Boxerworks.com

We've all heard about ME109 blowing his crank because of a broken oil filter housing pressure relief spring.
I think it happened to a few other forum members also. It's very rare.
Anyway, since hearing his story I kept telling myself that I should check mine,
but I always forgot to.
Hell, I didn't even know there was one until ME109's story appeared in the headlines.

I had a new ball and spring, but not the retainer, the retainer has been on back order for a while.
SOOO..today after smashing my engine back together, I changed my oil and filter.

I poked the ball with a screw driver to test it, and it offered virtually no resistance.
It was like the spring was way to soft.
I started to unsrew the retainer; it was completely loose, it had never bin peened into place to lock it,
it came out really easily within about a turn and a half! It almost fell out by itself.
This is a new one (left) beside my 399,000km spring. Same amount of coils.

It didn't break like ME'109's, it had just shrunk.
That, combined with the loose retainer was a disaster waiting to happen.

I highly recommend that you all check this at your next filter change. might save you a lot of cash down the road.
If the spring breaks you might scrap your crank.
If the spring weakens or the retainer falls out, your oil will bypass the filter, and possibly your oil cooler.
I wonder how long I've been running on mostly unfiltered oil?
Luckily I change my oil way too often so if some by-passes my filter it's no big deal.
BUT . maybe a piece of crap in the oil that didn't get filtered was fed to the crank and caused this:

Guess I'll never know.

Those shells are completely f***** out GS!
How did the crank look?
I forget who the kind person was that posted about there being two different length springs!
I think the lengths were like 11 and 16mm?
You probably don't need the new retainer.
I replaced my retainer because the ball had flogged around in there so much that it trashed the retainer.
Do you need help peening? I'll jump on the next flight over.
My new spring offers not much resistance. My brother found the same thing and I think he stretched it a little.

Who knows how to do the math on working out what pressure it will take to open the bypass valve?
Do our engines run at about 80-90 psi?
What is the square area of the hole in the retainer screw? (maybe just <4mm
Would the pressure required to open the bypass be proportional to the pounds per square inch?
I don't really expect answers 'cause I guess it's all very subjective.

11 and 16mm springs EH?

UH - OH

read the story in MOTORCYCLING, $80.000 dirt bike

Jeff, check out the third page in GSPD's thread in the Motorcycling board for pics of the crank journal
http://boxerworks.com/forum/viewtopic.php?f=17&t=138

I checked the ball a week ago. The blunt end of a wooden kebab skewer is the ideal tool. The retainer felt solid but I'm not sure how strong the spring pressure is supposed to be. Perhaps I'll do the next oil filter change when you are around Jeff, to get your experter opinion.

GS, you are very fortunate to have such a good mechanic, who charges 'mate's rates' and does 'foreigners' **

** Australian terms -
Mate's Rates: Work done cheap by a friend. Typically starts with a slab of beer. Can cost more.
Foreigners: Work done at Mate's Rates using his employer's facilities and time. Can lead to loss of employment, and mate.

ME 109 wrote: Who knows how to do the math on working out what pressure it will take to open the bypass valve?
Do our engines run at about 80-90 psi?
What is the square area of the hole in the retainer screw? (maybe just <4mm
Would the pressure required to open the bypass be proportional to the pounds per square inch?
I don't really expect answers 'cause I guess it's all very subjective.

1- The guys who designed it?

2- Sometimes, depends on rpm, oil viscosity, temperature amd wear.
i tested my oil pressure last week, before disassembly.
Snap-On tester (0 -100lbs)
Bike started cold ( overnite at room temperature)
Brand new 10w30 oil, just changed (to check the oil I rode back with for chunks)
I used 10w30 (instead of 20w50) to rinse it out before taking it apart.
rock steady 70 psi at idle,
off the dial over 2000 rpm

3- hmmmm....didn't measure it

4- I think it only opens if a clogged filter is causing a pressure rise in the filter housing

Airbear wrote:JWork done at Mate's Rates using his employer's facilities and time. Can lead to loss of employment, and mate.

He's not my employer.
I am his consultant and saviour.

Further to the tension of the spring..........the retainer can be screwed in past 'flush' with the engine casing, increasing tension. That may make it more difficult to peen the casing though.
The oil in the filter chamber will take the path of least resistance so it will open the bypass if/when the filter becomes blocked.
As I stated in earlier posts re the bypass, I can't see how a spring with seemingly light tension can resist 100 psi even with a brand new filter. Maybe it can at idle or low revs, but 100+ pounds??
I think oil is always bypassing the filter to some degree.

If oil passes through the filter at 100 psi, the bypass should be able to resist 100> psi.
My crude brain says the area of the hole in the retainer screw is 'maybe' 1/60th of a square inch.
Should the spring therefore be able to resist approx 6 pound pressure?

My theories need to be taken into context with the kangaroos that are hopping aroud my yard, and the fact that I can run a type 247 for thousands of k's with the valves around the wrong way.
It wasn't like I did it to both heads though!

Mine's flush with the housing, and I peened the sucka.
I'm riding with the longer spring, I don't care*.
I'll let you know how it blows up.

* watch " High Octane generation" video in MOTORCYCLING section

I done seen it yesserday. Sheeeeeeeyet!

gspd wrote:We've all heard about ME109 blowing his crank because of a broken oil filter housing pressure relief spring.
I think it happened to a few other forum members also. It's very rare.
Anyway, since hearing his story I kept telling myself that I should check mine,
but I always forgot to.
Hell, I didn't even know there was one until ME109's story appeared in the headlines.

I had a new ball and spring, but not the retainer, the retainer has been on back order for a while.
SOOO..today after smashing my engine back together, I changed my oil and filter.

I poked the ball with a screw driver to test it, and it offered virtually no resistance.
It was like the spring was way to soft.
I started to unsrew the retainer; it was completely loose, it had never bin peened into place to lock it,
it came out really easily within about a turn and a half! It almost fell out by itself.
This is a new one (left) beside my 399,000km spring. Same amount of coils.

It didn't break like ME'109's, it had just shrunk.
That, combined with the loose retainer was a disaster waiting to happen.

I highly recommend that you all check this at your next filter change. might save you a lot of cash down the road.
If the spring breaks you might scrap your crank.
If the spring weakens or the retainer falls out, your oil will bypass the filter, and possibly your oil cooler.
I wonder how long I've been running on mostly unfiltered oil?
Luckily I change my oil way too often so if some by-passes my filter it's no big deal.
BUT . maybe a piece of crap in the oil that didn't get filtered was fed to the crank and caused this:

Guess I'll never know.

The rod bearings look pretty bad. What did the mains look like? did you check the oil pump for damage?