05-06 340 Manifold / Riser Replacment

T

trit21

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Dec 16, 2007
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Live, Orlando: Boat, Ft. Pierce
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Friend of mine has an 05-06 (can't remember which) 340 with 8.1's. The manifolds are starting to weep so he received an estimate from MM in south FL to have them replaced. They stated they needed to pull the engine to replace them. WHAT? Is that true? I was hoping someone on here has done this and can confirm or deny the claims that the engines have to be pulled. While we are at it, can someone tell me the best place to get the parts for this, manifold, riser, gasket etc. I don't think he will do it himself but you never know. Oh yeah, price he received from MM was $7k. Thanks for the information.
 
only if there mounted up against each other. never heard of doing that for manifolds, starters yes.
 
Tom,

Mercruiser built some 8.1's with aluminum manifolds. It takes some diligence with the local Sea Ray dealer, but our dealer has gotten Mercruiser to repair 5 or 6 boats with early manifold failures. Here is a thread on the problem:


http://clubsearay.com/showthread.php/6038-Heads-Up-early-Mercruiser-8-1-s-w-aluminum-manifolds/page1


Your friend may not be affected with as late a boat as he has, but the change to cast iron was gradual over a fairly long time period. Its worth checking because it is an expensive repair. Our dealer charges about $5K, which is roughy $4K for parts and $1K for labor. They do not pull the engines on a 340DA, and for what it is worth, failing manifolds made of cast iron on 8.1's is pretty rare.....nothing like the old 7.4 days.

Good luck to your friend.........
 
He did have the original aluminum manifolds replace with the cast iron maybe 3-4 years ago (guessing here). I know he had one entire engine replaced due to the aluminum manifolds and at that time the other engine was inspected, heads removed, reworked and new cast iron manifolds installed. Currently they are weeping. Last year they were also weeping and they only replaced the gaskets which cured the problem for only 1 years. I am assuming the thought now is that since they are weeping again that the manifold need to be replaced this time and not just gaskets. Does this sound right? 3-4 years on manifolds? I will ask him of dates and see if he has them when all that work was done. Thanks for the replies.
 
I plan to change the manifolds and elbows this spring on our 06, 340. I do not plan on removing the motors and haven't heard of that before. I have been shopping around for the parts and prices for both the manifolds and elbows for both motors is between 3800-4200 shipped to the house.
Jason
 
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Did they remove the engines to replace the gaskets? Seems to me that replacing the gaskets requires removing the manifolds. I tentatively call BS on pulling the blocks for this job, but then I haven't see the engine compartment on that boat.
 
I can't imagine how water can weep from the gaskets on the 8.1 engines. Water does not flow through these gaskets, only exhaust.
 
The manifold are still water cooled aren't they so there is salt water somewhere in the manifold that I am guessing is leaking from the gasket area. I haven't seen it so I can't comment and don't know the plumbing of the manifold either so I am relying on the experts here. I just thought pulling engines to replace manifolds was a money maker for MarineMax and not needed.
 
stop the madness!!!! I replaced all 4 manifolds in a weekend. I probally could of done it in a very long day but wanted to change plugs and other service items while I had good access. I paid 550.00 per side online. ( 2200.00 for all 4 manifolds) HOWEVER.... I have inboards so I can only speak on behalf of inboard setups.
 
sfl-larry
Did you keep the original elbows with new manifolds. I know some have done this. I was going to check there condition when I remove them.
Thanks
Jason
 
Hi Guys,

Interested in this thread as I am getting ready to replace the manifolds on our 2008 38DA with 8.1 V-Drive. I created my own post earlier and got lots of good advise....thanks. The 38 has a little more room than the 34, that's why we went with the 38....but pulling the engine on the 34 to change the manifolds doesn't seem reasonable. You might check with our MM here in Clearwater, their service dept used to be OK.

I was told we may have stainless steel elbows (seems the case) which means I'll only need to change the manifolds, hopefully that's the case for your friend Tom.
 
I replaced mine 5yrs ago when I bought the boat. No need to pull engines as long as there is enough clearance between them to remove (which there should be on the 340 Dancer).

If there is weeping going on it would be a failure in the cast iron itself. Sea water is introduced via a hose/fitting at the bottom of the manifold, flows up through it and out of two hose/fittings at the top of the manifold. From there it has a 2-3" hose run to hose/fittings on either side of the stainless steel elbow (didn't have to replace mine - they were fine) where the sea water is pumped up through the elbow and flows out of two holes at it's end where the big exhaust hose is attached and the sea water mixes with the exhaust to keep the exhaust hose cool.

There are NO gaskets where sea water passes, only hoses and fittings. For that reason I can deduct that if water is seeping into the exhaust valve area, some part of the inner wall of the manifolds has failed.

This is a do it yourself job with a difficulty of 5 out of 10. Getting the hoses off is the hardest part - lots of WD 40!!
 
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Yes I was able to reuse my stainless steel elbows. fyi when ordering manifolds make sure you order your manifolds order the convertion kit (manifold) from water rails (older obsolete) to newer jacketed type. why u ask... well it comes with hoses and check valves which in a kit will save you money. if you are interest i can send you the part no. and where i ordered mine from. keep in mind I have 496 (8.1L) engines
 
Great thanks, the 06 doesn't have the water rails, so I am not sure this kit applies to my application but are you saying it's better to order the kit because it comes with the sensors, gaskets ect. And is cheaper in the long run if they need replacing. I see that some have had issues with the sensor removal from the manifold and had to replace, but other than the gaskets what else would you suggest needs replacing.
Thanks
Jason
 
Jason,
Is there a reason you plan on replacing your elbows as well? They should be stainless and in that case most likely are fine to re-use.
 
No I was just going to change the manifolds if the elbows look ok when I take them off. The sensors are mounted In the top of the manifold , but I read a few posts that the sensors are prone to break when trying to remove them from the old manifold.

How was the your vacation? , we had a blast in the BVI ready to go back!!!

jason
 
We had a great time in ST. Thomas. Warm weather and no kids so actually got to relax. We went on a wave piercing 45ft power cat that has twin Yamaha 250 outboards and cruises at 28kts with 20 people on board. Really cool vessel. Got to go to Virgin Gorda, cooper island, some snorkeling and ended for a few beers at Soggy Dollar bar all in 1 day.
Back to reality and the cold now. Already counting the days to take the shrink wrap off. I just scored a house in Edgartown to flip so may be a good reason to put the boat in early this year. Glad to hear you guys had a good time in BVI.
 
That's great, we stayed in a villa on jost van dyke, to the right of the soggy on the hill, we had a blast at the soggy dollar., too many painkillers, Also had no kids. Did you make it to the willy T? We chartered a boat for the day, hit the willy t, Tortola, the caves. What a great place. Glad to hear you had a good time.
 
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