Are these risers too far gone?

[william86]

Hey I’ve just removed the risers off my engine and have found them in this condition; obviously they are very bad but I really need to have the boat in the water this weekend. I’ll be covering very little distance (max 3 to 4 miles) at about 4 or 5 knots. They don’t seem too be leaking badly, one manifold seems to have a small bit of water in the bottom but the other is dry. I don’t want to ruin the engine but will it be ok until I get new manifolds and risers

[mmichellich]

Lots of rust In cooling channels. You need to replace them soonest. If it were me and I had to run the boat now I would use a light wire to remove as much rust as you can without poking a hole in the casting. Go easy.

[Nauti_Mike]

Hard to tell from those pictures as you have not cleaned off the old gasket material, the walls may be very thin. I would not wait long to replace them.

[Rick_Kenyon]

Surprised you’re not overheating already. Passages look like they are almost completely blocked. Personally, I wouldn’t waste the time to put it back together because, IMO, they are already way beyond done. Depends on how badly you need to run your boat this weekend. I’d try to get someone else to take you out.

[Centerline2]

if you see a small bit of water in the manifold, they may not be leaking too badly, but they ARE leaking.....and its only a matter of minutes before they begin leaking a LOT.

the rust is so bad that the elbow and manifold cant be trusted to do their job properly

you have the potential for damage due to overheating, and you have the potential for damage due to hydrolock/water in cylinders.

any bit of the rust inside the manifold or elbow could pop loose at any time and leave a bigger hole for water to rush in...

and even if you were to get lucky and not ruin the engine, the boat may become broke down and needing a tow..... either way its going to cost more time/money and the weekend will be ruined for you anyway...

my opinion is, there is way more risk than there will be gain by trying to get another couple hours out of them.... I would plan my weekend accordingly and save myself some headache and money and get the boat fixed.

[Don77]

+1 on what Rick and Centerline said.
Don

[william86]

Thanks for the advice and I will definitely heed the warnings, should I replace the manifolds at the same time and can I do this in the water? I have a lift in booked and don’t want to miss it, it looks like I won’t have the parts before the weekend now

[Centerline2]

Thanks for the advice and I will definitely heed the warnings, should I replace the manifolds at the same time and can I do this in the water? I have a lift in booked and don’t want to miss it, it looks like I won’t have the parts before the weekend now

replace both manifolds and risers at the same time... they both rust away at the same rate.

yes, you can change them with the boat in the water, as the water level in the exhaust "Y" tube is well below the elbow... check the flappers in the Y pipe also, as they may need replaced (or removed, if they havent already been taken out).....

[william86]

My engine is a mercruiser 5.7 efi, does anyone know if these will suit?

https://repowermarine.com/index.php/...l-5-7l-v8.html

[Nauti_Mike]

My engine is a mercruiser 5.7 efi, does anyone know if these will suit?

https://repowermarine.com/index.php/...l-5-7l-v8.html

Yes they will work however I have not been a fan of HGE's quality I prefer OCSO, Sierra, OEM merc, barr.

[Nickp]

I would not put them back on...the now dried crud will have lost whatever integrity it had and pieces will surely break off and do more damage. Launch the boat and barge and tow it to your home dock...3 to 4 miles will go quick and it will buy you the time to fix it right. Your engine will probably benefit from a good flushing also.

Good luck...call it an "adventure"...call a party for the home port arrival...bow as you push it into your slip and crack open your favorite drink...(yes, VOE...)

[88fourwinns]

Agreed with the above those are already leaking you can see the eroded spots on the gasket surface. If you want to use aftermarket, OSCO and BARR are good. If you are doing this job in the water I'd fab up a cover for the top of the Y pipe, do one side at a time and use a hose clamp to hold a plastic bag or similar over the opening of the y just in case the water level is higher than you might think or someone kicks up wake while you're doing this job. Also, prepare a pair of threaded rods or long bolts that are the same thread as the manifold bolts. Use them to hold up the manifold and keep the gasket aligned with the exhaust ports and bolt holes. Those exhaust manifolds are heavy, it's hard to get it all lined up otherwise....

[Masterman]

Put a fork in them they are well done.....

[william86]

Thanks for all the advice, its a hard pill to swallow after just buying the boat but I knew it would be a project beats rebuilding the engine.

[builderdude]

replace both manifolds and risers at the same time... they both rust away at the same rate.

yes, you can change them with the boat in the water, as the water level in the exhaust "Y" tube is well below the elbow... check the flappers in the Y pipe also, as they may need replaced (or removed, if they havent already been taken out).....

Verify this is the case, additional weight in the ass end (couple guys and their tools) can have the water level in the Y pipe very close and possibly above tthe level of the shutter/intermediate elbows coupler.