Sand in the motor...should I disassemble???

[dougamclean]

Hi guys..I just landed a particularly clean 1997 GTS(717) for a great price!! A perfect winter project.

It's getting new fuel lines(still the original grey), carb cleanup and jet drive rebuild as the previous owner had a nasty encounter with a gravel bar and knocked half fins out of the housing with rocks, etc! He limped it back to the trailer and went home. It's been parked for a couple years since the incident..

Besides this, it's a very clean, low hours motor with nothing touched..it still has 150PSI in both cylinders. A freshwater garage queen by definition.

Anyway, while exploring I found a large amount of sand and small gravel in some of the clear water hoses, obviously from the gravel bar accident.

I will be removing every single water hose and replacing with new. The jet pump is already rebuilt and ready to go back on.

But if there is anyway that some of this sand/gravel might be caught up in pockets in the motor/exhaust I best disassemble and remove it...? But if there is no reason to disturb it's originality, I'd prefer that.

I just did the top end of my GTS(787) and found small amounts of sand in the bottom of the cylinder jug passages. I cleaned it out while it was apart but not enough to worry about really. Small accumulations are normal I'm sure..as long as they don't fill the water void and cause hot spots on the cylinder walls.

This leads me to my question: Should I remove the cylinder head and exhaust to flush or will natural flow carry the debris from the inside back out well enough???

 

[AquaEye]

I've used "irreversible" engine temperature strips in industrial & PWC/MC applications as to make a more accurate determination(s) on the state of.
Always helped me into deciding keeping cooling circuit stock, increase line diameter, dual cooling lines, troubleshoot or lubrication/fuel ratio change. (especially Kawi's, seen to many with blow torch temps).
6 strips in "educated" strategic locations on the engine will suffice.(?)
On a a 2 stroke Rotax?(my first) Haven't a clue. Unfamiliar with the cooling circuit but will educate myself when the time comes.
Get plenty to make a "somewhat" accurate thermal map.
Low hrs (imo, 80hrs or below is "low hrs") along with good compression. Dive deeper into triage, attain more info.
Consider teardown as a last resort.
The "good" strips are not cheap so prepare yourself for sticker shock.

 

[dougamclean]

I've used "irreversible" engine temperature strips in industrial & PWC/MC applications as to make a more accurate determination(s) on the state of.
Always helped me to decided on keeping cooling circuit stock, increase line diameter or go with dual cooling lines or troubleshoot, (especially Kawi's).
6 strips in "educated" strategic locations on the engine will suffice.(?)
On a a 2 stroke Rotax?(my first) Haven't a clue. Unfamiliar with the cooling circuit but will educate myself when the time comes.
Get plenty to make a "somewhat" accurate thermal map.
Low hrs (imo, 80hrs or below is "low hrs") along with good compression. Dive deeper into triage, attain more info.
Consider teardown as a last resort.
The "good" strips are not cheap so prepare yourself for sticker shock.

Thanks Aquaeye, any response is appreciated...

However, I don't think temperature strips are a workable idea for me..it would require me to have a wet-tank to run the machine in, I don't.
Also as I'm in Ontario and the temp outside it below freezing so a trip to the river for a spin isn't an option. A non-running solution will have to be found.

It's sitting in my shop on a stand with intentions of prep for spring operation..

As far as full 'tear down', I don't think that will be needed even at worst case..more likely simple removal of head and exhaust to access for cleaning. I just don't want to remove the original bolts unless needed..

I believe I would only have to to get access to the cylinder jugs then a cleaning with a vacuum and small instruments to get the sand out should be all that is needed. The exhaust, once removed, I could flush in a work shop sink or with compressed air then reinstalled.

My hope is someone might know if the design of the motor and exhaust prevents sediment from accumulating..even if the engine is badly flooded with material. Thus remove the need to me to do any of it..

 

[AquaEye]

10-4 Your absolutely correct.
Canada cold, very cold. Shop warm very warm.
Sometimes I scan instead of reading & discerning. My bad.
I too had that issue when I did the teardown on my 1st 787. (40.3 hrs) Fresh water but the previous owners ( Daddy Warbucks & his 3 teenage sons) probably neglected any kind of flush & sand & sediment in the cylinder water valleys was nothing like I've seen before, PACKED. This ski had a tortured short life.
You have a good start & the smarts to see it back on the lake next season.
Good fortune.

 

[dougamclean]

10-4 Your absolutely correct.
Canada cold, very cold. Shop warm very warm.
Sometimes I scan instead of reading & discerning. My bad.
I too had that issue when I did the teardown on my 1st 787. (40.3 hrs) Fresh water but the previous owners ( Daddy Warbucks & his 3 teenage sons) probably neglected any kind of flush & sand & sediment in the cylinder water valleys was nothing like I've seen before, PACKED. This ski had a tortured short life.
You have a good start & the smarts to see it back on the lake next season.
Good fortune.

I think this and affirmation I needed. My gut was saying..open it up! But my desire to keep it virgin said NO!

Even though the 787 and 717 are the same motor..they are close enough in design to guess that sand would get stuck after such an event.

So I think I'll just follow my instinct and your advice...

I'll be sure to post some update pics when I get the top off and look inside. At least it might provide some intel for the next guy. I didn't see much discussion in any of the groups about this issue.

Thanks again..D

 

[AquaEye]

I think this and affirmation I needed. My gut was saying..open it up! But my desire to keep it virgin said NO!

