Johnson 1991 90hp crossflow rattle issue

[Fisherman1010]

First Post......
this board seems the most technical of all i visited since i got myself a 90hp old johnson.
Before i purchased this engine i did a comp test and visual check. Compression figures are within specs, 118,120,122,124, and piston/crank do not have noticable rod play. Checked it via the dowel tru plug hole trick.
Anway, engine runs fine, good top, and after adjusting the sync good idle aswell.
It rattles a little at idle, but is not hearable at mid and top.
Checked flywheel and it has some play. I can hear it, and feel it.
So that is probably what is causing the rattle.
Do i assume this correct, or do i need to do some other test aswell?
Can i assume that the shaft is within spec, and that is just the bearing out of spec?
What do i need to order to get the job done?
Top bearing, o-ring(s), gaskets?
Pls fill me in so i can order the right gear to get it done properly.
Thanks
George, netherlands

 

[Haffiman]

Re: Johnson 1991 90hp crossflow rattle issue

Your 'rattle' is most likely piston play in the cylinders. With all ball and needle bearings around for crank and rod movements, any 'play' would be an immediate disaster and most certainly not cause a 'rattle'.
A defective ball bearing would give a grinding noise, a defective needle bearing will break down totally rather quick.

 

[Fisherman1010]

Re: Johnson 1991 90hp crossflow rattle issue

Haffiman, thnks for the reply, much appreciated,
but.... my gut feeling is, there shld not be any play at the flywheel this much. Pls elaborate on this pls.
Once i had my crank bearing out of spec of my crossbike, it also started to rattle some more. After repair rattle was gone.
I hope to do the same with this v4 engine.
How the heck does this top bearing gets his oil supply anyway. Seems a little under lubed imo.

 

[Haffiman]

Re: Johnson 1991 90hp crossflow rattle issue

The top crank shaft bearing is a double roller bearing, hardly ever seen those 'gone'.
The bottom is ball bearing.
The top gets lubricated by a 'recirculation' system, the small hose going from top to bottom.
Take a stethoscope or screwdriver and listen and you should be able to diagnose the 'rattle'.
Is the flywheel play radial or axial (vertical)?

 

[emdsapmgr]

Re: Johnson 1991 90hp crossflow rattle issue

It is not unusual for these engines to "rattle" when they get a lot of hours on them. As the cylinder bore opens up slightly, the piston skirts will slap the sides of the cyl walls and can make some noise. That's pretty normal-esp at the idle speeds as you described. It is not necessarily an indication that the engine will fail anytime soon-it may run for many years into the future. If you were to bore the block and install new pistons, you would probably find the engine runs more quietly. A big expense just to quiet an already-good running engine.

 

[Solittle]

Re: Johnson 1991 90hp crossflow rattle issue

George - - I'm thinkin you should run the sucker and not be thinkin about fixin something that is running just fine and ain't really broke. If the "rattles a little" bothers you get some ear plugs.

 

[Fisherman1010]

Re: Johnson 1991 90hp crossflow rattle issue

Thnks guys, for trying to make me feel ok with the engine.
I am happy with it, it runs great and together with this boat it really flies, but.....
pls address my flywheel movement. I can clock it, but feel it is out of spec.
It is not such big a deal to repair this top bearing, i guess.

 

[emdsapmgr]

Re: Johnson 1991 90hp crossflow rattle issue

As was mentioned, this upper bearing is really a robust bearing. Hardly ever is a failure item. I have seen them fail on an engine which was running with water in the fuel, then shut off for the winter season (up north) and not winterized. The bearing and others completely rusted by the next boating season. If you do pull the top bearing and housing off and find the bearing is bad, OMC only sells it with the housingn (387432) nearly $400. It's hard to find the bearing only. It's a Torrington bearing and is/was made exclusively for OMC- only. Hard to get a new bearing only-it's a restricted sale item. You might be better off looking for a good salvaged bearing assembly. Be sure to put a new upper crank seal on it.

 

[daselbee]

Re: Johnson 1991 90hp crossflow rattle issue

I will throw my 2 cents in....not saying this is your problem at all...just my experience.

I have had two V6 loopers with bad upper crank bearings. The flywheel moved side to side slightly, (I never measured the side to side play) and the engine made what to me sounded like a ticking noise.

The upper bearing is available from ProMarine...www.promarineusa.com ....(part number 495) and runs about 100 bucks. FYI dealer cost is $59.95. Pull flywheel, stator, timerbase, etc, and the upper crank head will be removable. Press the old one out, press new one in... reassemble. I would put new o-rings on the upper crank head, and double check the line that oils the bearing....it runs from the bottom to top, and usually has a plastic check valve in it.

