Pressure Problem

[Gnommad]

Hi again, i am starting a new thread because i believe that i have found the root of my problem, and my old thread was going in the wrong direction/nowhere.

i have a 1990 seadoo bombardier, cylinder 1 has 150# of pressure, but cylinder 2 only has 75#, i am going to look at the manual and online to see what gasket needs to be replaced. However if you guys have advice on how to do this quickly, or even just a list of what i will need, that would be greatly appreciated!! thanks again in advance for your help!

 

[Dr Honda]

For a top-end?

you need a base gasket... exhaust gaskets... and if the O-rings for the head, and shell are hard... you will need them too.

As far as the internals... can't tell you since I'm not looking at them.

 

[Gnommad]

ug, took the head off, looks pretty nasty, the #2 piston is all pitted on the top, and the head is pitted heavily as well, it looks like a shear pin got in there based on the pieces of metal i am finding the gasket looked fine... i think its probably the piston rings, if i replace the piston rings, will it run decently with a pocked piston/head? or should i start looking at new motors, or just scrapping the beast?

 

[LouDoo]

With 75psi it's probably more than rings, what it really needs is a new top end, and possibly a rebuild. Post some pictures.

Lou

 

[Gnommad]

and doesnt look pretty

 

[SabrToothSqrl]

let's not also forget that crank is now 22 years old... what's going to happen to that engine with all this new power? (it will 'splode)...

Do it right and overhaul the whole thing to get another 22 years from it.

or don't and lose the crank after a season or two... your choice. (Don't ask me how I know).

 

[LouDoo]

From what I see it looks like a piece of a ring came loose and has been bouncing around between the piston and the head. I guess if and how you fix it is up to you. Sqrl is correct with a 22 year old engine its gonna be hard to predict how much longer the rest of the engine will last.

This is not necessarily what I would do but you might be able to by, for a couple of seasons by just getting a new piston, rings and honing the cylinder. You would need to take it to a machine shop and have the check it. From the picture I think you would be able to reuse the head. Of course the proper and maybe the best solution would be a "new" crate short block.

I realize that this is a 22 year old ski and it depends a lot on the overall condition of the rest of the ski and of course how much you like the ski. To be perfectly honest a 1990 SeaDoo is not worth much on the open market.

Lou

Added: I just went back and looked at the picture, I see no piston wash, this indicates that the motor has been running extremely lean.

 

[Gnommad]

thanks guys! i took the piston housings off, the gasket underneath was fine, untill i ripped it the problem piston actually has some pretty nasty groovs all up and down the sides. this is my first ski, and have yet to have it run.... but seeing as i got it for free, i will probably replace the piston, and run it till it it dies. My budget is pretty tight right now, saving for a house, so i could sneak 50$ past the budgetmaster, but a few hundred to do the job properly would definitely be noticed.

 

[THEREVIVAL]

thanks guys! i took the piston housings off, the gasket underneath was fine, untill i ripped it the problem piston actually has some pretty nasty groovs all up and down the sides. this is my first ski, and have yet to have it run.... but seeing as i got it for free, i will probably replace the piston, and run it till it it dies. My budget is pretty tight right now, saving for a house, so i could sneak 50$ past the budgetmaster, but a few hundred to do the job properly would definitely be noticed.

sounds like me- have a house for a year and a 4 month old. my wife controls the money- thankfully for me i have a father who likes to buy and fix things to i call him my invester he buys stuff i help him fix it and we sell it or keep it depending on what it was and how much we could make

 

[Gnommad]

ok, i found a new piston with rings in the area for 80 bucks, i think i will grab it, we are leaving for vacation tomorrow, so i am hoping i can throw it in, put it all together, and at least get a week of fun out of it...

 

[THEREVIVAL]

ok, i found a new piston with rings in the area for 80 bucks, i think i will grab it, we are leaving for vacation tomorrow, so i am hoping i can throw it in, put it all together, and at least get a week of fun out of it...

If the piston has grooves how are the cylinder walls ? If they are scored your wasting your time with just a piston

Sent from my ADR6400L using Tapatalk 2

 

[Gnommad]

cylinder walls look ok actually, i was kind of expecting them to be all mangled as well

 

[LouDoo]

Can you take a picture of the other piston, the more I think about it the more it concerns me about the lack of piston wash. Could be whatever was bouncing around in there cleaned it up but just to be sure lets check the other side.

Lou

 

[Gnommad]

ok, sorry for the slow reply, got the beast back together the morning that we were leaving for vacation. it ran! for about three seconds then as i was hitting the killswitch it made a horrable grinding noise. i reached down to the pto and could barely turn it by hand, out of curiosoty, i tapped the starter, and it turned right over. i think the starter may be stuck in engage. however, the question i have is this: when replacing the piston, i had the sleve out, and i notoced on the bottom of the sleeve, coated in grease, there were three needle bearings all goobered in grease. the impacts on the top of the cylinder and on the head looked like they were made from a needle bearing as well. when replacing the piston head, how imeritive is it to have ALL the needle bearings? also i saw this http://www.pwcengine.com/products/Seadoo-580%7B47%7D587-Wrist-Pin-Bearing.html
which just looks like a total time saver, so i think i will grab one if i did infact need all the needle bearings in place like i suspect i do...

 

[Dr Honda]

As above... 22 year old crank... physical damage to a piston... it's time for a full, and complete rebuild.

 

[Gnommad]

yea, i saw when you posted that earlier, for the price of a full and complete rebuild, i could just go buy a running seadoo of the same make and model. the question was, do all the needle bearings need to be present, yes or no?

 

[Gnommad]

k, so i decided to just take the motor out of the ski, and open up the bottom, have everything disconnected except the driveshaft, got too dark/mosquitoey.... not real clear on how to remove the driveshaft, it looks like i take the pump and shaft out as one unit, but dont see any clear instructions as how to detach the driveshaft from the PTO, maybe all will be evident when i can see, and am not being eaten alive!

 

[Gnommad]

ok, so, got it all apart, when i took the oil pump off, the motor turned freely! but when i looked at it, it was all grooved up i resumed taking the botom half of the motor apart, and found all sorts of brass shavings and also a fairly good sized brass tooth off the worm gear. so, i am thinking i will remove the oil pump, the question i have is this, can i remove the brass worm gear, and also remove the half circle flat plate thing? i know what you are supposed to do is just remove the plastic gear, but seeing as both the brass gear, and flat half circle plate thing are directly related to the oil pump, and i am going to premix, do i still need to leave them in?