT in SIZE or COLOR). The OEM exhaust valve seals are made of a higher maximum temperature rated material that's more suitable for the extremely high temperatures they're subject to. Which is probably silicone(maximum temperature 572°F/300°C). The intake valves run much cooler in comparison. Therefore don't require a seal that's as heat-resistant as those for the exhaust valves. And are probably made from Viton®(maximum temperature 400°F/200°C), or something similar. But that doesn't necessarily mean a more heat-resistant seal won't work just as good(or better) on the intake valves too.

So, the after-market valve stem seals that are all one color, and/or all one size, are more than likely all equivalent to the OEM exhaust valve seals in function(suitable for higher temperatures). But will more than likely work just as good(or better) on the intake valves too. Meaning, it probably doesn't even matter which valve stem you install them on. Since they will all function essentially the same on either the exhaust or the intake valve stems. Regardless of their apparent physical(size/color) similarities or differences.

;)

Thanks MudHippy, I looked at page EG2-74 and it really wasn't that obvious which one was taller especially with these old eyes. If I didn't get confirmation on which was which then that was the way I was going to go. It was frustrating when the first thing you pull out of the VRS gasket set and you are not sure.

This YotaTech forum is fantastic

Thanks again

Snapper5
93 4Runner with blown head gasket