1971 115 mercury ?

[Jhoppy]

Hello everyone I have a 1971 115 hp mercury ob short shaft serial number 3037534 and I have a few questions. First of all I Just bought the boat this motor was on and it was not running it need a distributor so I installed a used one and did the link and sink got it running and changed the lu lube it was very milky. Then took it out on the water for the first time to see how it ran. I had no problems and it ran fine. So now I want to go though motor and make sure there are no problems that way it will be ready for this summer. So my questions are
1. The mercury switch on this motor was unhooked and I?m not sure why it is there and how necessary it is or what exactly it dose?
2. I have removed the power head and lu, and the exhaust tube pn 38469 is missing it looks like it directs exhaust in to the prop of the lu, I?m not sure how necessary this was and if I need to find a new one, or where to find a new one.
3. I would like any input on what parts to replace out of maintenance so that I will have no problems with this motor . I planed on so far New water pump, pressure checking the lu and fix any seal leaks found, replace distributor bearings they were a little ruff when I put the used one in, fix the motor mounts some of the bolts are loose. Replace all rubber balance and fuel line hoses. I also would like some input on replacing the case seals and crank seals if that is a good idea to do just to be on the safe side and maybe kit the carbs?
Thanks for any input.

 

[RaScLeS]

Re: 1971 115 mercury ?

i would clean the carbs and replace anything that needed it in there. waterpump fuel lines hook up that switch youre talking about and make it so its back in all original condition. compression test new plugs new gas and go...also a good idea, but since you already had it running is to lube up the cylinders before you start it

 

[daveswaves]

Re: 1971 115 mercury ?

So my questions are
1. The mercury switch on this motor was unhooked and I?m not sure why it is there and how necessary it is or what exactly it dose?

The mercury switch is there to kill the ignition if the engine tilts up too high, for example if you hit a log at speed. Many people remove the switch as it can cause intermittent spark in rough water conditions.

2. I have removed the power head and lu, and the exhaust tube pn 38469 is missing it looks like it directs exhaust in to the prop of the lu, I?m not sure how necessary this was and if I need to find a new one, or where to find a new one.

The exhaust tube acts as a tuner and the engine will run better with it. I doubt that you will find a new one but used ones come up on ebay from time to time. Since you have a short shaft engine (very desireable) you can expect to pay more for the exhaust tube, they are getting rare.
The only reason that I can think of that the previous owner left it out. They do break and fall down and then things run really crappy.


3. I would like any input on what parts to replace out of maintenance so that I will have no problems with this motor . I planed on so far New water pump, pressure checking the lu and fix any seal leaks found, replace distributor bearings they were a little ruff when I put the used one in, fix the motor mounts some of the bolts are loose. Replace all rubber balance and fuel line hoses. I also would like some input on replacing the case seals and crank seals if that is a good idea to do just to be on the safe side and maybe kit the carbs?

I would also check the lower crankshaft seal(s) for wear and replace them. When you have the distributor apart check the c clip as well, they rust and can fall out, ruining an expensive distributor. I would not replace the case seals unless you are splitting the block to do rings.. Carb kits are always a good idea.
Thanks for any input.

My responses are embedded in your quote,,,,ooops.

 

[Jhoppy]

Re: 1971 115 mercury ?

Thanks for the Recommendations and sorry for the slow response. I have done some of my own research and found out that I really have long shaft 135 mercury not a short shaft 115. I had miss measured the shaft length and I have removed one of the carburetors to measure the reed stops and jet size to verify that it is a 135 not the 115. Anyways I now have more questions. I have torn down the Lower unit to replace the seals and inspect bearings and seals and everything looks fine with the exception of the driveshaft. The splines on the pinion end of the shaft have been slightly twisted, approximately 1/16 of an inch. I am guessing that the prop hit something at one time causing this to happen. My question is will this survive or do I need to find another driveshaft? I know at a minimum I will have to file the step down on the splines so that the pinion will sit on the taper on the shaft and not get caught on the step when it is tightened. Also what is the toque on the driveshaft nut? Thanks

 

[daveswaves]

Re: 1971 115 mercury ?

That drive shaft came just short of shearing off, it cannot be repaired, you will need another drive shaft without question. Its good that you have a 135, very snappy engine (no pun intended). The drive shaft from any of the 1970,s will fit so you should not have any trouble finding one.

edit: Your profile does not say what part of the country you are in, let me know and I can probably direct you to a source for a used drive shaft. Also, does your driveshaft have the preload pin in the top?

 

[Jhoppy]

Re: 1971 115 mercury ?

