Bearings…help!

[Robert Elder]

This is now the 2nd NR .21 5 port that I have damaged by having the bearings fail and letting little bits of metal fly around inside the motor. My first was so badly damaged that I just replaced it. This time I think I can just replace the head button, piston and sleeve and bearings.

This is very frustrating because these motors take SO LONG to break in and are a ROYAL PAIN to break in. Add to that the fact that I will have spent plenty on replacement parts and motors. I may be at the breaking point now. It might be time to give up and go back to electrics.

Why is this happening?

I don't believe they have been run too lean. In fact, in my JAE, I don't think it has ever gone more than maybe 50 mph. I have been using RedMax 50% or Wildcat 45% for boats.

After a days running, I take the plug out, spray some WD40 in and turn the engine over with the starter to blow the excess out then I put in AT fluid or tool oil and do the same thing again before taking the boats home to be wiped down and stored until next time.

As you can see the piston and sleeve are heavily scored. The head button has bits of metal imbedded in it and the bearing at the rear of the crank failed and came apart when I removed it from the casing. In fact, I still can't get the inner part of the bearing off the crank. I have tried 325 degrees in the oven and even freezing the part and it won't budge.

I thought that I have been being carefully, attentive and doing things "right" but I am clearly doing some things wrong. Please help. I am really close to giving up.

 

[anthony_marquart]

OUCH!!!

Not sure why you are having such issues.. Just replaced the bearings in my NR5p.. There is the chance that the bearing surfaces are not well aligned in that case. I have never had bearings fail that badly..

I am afraid to say but I think that you may no longer have a good seal between the crank and the case now,.. on the intake side.. look for scoring on the intake side of the crank and the case..

 

[Mike Larson]

Robert, IMO, the first failure you had ( did the running engine "lock up?"), possibly bent the crank enough to cause undue pressure on a limited area of the new bearing.... causing an out of round rotation, however minute it can be and taking the new bearing out in order... my old engine builder would not simply rebuild any failure i had.. ever.... on the theory a drastic failure ( rod end, bearing, or whatever it was), tweaked the case also enough to cause out of alignment bore to crank etc, issues, and another imminent possible failure...( we'd buy a new case) I've 3 bearing housings on my lifetime failure collage that mirror your picture bearing.... nova carries an alignment tool for installation, some guys make them, to safely align both bearings to the bore first... a good purchase, maybe..... I build "parts" builds alot and will use even heat to realign the bearings in the bore should i feel any resistance upon the crank... i have been able to feel a tweaked crank on various engines over time ( many times they'll show it, not slip fitting to both bearings easily in the case).... I also use the same air tool oil for assembly ( new bearings are dry, ), and a dab of light grease on the pin, as i dont want a dry start on my rebuild..... up to you, but the engine has failed you twice and something is seriously questionable.... i dont have machinist tooling to do an out of round crank check.... nor a case to crank bore check, etc... and, anytime i assemble a backyard bench build, i expect a failure, because, tolerances as things wear, etc, just help it along... i get lucky alot, and surprised here and there.... apples, but, i do run a little higher oil content than some will, and always infallibly use factory nova bearings in any nova i have..... parts bench build, new existing bearing build, every time.... something is mechanically not jiving with that engine... it should show up.... good luck..... thats the coffee end.... Mike

 

[Robert Elder]

The first engine I replaced out right. This is the second failure of the same model in the same boat. The 1st engine was a brand new NR.21 5 port I bought from Glenn and the one I replaced it with, (that has now failed) was also a brand new NR.21 5 port that I also bought from Glenn. Same failure, same model of engine but two completely new and different engines.

Since lots of folks run the NR .21 in the JAE it shouldn't be the boat design or the engine design. It has to be either an issue with the way I assembled the boat or be something I am doing wrong in operation/maintenance.

 

[Robert Elder]

and yes the engine did lock up. Both times it started and seemed fine but as soon as it hit the water it just locked up.

 

[anthony_marquart]

yes,.. something is wrong there.. that is an uncommon mode of failure,.. at least for me..

 

[Greg Bonahoom]

Is there any fuel in the line leading to the carb that is being drawn into the motor either during or after your after run oil treatment?

 

[Robert Elder]

There could be...I don't purge the line. I do empty the tank of any fuel at the end of the day, (the best I can anyway).

I have a VS-1/OS XM, Top Speed 3/K&B SS and Miss Vegas Deuce that all get treated the same way. So far, (fingers crossed) I haven't had those issues with them yet and would love to avoid the issues altogether - once we can figure out why this is happening and how I can avoid it.

 

[anthony_marquart]

You will probably need to have the whole boat checked out by someone that is familiar with these issues,,.. some kind of misalignment or unusual loading is causing that to fail,.

How well does the flex shaft and the the engine collet line up?

 

[Robert Elder]

Pretty well. It doesn't look out of line and, when all is hooked up, and you turn the prop by hand, it doesn't feel any tighter that my other boats.

 

[seawolf31635]

small props + more rpms + a little to lean when getting motor hot and too little of oil means blow UPs on bearnings & other parts .Tweaking little motors too much need whole new motor the block can bend out of shape where the bearnings go & missaline to the crank .about the only thing to save is piston & sleave if its not gauled & blued .I run my little motors a little sloppy rich cause when motor gets hot from all them RPMs it will lean more than you think .

