coolant in both float bowls after failure?

[simbatheking]

after blowing a lower con rod bearing due to detonation on mag side I found small amounts of coolant in both float bowls. the rod cracked the case and it burned coolant for about 5 sec then died. the failure was on a long climb. ive had a lot of similar failures in both my sleds since switching to premix and for the life of me cant figure out whats causing the deto. still getting the p0376 code on my other trygstad engine. my jetting is 500 main and needle up one shim on stock engine other than full ex and vforce reeds. non eth 91 octane fresh gas. new plugs. no air leaks. now sure how the coolant would get to the float bowls?? even after the engine was burning coolant briefly from the case how would it make it to the carb floats? could it leak inside the carbs from the heater lines???

 

[byeatts]

after blowing a lower con rod bearing due to detonation on mag side I found small amounts of coolant in both float bowls. the rod cracked the case and it burned coolant for about 5 sec then died. the failure was on a long climb. ive had a lot of similar failures in both my sleds since switching to premix and for the life of me cant figure out whats causing the deto. still getting the p0376 code on my other trygstad engine. my jetting is 500 main and needle up one shim on stock engine other than full ex and vforce reeds. non eth 91 octane fresh gas. new plugs. no air leaks. now sure how the coolant would get to the float bowls?? even after the engine was burning coolant briefly from the case how would it make it to the carb floats? could it leak inside the carbs from the heater lines???

If in both bowls its probably blow back and dripped down the along the needle. Your case likely filled with water. Pre mix does lean a bit and most trygstads need larger mains anyway.both our Trygstad 880 and 860 needed 540 mains. be careful where you buy your cranks, Many piece together used parts/rods ,toss on new bearings and call it good.

 

[mudpro9]

Have you ever checked the cylinder squish after assembling the motor by using a piece of bend soldier threw the spark plug hole? I know with my SHR 860 with a 13.5 compression clearance was supposed to be something like 60-65 thou. You squish might be to tight causing the compression to be higher then what the head actually is and that could cause your detonation problem. Worth checking should be able to get the specs from Dave.

 

[chumbilly1]

Saw a buddy go through engine after engine until he realized it was ingesting coolant through the heater circuit. IMHO carb heaters are a joke and make it way too hard to access carbs for main jet swaps. I would cap the coolant circuit and plug the nipples on carbs to be safe. Unless you ride in sub zero temps and don't have the stock intake on your sled I would bet you never experience carb icing.

 

[BBP]

Blown fuel pump?

 

[TreeThrasher]

It takes pretty violent deto to eat a rod bearing...violent and prolonged enough that I would bet decent dough the top end would fail before the rod.

Pre mix in a skidoo 800 engine is a tad hit and miss. Every pre mix one I have owned or worked with lost a rod bearing. And many times during the rod bearing failure it throws enough pieces around that it leaves what appears to be deto damage on top of the piston.

Just a thought!

 

[byeatts]

It takes pretty violent deto to eat a rod bearing...violent and prolonged enough that I would bet decent dough the top end would fail before the rod.

Pre mix in a skidoo 800 engine is a tad hit and miss. Every pre mix one I have owned or worked with lost a rod bearing. And many times during the rod bearing failure it throws enough pieces around that it leaves what appears to be deto damage on top of the piston.

Just a thought!

If you are contributing a rod failure to pre mix then your Not mixing the correct ratio, Thats the sweet thing ,It always getting the proper ratio. The oil system is just there for front wipers and for convenience .

 

[TT670]

If you are contributing a rod failure to pre mix then your Not mixing the correct ratio, Thats the sweet thing ,It always getting the proper ratio. The oil system is just there for front wipers and for convenience .

I would agree. Every lower rod bearing Ive seen fail (They've always been 800cc and mostly PTO side failures) has been on a injected engine. Ive never seen a 32:1 premix ski doo lose a rod bearing. Ive also noted that during a teardown, a pre mixed engine has lots more residual oil in the case than an injected engine.

 

[byeatts]

I would agree. Every lower rod bearing Ive seen fail (They've always been 800cc and mostly PTO side failures) has been on a injected engine. Ive never seen a 32:1 premix ski doo lose a rod bearing. Ive also noted that during a teardown, a pre mixed engine has lots more residual oil in the case than an injected engine.

Also Oils have different flashpoints, A lower flashpoint oil will burn off too quick for motors that run WOT for extended periods, Amsoil Dominator has been the best for leaving a very nice coating on all components even at WOT. And recognized by Doo on warrantee concerns.32-1 and you are Golden...