Thanks for the quick reply im in Kearney Nebraska witch in the southern middle of the state. No i dont think i have a preload pin? Im not sure what that is though, there is nothing on the top of the shaft but splines and a grove for an o-ring if thats what you mean. thanks.

 

[daveswaves]

Re: 1971 115 mercury ?

Middle of Nebraska eh? Well I know where there are used ones in South Carolina and in Washington state, either way youre in the middle. The preload pin would be sticking out of the top of the driveshaft if you had one. Yours will just have a hole in the centre. Just a way of identifiing what type of bearings you have in the lower end (under the water pump housing). Your shaft is probablly not stainless steel. Try to get a newer one that is stainless as long as you are changing it. The common steel ones will be pitted and coroded. I would suggest you look locally first, save shipping etc. Some merc dealers if they have been around a while may have a shaft kicking around, not cheap though. You can probably pick up a used lower end ready to go for less. I have 3 spare lower ends here if you get stuck and cant find anything, shipping is the problem.
​

 

[Jhoppy]

Re: 1971 115 mercury ?

Middle of Nebraska eh? Well I know where there are used ones in South Carolina and in Washington state, either way youre in the middle. The preload pin would be sticking out of the top of the driveshaft if you had one. Yours will just have a hole in the centre. Just a way of identifiing what type of bearings you have in the lower end (under the water pump housing). Your shaft is probablly not stainless steel. Try to get a newer one that is stainless as long as you are changing it. The common steel ones will be pitted and coroded. I would suggest you look locally first, save shipping etc. Some merc dealers if they have been around a while may have a shaft kicking around, not cheap though. You can probably pick up a used lower end ready to go for less. I have 3 spare lower ends here if you get stuck and cant find anything, shipping is the problem.
​

Thanks, I will keep you in mind if i end up needing one. I would really just like to find a shaft and not whole lu. I Was sercing here on this form about drivshafts and read that the stainless steel drivshafts would not interchange with the steel ones. I can not find the post now, But my shaft is deffinitly not stainless steel, it is steel. Can you be more spacific about what Hp and years i need to find a drivshaft out of and what to look for. Thanks Hoppy

 

[OldMercsRule]

Re: 1971 115 mercury ?

I don't think the 1971 1150 or the 1350 had exhaust tuners at all.

I have one that I will tear into fairly soon and find out fer sure.

I was told that by one of the inline6 Gurus here or on Scream n' Fly, (not sure which place), only one functional brain cell.

My 89.x 1969 Merc 1000s silver blocks both have tuners and me black blocks 1150s n' 1500s 1974, 1975,1976,1977, 1978, 1979 all did too.

I have (2) 1250s silver blocks that do not have exhaust tuners, (I know the 1250 was a different block, [cross flow]). That said: the silver blocks from 1970 to 1972 also didn't have tuners (so I have been told), and will verify within the next six months.

Me overpriced $.02 JR

 

[Jhoppy]

Re: 1971 115 mercury ?

I don't think the 1971 1150 or the 1350 had exhaust tuners at all.

I have one that I will tear into fairly soon and find out fer sure.

I was told that by one of the inline6 Gurus here or on Scream n' Fly, (not sure which place), only one functional brain cell.

My 89.x 1969 Merc 1000s silver blocks both have tuners and me black blocks 1150s n' 1500s 1974, 1975,1976,1977, 1978, 1979 all did too.

I have (2) 1250s silver blocks that do not have exhaust tuners, (I know the 1250 was a different block, [cross flow]). That said: the silver blocks from 1970 to 1972 also didn't have tuners (so I have been told), and will verify within the next six months.

Me overpriced $.02 JR

I think i read that somwhere in this forum too when i reserching the differences between a 1150 and 1350. It puzzels me though that the seal and retainer for the exhaust tuner were still in the lu? Let me know for sure when you do tear yours down if it has one or not. Thanks Hoppy

 

[Jhoppy]

Re: 1971 115 mercury ?

I have been doing more home work on my lower unit and have found out that it is not the original to my motor possibly explaining the exhaust tuner seal and retainer in the Lower unit. My lower unit is from a 65-68 and has a 2:1 gear ratio not the correct 1.78:1 ratio casting number 1623-2460. So now I?m looking for a mercury 45-38460 drive shaft with 6 pinion spines 8 motor spines one inch pinion gear bearing surface 30 3/4 long. I would like to know what shafts would interchange with this if any, if anyone knows? I would prefer to find a shaft and fix my lower unit vs find a used lower unit if a shaft is available for a reasonable amount of money.

Thanks

Hoppy

 

[OldMercsRule]

Re: 1971 115 mercury ?

