Super Jet FML. So I pulled my flywheel cover and.....

[SXIPro]

Yeah, so I've been having start issues and have concluded it's my stator and more than likely the pulser coil. No biggee, right? Well I pull the flywheel cover and the inside of the cover is loaded with gas, oil, and most worrisome, a pretty decent collection of metal shavings. Plus when I pulled the cover about 2-3 tablespoons of goo poured out)

So, I am guessing my crank seal is gone. But where did these shavings come from?

Also my compression seems low. It is dead even but low. However I did test it dead cold (Wiseco pistons).

Can a blown crank seal lead to low compression or are the low readings more likely from a cold motor?

 

[All stock 701]

If your compression is dead even it is most likely due to the seal. As for the shavings, if the bendix is coming apart internally that may be your problem

 

[kurtwolff]

Are you testing with throttle open? Leaky front seal rarely would cause a lean condition as the front cover is sealed as well. What compression are you getting?


Sent from my iPhone using Tapatalk

 

[SXIPro]

I am getting 158 per hole. But typically it was closer to 185. However I always tested it hot before and with a nice gauge. This was cold and with a Harbor Freight cheapo. And, yes, with throttle squeezed

 

[High Speed Industries]

What ski is this on? I had the same thing happen on my sxi pro and it was pretty gnarly.

 

[Big Kahuna]

could be wrong, but when checking compression, the measurement starts when the piston is passing the roof of the exhaust port until it reaches TDC. So, you could have a hole in the cases and it would not effect your measurement.

 

[SXIPro]

What ski is this on? I had the same thing happen on my sxi pro and it was pretty gnarly.

It's an '04 SJ.

 

[kurtwolff]

BK - While your statement is technically true, that hole in the case (or other air leak, most commonly a blown out rear seal) would have caused a lean condition which would have melted off the exhaust side of the piston crown and certainly caused low compression. But, the OP is seeing the same numbers on both cylinders, which does not point to a leaky crank seal.

I am assuming you have an aftermarket head to get 185 psi? If so, I would check with a known accurate gauge. I have had gauges go bad all of a sudden and read 90 psi on a good 160 psi motor...


Sent from my iPhone using Tapatalk

 

[Big Kahuna]

Kurt, Yes, with a hole in the case you would smoke the piston.......... I was referring to just checking compression. Same compression is either from a bad gauge or worn out bore or domes that are too large.

 

[SXIPro]

BK - While your statement is technically true, that hole in the case (or other air leak, most commonly a blown out rear seal) would have caused a lean condition which would have melted off the exhaust side of the piston crown and certainly caused low compression. But, the OP is seeing the same numbers on both cylinders, which does not point to a leaky crank seal.

I am assuming you have an aftermarket head to get 185 psi? If so, I would check with a known accurate gauge. I have had gauges go bad all of a sudden and read 90 psi on a good 160 psi motor...


Sent from my iPhone using Tapatalk

Thanks. I am guessing it's the combo of a cold dry motor and a cheapo gauge. I read on Group K that just the difference in the way a gauge is designed can make a 20-30 lb difference, (Snap on vs Harbor Freight as an example) because of where the measurement is actually taken from. I guess on the better gauges it measures it at the fitting you screw into the head, but on the cheaper ones it reads all the way at the top of the hose and the volume in the hose messes the reading up. But yes, I have an ADA Head with 33 cc domes.

 

[Big Kahuna]

Glad you posted this, relevant to another thread

 

[High Speed Industries]

I had something similar happen to my sxi pro. What actually happened was the crank started coming loose at the web. The front web started walking forward and ended up pushing my bearing into the seal. The seal came apart and filled the stator with oil. That's when I lost spark and it stopped running. This was with a hot rods crank. I ended up having to replace the crank, seals, cases, and stator. It even cracked the bearing.

The front bearing was so loose it came off by hand.