Nova 45 DD going lean?

[Tim Kish]

First off not pointing fingers here just posting what I found and believe the issue to be.

I brought the engine to work today and measured everything that I thought would cause this problem so mainly just the diameters of the crank, engine case, PTO housing and PTO shaft.I used a very high quality Swiss bore gauge and Mitutoyo digital micrometer.

What I found was this.

First I measured the crank case I.D. at .6330 , this was the area of the case that is designed to seal the engine and crank with very little clearance between them and the oil from the fuel.

I then measured the crankshaft and it was .6295, so that is perfect , typically I have seen a .003 to .004 range used between the crank and case to seal the engine.

Nothing wrong there.

Measured the PTO housing at .455 it's a straight bore unlike a case that has the seal bore and then clearance bore.

This is where I believe the problem is, the PTO shaft is stepped down(two different sizes), the largest dia being the bearing fit dia was perfect but the shaft dia is reduced right after the bearing to .4475 which leaves almost .008 clearance between the housing and the shaft.

If Nova Rossi just extended the bearing dia on the PTO shaft by .375 and opened the PTO housing .001 more I believe the issue will be solved and the engine will seal properly.

Tim

Hey Tim, there should be three different sizes on the PTO shaft. There is the dia for the bearing (about .4528 on the one I measured), the turned down middle section to reduce drag (about .415) and the front seal area (aprox .225" long) that measures .4522. I have never seen one without this seal area unless they have been modified. I will see if I can get a clear enough picture to show what I mean.

GQ

Just double checked Glenn and Al's PTO shaft only has one step as I mentioned, .4527 down to .4474.

Tim

 

[Tim Kish]

Your numbers would have a .03 step between the two dia., so they must have changed something in production.

 

[Tim Kish]

I should point out that there is actually three different dia., two different bearing sizes and the .4475 undercut, but no seal dia.

 

[Glenn Quarles]

Here is what the cranks look like. I have never seen one that did not look like this since we had Nova turn down the middle section. The earliest ones only had one step and the seal area was the entire length in front of the bearing. Maybe you got one of those???

 

[Tim_Duggan]

Can anyone confirm if the outboard PTO shafts have the same configuration (46 and 21)?

Might explain something I saw on the weekend with a new factory Nova 21 outboard motor.

Thanks,

TD

 

[Tim Kish]

Here is what the cranks look like. I have never seen one that did not look like this since we had Nova turn down the middle section. The earliest ones only had one step and the seal area was the entire length in front of the bearing. Maybe you got one of those???

Glenn I must have one of the earlier ones, the dimensions I posted are exact measurements of what I have.

It must have been groung undersize during production and not picked up in QC

Tim

 

[Glenn Quarles]

Here is what the cranks look like. I have never seen one that did not look like this since we had Nova turn down the middle section. The earliest ones only had one step and the seal area was the entire length in front of the bearing. Maybe you got one of those???

Glenn I must have one of the earlier ones, the dimensions I posted are exact measurements of what I have.It must have been groung undersize during production and not picked up in QC

Tim

Tim, it sounds like that may be the case. I will send you a new crank. Could you please send me the crank you have so I can send it back to nova. Where would you like me to send it?
GQ

 

[Tim Kish]

Here is what the cranks look like. I have never seen one that did not look like this since we had Nova turn down the middle section. The earliest ones only had one step and the seal area was the entire length in front of the bearing. Maybe you got one of those???

Glenn I must have one of the earlier ones, the dimensions I posted are exact measurements of what I have.It must have been groung undersize during production and not picked up in QC

Tim

Tim, it sounds like that may be the case. I will send you a new crank. Could you please send me the crank you have so I can send it back to nova. Where would you like me to send it?GQ

Glenn

We have spent a fair amount of time trying to get this motor to run properly and have most likely used up the best of this motors life trying to do so, I would think a complete motor swap would only be fair seeing how it has not been right from day one .

Its not my motor and I will tell Al about your offer and leave it to the two of you.

I think Nova Rossi and not you should look after this one .

