951 Woes

[highcam]

Good evening all,

I have a 951 carb which I have recently rebuilt. (New sleeves, crank, pistons, rebuilt carb, rebuilt jet pump....everything). Even checked and adjusted combustion volume by using a pipet as suggested in shop manual.

I have built quite a few engines in the past but this one is giving me problems.

Engine idled great in driveway on the hose, idled great in the lake while checking for leaks etc. Ran great for 10-15minutes lots of power, etc... Then the engine began to misfire.

I determined the PTO cylinder was fouling the plug due to water ingestion. (second set of plugs on more lake testing, same experience as above, idled great, lots of power for 10 minutes and then misfires began). When I pulled the plugs on the lake I found some water on PTO side plug.

I cannot find any water leaks anywhere, so I deemed the headgasket to be the problem. Pull the head with the engine in the ski, probably got a tablespoon or so of water into the bottom end in the process .

During head gasket removal the PTO side bolts were too loose, I mean obviously not torqued correctly. I can't understand this, as I am 100% I torqued everything to spec. Torque wrenches have been recently calibrated.

I see no obvious paths of water intrusion on headgasket, although the head does have some pitting from water corrosion.

Current plan:
-Not worry to much about the little bit of water leaked into the bottom end. I have chased it with copious amounts of fogging oil.
-Buy new head gasket
-Check flatness of head
-Reinstall head without removing engine from ski.

Worries:
-Water in bottom end (rust etc on rod bearings -- water through pulse line into carb???)
-Base gasket? (shouldn't be too disturbed although I did cycle engine with head off hoping to pulse the water out.)
-Have I even found source of water leak?

I'm open to suggestions, needless to say I am extremely frustrated at this point. I'm tempted to burn the entire ski.

[Grumpy Old Guy]

Head gasket was more than likely your problem.

Start & run get warm cool down retorque. I tend to go a little tighter than torque spec but thats just me...never had a issue.

Dont worry about the small amount of water in the bottom end. Use paper towel to suck it up

[Grumpy Old Guy]

Where you at in NC ??

[highcam]

Head gasket was more than likely your problem.

Start & run get warm cool down retorque. I tend to go a little tighter than torque spec but thats just me...never had a issue.

Dont worry about the small amount of water in the bottom end. Use paper towel to suck it up

Thanks. I think I will proceed this way. I've also never previously had an issue with a head gasket, from single cylinder yamahas to inline six bmw engines...

Any thoughts on the water that spilled on the piston and drained past the rings?

Where you at in NC ??

Charlotte

[Grumpy Old Guy]

Dont sweat the water,it will evaporate. Get a new head gasket,I would spray it with cooper coat.

I worked in Wilmington/Jacksonville a while back & my uncle has a place in Sylva. I love the mountains.

[highcam]

Dont sweat the water,it will evaporate. Get a new head gasket,I would spray it with cooper coat.

I worked in Wilmington/Jacksonville a while back & my uncle has a place in Sylva. I love the mountains.

Sounds good, and appreciate it. The headgasket I just took off had copper coat on it and I am not sure it helped... I only used the copper due to the pitting around the water passages. Although the lack of torque was probably the main issue.

Wilmington is a cool town, I don't know Sylva, but I was through Jacksonville on my way to Cape Lookout a few weeks ago. The NC mountains are gorgeous -- I try to get some backpacking in the Linville Gorge in a few times a year.

[Grumpy Old Guy]

Sylva is over by Cherokee...quiet town lots of mountains & trails

[highcam]

Sylva is over by Cherokee...quiet town lots of mountains & trails

Just googled it... looks like a nice place. Judging by the location, I would've driven by it on my way to Nantahala.

OEM head gasket ordered. Hope for the best when it arrives. I'll check the flatness of the head at work tomorrow. Nothing fancy, probably just on some granite with a flashlight.

[Grumpy Old Guy]

Yeah just run it on some light sandpaper & check for low or high spots.

I just built a 951 for my ski & had no issues with my head gasket but have heard of people that do. But has I said I tend to over torque cus I dont like loose bolts.

Hopefully you will get it fixed. If not I know a guy in the Denver NC area that knows his stuff on these motors.

[highcam]

Alright, I appreciate it the help.

I'll post back after I receive and install the headgasket.