4.3 Valve seals

[SeaRayboater95]

Hey Guys and Gals:

Was going to change the seals on 1996 Mercruiser 4.3 and automotive says they discontinued. Local Merc dealer wants over $250.00 for said seals. There is a little square O ring on the top of the valve that wont let the valve go past the seal. Thinking of just taking the valve out, cleaning it up and lapping it and putting it back in. That O ring on the top of the valve doesn't really seem to have a purpose. Worried about damaging it getting it out. Need a bit of help here, please.
Are these seals marine specific, or can I get them some where else.

Ken

 

[alldodge]

@Scott Danforth

 

[Lou C]

I can't imagine they are marine specific. The heads are just plain old Chevy V6 heads. Take the casting # off the head and go to a GM dealer! Merc loves to charge an absurd surcharge for a part GM made and is available in the aftermarket as well. Do not buy any GM engine parts from either Merc or Volvo they are just crooks! Look on Jegs, or Summit Racing, see if you can figure out the production year range of the engine from the block casting #; which is on the part of the block that is behind the cylinder head, I think on the starboard or passenger side if in a vehicle.

here you go, this is the later model Vortec style but the older Pre-Vortec which is what I think you have, should be similar.

 

[Lou C]

Part Details

www.drivparts.com

this is from Fel-Pro, I used 1995 as a model year because the one you're working on is a pre-Vortec, the true Vortec came online in 1996, and they supposedly fit from 1986-1995, so it might be the right seal.
I used their marine head gaskets and intake gaskets on my top end overhaul and they both sealed well.
BTW since it's raw water cooled you have to use marine style head gaskets.

 

[Scott Danforth]

Felpro and Mahle both sell seals and gaskets every day, nearly everywhere

If your motor has 8 intake manifold bolts, the motor is a 1996 to 2003 4.3

If your motor has 12 intake bolts , the motor is a 1993-1995

Just look up parts for an S-10 truck

 

[alldodge]

Felpro and Mahle both sell seals and gaskets every day, nearly everywhere

If your motor has 8 intake manifold bolts, the motor is a 1996 to 2003 4.3

If your motor has 12 intake bolts , the motor is a 1993-1995

Just look up parts for an S-10 truck

Scott, reason to mention you is it looks like it has 2 different type seals and have not seen the multi seal ones

 

[Scott Danforth]

Head has had work done prior. The valve guide on right is stock, on left has been cut and a different seal

 

[SeaRayboater95]

Head has had work done prior. The valve guide on right is stock, on left has been cut and a different seal

Thanks for that. Never a dull moment in this project. I'll pull a couple more and see what I find. Can I clean the valves and lap them with the seals in? In leak down, the valve were showing some leaking. The seals themselves really weren't that bad. Thought I'd just change them while I had the heads off. Nothing is ever easy or cheap when it comes boats.

Ken

 

[nola mike]

Thanks for that. Never a dull moment in this project. I'll pull a couple more and see what I find. Can I clean the valves and lap them with the seals in? In leak down, the valve were showing some leaking. The seals themselves really weren't that bad. Thought I'd just change them while I had the heads off. Nothing is ever easy or cheap when it comes boats.

Ken

This engine is as easy and cheap as it gets

 

[Scott Danforth]

Thanks for that. Never a dull moment in this project. I'll pull a couple more and see what I find. Can I clean the valves and lap them with the seals in? In leak down, the valve were showing some leaking. The seals themselves really weren't that bad. Thought I'd just change them while I had the heads off. Nothing is ever easy or cheap when it comes boats.

Ken

Just take them in and spend the $200 for the heads to be redone

 

[SeaRayboater95]

Just take them in and spend the $200 for the heads to be redone

Hear ya!! Not my boat and he doesn't want to pay for that. Couldn't even get him to get them tested. I phoned around, and its $250 ahead to pressure test and mill and then it goes up from there to have the valve train done. I thought I would just lap the valves while I'm waiting for the gaskets to come in. Maybe it will run a little better.

 

[Lou C]

I would not want to do work for a guy like that.
In fact, most mechanics here, would not do the job unless you let them do it right.
Not checking the heads, when you have water in the oil and no other smoking gun cause, is not doing it right!
So what's he going to say to you when you put it all back together, and it STILL has water in the oil?
I'm sure it's more now but when I bought those reman heads I installed like 9 years ago, they were $275 each. I took the advice of the machinist because my heads were cracked and due to raw water cooling in the salt, the cooling passages get eroded. So what could have happened is that even if they welded up the cracks, they could have rotted through behind the exhaust or intake valve seats in that water passage.
I figure that cylinder heads on a raw water cooled engine in salt water have a lifespan of about 15 to 20 years, at least in my area, so going with ones that were never in salt was a good plan for me. Still running the original un-rebuilt short block!

