Mercruiser165 exhaust dilema...

[Oshkosh1]

Hi all.

In the immortal words of Maxwell Smart..."missed it by THAT much."

I thought all was good now...tuned up running and ready to go, so I thought.

With a little time on my hands, I decided to check the water shutter. So, I took off the elbow, pipe etc...and found NO, shutter. Nada...gone. Ok, so that's easy, but wait...there's more.

I removed the elbow and noticed a rattle. Looked inside and it was all rusted out...no pipe, gone.

The original motor in the boat was (I believe from my research) a 3.7L. It was replaced with the I6. I believe the exhaust pipe is for the 3.7L, and the mechanic cobbled together the mess in the pictures.

Now...I would like to do this correctly and NOT put that 90deg piece back in. Can I use the elbow from a 3.7L to mate with the new riser that I will need to buy?

Thanks...hope this makes sense.

 

[Oshkosh1]

Re: Mercruiser165 exhaust dilema...

Are the risers interchangeable between the 160 and 165?

I just realized I have a riser from a 160 not a 165. The risers look identical. I can find part #76351 but not 55538.

Thanks.

 

[achris]

Re: Mercruiser165 exhaust dilema...

The elbows are the same... Where your problem is, is the pipe from below the elbow to the transom... That is not a standard in-line pipe. It looks like someone has use the port side of an old 3 piece V8 pipe... (and the centre of course)... and maybe just put a blocking plate where the starboard side pipe would be.... and on those the shutter is right at the bottom, where the centre joins to upright...

HTH,

Chris......

 

[Oshkosh1]

Re: Mercruiser165 exhaust dilema...

The pipe from the transom is the original from the 3.7L (#42421). I can see where the shutters were located to the top of the pipe(just to the right of the manifold, and below the throttle cable in pic#1)...that is still in the boat. Pic #2 shows the 90deg homemade pipe resting atop of it. My plan so-far is to buy a new riser/gasket, shutters and the exhaust elbow assembly used in the 3.7L (#42423), and use rubber bellows to mate the whole works up.

 

[achris]

Re: Mercruiser165 exhaust dilema...

I don't know why, but I missed the bit in your first post about the pipe being from a 3.7... :facepalm: Now it all makes sense... But, using 3.7 elbow will not line up... The reason is because the manifold is in a different location. You'll still have to use the cobbled up pipe... Which is not very efficient BTW... but you probably realize that....

Chris.....

 

[Oshkosh1]

Re: Mercruiser165 exhaust dilema...

Is there any type of flex pipe I could use in place of the severe bend in the current setup? As you said, I do realize that such a hard bend is not efficient at all and any way to mitigate it and shape it to more of a curve would be a bonus.

Any and all suggestions would be more than welcome!

 

[fishrdan]

Re: Mercruiser165 exhaust dilema...

I'd try to find the dimensions for a 3.0L riser as it's about the only thing that's going to match up 1/2 way decent.

(I'm pretty sure new style 3.0L Mercruisers use the same riser, a 3.0L is the same thing as a 165HP 6 cyl less 2 cylinders, so it might just match up...)

 

[Oshkosh1]

Re: Mercruiser165 exhaust dilema...

I'd try to find the dimensions for a 3.7L riser as it's about the only thing that's going to match up 1/2 way decent.

I'm thinking of using:

Merc part #42423A1(3.7L EXHAUST ELBOW ASSEMBLY, UPPER)http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=12488&ivar=images/COMMON/39473.png&inbr=908&bnbr=230&bdesc=EXHAUST+ELBOW
Barr Marine #MC-20-55538 - MERC RISER, 120/160.http://www.marineengine.com/newparts/part_details.php?pnum=BARMC-20-55538&ptype=&Engine=&Model=

It appears that the elbow has enough of a bend to get close enough to clamp together.

If not...Can I have a single piece of stainless steel tube bent, then secure it between the riser and the exhaust pipe?

 

[fishrdan]

Re: Mercruiser165 exhaust dilema...

Have you looked at the 3.0L riser? It has the exhaust offset 45 degrees so it should drop straight into your downpipe, or pretty close to it.

 

[Oshkosh1]

Re: Mercruiser165 exhaust dilema...

Have you looked at the 3.0L riser? It has the exhaust offset 45 degrees so it should drop straight into your downpipe, or pretty close to it.

I will take a look...
WIll it matter that on the 3.0 it appears to have only 2 mounting bolts as opposed to the 4 of my current setup?
Also, their are only 3, not 4, water passages.

 

[Oshkosh1]

Re: Mercruiser165 exhaust dilema...

I think the way to go is to replace the current elbow with an identical one, then use a modified tube or pipe to fashion a riser.

Because of the short distance, and bend...could I simply use a flexible 3" chimney pipe held fast by rubber bellows?

What temps would you think it needs to tolerate?

It appears that the pictured 90deg pipe is a cut and welded 2" exhaust pipe, and don't think any stock riser would fit...so I'll end up cobbling something together regardless.

