EGT Gauges?? - Would this have saved me?

[deerefanatic]

Hi guys... Well, my snowmobiling days are over for this season... Somehow my PTO side went lean while I was riding... Started noticing a bog.. By the time I pulled the plugs, the PTO side was grey and flaky..... Motor started knocking as I tried pulling it over to compression test and then locked up. I can turn about a half a turn either way and then it stops...... Piston IS moving up and down so at least it's not a rod/crank failure.....

But, that leads me to this question. I have no idea what happened.. I've gotten almost 200 miles on this year and my jetting was just spot-on or close there-to all season. Even last weekend it was running great..... Then today she bombed.. BUT, my question is this: Would the lean condition have showed up on an EGT gauge? At this point I'm looking at a $210 engine rebuild which is out of reach of my budget right now... An EGT kit costs close to that, but if it keeps a guy from cooking a motor, it's worth it....

I'm thinking one of those Dual EGT gauges by westach that Dennis Kirk sells with a probe for each cylinder...... I know in the diesel performance world EGT gauges are a must..... I'm beginning to think that if you have old sleds that you really intend to ride, it's the same story.

[400brian]

In the early '80s a lot of the Ultralight flyers started running EGts and CHTs in attempt to avoid seizures.
The problem was you had to watch the gauges for one thing, they were still getting seizures. So then they went to electronic systems, that would display a bar graph, and sound an alarm at whatever value you set to warn you of high temps.

Results were still uneven. If a seal is degrading, you might see it. If the rings are sticking from carbon build up, you might see it . But often temps would spike for whatever reason, and score a piston before any system could warn the operator.

Peter was talking about using an oxygen sensor in the exhaust for better results. You might ask him about that.

One of the long time UL pilots always insisted a well tuned ear was the best instrument. Jon says that Brian Nelson could hear detonation!

[deerefanatic]

So in other words, It might not have saved me? One thing I could think of was that if the sled was acting "funny" (which it was a little before this) it would have given me a way to check and see what's up.. Plus, it would make adjusting jetting easyier I'd think.... Wouldn't it?

Another thing, what do you all think of dial-a-jet? Does it really work out as well as it's made out to?

[VintageCatMan]

Sounds kind of like you broke a piston skirt and it got hung up on a port. Did you pull the head off yet? If it is a broken skirt, an egt gauge would not have prevented this. let us know how you make out.

Nick Freatman

[deerefanatic]

yah, but a broken skirt wouldn't have made it run lean...... If you'd seen the spark plug, you'd know it ran lean.....

At this point, I've got soo many projects that I HAVE to get done before spring, I won't be working on the sleds till probably september or october......

[400brian]

An EGT gauge can be an aid in carb tuning. Once you establish a baseline "normal" the EGT can be used to alert you to problems, but it is no sure preventative against seizures.

You could pressure test the engine before disassembly, it may show you what the issue was.

[deerefanatic]

Well, I did start on a compression test... Mag said had it's usual 100 psi on it like normal..... Pto side had nothing for the first pull and then clunk........

I may just have to pull the head to satisfy my curiosity......