Jhoppy states:I have been doing more home work on my lower unit and have found out that it is not the original to my motor possibly explaining the exhaust tuner seal and retainer in the Lower unit.

Yup, real likely.

My lower unit is from a 65-68 and has a 2:1 gear ratio not the correct 1.78:1 ratio casting number 1623-2460.

Why do ya care?

Ya want the overdrive LU? Why so?

Methinks a stainless driveshaft, (standard from 1975 on [2 to 1], or the snappier lookin' skeg 1979 or later with the pedo in the LU, also 2 to 1 on the inline6), would be more important then the 1.78 to 1 gear ratio. That said: (only one brain cell n' all).

So now I?m looking for a mercury 45-38460 drive shaft with 6 pinion spines 8 motor spines one inch pinion gear bearing surface 30 3/4 long. I would like to know what shafts would interchange with this if any, if anyone knows? I would prefer to find a shaft and fix my lower unit vs find a used lower unit if a shaft is available for a reasonable amount of money.


Hmmm.... then the 2 to 1 is not a problem????

Thanks

Hoppy

Thank you, JR

 

[Jhoppy]

Re: 1971 115 mercury ?

Jhoppy states:I have been doing more home work on my lower unit and have found out that it is not the original to my motor possibly explaining the exhaust tuner seal and retainer in the Lower unit.

Yup, real likely.

My lower unit is from a 65-68 and has a 2:1 gear ratio not the correct 1.78:1 ratio casting number 1623-2460.

Why do ya care?

Ya want the overdrive LU? Why so?

Methinks a stainless drive shaft, (standard from 1975 on [2 to 1], or the snappier lookin' skeg 1979 or later with the pedo in the LU, also 2 to 1 on the inline6), would be more important then the 1.78 to 1 gear ratio. That said: (only one brain cell n' all).

So now I?m looking for a mercury 45-38460 drive shaft with 6 pinion spines 8 motor spines one inch pinion gear bearing surface 30 3/4 long. I would like to know what shafts would interchange with this if any, if anyone knows? I would prefer to find a shaft and fix my lower unit vs find a used lower unit if a shaft is available for a reasonable amount of money.


Hmmm.... then the 2 to 1 is not a problem????

Thanks

Hoppy

Thank you, JR

To clarify The ratio of the lower unit is not important to me only that it works as it should. I only wish i had one braincell cuz i kinda missed what you typed are you saying that a drive shaft from a 75 on would work or that I should upgrade to a lower unit from a 75 on with a stainless shaft or 79 with the snappier looken skeg????????? sorry im a slow newbe

Thanks

Hoppy

 

[OldMercsRule]

Re: 1971 115 mercury ?

Hoppy: All inline6 Lower Units from 1975 and newer, (to 1988) had stainless steel drive shafts.

All inline6 Lower Units will werk fine and bolt up to yer midsection and powerhead.

All 1974 and older were mild steel drive shafts. Only a problem if ya run in salt water.

Most of the inline6s from 1962 to 1988 were 2 to 1 900, 950, 1000, 1100, 1150, 1250, 1400, 1500, 90, 115, 140. Only a few (in 1970 n 1971 or some such 1150 and 1350), were 1.78 to 1.

The 1979 and newer inline6 Lower units were both stainless and had a more aggressive angle on the skeg, (looked kooler). They also had a pedo pick up in the LU, which was also kool.

The inline 4 650 from the 1960s and early 1970s was also 2 to 1, (mild steel), and would bolt up and run fine on any inline6, (the 3 cylinder 650, and 3 cylinder 750 will not werk), they were made in the 1970s n' later.

The 800 and 850 inline4s will bolt up butt: they have a 2.3 to 1 gear ratio, (tooooo low fer an inline6). Me 1978 800 inline4 had the more agressive skeg n' the pedo pick up butt: 2.3 to 1, sniff....sniff

Hope that makes it clear. sorry fer the "cornpone". JR

 

[Jhoppy]

Re: 1971 115 mercury ?

Thank you JR, That will help me out allot. I had no idea what would interchange with what. That Will make it allot easier to find a good lower unit.

Thanks Hoppy

 

[crem1]

Re: 1971 115 mercury ?

Hi!

I have a MERC 500 1973 model, can you tell me whether I have a driveshaft with a pin on it or do I have a stainless steel one? Do you need any other information to determine that?
Thanks in advance

 

[OldMercsRule]

Re: 1971 115 mercury ?

Hi!

I have a MERC 500 1973 model, can you tell me whether I have a driveshaft with a pin on it or do I have a stainless steel one? Do you need any other information to determine that?
Thanks in advance

Hint: start yer own thread. The 500 was totally different then the larger inline4s and inline6s. JR