 

[Terry Keeley]

and yes the engine did lock up. Both times it started and seemed fine but as soon as it hit the water it just locked up.

Please elaborate...

 

[Robert Elder]

Sure. The first failure was 2 years ago. The boat had been running pretty well and I started it like normal and it seemed to be running OK but a soon as I tossed it in the pond, it died. When I retrieved the boat, then engine was seized up. Prior to this it had been eating plugs.

Fast forward 2 years to this past Sunday. Same boat but with a NR.21 that I bought new to replace the previous engine. It had been run in and had at least 2 gallons of fuel through it over the past two years. So far this year, it wasn't really performing as it should have but had been running reliably. It had used a couple of plugs too. It was suggested to me to try a bit less prop (it had an H7 that Mark S had worked on for that boat) so I put on a Grimracer 42x55 that I had.

Started the engine, it was running OK and there was smoke coming from the pipe. I launched in into the pond and it instantly died. When i retrieved it, it had almost seized up and the damage was done. Pieces of the rear bearing had come loose and scored the piston/liner.

 

[ALLAN YUEN]

Better you send crankshaft to Steve Wood Hope help to work !

 

[Terry Keeley]

Sure. The first failure was 2 years ago. The boat had been running pretty well and I started it like normal and it seemed to be running OK but a soon as I tossed it in the pond, it died. When I retrieved the boat, then engine was seized up. Prior to this it had been eating plugs.

Fast forward 2 years to this past Sunday. Same boat but with a NR.21 that I bought new to replace the previous engine. It had been run in and had at least 2 gallons of fuel through it over the past two years. So far this year, it wasn't really performing as it should have but had been running reliably. It had used a couple of plugs too. It was suggested to me to try a bit less prop (it had an H7 that Mark S had worked on for that boat) so I put on a Grimracer 42x55 that I had.

Started the engine, it was running OK and there was smoke coming from the pipe. I launched in into the pond and it instantly died. When i retrieved it, it had almost seized up and the damage was done. Pieces of the rear bearing had come loose and scored the piston/liner.

So both times it "seized up" was because the rear bearing failed?

I see you're in the Kitchener area, in other words up north here where it's cool. You also say that "it had been eating plugs". If I had to guess it sounds like you may have been running the motor too cool and therefore had to lean it down a bunch to make it go. Putting plugs through the motor and running lean eventually took out the bearings.

Not sure if you're aware, but we have a very good bunch of guys in our Northern Lights MBC that run in Alliston and Beamsville. The BVille guys run tech sessions once and a while and will run your boat and help with suggestions if you don't want to join the club and IMPBA right away. You could also bring it to Alliston some weekend and have someone look at it.

http://www.nlmbc.org/index.php/forum

 

[Tim Kish]

Hi Robert

We would love to have you come out to Beamsville and go over your boat with you, we have plenty of Nitro and Nova experience in our club and would like to help.

Send me a PM if you like and we can set up a date to meet at the pond.

Tim

 

[anthony_marquart]

I didn't think to ask you about your break in procedure. Did you run the motor fat blubby rich so that it won't spool up, with no water attached, for about 4-5 tanks? and slowly lean, and then add a restricted amount of water? A poor breakin and running too much water (cooling) will cause bearing failure for sure.. I think the previous post may have nailed it..

running too cool and too lean.. The NR like to be rich and hot.. in my opinion..

 

[Robert Elder]

I think we may be closing in on this mystery, thanks to all who have contributed. I often run with Joe Pohl at our club and he was just by here to check out the crank and discuss the issue. Here's the theory;

I used WD40 in the motor to remove any residual moisture after running followed by either AT fluid or tool oil. I am being told that is a terrible idea because it removes the residual oil from the bearings. That was step one of what I was doing wrong. The problem more acute with this boat because it was run more often than my others. I was less 'careful' with my other boats and usually just used the oil or AT fluid and two of them are outboards with the bearings above the rest of the motor so they would have had less contact with the WD40. I will be checking and replacing bearings on all my motors and the WD40 has been removed from my kit now.

The second issue would be running too cold. I have had a hell of a time getting it to run hot enough - even with the water turned off. In fact, I have never even turned the water on. There was a period of time after the motor broke in, that it would get up to temperature and was starting to come alive then it started eating plugs (beginning of the bearing breakdown). I have struggled since then yet was afraid to lean it out too much for fear of destroying another engine.

It sounds like my care routine was gradually damaging the rear bearing (which the WD40 could easily get to) which impacted the performance and started the plug eating and issues getting it to run hot enough. All combined to lead to catastrophic failure.

Does that sound right to you guys?

 

[Terry Keeley]

I doubt flushing with WD40 and using ATF as an after run would have anything to do with hurting a motor, quite the opposite.

You didn't answer my question, I'll ask again. So both times it "seized up" was because the rear bearing failed?

Please elaborate:

"I have had a hell of a time getting it to run hot enough - even with the water turned off. In fact, I have never even turned the water on."

Over propped, over cooled = over leaned

I think my initial reply is valid.

 

[Tim Kish]

WD-40 is definitely not the problem, been using it for thirty years without issue . I would say that it's next to impossible to diagnose the problem without seeing the boat, there is endless possibilities.

Maybe you need to get a second opinion from someone that can see the boat .