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Bought a boat with a 1999 mercruiser 5.7 EFI bravo 3. It has 100 hours on it. Other than winterizing and oil changes I dont think it has had any other maintenance. This is my second season. Should I replace the manifolds and risers? When I inspect them what should I look for? There is no leaking water out of the bottom of the risers and the engine starts and runs good. Engine is always at 170 - 180 degrees. When flushing the motor last the water exhausting out of the drive seemed hotter than I remember. Should I start with an impeller and see where that leads? I know that risers are to be changed every 3 years and manifolds every 5. This boat has had little use however the age may override the hours of use. Thanks for all input.
 

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I would at least pull the tail pieces off of the risers and see if they are substantially clogged. (the short outlets that the exhaust hose attaches to).
I have a 454 (Volvo Penta Conversion) that is totally fresh water except for the risers and tail pieces. I replaced both risers and tail pieces in June of 1999 (at the time $660). Just broke down about 2 weeks ago - started running rough at trolling speed and quit. Locked up and starter wouldn't turn it over. Found water in the back 2 cylinders on both sides. Ordered new risers and tail pieces again (this time to the tune of $1000 - have to be Volvo parts, nobody makes a replacement for this particular motor). The tail pieces that I had put on in 1999 were almost completely rusted shut and forced a small amount of saltwater past the gasket at the riser/tail piece joint, which dripped right into the exhaust at the rear of the manifold. When running fast the exhaust pressure would blow the water out - when at idle the water managed to build up and get into the rear cylinders.
Engine temp was fine the whole time - may have been a bit more steam out of the exhaust than before, difficult to tell. Luckily, my old starter was weak and couldn't turn it hard enough to bend anything up.
Your engine is the same age as my risers were, so I would certainly take the time to check them. Could save you a locked up engine.

Just a quick thought - my risers and tail pieces are separate parts - your small block risers and tail pieces are probably made as one piece. Also, if you are totally salt water cooled, risers that are rusting shut will normally cause your temp to start going slightly higher than normal while you are running fast, and run at normal temp when you slow down, until they get to the point where you run hot all of the time.
 

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Thanks Mikie. I appreciate the input. I am also in the market for a new boat. Volvo sounds like a more proprietary engine than mercruiser, that is they have the corner on replacement parts and they are more expensive. Has that been your experience?
 

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Most definitely!! I will say that their stuff is top quality and works well - but when it goes bad it's going to cost big bucks to fix. Even things like the raw water pump, which is made by Jabsco, has been modified for VolvoPenta so a standard Jabsco won't work. If I had to replace the motor, I wouldn't put in another Volvo conversion.
 

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I just changed risers I put on in 2000. Just a tad late though since they leaked into engine and I bent push rod and dropped valve seat. Not too bad since it only cost me about 125 plus the risers.
 

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It's time to replace the manifolds and risers. You can't really see the damage without disassembly, and while it's apart you might as well replace everything. It's cheaper than replacing a block. You can use a awl to poke at the underside of the parts to see if any weak spots are developing but since it's a 1999 you're already on borrowed time. Be prepared to work hard getting the bolts out.
 

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The Expected life of a saltwater manifold is 6 years,,while there are many that are older than this,,after 6 years you are on borrowed time,,its not If they are going bad and leaking, but When.

Corrosion takes place constantly regardless of engine hours.
replacement now would be a good idea
 

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[Q]v80z originally wrote:
Bought a boat with a 1999 mercruiser 5.7 EFI bravo 3. It has 100 hours on it. Other than winterizing and oil changes I dont think it has had any other maintenance. This is my second season. Should I replace the manifolds and risers? When I inspect them what should I look for? There is no leaking water out of the bottom of the risers and the engine starts and runs good. Engine is always at 170 - 180 degrees. When flushing the motor last the water exhausting out of the drive seemed hotter than I remember. Should I start with an impeller and see where that leads? I know that risers are to be changed every 3 years and manifolds every 5. This boat has had little use however the age may override the hours of use. Thanks for all input.
[/Q]

You do not mention whether or not it is fresh water cooled or raw water cooled. If it is raw water cooled then 175 to 180 degrees is too hot. The thermostat should be a 140 degree thermostat otherwise the salts (minerals in salt water) will condense out in the block and clog things up.

I would also recommend changing the risers and manifolds along with the water pump impeller in the lower unit.

Volvo is VERY proud of their parts. Their universal joints in the outdrive (without a jackshft) are sealed units and do not get greased on a regular (100 hours of operation) basis like a Mercruiser so you have no real idea of their condition until they go unless you pull everything apart periodically. That little U-joint/yoke coupling in a friend of mines boat went and it cost him in the neighborhood of $400 to repair doing all the labor himself.

Anyway, I would replace manifolds, risers, water pump impeller in lower unit, and grease the U-joints in the outdrive. I just did mine last night and it took about 50 minutes with the help of one other person (one ensures things are lined up going in while the other lifts the outdrive into place. Seal kit was $9.09 with tax.

Good luck.
 
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