1980 115 johnson midsection noise??

[mekkamaz]

Hello!

I have been on water this past weekend, and it has been several months since last trip.

Motor starts at first try, then leave the trailer and docked. At the time I was warming up, I think I?ve heard a little noise in the midsection apparently from the shaft, a little metal to metal noise......but it was too low....anyhow, took her for the trip, travel for over an hour @3500-3800 rpm (just planning, beautiful day!!), arrived a spot, be there and leave...ok! you know, the normal have fun trip!....I run it at 4000, WOT......Like 4 Hr motor-time trip....mostly in high....no notice for any symptom of nothing...run like a new one!! (yeah, right! I don?t forget this is a 32 yr old piece)...

Arrived at ramp, took her out and when flushing there was this sound again......I turn flywheel by hand but can?t feel or hear nothing unusual.....any ideas where to look or check? Where could this sound came from? .......oopss!!s Almost forgot...at the very beginning, temp alarm went on, but for a minute, and I rev it up just with the warm lever and shut off...nothing else in the whole trip...maybe a stucked thermostat..but they are not that old (2 yr tops)...but I?m afraid that could be something more and I really want to know if I should worry about.....Thanks!!!

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

Could it be a wrist pin? I?m suspecting maybe this is the issue...

 

[emdsapmgr]

Re: 1980 115 johnson midsection noise??

Could be a problem in the thermostat housing. When idling the thermostat must open to keep the engine cool. If you crack the throttle or come up on plane, the pressure relief valves inside the thermostat housing will open-flooding the powerhead with extra cooling water. You may have been lucky that you were planing, or running the rpm's fairly high while you were on your trip-to keep a large amount of cooling water flowing through the powerhead. To test for a hot horn: start the engine, let it idle for a long period of time-floating in the lake. See if you get the overheat horn again. Possible you will after 15-20 minutes at dead idle. It will heat up quicker if you leave it at dead idle and shift into forward-it should start to lug. See what happens. If you get another hot horn-check your stats and insure that the two pinholes in the thermostat valve body are open. (some later valve bodies have a larger oval hole.)

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

Thanks, what about the clunking noise? It sounds before the oh horn sounds..I removed the spark plugs and turn the flywheel by hand and put a screw driver just to touch the piston for hearing aid, I found that the upper left piston (front to propeller, cyl # 3, right?) apparentely is making this sound, force screwdriver against and jus turn over the TDC back and forth and there it is....actually you can feel this little hit on the screwdriver....time for open it up, right???? or I?m just freaking out???

 

[emdsapmgr]

Re: 1980 115 johnson midsection noise??

I thought you said the noise was in the midsection.. One thing to try. Unbolt/remove the lower unit. Connect the garden hose to the exposed water pipe in the midsection. Turn on the hose and run the engine. See if you still have the noise. If the noise is gone, the problem is inside the lower unit. Upon reassembly, make sure you regrease the drive shaft where it goes into the underside of the crank.

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

Ok, after a good rainy days finally I get my hands on my boat.....here are the results....any advice will be very appreciated.

Drop the LU and the noise still be.....now I remove the head from the cyl block I?ve suspected and this is what I found...

Now check this out....

The thing is: besides the clunking noise that the motor does when running, can it be operated a couple more times before (and most likely) rebore? Is better to stop it and do the job asap or maybe it can carry this season on?

Thanks again!!

 

[emdsapmgr]

Re: 1980 115 johnson midsection noise??

I did not see the most usual crossflow failure: that of cracked rings and pitted piston crowns. Looks like the rotating assembly is still intact. The piston slop in the video is very normal on a crossflow. Once the pistons heat up in the cylinders, the clearances will tighten up. I would not be so quick to rebuild this powerhead. What I do see is horrible water flow passages around the cylinder liners. The rubber water diverters are nearly impossible to see. My guess is that the engine get severly overheated due to poor water flow in the block. You really need to clean all the block passages. Also, pull the head covers off and check water passages in the head for similar debris blocking water flow. I've attached a picture of a normal block. You can see the water passage clearances around the cylinders. Also, note the correct placement of the rubber water diverter between the cyls. If you can locate a factory service manual, it will be of great help to you.

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

Thank you emd...that picture tell me a ton. Do you think I should open the exhaust manifold cover as well to clean things or nothing to do with cooling? I will clean all thouroghly tomorrow if weather lets....and shall I get new diverters before moving them or isveasy to remove them? My guess is that they shall crumble when attempted to clean....or there's no need to take them out?

 

[emdsapmgr]

Re: 1980 115 johnson midsection noise??

