Question on valve seals
 

My question is regarding the valve stem oil seals used on all the carburated HP500's. In the parts breakdown there is a note next to the seal part number that says "When installing seal on valve, remove spring clip from top of seal and discard". I only find that statement again the HP500 (502cid, Gen V or Gen VI block. See the link below.

http://http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=853984R%201&ivar=images/CRUISER/853984.R1/14.png&inbr=2450&bnbr=14&bdesc=CYLINDER+HEAD%2FROC KER+COVER+%28SERIAL+%23+0K000001+THRU+0L001772


Was there a problem with the valve stem not getting enough oil? I have been battling sticking exhaust valves on my 502 and my seals have the spring clip still on the top.

Anyone?

Have you had the heads off?

You really don't need to run valve seals on the exhaust side at all. There is no vacuum on the exhaust side to pull oil through the guide. And what does go through the guide, won't end up in the combustion chamber.

Yes, I have had the heads off - there have been no signs of scuffing or sticking on the stem or the guide.

Just curious why Mercruiser chose to remove the spring clip on the HP500's (on both the intake and the exhaust). There must have been some type of problem.

I wonder if they had issues of the retainer hitting them...had that happen before..Rob

Ahh, could be - I guess I was thinking it was oil related. Even without the upper clip if there is not enough clearance, the retainer is going to hit.

I'm confused in the first post you said you have problems and now you don't?
If you had no signs of them sticking what makes you think they were?
Most of the time they stick in a guide from the valves and seats not being cut properly or from the contact area being to far in on the valve face and the valve can't cool properly.

If this was true, then no engines would have exhaust valve stem seals. In reality almost every engine produced today does have them. You would be surprised how much "vacuum" the exhaust passing through the port creates on the valve guide. Sort of like a carburetor venturi.

As far as the original question goes, I dont ever remember seeing a set of Mercruiser heads with the springs missing off the exhaust valve seals. We use a metal cased viton seal on bith intake and exhaust and have not had any issues.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

[QUOTE][/I'm confused in the first post you said you have problems and now you don't?
QUOTE]

I have had problems a couple of times in the last 3 years. Always sticking exhaust valves - and never any signs of scuffing on the stem. Just trying to cover all my bases.

I have'nt seen it either, I just know what I see in the parts breakdown for all the HP500's - says to remove the spring clips. Merc. must have had a reason at the time for doing this.