advice on rebuilding 1973 Johnson 135

[monk-monk]

As my Thread title states, im looking for advice on rebuilding a 1973 Johnson 135hp. First, I will give a little info about me: I am very mechanically inclined, I have built all types of motors, everything from lawn mowers to V-8 car motors, I have rebuilt many of the Mercury "tower of power" outboard motors, all with great success, and with great advice from others, I might add. All answers and advice can be given "straight forward" and concise, to state that another way, I don't require the "elementary" version, I will understand what you are saying! NOW on to this motor: I have a Factory manual and I've been reading up on it. This motor was used in salt water, when I got the motor it was locked-up, I disassembled it and found that it had small grit in cylinders 3 and 4...that was the cause of it being locked up. The good thing is, there is no obvious damage to the cylinder sleeves...both pistons were below the cylinder ports also (or right at the ports)...the debris in the cylinders apparently got between the pistons and rings and prevented the pistons from making a full travel through the cylinders. From what I observe, I believe the debris got in there while the motor was not running, then I think someone tried to start it and it locked-up immediately. The entire reciprocating assembly looks absolutely perfect, no damage what so ever, only to the #3 and 4 pistons. Crank looks perfect, the connecting rod crankpin bearings look like new, upper and lower crankshaft bearings look great (I have examined these with a lighted 10x magnify glass) One question I have is with removing the outer and inner exhaust covers...with a mercury tower of power, you NEVER attempt to remove certain covers as you will definitely break the bolts doing so. It's little things like that, that I want advice on. I am sure there has to be some nuances with these 135 motors, so im trying to look ahead and get advice from people that know these motors. Any help/advice will be greatly appreciated! Thanks!

 

[Faztbullet]

Re: advice on rebuilding 1973 Johnson 135

My opinion is ...save them money your about to drop and headaches and find a newer engine. That motor has some parts only 73 engines use and not much interchanges. Piston is one of a kind as is rod.

 

[boobie]

Re: advice on rebuilding 1973 Johnson 135

Fazt is correct about the '73 motor. Been there.

 

[monk-monk]

Re: advice on rebuilding 1973 Johnson 135

Well, not a good start as far as advice goes...thanks for your input...I already have a whole new set of pistons, I have all the parts to rebuild the water intake system....I have all new bearings through-out motor...I have every part, new I might add, I have connections and knowledge of obtaining parts! I have already rebuilt and installed a complete power trim system on the motor...and yes, with all new parts on it...even the hydraulic valve body on the bottom of the pump..and it works like a champ..not to mention the hydraulic rams are completely rebuilt and operate perfectly...y'all must have missed something in my opening statement, your words of discouragement does not discourage me...im sorry y'all didn't succeed with positive results at your attempt, but trust me, this motor ran just fine from the factoryand it will run just fine when im finished with it....anyone else wanna give it a shot???

 

[monk-monk]

Re: advice on rebuilding 1973 Johnson 135

....Plus, I will add this: I already have lower unit disassembled and ready to re-assemble, I have a brand new fluid pump, brand new prop bearing carrier and all other associated parts needed....im just looking for that one person that knows these motors inside and out, that might want to share some knowledge. I don't really need that person to be able to rebuild this motor, I just thought it best to ask if someone had some words of wisdom before I proceed....I accept all good advice/words of wisdom...but please carefully read my introduction...I can/have rebuilt more mechanical things than you can imagine...I have "ways" and I have "means"....Plus, I have people "lined up" wanting to buy this motor from me...

 

[emdsapmgr]

Re: advice on rebuilding 1973 Johnson 135

Taking the inner and outer exhaust covers off on any bubble back V4 is not a big deal. Unless all the bolts are frozen. When re-installing there is no critical alignment issues like the exhaust covers on the 235 V6 blocks. Would be interesting to know if the sand inside the powerhead came in through a cooling system leak. Not unusual for some sand to get sucked up into the impeller and distributed throughout the block-esp for fishermen. It is very unusual for the sand to get into the rotating assembly-unless there is a water leak inside the block somewhere. Think I'd pull the head covers off and have a look inside the water cooling passages of both heads. Also pull the water passage cover off the top of the block and look down inside that cooling passage between the V heads. Inspect for sand or other debris. I'd check that inner exhaust cover to make sure it has no casting porosity that would pass water from the cooling side into the exhaust chest.

 

[monk-monk]

Re: advice on rebuilding 1973 Johnson 135

Thanks emdsapmgr! I will definitely take a look at all the areas you mention! I have the motor completely disassembled except for that top cover and the exhaust covers....I too, am wondering how that sand got in there...I will closely examine the water jacket area of the block and heads. As I stated, there was no sand in the bottom end, it was confined to the top of the piston area and in and around the top ring...#3 actually had more in it than #4...#4 had a small amount, but very little. My strong feeling is that the sand came in via the exhaust ports because I can see some build up inwards into the ports. I might try to figure out a way to pressure test water jacket area of block and heads, I can come up with something. Thanks for the advice!

 

[emdsapmgr]

Re: advice on rebuilding 1973 Johnson 135

Exhaust leaks in the inner mainfold tends to affect the lower cylinders in the exhaust chest-rather than the upper ones. It's possible the saltwater may have corroded the inner exhaust manifold. You can lay it flat and test it by pooling water on it to see if it leaks, or shine a light behind it and visually inspect for light leaks. If water leaks into the exhaust chest while running, it can get forced back into the bottommost cyls by the force of exhaust from the other cyls. The big thing is to see where the sand came from-surely there must be some sign inside the cooling passages of the block, heads. Also, if sand got sucked up into the cooling system, the impeller will show abrasion (grooving,) as will the stainless steel cup (around the impeller.)

 

[James R]

Re: advice on rebuilding 1973 Johnson 135

It has been known for water to be forced up the exhaust by stopping suddenly when running WOT across the pond. Consider if this was done to avoid beaching on a sand bar. Just a thought.

 

[Faztbullet]

Re: advice on rebuilding 1973 Johnson 135

All answers and advice can be given "straight forward" and concise, to state that another way, I don't require the "elementary" version, I will understand what you are saying! NOW on to this motor: I have a Factory manual and I've been reading up on it. This motor was used in salt water,

These is the reasons you got my opinion on that motor.

 

[boobie]

Re: advice on rebuilding 1973 Johnson 135

Good point Fazt....

 

[V153]

Re: advice on rebuilding 1973 Johnson 135

You have sand on top of your pistons?

 

[monk-monk]

Re: advice on rebuilding 1973 Johnson 135

Hey...no hard feelings Faztbullet..after all, you've been a big help to me with my mercury motors, always interested in your opinion! Im cautiously moving forward with this motor...I will be examining things with the eyes of a hawk...I appreciate all the replies, very much! Y'all will be the first to know (no make that second to know, lol) just as soon as I figure out how/what happened. Again, I feel very strongly that the debris got in there while the motor was sitting...it did no damage at all to the cylinder sleeves...its like, the debris got in there, someone tried to start it and it immediately locked when #3 got to the ports...other than that, the thing looks brand new inside. I will figure it out. Thanks a bunch!