Port motor down...choices choices choices! What did you choose?

PlayDate said:
Yup....that is the one Mercruiser recommends. My problem is that on four sizeable spots there is 15-20 lbs of antifreeze pressure. After pulling apart dozens of these things....the Mercruiser block off gaskets distort and in some cases weep antifreeze into the raw water jacket. When a customer says I'm losing antifreeze and it isn't in the motor.....it is one of the likely culprits which is why I use something else.
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So quick request for confirmation from you seasoned marine mechanics that I'm not doing something I shouldn't....

My boat is 100% freshwater since new. It has the OEM stainless elbows which theoretically shouldn't deteriorate in freshwater. Inspection looks like no sign of internal or external degradation, rust or otherwise. Manifolds also show no internal degradation and minimal external rust, but I know they're cast iron and contain coolant mixed with water, so internally I question their robustness WAY more than the stainless elbows--I plan on replacing them on both engines.

My question is, could I feel confident re-using my 100% freshwater stainless elbows and replace just the gaskets/manifolds? Or should I definitely replace the elbows too, just to be safe? I plan on installing the full restriction Quicksilver gaskets that Air O'Nautical showed above and below a stainless blanking plate that Play Date showed. I don't like being a "parts changer", I'd rather troubleshoot, find the problem, and repair as needed...but I sure don't want to be doing the risers in a few years because I missed something internally on the stainless risers.
 
Keep the stainless elbows. Replace the manifolds and gaskets.

Put your old manifolds on craigslist. Someone will buy and give you a couple hundred bucks for them.
 
Mikentucky said:
So quick request for confirmation from you seasoned marine mechanics that I'm not doing something I shouldn't....

My boat is 100% freshwater since new. It has the OEM stainless elbows which theoretically shouldn't deteriorate in freshwater. Inspection looks like no sign of internal or external degradation, rust or otherwise. Manifolds also show no internal degradation and minimal external rust, but I know they're cast iron and contain coolant mixed with water, so internally I question their robustness WAY more than the stainless elbows--I plan on replacing them on both engines.

My question is, could I feel confident re-using my 100% freshwater stainless elbows and replace just the gaskets/manifolds? Or should I definitely replace the elbows too, just to be safe? I plan on installing the full restriction Quicksilver gaskets that Air O'Nautical showed above and below a stainless blanking plate that Play Date showed. I don't like being a "parts changer", I'd rather troubleshoot, find the problem, and repair as needed...but I sure don't want to be doing the risers in a few years because I missed something internally on the stainless risers.
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Mike,

I really don't have an opinion on reusing the risers. They are 26 years old and we still have not figured out exactly what happened to your engine. If we go with the theory it was water......the only part of the engine exposed to raw water is the riser. I have a hard time believing both failed at the same time which makes me focus back on the cause.

If we go with the water theory and the blowout pattern on the head gaskets......it looks like water entered 7/8 compressed and blew out 5/6, compressed again and blew out 3/4. The basic problem with that theory is 5/6 should have blown back into 7/8 unless they were all flooded basically at the same time.

Setting that aside for a moment.....I believe your boat has side exhaust ports (like mine). If we go with the water theory .....an exhaust port got blocked as you spun around causing the water to fill the muffler back up to the exhaust manifolds. I suppose a large surge of water would explain the damage to both sides of the engine at the same time. It probably is the only scenario that makes sense. If enough water backed up suddenly.....it would have overwhelmed the exhaust pressure and flooded the lowest cylinders first.

If we go with that theory.....it would be okay to reuse the risers after a thorough inspection. I replaced mine when I did the manifolds because I wondered why Mercruiser never made them again out of stainless steel and I wanted to be certain the new parts would last. I'm on fresh water as well.:)
 
PlayDate said:
Mike,

I really don't have an opinion on reusing the risers. They are 26 years old and we still have not figured out exactly what happened to your engine. If we go with the theory it was water......the only part of the engine exposed to raw water is the riser. I have a hard time believing both failed at the same time which makes me focus back on the cause.

If we go with the water theory and the blowout pattern on the head gaskets......it looks like water entered 7/8 compressed and blew out 5/6, compressed again and blew out 3/4. The basic problem with that theory is 5/6 should have blown back into 7/8 unless they were all flooded basically at the same time.

