i think i mighta blown it!

popknot

Petty Officer 3rd Class
Joined
Jun 23, 2012
Messages
84
Hello everyone, total newb to the forum and the world of boating in general. And I think I may have gotten my first lesson the hard way. Long story short my son wanted a bass boat REAL bad so I looked around finally found an old procraft fish and ski (1986 ) with an 1986 mercury 115 "tower of power" Oh yeah we were both excited. The old man who had it was an avid fisherman member of bass club had fished numerous tournaments etc etc. He was the original owner of this rig bought it brand new in 1986. had all original manuals keys etc everything, took meticulous care of it. He was getting pretty old and had injured his ankle and just could not use the boat anymore. I think the boat had set for at least a year because the registration tags were from 2011. Anyway took it to the lake yesterday ran it around for a while and seemed to do pretty good. It kinda wanted to die everytime I tried to put it in reverse but I just attributed that to setting for a while old gas etc. He said it had been treated with sea foam. Anyway got her going pretty good and decided to see what the Ol Girl would do. Had her cooking along "oh boy Look at that Tower O Power Go! Then all of a sudden da da da da da da da dead. Uh oh out in the middle of the lake and ka put! Managed to get it to start again but sounded like the motor was knocking and everytime I went to idle to try to engage prop it would die. Got towed in by another boat and took her home with my tail between my legs and head down. Now I've gotten alot of great advice off these forums in the past on autos, motorcycles etc. Any words of encouragement from you guys? Or did I just probably get a good $2500.00 lesson in the world of boating? I'm not a great mechanic but I have done some engine work and if I had to guess I'd say probably a rod, bearing, piston etc. Probably fairly serious. Is there any hope for the ol merc 115?
 

countryboy26047

Petty Officer 1st Class
Joined
May 25, 2012
Messages
303
Re: i think i mighta blown it!

I'm not sure on what the damages may be, but I will ask, did u check to see if it was pumping water?? Did use 50:1 oil/gas mix with TC-W3 oil?
 

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
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May 19, 2001
Messages
26,046
Re: i think i mighta blown it!

Welcome to iboats.

First thing is to perform a compression test. You might need an adapter for that bottom cylinder but all 6 need to be within 10% of each other.

The tower of power does NOT have a separate head. The head is actually the block but it does have a water jacket over it.

Do the compression test. You may have over heated it, it may have leaned out a cylinder or two....... really unknown. The other advantage of removing all 6 plugs is you get the ability to peak inside and look at the pistons and cylinder walls. I have seen a few inlines with holes burned right through a piston.

Check it out and post your results here.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,669
Re: i think i mighta blown it!

I'm not sure on what the damages may be, but I will ask, did u check to see if it was pumping water?? Did use 50:1 oil/gas mix with TC-W3 oil?

ditto. They didn't use thermostats on that engine so you don't have to worry about that for a problem.

Mark
 

popknot

Petty Officer 3rd Class
Joined
Jun 23, 2012
Messages
84
Re: i think i mighta blown it!

I'll hook up the muffs and check to see if it's pumping water. Also it has oil injection, oil tank was full. Penzoil synthetic was what he used. Worst case scenerio is it cost effective to rebuild? Like I said I have rebuilt the top end of some motorcycle 2 strokes so I do have some capabilities and could do some of the labor myself.
 

BonairII

Commander
Joined
Jun 7, 2011
Messages
2,727
Re: i think i mighta blown it!

Check compression FIRST. No need to see if it's pumping water or has oil injection or anything else for that matter.

Checking compression is your first priority plain and simple. If compression checks out ok....then you'll move on to the next step.

The "pros" here will walk you through diagnosing your problem, but it's imperative that you troubleshoot your motor systematically.

Probably a bit early to be speculating about the cost of a rebuild. You could have a simple/cheap fix ahead of you.....or you could have a completely destroyed motor.....or something in the middle.
 

popknot

Petty Officer 3rd Class
Joined
Jun 23, 2012
Messages
84
Re: i think i mighta blown it!

Yeah, thanks again so much for all the responses. I knew a forum like this was the place to check. Will check compression first and go from there. About what should compression be on that engine?
 

BonairII

Commander
Joined
Jun 7, 2011
Messages
2,727
Re: i think i mighta blown it!

There's no magic compression number(although 120lbs+ would be nice). The key is all cyls are within 10% of each other.
 

popknot

Petty Officer 3rd Class
Joined
Jun 23, 2012
Messages
84
Re: i think i mighta blown it!

What's the general consenses on these Ol inline six mercs. Great motors, good, average, indifferent.....?
 

justchecking

Petty Officer 2nd Class
Joined
Oct 1, 2010
Messages
152
Re: i think i mighta blown it!

GREAT motors. I have a Mercury 1984 115HP running great and a 91 I'm rebuilding because the carbs were run dirty/plugged (I got it on a boat). Lots of parts and advice available.
 

popknot

Petty Officer 3rd Class
Joined
Jun 23, 2012
Messages
84
Re: i think i mighta blown it!

GREAT motors. I have a Mercury 1984 115HP running great and a 91 I'm rebuilding because the carbs were run dirty/plugged (I got it on a boat). Lots of parts and advice available.

That sounds encouraging. I have a special son who was so happy when I got this boat and motor, he was out polishing on the motor at 6am the next morning. I felt sooooo bad when it quit. I'll check compression first chance I get and report back. Hopefully I can get it up and running. Thanks again for all the responses.
 

CV16

Chief Petty Officer
Joined
Aug 30, 2007
Messages
445
Re: i think i mighta blown it!

I love the towers. I have a 1966 850 and a 1973 1500. Both run like new.
 

popknot

Petty Officer 3rd Class
Joined
Jun 23, 2012
Messages
84
Re: i think i mighta blown it!

Well, now the bad news. had a nearby marine mechanic look at the motor today cause I didn't have a compression gauge. This guy has been in business here for years very nice reputable and helpful I must say. Anyway he cranked the engine for just a second and said its got a piston out of it. So then he pulled all the plugs and put a guage on them all right around 140# except for #4 cylinder about 20#. Only positive sign was he didn't see any aluminum shavings anywhere on the plug. I told him my whole story and I think he felt for me but I could tell his opinion was get another motor. Upper 90's or newer as todays fuel is very hard on these older motors. He wasn't interested in rebuilding this one as he is overloaded with work on newer models and boats and said he wouldn't be able to guarantee it when done and would still have a 26 year old motor that could have other issues ahead too. Not sure what I'll do. Hate to give up. Like he said I might be able to take it apart hone the cylinder and drop a piston in it but unless I fix what caused what he thinks was a lean fuel issue I might be just $1000.00 poorer and back in line for the same thing again. Not sure if I should just try to find another used motor(which might quit just like this one did) or try to fix this one myself. Or try to find a good used power head to put in this motor. Or just sell it for what I can get and cut my losses and forget it. Need good adivce.
 
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