What debris you find clogging the inside of the heads (if any) will also be inside the exhaust covers. You may need to pull the inner and outer covers off and clean them out also. If it's really bad, you may even have to pull the water passage cover off the top rear of the block. (between the two V-bank heads) Check inside for any debris, deposits also.

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

Ok, friends, after checking the diverters, I found that there is no clogging around them, they?re that big!, but still hearing this what I think could be a wrist pin, but help me with this...check it out and throw me a bone here!!! Thanks!!!

Left and right banks...everything else normal, no broken rings...exhaust cover removed and all is fine (except gaskets, obviously, and a damn bolt that rather broke than loose!!)

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

The other bank.....

 

[emdsapmgr]

Re: 1980 115 johnson midsection noise??

The suction sound you hear is the intake suction sound. A good sign. If you have good rings- which will provide good cylinder compression, you will also have good intake compression. Both are vital to a running 2-stroke. As these engines age, they will develop more clearance between the cylinder walls and the pistons. Actually, the cylinders will get somewhat egg-shaped. If you have a high-hour powerhead, it will likely develop piston slap. Sounds like a sort of rattle. Normal on these high-hour engines. The piston skirts will slap the cylinder walls on each rotation. The more the clearance, the more the slap is noticeable. Piston slap is more noticeable at low rpm's. Once the engine is at WOT, it's hard to hear. Piston slap is not a necessarily a prelude to imminent failure. It's a little hard to hear the wrist pin concern that you have on the video. (maybe I'm just hard of hearing..) I do hear a sort of knock, which would be worth investigating further. If it is of concern to you, perhaps it is best to consult with a local outboard expert for a second opinion. Can you tell from any markings on the crown of the pistons-whether they are oversize or not?

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

Yeah, that knock is my concern....actually what I fear the most is a failure in open water and a substantial damage... most to the damage side....that is what I?m trying to prevent, rather cure-in-healt more than visit local junk yard to drop it.....agree?

found no marks, so is std, right?

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

and if that knock is normal for the age, I can live with it....just don?t want, as said before, my good old trust motor get killed....(maybe I?m exagerating) but from the other hand, good hearing emd!! you hear it right!

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

Ok! After a good rainy days I got to work in the beast......piston numbers are 393924...except for the top left one (from rear or standing front of it in the street). Seems like PO replace that piston only but no marks on it just a star! ...anyway, half strip now, all electrical are gone, main top bearing out, heads off...pistons truly has play like shown in video, and the knock is my major concern, and it happens to be in that piston also!... but as a step before open completely and of course facing a $$$$ repair, advice for this from you johnny-rudes experts, Can this still running as is or the repair is in order? Thank you!!!

 

[emdsapmgr]

Re: 1980 115 johnson midsection noise??

Your video shows to top, starboard piston with a noise. Your last post says the top port piston was replaced and it is the one with the noise. I must have missed something. Best to try to determine if the rod crank bearing is noisy or the piston pin bearing-or neither. It is acceptable to replace one piston during a repair. Best to replace the one new piston from the same manufacturer as the other 3 pistons. That way they all have the same thermal expansion rates. Mixing pistons from different mfr's can be problem.

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

As you can see in the video, the piston I?m talking about is the one which does not have the center hole in it. Maybe I?m not using proper port-stbd as I locate me in front of the rear engine (as you put yourself in the street, facing the engine). from here is my port side top.

Now I?m just a few bolts from cracking it apart, I?ve decide go all the way and find If it is as I think, the wrist pin, or other thing, which I really doubdt cause is very smoot in turns, (as in a bad bearing it has to be a step or a little bump). But where I am there?s really no good OB mech or shop, just a couple lawn-mowers or pumps techs, which do a now and then OB jobs....but I?m mech myself so I you guys can help me at the time I have to rebore, measures talking and other tips for this, I?ll be more than grateful...

 

[mekkamaz]

Re: 1980 115 johnson midsection noise??

Update: So it is now open, starting from found nothing wrong with wrist pins, bearings or else, but the culprit was that this piston bumps in one side of the cylinder making the knock, if you force to the admission ports side the piston, it starts the knocking noise...if you force it exhaust ports side...nothing...sweet and soft......remove the piston (which seems been changed as stated before) and found a groove in the cylinder wall just as if the original piston break it rings and damage the cylinder walls an itself. There?s no other way to this but rebore.

Will start another thread with its rebuilding....and of course expect all the great help as always.

Emd: I also correct the cooling issue...diverters are on its way. Good one there! thanks! Major problem on its way for sure!

Thanks to all!