 

[daselbee]

Re: Johnson 1991 90hp crossflow rattle issue

Quickly looking at the parts list for your engine, I can't find that oiling line or check valve that I just referred to. But there has to be a way for that bearing to be oiled...so examine the crankcase head for oiling holes, trace back thru block/hoses/etc. and make sure those passages are clear.

 

[Haffiman]

Re: Johnson 1991 90hp crossflow rattle issue

Quickly looking at the parts list for your engine, I can't find that oiling line or check valve that I just referred to. But there has to be a way for that bearing to be oiled...so examine the crankcase head for oiling holes, trace back thru block/hoses/etc. and make sure those passages are clear.

If you look at the bearing head, I think to remember it has a 'lubrication hole' between the 2 O-rings.
Leads to a channel through the crank case and ends in hole in the vertical wall, through the gasket between crank case and leaf/intake manifold. The upper crank balance works as a 'pump'.

 

[Faztbullet]

Re: Johnson 1991 90hp crossflow rattle issue

I have had several of the upper bearings and lower also fail this year also. The last one was a V-6 looper 225 and the lower part of race broke and rollers was rattling around top of crank and locked it up luckily at a idle. It did ruin crank and beat up bottom of bearing housing. Also had several of lower bearings ball cage fail, this is a weird noise as ball keep rolling after engine is shut off. Sound reminds me of the little electric cars on a Sizzlers track. Beside Promarine you can also get the upper bearing from WSM($84 list) and OBR($98 list)

 

[Haffiman]

Re: Johnson 1991 90hp crossflow rattle issue

When those bearings goes, it is normally for a reason.
Submerged engines that has not been properly 'saved'. Water in those bearings kills them quickly!!
Use of sealant on the intake manifold gasket blocking the hole.
Use of sealant on upper bearing housing blocking the hole.
Defective upper/lower crank seal making it loose the compression needed for the crank balance to work as 'pump'.
However most bearings of this kind that starts failing starts making a grinding noise and not a 'rattling' (knocking) noise.
If you get a radial play, most likely the upper bearing (double roller). If you get an axial play, more in direction of the lower bearing.(balls)
But these engines are famous for piston rattle, particularly if forged pistons and low load and cold engine.

 

[Fisherman1010]

Re: Johnson 1991 90hp crossflow rattle issue

Guys,
thnks for the information.
The rattling is more of an gearnoise, like straight gears driving each other around.
That besides, i will try to pinpoint the noise more carefully.
And Haffiman does give good points why such a bearing cld fail in the first place. As he mentioned it is a very stout bearing in the first place.
I can live with noise(i own a crossbike 2stroke), but since i purchased this engine second hand, i am a little weary to go far offshore with it right now. Maybe when hours go by i will trust this baby more and more.
Thnks again, will shop around for the bearing and make up my mind.

edit: btw do we all agree that i shld not feel any radial play in that top bearing? I do not feel axial play.

 

[Haffiman]

Re: Johnson 1991 90hp crossflow rattle issue

Definitely no radial play in upper bearing. Remember that the crank is the inner bearing race and if bearing fails so does the crank!

 

[Fisherman1010]

Re: Johnson 1991 90hp crossflow rattle issue

so, i carefully check the crank journal aswell. My clymer manuals says journal diameter is 41.145 - 41.161mm, 1.6199 - 1.6205 in. That is correct?

 

[Haffiman]

Re: Johnson 1991 90hp crossflow rattle issue

Can not confirm that as I have no books and memory limited!

 

[Fisherman1010]

Re: Johnson 1991 90hp crossflow rattle issue

Ok Haffiman,
apology accepted
Right now i am calling the dutch brp dealer to see if they can help me out with the parts.
will post my progress later on.
thnks you all for now.
happy boating!!

 

[Fisherman1010]

Re: Johnson 1991 90hp crossflow rattle issue

Ok everybody,
i managed to put in a new upper main bearing. Made a picture of the upper part, showing a slightly colored tap end of the crank, but other than that every thing looked fine.
The new bearing has also some radial play in it. I check this by wacking it lightly with my hand so you can hear the freeplay.
I do know that every bearing shld have play, otherwise it would not turn at all. Besides that, heat will expand bearing aswell, so freeplay is a must.
The question is always, is that play too much, or can we run it.
Anyway, took her out yesterday for a test run, and the gear noise at idle is less, but there is still some to be heard.
But haven seen this old bearing and the crank tap, i feel more safe for running this baby in wide open see.
I accept the fact that these twostrokes can produce some sound, so i don't worry anymore.
Here is a pic of the tap and bearing housing.
Btw i heated up the housing in the oven at 200 degrees celsius and gave it a slight wack after 10minutes. Bearing just fell out. Piece of cake.
Flywheel was a @#@& though. Had a heavy puller, but man is this baby tight.