Testing 2 stroke crankshaft seals.

cart around

We always get a lot of questions about non running carts. One of the things we talk about is testing crankshaft seals with ether, and other flammable sprays.

I've been thinking that there has to be a more reliable way, especially if the cart won't run at all.

I believe that we could test crankshaft seals through the fuel pump pulse hole by pulling a vacuum with a tester like this one. http://www.harborfreight.com/mityvac...ump-39522.html

I just fixed my kid's 4wd with this tool, and found all of her vacuum leaks.

Another option might be positive pressure, but you would have to be careful about using too much pressure and popping the seals. A blowgun with a rubber tip would make a good seal, and then you could listen for leaks around the seals.

Any opinions, or ideas?

BGW

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BrewCityMusic

I would think that there would be no reliable indicator using vacuum - you're not going to hear a seal leak over the sound of the engine turning over. I could see positive pressure and some sort of indicator (like soap suds when checking a bead/rim for leaks) but in that case, the entire front end of the motor would have to come apart (shroud, fan, flywheel) in order to visibly see a leak due to a bad seal ... And with the rear, it would involve having to contort into about 6 different positions in, over and under the rear of the cart in order to fully see any indication at the rear seal...

Using a tester like the MightyVac wouldn't give a reliable reading either, as there is going to be quite a bit of leakage at the rings without plenty of fuel to seal it up, so now you're pulling the plug, ensuring the piston is at bdc to keep any leakage from the intake or exhaust from hampering the test, depending on the condition of the rings and cylinder there's going to be a difference from engine to engine as far as leakage ...

Jack up cart, press pedal, and spray. It's found several bad seals for me. Not that you're idea might not work, it's just a little more work than I'm willing to accept when again, jack-pedal-spray works so well. Cool idea though, others may have different opinions

cart around

Jack, pedal, spray only works if the cart is already able to run.

I run my cart every day, so I'm not willing to take it apart right now. I'll experiment on mine this Spring to see what kind of baseline indications I get on a fully functional cart.

TheGDFP

Sound advice from old Harry:
http://www.klemmvintage.com/airleaks.htm

BrewCityMusic

I agree - but I was of course assuming that all the basics (fuel to carb, carb cleanliness, spark, etc) were addressed prior to checking seals, that's the path I generally take - if You're starting from nothing generally those are more likely culprits than the crank seals. My theory is that You don't remove the shroud, fan, flywheel, carb, exhaust, clutch, etc to INSPECT seals, if the engine is already down that far then take the 5min and $12 and just do it either way as a preventative, save the plugging and pressurizing, waiting, etc - just do it - it's going to take less time and probably cost less than the beer you'll drink waiting around to see if the engine holds pressure, LOL.

cart around

I like Harry's advice. He is going a little more elaborate, but we are saying pretty much the same thing. I troubleshoot for a living, and I'm a firm believer that there is more than one way to cook a goat.

The Hurling Buffalo

Looks like I'm about to jack pedal and spray lol!

The Hurling Buffalo

I guess it doesnt matter how much ether you spray if theres no spark.... This HEI conversion is such a massive headache thus far. 3 days of no cart :(