'80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter and

[Skunked Again]

Great forum! My engine lost power and sounds like it's got a rod knock. All spark plugs look similar - oily - maybe milky :~( When checking compression with all plugs out (I didn't open the throttle) the engine spins quickly and pretty noisily. All cylinders except #3 read 135 to 140. When checking #3 the engine spins slower and quieter and only develops 60 psi. I've done plenty of car engine work but this fancy 2 stroke is a new deal for me. What's wrong with my tower of power and what parts/tools/books do I need to fix her ? Thanks in advance - this forum looks awesome!

 

[highaltitude]

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

good luck. i would look inside the cylinder through the spark plug hole and check the condition of the cylinder. if it is scored-its all downhill from there. i personally would not rebuild an i-6. they were not designed to run on the low quality fuels of today.

 

[jheron]

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Sounds like BS to me highaltitude!! <br />What do you think the octane of gas in 1980 was compared to now??<br />Skunked Again I would go get a good book on your motor. There is not much to a 2 stroke, I think you will be in for a pleasent surprize if your used to 4 strokers.<br />regards Jon

 

[Skunked Again]

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Thanks for the replys, guys. - highaltitude - I can't just give her up - she's got a jet pump instead of a lower unit that I need for shallow water use - even If I replace the engine, I'll need the same basic unit to mate up with the jet.<br />Jon - What do you suppose is wrong in there? The symptom is backwards - she turns fast when I test a high compression cylinder, but she turns slow and quiet when I check the low cylinder! What can cause this? Only a bent pushrod or non-rotating camshaft would in a conventional car V8 - you know - can't pull in an intake charge or get rid of exhaust. Can my 2 stroke do this? thanks!

 

[rodbolt]

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

shes blowed up<br /> with 60 psi in a hole and milky plugs shes toast.<br /> time for a tear down and inspection. on a tower o power its imperitive to remove the exhaust covers and inspect the divider as well as the deflectors for integrity.<br /> a werd o ad vice<br /> forget you ever worked on a car<br /> forget all you car buddies advice<br /> buy a shop Merc manual. read and reread before wrench twisting. ask lots of questions but none from the auto guys. most aint got a clue either. there are several on this forum that have a lot of technical capeabilities with the merc inlines. I dont see many anymore cause they all corroded away in my area. here in the salt pond motors dont last but 6-8 years and they are over it.<br /> but do heed the non-auto tech advice. it will save you some grief.

 

[prolinews]

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

clams camino is your man he seems to be the resident guru on the tall boys. Old motors don't die people just give up on them.

 

[Skunked Again]

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Good advice rodbolt - just lookin' under the wrapper I said to myself "hey - where's the dipstick on this thing?" and realized that car guys are about as much help as a cattle rancher at a chicken farm in this outboard world. <br /><br />Where besides ebay can I get a factory book for the 1980 tower? <br /><br />I should mention that the plugs have looked that way for years and she's spun 5kRPM+ with glee for hundreds of gallons of gas. What should those wierd plugs look like?<br /><br />I assume the magic book you speak of will clue me in on what dividers, deflectors, and exhaust covers are. (where is the timing chain cover on this baby, anyway :~O<br /><br />Prolinews - I've noted the greatness of which you speak - I patiently await pearls of wisdom from the all knowing Clams........ Meanwhile I'm looking for the air cleaner wingnut.......<br /><br />Thanks again for everybody's input!

 

[bh357]

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Where besides ebay can I get a factory book for the 1980 tower?

Skunked, you should be able to get the service manual through a Mercury parts dealer. You can order through Mercury Parts Express and have it sent to a local Mercury dealer. I do know that they carry the manual for 1965 and prior outboards.

 

[Clams Canino]

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Originally posted by jheron:<br /> Sounds like BS to me highaltitude!! <br />What do you think the octane of gas in 1980 was compared to now??<br />Skunked Again I would go get a good book on your motor. There is not much to a 2 stroke, I think you will be in for a pleasent surprize if your used to 4 strokers.<br />regards Jon

Hey, at least he didn't say "the reeds are shot" (snicker). The inline six can run on toadays gas with 21 degree max-advance and propped to make at least 5500. You can have #3 bored .015 over and be up and running in a jiffy. Find out what fried it too, usually a clogged carb or too much advance.<br /><br />That motor is only dead when you say it is.<br /><br />-W

 

[Clams Canino]

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Re: '80 115 Merc Comp. 135 and noisy on 1,2,4,5,&6, 60 on #3 spins quieter

Originally posted by highaltitude:<br /> I personally would not rebuild an i-6. they were not designed to run on the low quality fuels of today.

I FIND YOUR LACK OF FAITH DISTURBING.<br /><br />-DARTH MOLLUSK