1971 Johnson 50HP compression repair

[Somerowl]

No Title

Here are the pics, the pieces in between the Powerhead and Mounting Plate are plastic wedges.

 

[racerone]

All I can say is put the hammers away and look for the nut !!!!!!

 

[Somerowl]

All Nine main nuts are off (it's a little hard to see in the second picture above, but the one at the rear is off) and all four main bolts are off as well so what else could be holding it? I've heard where there could be a little corrosion holding the splined portion of the shaft, but other than that...........
Thanks again for all your help, was relieved to see the stud directly under the cylinder head exactly where you said it would be that did not have a nut on it, whew.

 

[Somerowl]

OK, here's the deal, ABSOLUTE rookie mistake here. If you notice in the pictures above I was separating the WRONG SIDE OF THE PLATE between the Block and the Exhaust Housing :frusty:. Unbelievable. Humility 101 right here right now :bolt:. You know what? Once I realized this and removed the wedges I was working the block came off by HAND!!! Yep, this one is here for all to see and I'm just glad I didn't screw anything up, got super lucky and now the fun part comes of getting the motor evaluated for rebuild, replacing the water pump, checking all the solenoids and play and hopefully getting the motor on the boat before the end of summer.
Someone's looking out for me as there were a few things that could have really screwed me up if the beast had compression and I tried to run it as is :cheer2:.
1) There was literally a mummified mouse up inside the exhaust housing with all it's assembled nest sundries including a few emptied out acorns for good measure. Had we run the beast, there could have been serious issues (fire/over pressure) with the exhaust being plugged.
2) The solenoid wires came off by hand.........they were hardly crimped at all and the electrical tape holding them on was toast, really? Electrical tape? You go through all the trouble to drop the lower unit and check things out and all you can do is electrical tape? Damn, hope that isn't an indicator of the rest of the motor condition.
3) Last and not least, the "hidden" bolt to fasten the lower unit to the exhaust housing was inaccessible due to the 3/8 bolt being frozen. It broke one of my six point deep sockets and I'll need to use an impact version to get it off but..........I didn't need to in order to remove the lower unit..........the "hidden" bolt was NEVER INSTALLED by the P.O. Unreal..........

So, short story long, it's done, completely disassembled, ready for rework to the highest degree and big fingers crossed that the motor will be able to be rebuilt.

Thanks very much to all of you who helped me get this beastie apart, now it's on to the next phase of the journey.
eace:

 

[Somerowl]

Update on the rebuild.
Got everything apart, looked great, no ridges on the cylinder walls, evidence of a head gasket failure, but not catastrophic and all the needle bearings and races look great. One problem, there is apparently corrosion on the cylinder walls in two small places. It appears slight (hard to show on a photograph), but definitely there. There is a great machine shop I work with locally that I'm going to take it to for evaluation, but I'm concerned about being able to find parts for it if I need to go 30 over. Also, concern about the wall thickness and the sturdiness of the motor after boring it out that far.
Are these valid concerns or am I just paranoid/over thinking it?
I have an option with a great reseller of used parts locally that has a block for sale that just needs to be honed out a bit, looks good and straight, but the intake side of the set has been repaired and looks like crap, might be functionally fine, but that stuff bugs me. Another question is can I mate up my intake side of the block with a different half and expect everything to seal well and bearings line up well or is that just asking for trouble?
Thanks for your help!!
:yo:

 

[interalian]

I doubt the corrosion you describe would condemn the block to overbore if it's within wear limits. And no, you cannot mate the front half from another crankcase to the back half of another - they're machined as a unit.

 

[Somerowl]

Thought so, just like a VW bug motor. I read where the rods are machined out of one piece and then split for truly matching sets, sounds like the same for the block. I'll hand it over to the shop and see what they can do for me. Thanks very much for the quick response !!

 

[Somerowl]

Ok big trouble, can't find any 30 over pistons and rings anywhere and I'm dead in the water without them. Anyone have ideas??? Part number 396578.....

 

[Somerowl]

Need help on specs for the 50ESL71S bore dimension. My manual shows it as 3.188 and the shop I'm working with tells me it shows the bore to be 3.06? Which is correct?

 

[racerone]

Shops are usually correct and in this case they are.------:looked it up in the factory brochure and bore is 3.060"

 

[Somerowl]

Wow, thanks Racerone, my "shop manual" on dvd shows the attached. There may be hope for my motor yet! View attachment Johnson 50 Powerhead Specs.pdf

 

[racerone]

Some folks who make up manuals are NOT knowledgeable !!!!!!!

 

[Somerowl]

Got that right, The instructional side of the manual seemed to be good, but the specs are obviously incorrect. Glad I didn't give that to my machine shop guy doing the work!

Does anyone have a spec sheet available for this BORE so I can take it to the shop for evaluation??

:help:Thanks very much,

 

[Somerowl]

Good day all, Following up on this process. The parts for the oversize bore are not available any more from any manufacturer I could find. I was able to come up with one piston, not quite enough. The whole beast in parts is now available on Ebay. Bummer. Thanks for the learning along the way, well worth the experience!
:hail::hail::kiwi-fruit::kiwi-fruit:

 

[Texas Prowler]

Have you tried maxrules.com?

 

[Somerowl]

Just sent them an email. I think I did, but couldn't hurt right?
Thanks!!

 

[Texas Prowler]

No prob. They are great people. I bet they can find what you need.

 

[Somerowl]

Guess what, no luck. Said they haven't had anything for that motor for years. That makes my parts either really valuable or worthless......

 

[Dizz]

Are you sure you can`t just bottle brush hone it out,and use standard sized new rings?

 

[Somerowl]

Yes, unfortunately the corrosion appears to be the reason for the low compression to begin with. I guess I could try but that's a couple hundred bucks and a day's work for a "maybe" best case. Even then I'd probably always be worried about it in the middle of nowhere......