Tim

 

[Glenn Quarles]

Here is what the cranks look like. I have never seen one that did not look like this since we had Nova turn down the middle section. The earliest ones only had one step and the seal area was the entire length in front of the bearing. Maybe you got one of those???

Glenn I must have one of the earlier ones, the dimensions I posted are exact measurements of what I have.It must have been groung undersize during production and not picked up in QC

Tim

Tim, it sounds like that may be the case. I will send you a new crank. Could you please send me the crank you have so I can send it back to nova. Where would you like me to send it?GQ

Glenn

We have spent a fair amount of time trying to get this motor to run properly and have most likely used up the best of this motors life trying to do so, I would think a complete motor swap would only be fair seeing how it has not been right from day one .

Its not my motor and I will tell Al about your offer and leave it to the two of you.

I think Nova Rossi and not you should look after this one .

Tim

Tim, I do not have any .46 motors in stock right now. Would you go ahead and send it to me and let me take a look. Nova will gladly cover any parts that are not right, but they normally will not cover any residual parts…that will be on my dime if we decide to go that way. If you could send it soon that would be good…we are going to be packing for the move back to Texas in a few weeks.

GQ

 

[Tim Kish]

Will send itout tomorrow Glenn and you should not be out of pocket for a QC problem .

You do enough for this hobby just doesn't seem right .

Tim

 

[Andy Brown]

Good find Tim!

 

[Terry Keeley]

Good job Tim, figured it was something like that.

Here's a video of Olly's SP40 from last weekend, he has the throttle pegged the whole time:

https://www.youtube.com/watch?v=0d6uI9OQ-68&feature=youtu.be

Good points for style at 24 secs!

 

[dion smith]

Sweet recovery

 

[Elias Vazquez]

Awesome Tim!..glad to hear you found something.

 

[Olly]

OK - I have checked my PTO and it looks like the picture Glen posted. Not being able to look at both motors together, hard to know if it's the same problem.

Here's what I have observed. Every time I run the motor and bring it back in, it is so hot that you can't touch it. It would seem therefore, that it is not getting enough cooling. It doesn't however burn any plugs. I am running it in my Sport 40 without the cowl at the moment so that isn't causing any overheating. I have a sealed bearing on the PTO end and not on the crank. Is that normal?

It has been a real challenge for us, especially Terry, as he is more of the motor guy than me, but I thought I should share my observations and also thank everyone for their input.

Olly

 

[Tim Kish]

Olly

Very easy to tell if you have a good pto shaft .

There needs to be three different dia on the larger part.

So you should see the bearing dia then a step (reduced dia) then it bumps back up to the seal dia.

We are not including the smaller bearing dia in this.

Hope this helps,

 

[Glenn Quarles]

OK - I have checked my PTO and it looks like the picture Glen posted. Not being able to look at both motors together, hard to know if it's the same problem.

Here's what I have observed. Every time I run the motor and bring it back in, it is so hot that you can't touch it. It would seem therefore, that it is not getting enough cooling. It doesn't however burn any plugs. I am running it in my Sport 40 without the cowl at the moment so that isn't causing any overheating. I have a sealed bearing on the PTO end and not on the crank. Is that normal?

It has been a real challenge for us, especially Terry, as he is more of the motor guy than me, but I thought I should share my observations and also thank everyone for their input.

Olly

Olly, it the motor hot or the exhaust? The typical issue with these motors is getting them warm enough...I have never seen one that is too hot. This leads me to think it is too lean. I often run my outrigger with no water at all, but it is rich enough that the fuel provides all the cooling it needs. Now the exhaust is a different story..these motors always have a smoking hot header and pipe!

GQ

 

[Tim Kish]

Olly have Terry measure the pto or we can meet one night this week about half way for a coffee and Ill check it for you .

Als engine ran hot to , sign of being to lean from loss of fuel pressure.

 

[Andy Brown]

Olly, have you tried changing your throttle servo?

 

[Andy Brown]

Olly have Terry measure the pto or we can meet one night this week about half way for a coffee and Ill check it for you .

Als engine ran hot to , sign of being to lean from loss of fuel pressure.

The wrap around engine we ran in out rigger ran very hot too. But no issues.