 

[fishrdan]

Re: Mercruiser165 exhaust dilema...

WIll it matter that on the 3.0 it appears to have only 2 mounting bolts as opposed to the 4 of my current setup? Also, their are only 3, not 4, water passages.

I thought the 2 bolt riser mounting (instead of 4) was kind of cheesy, not sure if there are any issues with it. I don't think there would be a problem with the 3 water passages instead of 4, just a different design. I doubt there's a perfect solution as you'll be cobblin' up parts either way. I would also verify that the riser bolt pattern matches your manifold, if going with the 3.0 45* offset riser. Would suck to get it and find out it won't fit the manifold... (Maybe cross reference the riser gaskets?...)

One thing, I don't like the z shaped exhaust adapter tube that was cobbled up to make it work, that has to be a huge performance killer.

Post up a thread asking if someone had the dimensions of that 3.0L offset riser. I used to have one, but must have got rid of it as I didn't find it in my box of misc 3.0 parts.

 

[Oshkosh1]

Re: Mercruiser165 exhaust dilema...

One thing, I don't like the z shaped exhaust adapter tube that was cobbled up to make it work, that has to be a huge performance killer.

Yeah...now I know why my water only exits through the relief ports.

I think ANYTHING other than that cheesy hack-job would be better.

That's why I was thinking of the flex pipe. It's designed to take the heat of a pellet stove and I wouldn't think the temps would be THAT high in the boat. As far as the watertight integrity...it's also designed not to leak smoke, so it may be a viable(although not entirely correct) ad hoc solution.

 

[Will Fish]

Re: Mercruiser165 exhaust dilema...

I'm in the process of doing the same. During my motor swap decided to change the transom assembly to an Alpha 1, which requires the lower exhaust tube to run outside the mounts, where my old transom plate had a wider mount set up.

I'm at the point where the motor is in and I'm doing the finishing touches today after work. I'll let you know how I make out. I have the same parts you mentioned above Merc part #42423A for the upper exhaust, I was able to take off an old 3.7L boat in the marina (exhaust looked clean and held pressure). Hopefully she will mate right up to my riser with little or no mods (everything I touched basically had to be customized to fit).

 

[Oshkosh1]

Re: Mercruiser165 exhaust dilema...

The elbows are the same...

Nope...
I picked up a #76351 from a salvage. Bolt pattern is about 1/8" too wide for the 160 Manifold. I'll take it back and look for the OEM, if not, has anyone had any luck buying from Osco?. They make an exact replacement for the #55538.

 

[achris]

Re: Mercruiser165 exhaust dilema...

Nope...
I picked up a #76351 from a salvage. Bolt pattern is about 1/8" too wide for the 160 Manifold. I'll take it back and look for the OEM, if not, has anyone had any luck buying from Osco?. They make an exact replacement for the #55538.

That is the later 165 elbow number. They changed at serial# 4608760. Prior to that number, they were the same.

 

[Oshkosh1]

Re: Mercruiser165 exhaust dilema...

No worries...
The "Ancient Mariner"(and I'm NOT kidding...90Y/o+)at the yard told me to make sure it fit, if not, bring it back and he had "a pile" of 6cyls at a different location he could look through.

He also suggested using a riser from the 3.0L to mate up between the pipe and elbow. I'll take a look tomorrow.

 

[fishrdan]

Re: Mercruiser165 exhaust dilema...

I'll take a look tomorrow.

Take a spare gasket, so you can match it up...

 

[Will Fish]

Re: Mercruiser165 exhaust dilema...

I'm in the process of doing the same. During my motor swap decided to change the transom assembly to an Alpha 1, which requires the lower exhaust tube to run outside the mounts, where my old transom plate had a wider mount set up.

I'm at the point where the motor is in and I'm doing the finishing touches today after work. I'll let you know how I make out. I have the same parts you mentioned above Merc part #42423A for the upper exhaust, I was able to take off an old 3.7L boat in the marina (exhaust looked clean and held pressure). Hopefully she will mate right up to my riser with little or no mods (everything I touched basically had to be customized to fit).

Well I'm in the same perdicament. if I take the upper rubber coupler from the upper exhaust pipe to the riser out, the riser will fit into the pipe. I am going to try and mate something this way (maybe Tommy Tape - I have to find out the heat limitations first). After all, the exhaust should have enough pressure to push the water down and prevent a leak.

 

[Oshkosh1]

Re: Mercruiser165 exhaust dilema...

I hope we all here are speaking the same language...
There seems to be some disparity between what we are calling certain parts.
So...here's MY definitions:
Elbow...the part that looks like an elbow. Attached directly to the manifold which connectes via rubber bellows to the----
Riser...The "pipe" which contains no other parts(in my application)...simply "rises"(and it attatched via bellows) from the---
Exhaust Pipe...which is attatched directly to the transom and (in my application) has the Exhaust water shutter contained at the very "top" of it.

I think that covers it!