Challenger 1800, 120psi compression but has oil in cyl.

[mrjimbov]

I just purchased a 97 Challenger 1800 with twin 110hp 800 engines at a bank repo auction. I got it home and charged the battery and noticed the starboard engine cranks over very slow. Pulled the sparkplugs and checked the compression. Rear cyclinder had 120psi, front cyl. 125psi. I noticed oil all over the engine compartment after I checked the front cylinder. I put a towel over both plug holes and cranked the engine and the rear cylinder spit out LOTS & LOTS of oil.
I'm sure this is something that half of the people on here have had happen but I'm new to the SeaDoo's and Rotax engines so I have no clue what could cause this.
If the engine is toast could a motor from a 96 XP 800 be swapped in place of the current motor?

 

[RFoster130]

Yeah that motor is prolly done. I would plan on rebuilding it or getting a rebuilt one swapped for yours.

 

[parrothd]

Probably a bad inner seal....

Get all the oil out and get it running. You may get lucky and have a very slow leak, depending on how fast it happens again, but sooner or later you'll need at least a new crank...

120 psi seems a little low, but since both cylinders are near the same I think you're gauge is a off, but check it against the other engine..

 

[mrjimbov]

Found my good compression tester and the port engine has 160 in both cylinders. The Starboard engine has 170 in the front cyl. and 150 in the rear cyl. I've dumped straight gas into the cylinder but I haven't had any luck getting it started. It acts like it's going to start but then the starter motor stops. And it pumps A LOT of oil out every time I pull the spark plug to put more gas in the cyl.
A friend who once worked at a Yamaha dealership said I should switch everything over to premix and that would eliminate the problem.

 

[Badboyr6]

while premix will help the situation, you might have a problem with your seal. I personally changed my motor and all my 2 strokes over to premix. i dont want to rely of a little oil pump to save the day. You can try switching it over to premix and see if it helps, just take off the oil pump and pull the plastic lever inside, and install. Do it to both motors, and add oil to your gas via a measuring cup and see what happens. Have you checked to see if you have spark? or maybe your plugs are fouled, thats why it wont start..?

 

[parrothd]

Don't listen to your friend, switching to pre-mix will not solve your leaking seal. keep replacing the plugs and try some starting fluid..

 

[mrjimbov]

Yes, I have spark. I tried starting fluid 3 times (very small squirt) and it still doesn't start but I can NOT stress enough the fact that I have A LOT of oil comming out of the rear cyl.

Plan B- I can get a good running (but very ugly) 96 XP for $800. Can I swap the motor out of the XP?

 

[Badboyr6]

if your motor is the same, then yes, but before you go buying a motor, i would try to fix that one first. And if you do decide to buy the ski, make sure compression is an even 150-150


you need to find out where that oil is coming from...have you tried taking the oil pump off? and just premixing it?

 

[ocod]

Yes, I have spark. I tried starting fluid 3 times (very small squirt) and it still doesn't start but I can NOT stress enough the fact that I have A LOT of oil comming out of the rear cyl.

Plan B- I can get a good running (but very ugly) 96 XP for $800. Can I swap the motor out of the XP?

I have a 720 engine which is a little different.

One would be remove carbs and make sure they are rebuilt to eliminate possible fuel issue.

While your there check the rave vavle which is what is different in the
800(787). It has something to do in the exhaust that opens/closes.
Not sure if this makes a difference but there is a great write up of the 787 engine by seadoosnipe

If you remove the oil injection remove intake cover and remove plasctic wheel of ea motor then bolt it back up.
The oil lines coming from the tank w/the filters, remove them from the pump and loop them together.
Leave others connected to provide oil to the RV.
Mix only (purple or brown?) API-TC only.
Not that blue TC3 oil. It is not good for rotax motors.
10 gal = 1qt

Make sure you have FRESH gas.
Don't trust whats in the tank esp if you can't get ignition.

hope this helps getting it running

Don't listen to your friend, switching to pre-mix will not solve your leaking seal. keep replacing the plugs and try some starting fluid..

#7 http://www.seadooforum.com/showthread.php?t=3554

If your going spend 800 bucks for a new ski to swap engines. Here is another choice.
You could send it out to fullbore where he rebuilds your motor for under a 1K and one year warrany.
or get a SBT engine by swapping your bad one and get a 2 yr warranty.

 

[parrothd]

Don't bother with premixing, the inner seals are bad.

You say a small squirt? Take the airbox off, start the boat, open the throttle wide open and spray while it's turning over...

If for some reason the engine won't turn off after you've pressed the stop button or pulled the lanyard pull the choke or full throttle(engine is dieseling).

If it was my boat, I'd take that $800 and either buy a rebuilt crank and new pistons for SBT, and rebuild the motor my self, or spend an extra $200-300 and get a complete rebuilt engine from sbt with a 1 year warranty. Either way you would have a fresh new engine and not some other engine with a bunch of unknowns...

 

[parrothd]

Also, forgot to mention, you may get extremely lucky and have a leaking RV seal. You'll need to perform a leak down test on the lower end. It'll tell you if it's the inner seals leaking or the rotary valve seal(unlikely)...

 

[RFoster130]

Yeah I was thikning if you were gonna spend 800 for a motor that you know nothing about, you can get a rebuilt for a few hundred more.

 

[ocod]

Also, forgot to mention, you may get extremely lucky and have a leaking RV seal. You'll need to perform a leak down test on the lower end. It'll tell you if it's the inner seals leaking or the rotary valve seal(unlikely)...

Don't bother with premixing, the inner seals are bad.

You say a small squirt? Take the airbox off, start the boat, open the throttle wide open and spray while it's turning over...

If for some reason the engine won't turn off after you've pressed the stop button or pulled the lanyard pull the choke or full throttle(engine is dieseling).

If it was my boat, I'd take that $800 and either buy a rebuilt crank and new pistons for SBT, and rebuild the motor my self, or spend an extra $200-300 and get a complete rebuilt engine from sbt with a 1 year warranty. Either way you would have a fresh new engine and not some other engine with a bunch of unknowns...

I thought it was the same..
I thought happens b/c of seal on crank
(rv seal) gets blow by??

 

[parrothd]

There's 2 inner seals on the crank and one outter seal on the brass gear. The brass gear one you can replace without rebuilding the engine, but I've heard its very rare for that to be the cause...

 

[ocod]

There's 2 inner seals on the crank and one outter seal on the brass gear. The brass gear one you can replace without rebuilding the engine, but I've heard its very rare for that to be the cause...

yep I went to seodoosnipes thread and next pic shows bottom end and the two seals..