Rust on Riser and how difficult to remove 5.0 MPI

[douglee25]

If it's visibly leaking on the outside, then the mating surface is shot. It also means it's probably leaking on the inside. These are 8 year old parts on a salt water cooled engine. I can't believe anyone would recommend putting those back on.

Again, respectfully disagree. It's a paper gasket. They leak over time. It's the nature of the beast. It's similar to cork gaskets. Once torqued, they compress, and over time they become hard and brittle. Then they leak. Yes, the surface 'could' be shot, but just because they're leaking doesn't mean they are. You don't know until you pull to inspect. And yes, there could be water leaking 'slightly' into the engine right now. I would assume that 'if' it's leaking into the engine, it's leaking no worse than what you see on the outside (a dribble). And if it's leaking into the engine (most likely while it's running only), the slight dribble is vaporized immediately.

Since the OP has caught the issue now, again my recommendation is pull and inspect. Post some pictures up at that point, then we can all debate if he should repair or replace.

Doug

 

[smittyasc3]

I will pull and inspect then make a decision from there. FYI I did pull the plugs and they look fine. No appearance of water fouling them.

 

[Turtlesboat]

Ok, it's your engine. Doug will buy you a new one if he's wrong.

 

[edsmax]

At the very least you need new gaskets between your manifolds and risers. Listen to what Doug said to do and pull the manifolds and risers off. Due to your low clearance, you will need to remove each side as an entire assembly (you will not be able to undo the nuts on top and lift off the risers). Once removed, look at the water passages.

Either way, your gaskets are shot. Even if your manifold and riser water passages are ok, the gaskets will need to be replaced NOW. Do a search on leaking riser gaskets. On my boat, my manifolds were still ok (probably had 1 season left), but my riser gasket failed which allowed water to drip (just like in your pics) down the riser assembly and it pools on top of the manifold. eventually, it WILL leak into the manifold gasket and work its way into the head via the center exhaust passages. This will cause internal valve damage and rust. Ask me how I know.

 

[rcknecht]

You have studs that go from the manifold throught the 3 inch riser block and out the top of the elbow. If you unscrew the nuts a the top, and use a vice grip, you maybe able to remove the studs from the manifold. You can then get the parts out without removing the manifolds. You may just need new gaskets for the short term, but you will need all new exhausts soon. When, and if, you get the elbow and riser blocks off, you can inspect them to see if they can last longer.

 

[edsmax]

You have studs that go from the manifold throught the 3 inch riser block and out the top of the elbow. If you unscrew the nuts a the top, and use a vice grip, you maybe able to remove the studs from the manifold. You can then get the parts out without removing the manifolds. You may just need new gaskets for the short term, but you will need all new exhausts soon. When, and if, you get the elbow and riser blocks off, you can inspect them to see if they can last longer.

There is no way he is going to be able to remove the studs with a vice grip. Those look like original exhaust pieces and if they are, even doing the double nut manuever (which is how it should be done) will require Herculean strength.
Regardless, he cannot do this as an option anyway. Due to his low height clearance, he probably doesnt have the room to lift the elbow and spacer off the studs without hitting the engine hatch.
New manifold gaskets (Merc # 33395??) are cheap at $6-9 each for OE.

Also, to the boat owner - do you have a Merc manual? You need to know the torque specs and you need to drain the manifolds prior to attempting this. And yes, you need to undo the shift bracket and ecm mount.

 

[smittyasc3]

Anyone want to buy a boat? I'm going to see tonight if I can double nut and try to back out the studs and ensure I have clearance to remove. Do the shift brackets and ecm come off in 1 piece or does it have to all be disassembled? I ordered the manual.

 

[edsmax]

Anyone want to buy a boat? I'm going to see tonight if I can double nut and try to back out the studs and ensure I have clearance to remove. Do the shift brackets and ecm come off in 1 piece or does it have to all be disassembled? I ordered the manual.

I got my manual on ebay for $5 on CD ROM.

Mine came off in one piece. Very easy, just make sure you tag the bolts and screws.

 

[smittyasc3]

And it figures...Parts diagram shows it's a 3/8-24 nut! I have thousands of 3/8-16 but not a one 3/8-24.

 

[Larry]

To take the manifold off it's relatively easy as the bolts on small block engines are not subject to the same heat as a big block engine which is usually harder to get the bolts out of. You have to remember these parts have a finite life span, and 8 years in salt water is pushing a catastrophic failure. It does not make any sense to disassemble everything and then replace 4 gaskets and clean and check 8 separate surfaces (not including the exhaust to head gaskets and surfaces). To replace all the exhaust components and gaskets will run you less then a grand and there will not be any additional labor on your part. This is the single biggest cause of engine failure, for $1000 why take the chance and it is something that every gas powered boat owner has to consider changing every 3-5 years...

