Risers/Manifolds

buggyjdav

Good Morning. I have a 2004 342 with twin Merc 350 MPI Horizon engines. I believe risers and manifolds were only replaced once. I got a quote from my boat yard... $6K! with only $1100 in labor. I was able to order a complete set of Barr for both engines for $2300, that's some parts markup. Anyway I am doing it myself, I am very, very handy/DIY but wanted to ask for any tips from others who have done this job.

Dream_Inn

there is a lot of info here on this site if you do a search.  One good piece of info is to buy all new hardware and buy a couple extra (or some cheaper hardware of the same size).  Take those extra and cut the hex heads off and put them by hand into the block.  This will allow you to slide the manifolds right over them, freeing up your hands to put the other bolts on.  Basically, you are using them to hold all the weight while you install.  Really makes life easy & can be a one person job (too difficult to get another person in there anyhow).  Make sense?

Lifes Good

When putting the manifold bolts back in, use a non locking antifreeze compound on the threads.  That will make future changes a breeze.   Follow the torque procedures.  It will be something like. Tighten all bolts to 5lbs.  Then alternate each bolt to 7lbs. Again to 10 lbs and again to the final spec torque.  

LG

rasbury

I really need to do mine......

F1100

if there is a multi stage torquing procedure 90% of the time you have to use new studs/bolts  due to bolt stretch

Lifes Good

F1100,  true; though the torque on the manifolds is low. Some where around 8 to 12 lbs.  Not much stretching at that level. 

awhires

Could you imagine if it wasn't "your boat yard" they friggin get you coming and going. And the homeless dude who actually does the work makes $9. An hr. And couldn't care any less what condition he leaves your boat in.
I just had a guy I've known for 28yrs. Send his son over to quote me on a small plumbing job, basically no time to do it myself. Well a 40min. Job with $60. In parts, somehow came to be $275. Needless to say I'm doing it myself. 

LaRea

Hey, yards charge like that because it's what people will pay when they can't DIY.  Can't blame the yard ... it's supply and demand.  

Remember the old days before this forum and other online resources became available?  DIY is so much easier now.  But I have a mechanic I trust, and I don't mind paying him handsomely when I need him.  

06Rinker270

I have been there, only the marina owner/head mechanic was a cocaine addict and left my boat in pieces in the middle of a large project.  Worst boating experience ever and I had only been in boating for 1 year!  Didnt know he was a POS until the damage was done.  Lost half a season of boating and god knows how much money.  And the current yard at my Marina, has a HORRIBLE reputation.  After asking around I found a guy who only takes on certain customers and his customer service and skill is impeccable.  

I also feel yards charge above normal just like everything in boating.  If its marine related, there goes the price.

Ras, if think you need to do your risers and manifolds, dont wait until its too late.  Especially in salt water.  Small price to pay for saving that motor.

craigswardmtb

Soak the manifold bolts in PB Blaster or like for a couple days prior.  Those things are known to break.  I lucked out when I did mine and everything came out nicely.  The cut bolt piece of advice from DI is spot on.  Those cast iron manifolds are really heavy and hard to hold in place.  I was able to purchase studs at a hardware store and that worked great.  I had some rust seepage on my risers and manifolds prior to change.  I was surprised when I took them off as they were actually in great shape for a 10 year old boat, and they were the more issue prone aluminum manifolds that use to come on the 496's.  My boat was operated mainly in fresh water up until a few years ago.  So that likely contributed to their health.  I still have to do my other engine before this season...

Last piece of advise, don't use any RTV sealant, just new gaskets.  Only use factory gaskets.  Barr and others use cheapo alternatives that do not hold up.  Bring lots of ratchet extensions and a breaker bar.  Some of those manifold bolts are hard to get at.  And lastly make sure you follow the torque specs and tightening pattern.

buggyjdav

Thank you all for the feedback. Anyone know the torque I should use on the bolts? The engines are Mercruiser 350 MAG MPI horizons

Lifes Good

Correction on the torque lb I mentioned ealier.  496l cast iron manifolds torqued to 28lb.  Just did my yesterday per the instructions that came with the kit.