"y" pipe connection question

[Fishermark]

In the ongoing saga of trying to find and eliminate a leak from the transom area that has been hard to correct, I am pulling the entire transom assembly off and resealing everything.<br /><br />When I put a new engine in my boat last fall, (a 5.7 liter Mercruiser - to replace a 5 liter engine) I noticed that the transom assembly was apparently the wrong one for the boat/engine combination, although it appeared original. Where the "y" pipe bolts up to the transom assembly, the bolt holes did not match up completely. Three did, but one was cocked to the side. Later I saw where that is for a single pipe like found on a four cylinder engine.<br /><br />I went ahead and bolted it up, but, (and this may be a dumb question ), is that likely to cause a problem? Has anyone else done this and had experience good or bad?

 

[Fishermark]

Re: "y" pipe connection question

Anyone?

 

[achris]

Re: "y" pipe connection question

Another area worth looking at is the shift cable bellows. If that gets a split or hole in it you'll have a slow leak of water into the boat.<br /><br />For the V8 exhaust 'Y' you should have 5 bolts holding it on. 2 at the top, 1 long one through the middle and 2 short ones right at the bottom. If the 2 bottom ones are missing, this could also cause a leak. When you remove the 'Y' there should be a large 'o' ring for the main port and 2 smaller ones below.

 

[Fishermark]

Re: "y" pipe connection question

I know what SHOULD be there, and it isn't. The gimble housing on my boat is the one that is supposed to be used with the inline four or six - with one of the top holes cocked to the side. I went ahead and used it anyway since that was what was on there with the engine that was in the boat when I bought it. It looks to me as if it came from the factory with this engine (v-8) and transom assembly matched up. Almost like they did not have the correct one handy, so they put the wrong one on.<br /><br />My question really is this: has anyone else used this combination (even though it is wrong) and had any experience good or bad.<br /><br />It may be a moot point at this stage as I think I have found a good used "fresh water" replacement for a reasonable price and will probably use it.

 

[achris]

Re: "y" pipe connection question

Once you get the 'Y' off you'll be able to see if the holes are there for the 2 lower bolts. If they aren't, put the 'Y' back on with the all the bolts and mark the two missing ones. Then remove the 'Y' and drill and tap the holes. Memory is telling me they are 5/16" UNC, but check it. I also have vague recollections of doing this conversion so years ago. I also drilled the lower exhaust ports through the transome housing. If you don't water will pool on the bottom of the 'Y' and accelerate corrosion.<br /><br />Chris....

 

[Fishermark]

Re: "y" pipe connection question

Hi Chris,<br />All the bolts are there except one of the top ones doesn't line up - I went ahead and bought the right gimble housing - it should be in sometime next week.<br /><br />By the way - I agree wholeheartedly with your signature line "Nothing puts the world into better perspective than seeing it from 100' below the sea...." I'm hoping to have this done by the end of the month as I drive down to the keys for a well deserved break and some great diving and fishing!

 

[Fishermark]

Re: "y" pipe connection question

I'm reviving this post because I just got some information that surprises me if it turns out to be true. In searching for another gimbal housing, I was told by a shop which rebuilds them that Mercruiser says it is okay to just use the three holes that match up. I e-mailed Mercruiser, (I may or may not hear back from them ), if and when I get a response I will let you know. <br /><br />In the meantime, once again, is this a situation that anyone else has faced? What about you Mercruiser techs out there?

 

[Fishermark]

Re: "y" pipe connection question

Here's a couple of pictures to show what I am talking about for those who aren't sure:<br />Here is the four cylinder pipe - see how one of the top holes is cocked to the side?<br />

<br /><br /><br />Here is a "y" pipe, you can clearly see the top holes sided by side:<br />

 

[anesthes]

Re: "y" pipe connection question

I'm using a 4-cyl gimbal with v8 exhaust. DOn't leak, even with the missing hole. I think 1 didn't line up.

 

[Fishermark]

Re: "y" pipe connection question

Well, here's the final word from Mercruiser. Their initial response to my question was this:<br /><br />

Thank you for your recent inquiry. The sterndrive and transom assembly do not change regardless of the model of the engine. The setup on the transom side is either for an Alpha assembly or a Bravo assembly. The "Y" pipe setup needs to be the approved exhaust application to work with your 5.7L and Bravo sterndrive. I cannot authorize the use of only three bolts when four bolts was the original planned design. MerCruiser recommends making any necessary changes to insure that both top bolts do line up and attach accordingly. I hope this information is helpful and please let MerCruiser Consumer Service know if we can be of further assistance.

After writng back with a reminder that my boat doesn't have a Bravo drive, but an Alpha one, (as I had originally said!), I received the following response back:<br /><br />

I spoke to a technical expert in the MerCruiser OEM department about how that should bolt up. He said that on some applications that you will only be able to access three holes to complete the assembly. It is completely normal and an approved method. That is officially MerCruiser stance. Sorry for any confusion.<br />

So there you have it - straight from Mercruiser. I guess it's okay to only use the three bolts for the "y" pipe after all!

 

[achris]

Re: "y" pipe connection question

Hey Fishermark,<br /><br />I am without doubt a complete d***h***. The top photo is an exhaust tube from an Alpha one, or earlier, transom assembly. The bottom photo is of an exhaust pipe from an Alpha One Gen II assembly. THAT'S why they don't match up! I'm kicking myself for not seeing it earlier. Guess I've been out of the game for too long, ah?<br /><br />Sorry I didn't spot it earlier.<br /><br />Chris...........<br /><br />P.S. Could I have that e-mail address for Merc. I have a small issue of a carb adaptor I would like to shove up their.... discuss with them.

 

[Fishermark]

Re: "y" pipe connection question

Hi Chris,<br />The picture I posted of the "y" pipe above is not an actual picture of mine, but it is like mine - the holes are the same. And mine is from an Alpha 1, gen 1... not gen 2.<br /><br />I went to www.mercruiser.com and found the "contact us" page. It is a little difficult to do so however - it looks like they want you to contact them through a dealer. You have to use an e-mail form and include your serial number in order to contact them. Fortunately, (well, for me at least ), the crate engine I purchased from them is still under warranty, so I was able to give them a serial number for them to go by.