80s 50hp Merc. exhaust leak and motormount problem

[checkoutmyjunk]

Hello,

I had another thread but feel that is was misleading, if you want to take a look at the history check the link below http://forums.iboats.com/showthread.php?t=412877

Motor has a loud exhaust leak, sound like it's coming from where the power head connects to the bottom (see my finger pointing to the general area) As you can see I separated the power head from the lower half.

The gasket that was there came off in pieces so I know I need to replace that.
If I jiggle the exhaust stack there is clearly movement under the shroud where the upper part of the exhaust stack meets the power head (click image below to see video)

The marina / mechanic that "fixed" this motor for me told me that he thought the stack was plugged, this is not the case (see pics again)

I am hopelessly lost and fell that I am getting deeper.

1. I know that while I have things apart I should replace the gaskets and impeller.
2. The movement shown in the video, should I replace the gasket that is between the power head and the upper part of the exhaust stack?
3. If I do need to replace that gasket how do I remove that upper stack part it seems to be trapped by the shroud?
4. Where are the motor mounts and how do I replace them
5. Should that oily circle thing be in the exhaust stack
6. If there is a loud exhaust leak up where the above photo illustrates (see image of me pointing) what is the typical cause of that?

Thanks in advance!

 

[checkoutmyjunk]

Re: 80s 50hp Merc. exhaust leak and motormount problem

100 clicks, this must be a stumper

 

[checkoutmyjunk]

Re: 80s 50hp Merc. exhaust leak and motormount problem

So I dug a lil deeper, still have not found the the source of the exhaust leak. I plan to button this back up with new gaskets and hopefully I can get it back together correctly and then tear the lower unit off and start looking for the source of the leak there. Since I have so many clicks I assume that yall like to look at the pictures

Gonna clean the buildup out of the exhaust area and all the years of grime that have accumulated, a new set of plugs wouldn't hurt while I got it torn apart. Looking at the serial number I discovered that this is a 1981.

Taking the pull cord off was task and of course it sprung back in to the fly wheel area so that might be another puzzle to sort out.

I found a lot of newer looking zip ties holing the choke and gas lines together, is this acceptable for a certified Merc dealer to install zip ties like that? Also found several plastic shields that were broken or glued that makes me wonder. I know for a fact that this motor was purchased new and never serviced by anyone but the same shop.

If any one cares to comment, thanks in advance!

 

[checkoutmyjunk]

Re: 80s 50hp Merc. exhaust leak and motormount problem

Not sure why I keep coming back, over 100 clicks and no help, I dunno thanks............

Update:

More dismantling, I dropped the lower unit tonight. All went well till I saw this piece drop out, I have been careful to keep an eye on how things come apart but this guy kinda surprised me and now I am no sure how to put it back in.

Here are some other shots, I suppose the impeller is under that black plastic housing. There seems to be no gaskets between this lower unit part, should I just be using a marine grade RTV? I suppose I need to clean up the surfaces with some emery cloth?

I think it's an 81

 

[carholme]

Re: 80s 50hp Merc. exhaust leak and motormount problem

Do you remember what fuel/oil mix you were using?

The service manual for this engine is P/N: 90-86135--5

http://www.ebay.ca/itm/ws/eBayISAPI.dll?ViewItem&item=140452275932&clk_rvr_id=327855900273

http://ie.picclick.com/USED-93-Mercury-Outboard-270801861441.html

Or you can use this condensed version of the Clymer manual which will help you out. Let the page load for 30/40 seconds and download to your computer soonest as the link is short lived.

http://web.ebscohost.com/serrc/pdf?...9-9869-4afb66f19869@sessionmgr15&vid=4&hid=14

Parts Listing:

http://www.crowleymarine.com/mercury-outboard/275.cfm

If you look at GEAR HOUSING (DRIVE SHAFT), items 43 thru 50, that is the stackup that dropped out on you. That is the lower shift shaft and the reverse lock cam and it actuates items 24/25 which you see under SWIVEL BRACKET AND REVERSE LOCK. When in Fwd gear the hooks on item 24 engage the pin, item 20 and prevents the engine from potentially flying up and into the boat if it contacts something in the water.

What stage are you at now?

