40HP exhaust Tube - is it missing ?

M

Moody Blue

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• Apr 2, 2005

• #1

I started an new topic here with more of an appropriate heading. My earlier post (waterpump woes) was not very representative of the issue. As for the exhaust tube, I'm still not sure what to do. If it had one originally I want to put one back in. If it was not designed for one, I don't want to start re-engineering it. Can anyone say for certain whether this motor/year had an exhaust tube ? Again it is a 1992 40HP 4cyl Mariner. Seems to have run OK for the past year that I've owned it. Hope someone here can steer me in the right direction. Thanks.

 

R

rodbolt

Supreme Mariner

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Sep 1, 2003

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20,066

• Apr 2, 2005

• #2

Re: 40HP exhaust Tube - is it missing ?

look up the midsection. if there is about a 2" diapipe looking thing about 1 1/2ft long its all it had

 

M

Moody Blue

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• Apr 2, 2005

• #3

Re: 40HP exhaust Tube - is it missing ?

had a good look with a flashlight. All I can see is a round tube about 2-3" dia and about 2" (inches) long protruding from the bottom of the powerhead. The inside of the midsection is surprisingly clean with the exception of an oily residue on the walls. No carbon buildup at all. Can't see anywhere that an exhaust tube could attach to. In the on-line parts diag's, the exhaust tube is shown as rectangular in shape and appears to be seated in a seal in the lower unit. I'm so confused

 

R

rodbolt

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• Apr 2, 2005

• #4

Re: 40HP exhaust Tube - is it missing ?

the exhast tube presses onto that 2" projection. it may well be missing.YOU NEED THE APPROPRIATE SHOP SERVICE MANUAL. NOT AN ONLINE DIAGRAM. look on page 5a-6 of manual 90-814676and page 5a-3 of the same manual. this was printed in 92. manual ID 2-1092

 

M

Moody Blue

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• Apr 2, 2005

• #5

Re: 40HP exhaust Tube - is it missing ?

Rodbolt, many thanks. The only manual I have is a Clymers. Seemed thorough until now. The entire middle section of the motor detail is missing. Only the powerhead and lower unit is covered, nothing in-between. Crap !!! I don't want to spend more money on another manual. Guess I'll buy the parts and see how it works out. I don't understand how the exhaust exits the upper relief ports when idling if the tube connects the powerhead to the lower unit. Would that not buildup alot of backpressure ? Sorry for the rambling but I like to understand what I am doing as opposed to just getting it done. Do you have a way of e-mailing me those specific pages ? I would be most grateful.

 

S

Scali

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Dec 18, 2004

Messages

299

• Apr 2, 2005

• #6

Re: 40HP exhaust Tube - is it missing ?

RodC,<br />Did you<br />reach up into the midsection & try to pull it down, maybe it's stuck they slide up & down???

 

R

rodbolt

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• Apr 2, 2005

• #7

Re: 40HP exhaust Tube - is it missing ?

hello<br /> maybe tomorrow I will attempt to scan them

 

M

Moody Blue

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• Apr 3, 2005

• #8

Re: 40HP exhaust Tube - is it missing ?

Scali, wish it were so but definitely nothing in there.<br />Rodbolt thanks a bunch.

 

AMD Rules

Lieutenant Commander

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1,707

• Apr 3, 2005

• #9

Re: 40HP exhaust Tube - is it missing ?

RodC... you have an email address?

 

M

Moody Blue

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• Apr 3, 2005

• #10

Re: 40HP exhaust Tube - is it missing ?

AMD, my email is rodc@sympatico.ca<br />Grew up in St.Catharines just down the road from you. Don't get down that way very often anymore.

 

M

Moody Blue

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• Apr 10, 2005

• #11

Re: 40HP exhaust Tube - is it missing ?

Thanks AMD for the info on the drive shaft housing assembly. This confirms the presense of the exhaust tube and seal. <br /><br />Scali, I decided to continue with this post rather than hijack the other post under Non-Repair. I have obtained info from several different sources and they all show the presense of the exhaust tube. Sometime in the past this must have been removed from my motor. The powerhead and transom bracket s/n's don't match so this motor has had work done to it. Not sure how many hours on it since but everything looked OK inside. Am going to order the parts tommorow. Don't really understand the hows and whys of needing it but I'm not going to second guess the "experts" at Mercury.

 

S

Scali

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Messages

299

• Apr 10, 2005

• #12

Re: 40HP exhaust Tube - is it missing ?

I wonder how many hours it ran without it ?<br />I dont blame you though, wanting it set up right.<br />Good luck

 

A

astro1800

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Apr 28, 2005

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6

• Apr 28, 2005

• #13

Re: 40HP exhaust Tube - is it missing ?

the only thing that the exhaust tube will help is your bottom end power. if you have plenty bottom end power i would probably leave it off. the shorter the tuner the better the top end.

 

M

Moody Blue

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• Apr 29, 2005

• #14

Re: 40HP exhaust Tube - is it missing ?

Too late astro, just finished putting everythink back together today. Had to pull the power head to install the exhaust tube. Just as well. I ended up repairing an engine mount in the process. Got it cleaned up nice and everything is finally back to factory original. Next step is to start her up. Got my fingers crossed <br /><br />I had heard from several people that you gain a little more top end without the tube but I feel more comfortable knowing its in place as it should be. Had lots of bottom end power before, now it should rock !!!