Even though the 787 and 717 are the same motor..they are close enough in design to guess that sand would get stuck after such an event.

So I think I'll just follow my instinct and your advice...

I'll be sure to post some update pics when I get the top off and look inside. At least it might provide some intel for the next guy. I didn't see much discussion in any of the groups about this issue.

Thanks again..D

One more item I would like to share to you & maybe others. Me thinks you already know this..
Plug reading.
Down in my neck of the woods we have the good fortune of having the " non ethanol" gas ranging from 88 to 92 octane.
I have always used a metal hole saw to remove the threaded housing around center electrode as to get accurate optics of the "burn" @ the base. On the dual carb engines of the past, new plugs> plug chop>discern reading>adj>new plugs> plug chop, etc. I've gone thru as many as a dozen sets of new plugs to get that perfect burn. Expensive? Yep. Pay off? In spades.
Also on dual carbs I use pin gauges to set the plate gap on both carbs @ idle position, Pins drop stimulatingly when opened, tighten linkage. One & done.
Anyway, I myself will be concluding this Deep Dive project into oil delivery amounts soon enough. The tough part will be editing the YT video into a cogent, discernible video so as to share with others & make some sense. Lubrication is paramount. Fuel ratio soon after then single malt Scotch.

 

[dougamclean]

One more item I would like to share to you & maybe others. Me thinks you already know this..
Plug reading.
Down in my neck of the woods we have the good fortune of having the " non ethanol" gas ranging from 88 to 92 octane.
I have always used a metal hole saw to remove the threaded housing around center electrode as to get accurate optics of the "burn" @ the base. On the dual carb engines of the past, new plugs> plug chop>discern reading>adj>new plugs> plug chop, etc. I've gone thru as many as a dozen sets of new plugs to get that perfect burn. Expensive? Yep. Pay off? In spades.
Also on dual carbs I use pin gauges to set the plate gap on both carbs @ idle position, Pins drop stimulatingly when opened, tighten linkage. One & done.
Anyway, I myself will be concluding this Deep Dive project into oil delivery amounts soon enough. The tough part will be editing the YT video into a cogent, discernible video so as to share with others & make some sense. Lubrication is paramount. Fuel ratio soon after then single malt Scotch.

Cool..the plug cut technique is new to me. But then I've never gotten into "fine tune" carb setup. I'm more set it..runs good? ride it...!!

The needle drop to precisely setup carb sync I'm familiar with..often use is for snowmobile carb setup. Micro drill bits are my weapon of choice as they offer good size increment choices..

Thanks again and in advance, I'll likely be back with more question.

I just got back into classic Seadoos and have several to cleanup for next season. Projects to keep me from getting bored in the winter months..at least until snow hits the ground and my other 2stroke hobby hits the trails!!

 

[BrianMoore]

Read the operation manual first. It says flush the system on the hose.
Does the beeper work so you get the overheat alarm?
Let's see what the experienced mechanics say. I would blow out all the hoses first and take a look at the orifice fitting before running it on the hose.

 

[BrianMoore]

Watch this

 

[dougamclean]

Watch this

Thanks..pretty useful video, thanks Brian. I understood the principles but his direct explanation helped me to determine where in the exhaust I might check for sand to collect. I'd say the waterbox needs to come out next and get cleaned. I'm betting it's a 'sandbox'!!

I considered it but didn't think simply flushing the hoses would get any significant amount of sand that has settled in the engine to come out..and for that reason and after talking with AquaEye, I decided to go full exploratory!!

I spent this morning doing this and I've done and learned much!!

...here are some pics!!

1st the top of the cylinder head had quite a bit sitting in the valley..not a great sign I thought!

2nd.. once I took the head off there was at least 1 inch of gravel on the intake side of the cylinder jacket(a bit tough to see in my pic as the water in there was reflecting my light).
Additionally the very small passage between the cylinder and both sides of the jacket were full..prime spot for an nasty choke point and engine hotspot!!

Using my vacuum cleaner, a small slim screw driver and about an hour of patience, I sucked all the debris out. I was happy I had a gasket set on hand as it allowed me to clean the head and cover, replace the seals, and reassemble without having to wait for parts to arrive..

So in closing..I'm really going to say I VERY much recommend to people who buy a machine that has been beached to any degree to perform this service.

Particularly easy on the 587/657/717 as the engine sits directly vertical in the engine bay...it's actually quite easy and if I'd been a Youtuber, I'd have recorded and shared it.

I'm sure there are a lot of people that could benefit..I'm sure there are those out there that have blown a piston for no reason just to take it apart and find what I did, a sand packed cooling jacket that hot spotted and burned the piston up. I'm happy I got ahead of it!!

Total work time is about 2,5 hours, a new gasket set and your torque wrench to resecure the cylinder head after..a good piece of mind once done.

I'll still be replacing all the small hoses and figuring out how much of the exhaust I want to remove..starting with the 'waterbox' looking for accumulated sand.(I'll update what I found there too..)

 

[AquaEye]

Right on!
Going full measure pays off.
Good catch!

 

[dougamclean]

Right on!
Going full measure pays off.
Good catch!

Agreed..full report. Exhaust was completely clear so nothing to worry about there..

The water outlet lines were badly plugged. I cleared the transparent lines and replaced the black lines with transparent to allow for visual condition check and flow when running.

I think my work is done here!! On to the next thing..hopefully this helps someone else here in the future.

I will certainly be adding it to my 'to-do' list whenever I buy a used Seadoo. It's cheap insurance for sure and easy to do...