96 GTI died on me on the water, what could it be?

[sookati]

Hey Everyone,

I was running my 96 GTI on the lake today, and I had stopped to relax for a bit on a small island. When I went to start off again, it ran for about 10 seconds then conked out. I don't remember there being any loud banging or anything.

When I tried to restart it, I made a real nasty sound from what seemed to be the front of the motor (magneto?), and wouldn't start. I was immediately concerned that I locked up a piston, so when I manually turned the crank, everything seemed to move ok, but I was getting a knocking sound as I turned it (again, sounds like it's in the front).

I made sure I clamped the intake water line before I was towed back to the marina (thanks for the recent thread on that!). As soon as I got home, I checked the compression and both cylinders are good. The spark plugs looked fine as well.

I have no idea what this could be. I have attached videos I made of me trying to start it, and of me turning the crank. Please let me know what you think it might be. Thanks!

[video=youtube_share;GzURBZ0Vmzc]http://youtu.be/GzURBZ0Vmzc[/video]

 

[sookati]

Video 2

[video=youtube_share;_uvun9LHLhU]http://youtu.be/_uvun9LHLhU[/video]

 

[Seadoobuddy]

I didn't view your videos.......... so

My neighbor has had similar problems with his 96 GTi.
Turned out was dirt in the carb filters, and bad fuel lines.

Do you still have the gray tempo fuel lines? Have you rebuilt the carbs lately?

 

[sookati]

I didn't view your videos.......... so

My neighbor has had similar problems with his 96 GTi.
Turned out was dirt in the carb filters, and bad fuel lines.

Do you still have the gray tempo fuel lines? Have you rebuilt the carbs lately?

The carbs are good, the fuel lines have been replaced. How can I check for spark?

 

[AdamXP800]

Edit***

What is "good compression" to start? Do you have numbers

 

[sookati]

On my gauge it's 135 and 130, but that's the same reading it gave me when it was running great.

 

[BlakRat]

Maybe your pick up bracket broke off inside the stator housing.

 

[sookati]

Maybe your pick up bracket broke off inside the stator housing.

Hmmm good thinking. Can I just pop the housing off with the motor place?

Edit: More backstory. That makes sense that it could be the bracket, because I was really hitting some big wakes before I stopped.

 

[AdamXP800]

In the second video, is that your trying to turn the motor over by hand? If so you should not be able to move the shaft that easily with the plugs in

 

[AdamXP800]

And it should not make that metal on metal knock sound

 

[sookati]

I can turn it the same way with my xp. There's a lot of resistance, but I just muscle it over.

Edit: yes the knock is concerning. It feels like it's knocking from the front.

 

[AdamXP800]

In the first video something does not sound right. Not at all to me

 

[AdamXP800]

I'm not 100% sure but you shouldn't be able to turn that shaft with 1 hand with the plugs in and that knock sounds like a rod let go

 

[sookati]

Maybe your pick up bracket broke off inside the stator housing.

Crap, I think the pickup bracket is on the outside of the cover on the 720. I'll pull the cover off tonight or tomorrow and take some pics.

 

[fitty650sx]

My money is on: front crank bearing let go and the flywheel ate the stator.

 

[sookati]

My money is on: front crank bearing let go and the flywheel ate the stator.

Hmm, sounds expensive/fun. I've never done any engine work before, but if done other stuff like rebuilding carbs, vts motors, and starters. What would I have to do to get at the bearing?

 

[AdamXP800]

If it comes to that you will be rebuilding from the bottom up. A reman engine is easier and will have you back on the water in no time with a no fault warranty.
Don't jump too far ahead yet though, let's figure out exactly what is going on here

 

[sookati]

Yeah, first things first, I'll get that cover off and I'll root around a lil bit and get some pics.

 

[sookati]

So I went to take off the magneto cover and... three of the bolt heads sheared off. I'm exploring ways to get them out, but my fear is that I won't have enough room to get my drill in there...

Two of the bolts are on top, one is on the bottom.

 

[sookati]

Well, I went ahead and pulled the motor out. I wouldn't have been able to get at the magneto cover with the bolts broken off like they were. It appears that the clanking sound is the rotary valve. The pistons are moving normally, but that valve is clanking away. Here's a video:

[video=youtube_share;IQgk0KLvFRU]http://youtu.be/IQgk0KLvFRU[/video]

Needless to say, I think I'll be getting a new motor from SBT.

 

[sookati]

And to add icing on the cake, I got the magneto cover off and it had a bunch of muddy looking crap on the bottom. Check it out:

[video=youtube_share;KGrBcN0ANJg]http://youtu.be/KGrBcN0ANJg[/video]

Looks like I'll be ordering some more parts too.

Does anyone have any thoughts on this? The compression on the top end is good and the driveshaft looks like it's in good shape, but I don't know anything about rotary valves.

 

[fitty650sx]

Grab the flywheel and try to move it up and down/side to side.

 

[Mekanix]

What you have here is a stripped rotary shaft gear. That knock your hearing is the gear moving out of the way against a spring and then when it jumps a tooth, the gear moves back into place and that is your clunk.

Its repairable but consider the reman replacement route.

 

[sookati]

Ok. Now if I go the rotary shaft route, should I be concerned about this?



I noticed this little chunk of metal hanging out on the face of the engine where the rotary valve hangs out.

 

[Mekanix]

Well I was going to mention you could just replace the gear and possibly the shaft if its bent but you might find that the cause of this is something bigger.

Either the debris is coming from the carb and jamming up the rotary valve which strips the gear OR something could have come apart inside the engine and then come back through the intake.

Because of that it would be worth looking into the engine unless you know of something that came into the engine from the intake side. Often the bolts for the breather fall down the carb and cause this. But that debris looks weird, not sure what it is, definitly doesn't look like a bolt fell down. There would be more damage than that.

I've had a needle bearing on one of the connecting rods come apart and come back through the intake. That jammed the rotary valve and stripped the gear followed by bending the shaft. looking at the rotary valve surface I'd say something definitly went through there and went all the way around.

You would have to split the case and clean that cavity out really well + replace the seal and bearings on the shaft if that was all it needed.
But mainly your in there to look at the crank gear to see if it has moved. If so, the route to take is install another crank. and at that point the cost is heading towards a new engine.