Mercruiser 3.0L valve guide seals

[Mile-High Mariner]

Does anyone know of a good source for replacement valve guide seals? I have found the valve STEM seals at several sites, but can't seem to locate the GUIDE seals anywhere. Thanks!

 

[Don S]

Re: Mercruiser 3.0L valve guide seals

Mercruiser Dealer!

 

[Mile-High Mariner]

Re: Mercruiser 3.0L valve guide seals

Knew I'd get a concise response from you, Don! I live quite a ways from the nearest Mercuiser dealer - any online sources? And, again, do these actually NEED to be replaced, anyway? The Service Manual specifically adresses replacement of the valve stem seals, but not the valve guide seals - thought there must be a reason.......

 

[Don S]

Re: Mercruiser 3.0L valve guide seals

Originally posted by Mile High Mariner:<br /> Don:<br /><br />I posted a query re: valve guide seals earlier this evening. As you are an experienced pro, can you direct me to a good source? Motor is a 1992 Mercruiser 3.0L (S/N: 0D805131). I'm pulling the valve cover to replace valve stem seals and check valve action on Cyl. #2 (low compression), and I noticed on p.3A-15 of the Mercruiser manual a reference to the guide seals - do these even need to be replaced? I'm trying to rule out the valve train in my low compression issue, so I'm going to check all possible causes of sticky valves. Thanks for your time - you've previously made valuable contributions to my ongoing efforts to get my engine back into top running condition.

You should have posted that question here not just stuck into someone elses post.<br />Here is a couple of places for parts.<br /><br /> http://www.mercurypartsexpress.com/PartsExpress/HomePage/homepage.asp <br /><br /> http://dougrussell.com/partscatalog/collections/index.cfm?fuseaction=collectdetails&colid=04 <br /><br /><br /> http://www.mercruiserparts.com/ <br /><br />If you have low compression, it's because the valves aren's sealing or the rings are worn or the head gasket blew or a crack in head or cylinder. <br />Valve seals don't even come into play for compression.<br />What you need to do is a cylinder leak down test to determine the reason. Pulling the valve cover won't help at all.

 

[Bondo]

Re: Mercruiser 3.0L valve guide seals

The Service Manual specifically adresses replacement of the valve stem seals , but not the valve guide seals - thought there must be a reason.......

I Hope I'm about to Learn Something,............<br /><br />What's the Difference,..???......<br /><br />While there are different Styles of seals,.... Umbrellas are the most common,........<br /><br />If you've gotten your Head Set Gaskets,... By #,+ Application,...... <br />You Should have "Like" seals to replace the 1s on the head Now..........

 

[Mile-High Mariner]

Re: Mercruiser 3.0L valve guide seals

Haven't ordered anything yet, as I want to know what I'm dealing with first. I'm not a certified marine tech, so I don't know nearly as much about my systems as Don or some of the other pros on here, and I may accidentally post in what may be considered the "wrong" place from time to time. Please allow that not all of us are command-level officers in this forum (although some of us may have been at one time in real life).<br /><br />The valve stem seals for my app. appear to be o-ring type seals that fit into the lower of two grooves on the stem; the valve guide seals appear to be umbrella-type seals that mount at the top of the guide on the head itself.<br /><br />Don - I'll do the leak-down you recommended. I've already performed a wet-test with no appreciable improvement in compression, so I'm not thinking rings and desperately hoping not cracked block or crack or hole in piston. Wouldn't a blown gasket yield a compression drop in more than one? All other cylinders return 150 or better.

 

[Reel Poor]

Re: Mercruiser 3.0L valve guide seals

Wouldn't a blown gasket yield a compression drop in more than one? All other cylinders return 150 or better.

Not if its blown into a water-jacket. Only if its blown between cylinders, or blown on multiple cylinders.