Setting that aside for a moment.....I believe your boat has side exhaust ports (like mine). If we go with the water theory .....an exhaust port got blocked as you spun around causing the water to fill the muffler back up to the exhaust manifolds. I suppose a large surge of water would explain the damage to both sides of the engine at the same time. It probably is the only scenario that makes sense. If enough water backed up suddenly.....it would have overwhelmed the exhaust pressure and flooded the lowest cylinders first.

If we go with that theory.....it would be okay to reuse the risers after a thorough inspection. I replaced mine when I did the manifolds because I wondered why Mercruiser never made them again out of stainless steel and I wanted to be certain the new parts would last. I'm on fresh water as well.:)
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Heads will be back from the machine shop Thursday to being putting everything back together....in the meantime, I'll be getting everything ready. Part of that is I'm going to pull the risers and manifolds apart with the expectation of reusing my SS risers. I'll run a scope into the risers, specifically the raw water passages, just to see what things look like inside. On why they moved away from them...I've read that Mercruiser shifted away from stainless because production costs were way more expensive than they projected, and with the much harder material it was hard to get a perfectly flat gasket face, meaning high warranty costs to repair the leaks? If that's the case, mine apparently didn't leak for 26 years so had/have a good flat mating surface...and using 2 gaskets with a stainless plate sandwiched in between should create a good new seal and keep me in business another 26 years LOL
 
Okay, definitely a leaking gasket on both risers (see pictures), letting coolant drop into cylinders 5 and 6, which probably caused the head gasket to blow into the adjoining two cylinders on each side. Play Date, I think it was an optical illusion on the "rear to front" blowing off the head gaskets, probably the way I peeled them off the block... when I press them flat, it looks like 5 and 6 both deformed out into the opposing two pistons simultaneously. I think this also saved me from bending or breaking the 5 and/or 6 piston rod, since the hydraulic force of compressed coolant in the cylinders was apparently able to go sideways rather than out the bottom.

But now I'm conflicted....I took my handy dandy "scope on a rope" and ran it into the manifolds and risers. Wow! Definitely reusing the SS risers, they're clean as a whistle inside and look great. Both manifolds are also clean in the coolant chambers as well--not a bit of rust, flaking, deformity... nothing but smooth, clean cast iron. The dry side is uniformly velvety black other than the two spots at the bottom of 5 and 6 where the small rusty witness marks where coolant has obviously been dripping. And the gasket faces are all not pitted or deformed at all, once I cleaned the old gasket material off of them. So the conflict....seeing where they look great internally with no apparent degradation, I would feel safe reusing manifolds and risers both--but replacing the OEM gasket with Play Date's better choice of a stainless blocking plate with a blocking gasket on each side. Am I playing with fire? Are these manifolds like the timing chains on a Honda--you're better off replacing them at specified intervals even if they look great?
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Just wondering out loud, but if the manifolds are still good, having them ceramic coated before reinstall.

We use to ceramic coat the manicoolers on the Hino diesels and reinstall them.
 
CaptRonn said:
Just wondering out loud, but if the manifolds are still good, having them ceramic coated before reinstall.

We use to ceramic coat the manicoolers on the Hino diesels and reinstall them.
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A plan in motion, thanks for the idea--spoke with a local shop that does high temp work. Manifolds will be sandblasted and then magnafluxed to check for cracks or weak spots. Assuming good, they'll then be ceramic coated with Cerakote (good to 1500 degrees) for $150 per side. I'm also having him sandblast the stainless risers to make them shiny and pretty, wondering if I need to Cerakote them too for corrosion resistance but I'll hate to cover up those beautiful hunks of shiny stainless steel LOL

I'll post pictures of the finished product or updates if they advise against reusing them.
 
Mikentucky said:
Sorry my words weren't clear--he's sandblasting and then magnafluxing looking for hairline cracks or weld breaks, and also checking for noticeable weak spots. If everything looks good he'll apply the Cerakote.
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Mike,

Have your guy pressure test the manifolds. He will need to build a plate to block off the riser mount. It is a far more reliable test. Have him crank up the pressure to 20 and see if it holds for 30 minutes.

I did one probably 15 years ago that had a pin hole leak into the exhaust port.....it was the only way to find it and it was a new Mercruiser exhaust manifold.

Just a suggestion.....if one side looks like that .....the other engine is not far behind.
 
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