Gerry

 

[carholme]

Re: 80s 50hp Merc. exhaust leak and motormount problem

Further;

Looking at your questions above, I did not see a video.

For the motor mounts, see under DRIVE SHAFT HOUSING ASSEMBLY, item 27 which are the lower mounts. The areas of play that usually show up are;

1. The splines at the lower end of pin, item 5 where it is splined into the yoke, item 13.

2. The lower grease seal, item 2 wears out, especially if there is spline wear on the pin.

3. Weakened/soft mounts or play in the housing where the mount fits. I have had to build shims around the circumference of the mount
to prevent horizontal movement. They should fit solidly in the housing recess.

Didn't understand "the oily circle thing in the exhaust stack". Are you referring to the copper coloured tube which is the tube which transfers water from the waterpump housing to the powerhead?

Gerry

 

[checkoutmyjunk]

Re: 80s 50hp Merc. exhaust leak and motormount problem

Further;

Looking at your questions above, I did not see a video.

For the motor mounts, see under DRIVE SHAFT HOUSING ASSEMBLY, item 27 which are the lower mounts. The areas of play that usually show up are;

1. The splines at the lower end of pin, item 5 where it is splined into the yoke, item 13.

2. The lower grease seal, item 2 wears out, especially if there is spline wear on the pin.

3. Weakened/soft mounts or play in the housing where the mount fits. I have had to build shims around the circumference of the mount
to prevent horizontal movement. They should fit solidly in the housing recess.

Didn't understand "the oily circle thing in the exhaust stack". Are you referring to the copper coloured tube which is the tube which transfers water from the waterpump housing to the powerhead?

Gerry

Thanks!

I think its a baffle, in the image.

 

[chum1]

Re: 80s 50hp Merc. exhaust leak and motormount problem

I guess from your questions that your main problem is the loud exhaust leak, more then likely the gasket from your description , why did it blow out? not tight perhaps?

If it was mine i would change the gaskets that were taken apart with new from parts book in carholmes description, grease splines,replace impeller, call it good and enjoy.

 

[checkoutmyjunk]

Re: 80s 50hp Merc. exhaust leak and motormount problem

Thanks for the help, I bought a corvette a few days after my last post. I think my time limit is up on that manual, is there any chance there is another one out there?

Got some new gaskets and plugs, started removing the old gaskets and ran into some trouble. On a few places I can't seem to get the gasket off the motor, in other places there seem to be a thin layer of the gasket stuck to the surface. Are there any tricks to getting these off with out scratching the surface?

This piece dropped out of somewhere tonight, looks broken, any ideas on this?

 

[dkonrai]

Re: 80s 50hp Merc. exhaust leak and motormount problem

try a little gasket remover, permatex is best. amazing stuff.
good luck

 

[carholme]

Re: 80s 50hp Merc. exhaust leak and motormount problem

The piece that dropped out looks like it is broken off the end of the exhaust plate. Look at item 23 in this link and I think it fits into the broken piece. Can you confirm that?

http://www.crowleymarine.com/mercury-outboard/parts/275_130.cfm

Here again is the link to the condensed version of the service manual:

http://web.ebscohost.com/serrc/pdf?sid=525bd645-0e14-402c-96c1-c58c1d8d16df@sessionmgr4&vid=4&hid=13

Gerry

 

[aussieflash]

Re: 80s 50hp Merc. exhaust leak and motormount problem

Try using scourer like plastic wool to remove old gasket.

 

[checkoutmyjunk]

Re: 80s 50hp Merc. exhaust leak and motormount problem

The piece that dropped out looks like it is broken off the end of the exhaust plate. Look at item 23 in this link and I think it fits into the broken piece. Can you confirm that?

http://www.crowleymarine.com/mercury-outboard/parts/275_130.cfm

Here again is the link to the condensed version of the service manual:

http://web.ebscohost.com/serrc/pdf?sid=525bd645-0e14-402c-96c1-c58c1d8d16df@sessionmgr4&vid=4&hid=13

Gerry

Thanks!

I am getting an error

A System Problem has Occurred.

We're sorry, your request could not be processed due an internal server error.
To continue with your session, please click here.


It does not seem to fit anywhere in that area, What is normally attached to that area? Does it help to say that this was just a tiller controlled out board?

Thanks every one for the input, I didn't know they made gasket remover!