Ski-Doo Snowmobiles Forum banner
1 - 3 of 3 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
Hello all, new to the forum but not to doo's. Here's the issue. My brother took out my 7500 about a week ago. Sled was in mint condition. He thought it was oil injected and did not put any mix when he filled the tank. He says............it started sputtering after he took off on the lake and he turned it off. He couldn't pull the engine over after he turned it off. He called me and we went and picked it up and put it in my shop. I could turn the motor over but it wouldn't start.

Without ripping it apart is there any way to test or tell what the problem would be ?? It turns over, no clanking grinding etc, seems to have compression still but I'm worried about the crank.................

Any help would be appreciated.

Thanks in advance.
 

·
Registered
Joined
·
142 Posts
Usually the first thing to go is the pistons. The aluminum will start to melt and stick the rings deep into their grooves. Aluminum will be deposited on the cylinder walls, and a loss of compression is the result.

First thing is to check the compression, when you pull the spark plugs out, look at the electrodes. If your pistons did start to go, there might be real small aluminum deposites on the tip of the plugs.

If the scoring is not too bad, it is possible sometimes, pour a little oil into the plug holes, replace the plugs, put premix oil into your fuel tank so it is running very oil rich, you might be able to get it to run. This trick might help get you out of the woods sometime if you're stranded. This does not fix the problem, but it might same a tow.

The crank bearings are roller bearings, so if your brother turn the engine off right away, you might just need a top end rebuild, hone the cylinders, new pistons & rings.

If you are looking for pistons for that 7500, know that the Kohler 340LC piston is exactly the same and used to be about half the price of ski-doo pistons. I used to race my 7500 back then and know they work for sure. The Kohler 340LC was used is a few different brands, the one that comes to mind is the Merc Sno-Twisters.

Good Luck!
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #3 ·
Well I put a compression tester on the sled and had 125 on the pto side and 25 on the other..............seems like a problem. Thanks for the advice. I'm going to pull it apart and do both at the same time. Hopefully the crank is still O.K. any way to do a quick test on it ??
 
1 - 3 of 3 Posts
Top