 

[Turtlesboat]

there is no chance here. These will fail 100% Guaranteed. The only question now is... have they already failed.

 

[Larry]

there is no chance here. These will fail 100% Guaranteed. The only question now is... have they already failed.

+1!

 

[Presentation]

........ it is something that every gas powered boat owner has to consider changing every 3-5 years...

Do you mind if I clarify that this does not apply to fresh water only boaters?

10+ years in Fresh water only.

 

[Larry]

Do you mind if I clarify that this does not apply to fresh water only boaters?

10+ years in Fresh water only.

Sorry, you are correct... I had to much salt water on my brain!:grin:

 

[Turtlesboat]

Not so quick. He's got 1+ years to go before he can verify this.

 

[Russ Calasant]

Russ - Sorry but I respectfully disagree. I would absolutely inspect and then seal with new gaskets if nothing appears suspect. What you're concerned about is two fold - 1. You're concerned with the mating surfaces. Are they true/flat and are the surfaces dimensionally still good (ie - not corroded where the flange surfaces are no longer equal from one side to the other). Use a machinists ruler to check. 2. You're also concerned with gross, flaking corrosion on the interior of the pieces. Over time the water flow will be reduced as the pieces become plugged with flaking rust. If after the parts are pulled, inspected, and they still appear to be OK - by all means throw new gaskets with some sealer (using sealer is the new recommended Merc method too by the way) and run it again.

Doug

Don't be sorry Doug, you can disagree and be wrong- or we could all be wrong but I would much rather err on the side of bad than good. If they are still useable "good", how long will they be good? Are you going to risk it for one season? Part of a season? Risk it at sea with family on board? Do all the labor anyway? Just to inspect passageways you cannot completely see or properly test with out pressure testing? Just to do it again next, week, month or season? How much failure is necessary? Delay the inevitable to do the labor twice? Just spend the money, it's the smart thing to do. I would and have, don't know about you but I would much rather ride in or buy a boat from the guy that erred on the side of caution than the one that took unnecessary risks, took chances and pushed limits to save spending a buck for a few months.

We are assuming and hoping of course t it's not too late now or then.

Smitty, I know all of this is not what you want to hear- sorry, boating is not for the faint of wallet. I wish you luck.

 

[smittyasc3]

I understand. I am going to replace manifolds, and risers. Anyway I tried pulling the first riser last night. Doubled nutted the first stud and she came right out. I was like wow! This isn't as bad as I thought it would be.....Then I couldn't get any more out. I was afraid that I would break the studs. I don't know if I want to take it upon myself to pull the manifolds. I'm 6'8" tall and it's a pain in the arse for me to contort in that engine compartment.

 

[edsmax]

I understand. I am going to replace manifolds, and risers. Anyway I tried pulling the first riser last night. Doubled nutted the first stud and she came right out. I was like wow! This isn't as bad as I thought it would be.....Then I couldn't get any more out. I was afraid that I would break the studs. I don't know if I want to take it upon myself to pull the manifolds. I'm 6'8" tall and it's a pain in the arse for me to contort in that engine compartment.

As an FYI, its 4 hours of labor for a merc mechanic to do the job. My marina charges $93 p/hr...so weigh that in before you have to contort yourself, bang your knuckles, and lift/maneuver these heavy pieces. Parts will run you $1100-1200 for OEM. Look at boats.net for prices (and free shipping). Just make sure you have your engine ID number.

 

[MaddyDean]

I purchased my raisers a few weeks ago from here (http://www.perfprotech.com/store/default.aspx) I did not go with OEM because they were both rated for 5-yeas so I saved over $600. and Call them because they have complete kits for even cheaper and includes gaskets.

Also, someone on CSR gave me the best advise EVER. he said to cut the heads off of some long bolts to make studs or just get studs. Loosen all the manifold bolts | take to the end bolts out and slightly install studs | take remaining bolts out | Put down your tools and then you can easily remove the manifold being held in place by the studs.

Clean the surface | Slide the new manifold on the end studs | Put the gasket on which come pre-notched | Torque and then raisers.

This technique saved me hours.

Good luck and I am on the side of Replacing them now while everything is out, to not do this now prolongs the agony and every time your out this season your going to have a concern and say, I should have just changed them--that is what happened to me last year and I started over heating by the end of the season because I thought I could get another year.

 

[smittyasc3]

Anyone have comments on this kit?





Exhaust Kit - Mercruiser, Small V8, Coated, 3" Spacer (#EK-MERC-SB-C-3S)

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Exhaust kit for a Mercruiser small block V8 engine with a 3 inch spacer. This kit includes the manifolds, spacers and risers along with the gaskets and mounting kits necessary for installation. The parts in this kit are made from cast iron and are internally and externally electro deposition coated for corrosion resistance.