Evo Oil Pump Seal

[choseneasy]

I have an oil pump with the seal between the feed/return gears that is really loose on the shaft.
  Has anybody ever seen this and what were symptoms? Kinda curious what it affects- low oil pressure and maybe poor return?
 

[Mule]

More than pressure effected , I would suspect it would cause sumping as oil would leak past it when sitting...

[choseneasy]

Possibly draining into the case sitting- but it was not sumping running. Did have oil light come on for a moment.

[Burnout]

Did have oil light come on for a moment.

This would be my concern as air from the scavenge side might migrate to the pressure side.

[turboprop]

I have an oil pump with the seal between the feed/return gears that is really loose on the shaft.
  Has anybody ever seen this and what were symptoms? Kinda curious what it affects- low oil pressure and maybe poor return?

Curious why you didnt simply replace those parts whenever you had the pump apart to identify the loose shaft/seal. I think a new shaft is under twenty dollars and the seal might be two. 

[choseneasy]

I am taking the motor apart- the pistons scored the cylinders bad and the skirts collapsed. ( S&S forged pistons)
  The bike might have been a bit lean and advanced but not to cause damage to this extent.
  I have a rebuild kit for the pump- just not 100% sure why the pistons got so hot.
  The cylinders measured good so clearance wasn't an issue.
Anything questionable is getting replaced.
 

[Burnout]

I am taking the motor apart- the pistons scored the cylinders bad and the skirts collapsed. ( S&S forged pistons)

Slow idle speed and extended idling to "warm up".

EVO's don't have piston squirters....

[turboprop]

I am taking the motor apart- the pistons scored the cylinders bad and the skirts collapsed. ( S&S forged pistons)
  The bike might have been a bit lean and advanced but not to cause damage to this extent.
  I have a rebuild kit for the pump- just not 100% sure why the pistons got so hot.
  The cylinders measured good so clearance wasn't an issue.
Anything questionable is getting replaced.

How many miles were on those forged pistons when this was discovered?

[Billy]

I am taking the motor apart- the pistons scored the cylinders bad and the skirts collapsed.

Not sure what you have but some mid/late '90s EVO's had pinion bearing issues and would send swarf in the oil off the flywheels to the cylinders under the pistons and cause major scoring.

[choseneasy]

Approximately 2000 miles on build. Guy was riding, oil light flickered then kinda coughed and engine quit cruising on an incline.
All specs on engine look really good so far- runout, endplay, clearances etc.
Still want to check all oil passages for blockage. Front cylinder was the worst.
Pistons definitely got hot.
Pinion bearing looks great but I want to take a good look at the rod/crank pin when I pull that apart. Still rolls over real smooth.

[Hossamania]

A lot of lugging trying to "take it easy" on the engine?

[choseneasy]

No- guy riding it is good with bikes.
Not sure if that seal would cause it to lose pressure - but sure wouldn't help.

[Mule]

The bike might have been a bit lean and advanced but not to cause damage to this extent.
It only take minutes!!!

[Ironheadmike]

Long idles will do this if the idle is under 850 rmp . There's not enough rpm's to generate any oil pressure to get to the engine .

[turboprop]

Approximately 2000 miles on build. Guy was riding, oil light flickered then kinda coughed and engine quit cruising on an incline.
All specs on engine look really good so far- runout, endplay, clearances etc.
Still want to check all oil passages for blockage. Front cylinder was the worst.
Pistons definitely got hot.
Pinion bearing looks great but I want to take a good look at the rod/crank pin when I pull that apart. Still rolls over real smooth.

2k miles, front cylinder looks worse? Have seen this too many times. Never oil related, always the tune. Higher compression, lean AFR in the cruise area, and timing too advanced. For a carb'd engine the condition will typically not show on the dyno as the operator will typically do a WOT pull and declare the tune as done. Meanwhile there is a dangerously lean area. Done it. Got the t-shirt.

How does the underside of the pistons and the wrist pin look?

[choseneasy]

That probably makes the most sense Turbo.
  Definitely piston got hot- underside of piston and pin  showed lotsa heat for sure.
  The oil light flickering maybe was coincidence with crud in the oil pressure sensor....

[TexNorth]

Sounds like some of the oil pressure was going from the pressure side right to the scavenge side and not making it to the engine.  Pressure sending unit is right there at pump  and could show decent pressure but not enough volume.    I know, if it shows pressure it should have enough volume, but it may be acting weird in this situation.   Maybe fluctuating pressure while while running down the road, who know. 

Maybe sometimes air moving from side to side in the oil pump, maybe aeration of the oil, hard to say.....


Definitely a bummer......