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valve stem seals

M

mkwns

Member
Hi Guys,
I have a long block Mercruiser 1987 5.7 260hp. Purchased 6yrs ago for a boat I sold two yrs ago. Never installed. So here's my question, I noticed the exhaust valve stem seals were not installed but intake are upgraded and installed. So as I try to find paper work and rack my brain for info on purchase, I'll ask the question here. Are they needed on exhaust side?
 
I am pretty sure they had different seals for the intake and exhaust others here will know better but my guess is you will get alot more blowby without exhaust valve stem seals?
Maybe check the casting numbers on the heads to confirm the year?
 
Thanks for reply. I did find a site that said they are some times left out to allow oiling and cooling for valve seat. I will be running it out of the boat for a while. That was the plan anyway. Thanks again.
 
Good engine builders ALWAYS leave the exhaust seals out--the exhaust valve needs oiling, which it can't get with seals in place.

Jeff
 
mkwns said:
I will be running it out of the boat for a while.
Click to expand...

If this is a fresh 5.7L engine, DO NOT operate it out of the boat for any long durations.
A fresh engine must be loaded in order to properly seat piston rings.
If you miss this oportunity, there is NO going back!

It would be OK to fire it up...... set cam followers........ adjust ignition timing, etc...... but shut her down until you can later load it for proper run-in.


.

 
Thanks guys, I don't have procedure's in front of me right know but will have my ducks in a row when I fire her up first time. It is a fresh rebuild I plan on installing in boat later in May. I remember reading running for certain amount of time at about 1500 rpm or so for cam run in. I'll have it down by then no question. Too expensive not to. So know I have to tell my Wife she was right to tell me to call the rebuilder and just ask them why they were not installed. At the time I just dismissed her idea. Oh well. I'll keep updating status.6e.jpg2e.jpg7e.jpg1e.jpg
 
FYI..... the 15-20 minutes @ 1,500 - 2,000 rpm is for flat tappet cam follower run-in. Not necessary for a roller cam engine.

Nonetheless, I'd suggest using the 8-stop static cam follower adjustment procedure. Do this, and you won't need to go back through them later!
If not familiar with this, let us know.


.
 
Dump the chrome valve covers............all they will do is rust!! Mercruier is BLACK........................only the Blue water motors had colors...........lol

In my opinion if the exhaust valve seals are not installed I would say you will have a lot of problems with oil control and carbon build up on valve stem. Not to mention blue smoke out the exhaust.

I am not sure why they would not install them...............The intake and exhaust are different as the heat generated by the exhaust requires a different material to handle the heat.

The heads used on that engine were used for many years........I believe mid '80s to mid '90's

I have replaced a few along the way but never looked at the valve seals. Simply gave the heads to the machine shop and took delivery and installed.
 
You can install the valve stem seals with the heads mounted just stuff a length of nylon rope in the spark plug hole and push the piston up to hold the valves in place. Another method is to apply 30psi air pressure to the cylinder with the piston TDC on the compression stroke for that cylinder. Just be careful if you dont have the piston all the way up TDC the air pressure will turn the crank.
 
Yes I have the flat tappet. And no I've not heard of the 8-top static adjustment? Interested in what that is. And thanks guys for your help.
 
mkwns said:
Yes I have the flat tappet. And no I've not heard of the 8-top static adjustment? Interested in what that is. And thanks guys for your help.
Click to expand...

I will advise you not to go there................................................................................That was a bait post to see if you were susceptible..........

I am sure you understand what you are doing with regards to reassembly and setting up the pre load on the lifters...........every engine manual contains this information.

Again dont go there...................................................................you will be overloaded with a books worth of information and i can guarantee you it is more than you bargained for!!
 
Jack, your comment is BS and you know it.
(just read his signature.... he has a rather negative attitude)

**********************

mkwns said:
Yes I have the flat tappet. And no I've not heard of the 8-top static adjustment? Interested in what that is.
Click to expand...

mkwms, every good and well seasoned mechanic knows full well what the 8 stop procedure is. (Jack is apparently not up to speed on it)

I've posted to this topic here many times. The 8 stop is a tried and proven procedure, and will eliminate any errors that may occur when using the 2 or 3 stop method!

Start with #1 cylinder @ TDC on the C/S.
Set the intake and exhaust cam follower plunger depths according to OEM specs.

Rotate crankshaft 90 degrees and set intake and exhaust for #8 cylinder .

Repeat this process right down the ignition firing order!




.
 
Last edited:
RicardoMarine said:
Jack, your comment is BS and you know it.
(just read his signature.... he has a rather negative attitude)

**********************

mkwms, every good and well seasoned mechanic knows full well what the 8 stop procedure is.
I've posted to this topic here many times. The 8 stop is a tried and proven procedure, and will eliminate any errors that may occur when using the 2 or 3 stop method!

Start with #1 cylinder @ TDC on the C/S.
Set the intake and exhaust cam follower plunger depths according to OEM specs.

Rotate crankshaft 90 degrees and set intake and exhaust for #8 cylinder .

Repeat this process right down the ignition firing order!
Click to expand...




As any well seasoned participant on this web site knows.......................repeat repeat and repeat.

Also as any well seasoned anyone who works with engines knows they should have a manual.

therefor no need to copy and paste a books worth of information.

Besides his engine looks assembled..................Duh!
 
kimcrwbr1 said:
You can install the valve stem seals with the heads mounted just stuff a length of nylon rope in the spark plug hole and push the piston up to hold the valves in place. Another method is to apply 30psi air pressure to the cylinder with the piston TDC on the compression stroke for that cylinder. Just be careful if you dont have the piston all the way up TDC the air pressure will turn the crank.
Click to expand...

Yea, I was going to use the compressed air method but will leave them out for oiling and cooling.
 
Re:... valve seals on the exhaust... what I know

1) When the valve seals wear, engine smokes, oil consumption goes up and the oil on the exhaust valve stems gets carbonized.
2) When Andy Granatelli of Paxton built the R3 engine (a 304.5 CID 375HP 7500 RPM mechanical pushrod supercharged engine) for my Avanti he put valve seals on both intake and exhaust.
3) When Frank Iaconio ( a professional drag engine builder now doing business in Flanders NJ) who was my mechanic in the day, rebuilt that engine, he put in new valve seals.
4) When GM builds the engines that Merc "marinizes", they put seals on both the intake and exhaust valves.

Believe me, if GM could even invent a reason to not put seals on the exhaust valves and save money they would do so.

This "no seals on exhaust valves" seems to me to come from the same school as "removing the T'stat" so the engine "runs cooler".
 
I hate to tell you how many stuck exhaust valves there are in marine engines (Big Block Chevies, a common example) that came from the factory with seals. A bit more oil on the steams and the valves might not have rusted in place.

As far as carborization, fresh oil getting in there is the best way to avoid that. Blue smoke in the exhaust comes from oil leaking past the INTAKE valve seals under high vacuum conditions, not the exhausts where pressure is pushing the oil back into the motor. (Think about it.)

Concerning oil usage, modern car manufacturers are paranoid when it comes to oil loss; ditto the need to pass emissions regulations. ANY oil getting out of the motor for any reason is a No-No to them, even though that tiny amount to get by actually improves lubricity and valve operation.

One the smartest engine builders I ever met said "Leave 'em off" and that's what I do.

Jeff
 
Jeff,

You make a good point there. Marine engines are subject to condensation in exhaust ports, especially with center rise manifolds and the odd bit of water reversion. The oil would surely still carbonize on the valve stems, however I could see that a thin coat of carbonization would actually be protective to the valve vs rust which is progressively degenerative.
 
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