 

[rodbolt]

Re: Mercruiser 3.0L valve guide seals

stem seals and guide seals are the same with different nomenclature. some engines use a "umbrella" seal that pushs down on the guide and other engines use a "doughnut" seal on the valve stem just below the keepers. and some engines dont use a seal at all. depends on who made it and when. quite often on chevy motors with marginal guides we will use the umbrella type seals to assist with oil control. however the valve stem or guide seals only control the amount of oil that will leak past the stem to guide clearence. gotta have some or it would seize. can ya repost your compression test methods and results ?

 

[Bondo]

Re: Mercruiser 3.0L valve guide seals

stem seals and guide seals are the same with different nomenclature.

Ayuh,.......... That's what I thought.......

 

[Mile-High Mariner]

Re: Mercruiser 3.0L valve guide seals

Thanks for the responses, fellas. The information I found on pg. 3A-15 of the Mercruiser Service Manual (#13) seems to indicate that this motor has both stem and guide seals - not that I'm all fired up to replace everything - I just want to get my boat back to speed.<br /><br />Reel - what symptoms would head gasket blown into water jacket demonstrate?<br /><br />Rod - static compression test results (following guidelines contained in Merc. Service Bulletin 97-25) yielded ~150 psi in cyl 1-3-4 and variable compression in cyl 2 (0-90 psi).<br /><br />Root problem is lugging under load, with max rpm ~2500 on any prop (15-19"). 2 chief issues seem to be (1) low compression in cyl 2 and (2) limit of timing advance is ~18* at 2500 rpm). Revs fine in neutral<br /><br />Motor is a '92 Merc 3.0L (S/N: 0D805131) with a 9562-series Mercarb, Delco EST ignition, 811637 module (new one to be installed), fresh OEM wires, fresh 100-hour service. Timing set to 2*BTDC (routine operation at >5000 msl) and I believe carb settings (idle & mixture) are correct. Have high-alt jets (1.40 & 1.35) ready for upcoming carb rebuild.

 

[Don S]

Re: Mercruiser 3.0L valve guide seals

Rod - static compression test results (following guidelines contained in Merc. Service Bulletin 97-25) yielded ~150 psi in cyl 1-3-4 and variable compression in cyl 2 (0-90 psi).

Pull the head and find the problem. It's that simple.

 

[rodbolt]

Re: Mercruiser 3.0L valve guide seals

with the compression not steady and varying between 0 and 90 PSI I would suspect a sticking exhaust valve most likly caused by water in the exhaust manifold due to a bad riser or manifold.<br /> either way its about time to pop the head for closer inspection and repairs.

 

[Reel Poor]

Re: Mercruiser 3.0L valve guide seals

Reel - what symptoms would head gasket blown into water jacket demonstrate?

It would most likely have a tendancy to overheat. It could also be a source for water getting in the cylinders after shut down.<br /><br />I actually agree with Don S and rodbolt. <br /><br />

Don S <br />Member # 49090 posted November 19, 2005 10:23 PM<br />--------------------------------------------------------------------------------<br /> Pull the head and find the problem. It's that simple. <br /> <br /><br /><br />rodbolt <br />Member # 32169 posted November 20, 2005 08:18 PM<br />--------------------------------------------------------------------------------<br /> with the compression not steady and varying between 0 and 90 PSI I would suspect a sticking exhaust valve most likly caused by water in the exhaust manifold due to a bad riser or manifold.<br />either way its about time to pop the head for closer inspection and repairs.

Good luck with the repairs.

 

[Mile-High Mariner]

Re: Mercruiser 3.0L valve guide seals

Thanks, guys. I admit I'm dragging my feet on pulling the head until after I've investigated all possible causes of my performance issues, but my learning curve on my systems sure is steep! This will be only the third head I've had to pull on anything, and I've already learned volumes about the various integrated systems in my boat, thanks in no small part to generous and regular contributions by yourselves and others here on iboats.<br /><br />Reel - motor's never overheated; temps are pretty reliable, usually in the 140-160 range. Gasket's probably in fine shape - too bad, since it'll be unceremoniously scraped off soon, after giving well over a thousand hours of faithful service. Wait - am I anthropomorphizing a GASKET? I may be spending too much time with my boat.....