 

[SeaRayboater95]

I would not want to do work for a guy like that.
In fact, most mechanics here, would not do the job unless you let them do it right.
Not checking the heads, when you have water in the oil and no other smoking gun cause, is not doing it right!
So what's he going to say to you when you put it all back together, and it STILL has water in the oil?
I'm sure it's more now but when I bought those reman heads I installed like 9 years ago, they were $275 each. I took the advice of the machinist because my heads were cracked and due to raw water cooling in the salt, the cooling passages get eroded. So what could have happened is that even if they welded up the cracks, they could have rotted through behind the exhaust or intake valve seats in that water passage.
I figure that cylinder heads on a raw water cooled engine in salt water have a lifespan of about 15 to 20 years, at least in my area, so going with ones that were never in salt was a good plan for me. Still running the original un-rebuilt short block!

Let me be clear, while it is easy to say "I would not work for this guy" I'm elbows deep into this Job. I have done all three bellows, gimble bearing, water and oil monitor hose and lower shift cable. Also exhaust shutters, one of which was missing. Full tune up, including plugs, wires, cap, rotor and pugs. Oil and filter. Also water separator. I also took the carb off and cleaned it and reinstalled. This Boat had been severely neglected for the last 5 years and who know before that. Upon completing this work , I ran it up in the drive, on the hose a few times to adjust shift linkage and fine tune carb before water testing. This is when I discovered a half liter more oil than I originally put in. Pulled some out the dip stick, and we had a milkshake. Sorry about the novel, but bear with me. The boat came to me with the intension of a tune up and possible carb rebuild. So having to do all this extra work on a budget he doesn't have, he has become very frustrated. I'm trying to get his boat back to him running a good as possible. While he doesn't want to test heads, he is willing to take the chance and hope it was a gasket or exhaust shutter, as we don't have "a smoking gun". I told him I would stand behind all the repairs, but would not guarantee the water intrusion issue was resolved. He is ok with that, in writing, with fingers crossed! . The boat runs awesome after I did all the work. Having said all that, What I want to know, is can I lap the valves and try to get his compression a little more even with out changing the valve stem seals while I wait for parts to get here sometime next week. The engine is not smoking or using oil. Again., sorry about the novel.

Ken

 

[Lou C]

I think that would be fine because cool running marine engines often have deposits on the valves esp if the oil seals were leaking a bit. What were your compression test results? A good 4.3 will have between 160-170 psi.

 

[SeaRayboater95]

I think that would be fine because cool running marine engines often have deposits on the valves esp if the oil seals were leaking a bit. What were your compression test results? A good 4.3 will have between 160-170 psi.

Looks like some pitting too. #2 was 130, #6 was 170, a couple 150' and a couple 160ish. Leak down did show quite a bit of valve leaking

 

[SeaRayboater95]

I think that would be fine because cool running marine engines often have deposits on the valves esp if the oil seals were leaking a bit. What were your compression test results? A good 4.3 will have between 160-170 psi.

Compression test was done on a non running cold engine.

 

[Lou C]

Hard to say then, you'll get better results on a warmed up engine.
One thing the owner should know, boats need more maintenance than vehicles, and an I/O power train is the most maintenance intensive type of marine propulsion that there is. So much so that I'd never buy another one for myself. Not because I had so much trouble, actually the OMC Cobra system was very reliable. It's that, normal maintenance is very extensive if you want it to be reliable.
Winterizing (done properly you must remove the plugs and rod them out)
Drive R&R, if not done yearly and your bellows leaks, you have to change the ujoints and gimble bearing
Exhaust in salt water, by at least 8 years, you are replacing the whole thing again ($1200 USD just for good aftermarket)
Older boats esp Mercruiser often have leaks via the steering arm on the Alpha and Bravo drives, and many more places to leak water and most are totally inaccessible with the engine in place.

The ONLY benefit of them, IMHO, is the ability to use the simple and cheap to repair GM marine engine, because they were used in millions of GM vehicles. That's it. Everything else is a potential headache.

Modern outboards are very expensive but you're not dealing with any of this!

 

[Lou C]

Looks like some pitting too. #2 was 130, #6 was 170, a couple 150' and a couple 160ish. Leak down did show quite a bit of valve leaking

That is pretty typical, my old cyl heads I'm sure would have been the same, so I would have had the machine shop do the valve job if they weren't cracked and the cooling passages weren't rust eroded. So you might wind up with better compression test results from doing that.