detontated cylinder

[EuropeanAM]

Should use Dawn Dishsoap on the impeller.

Grease or oil on the thermostat... I would be inclined to go back and recheck it after running it.

[fscott1520svx]

good morning. i am still having water pressure issues. at any speed above idle pressure is way too high. at 4000 to 4500 rpm just cruising on plane at about 3/4 wot my pressure is jumping around from 35psi all the way to 50 psi. i haven't hooked another guage up to it yet to double check it but i really think the guage is correct or close anyway. i actually think i may be reading engine compression from somewhere. i pulled the head on the port side and found water contamination in 4 and 6 chambers. 6 had a small tear in the o ring gasket so i replaced all the orings and the outer seal. i ran it sunday again and water pressure is still high. i did notice that the guage is running almost parallel with the tachometer; both needles moving almost together it seems. maybe electrical? the engine is not running hot but i also haven't run it hard at all. i am afraid to push it all the way to wot for fear of catastrophic failure. even after a 10 or 15 minute run at 3/4 throttle i only have a sporadic amount of water from the tell tale; never a steady stream as one might expect. lets assume i am reading compression from somewhere; it would have to be from the piston chamber correct? or could it be on the exhaust side after leaving the chamber? i am scratching my head on this one before i tear it down completely again. any help is much appreciated. thanks.

[fscott1520svx]

oh and there was no more oil residue on the thermostats when i rechecked them.

[leonreno]

The water pressure gauge is not electrical so that is not possible. Water in the block pushes against the air in the line that pushes a spring in the gauge that moves the needle. Water in the cylinders is really bad and you need to make sure you fixes that problem before anything else is done. Possible that exhaust or combustion gas is leaking into the water chamber causing the problem. Could be head gaskets or gaskets in the divider or exhaust plates. You should also check your gauge for accuracy. I bought a cheap air pressure gauge at hardware store, the kind use on air compressors and screwed on a barb fitting and tested it with the line off the motor. Don't know if you have checked but I would check your poppet valve too.

[JOE54]

leak down test will show if cyl o rings are leaking/did you replace all 6 ??????

[EuropeanAM]

leak down test will show if cyl o rings are leaking/did you replace all 6 ??????

[fscott1520svx]

good morning. yes all head gaskets were changed and exhaust divider plate gasket and tube seal has also been replaced twice. performed the leak down test. #6 is definitely bad. 25% loss consistently. i have removed the head again. i can feel a small rough spot on the cylinder wall now so i am sure at the least i will need to hone it and put new rings on minimum. how do i determine if the o ring seal in the head is also bad? i am getting water inside the cylinder and my water pressure is still running between 30 psi and 50 psi at any rpm over 2000. the sleeve installed in #6 is also not flush with the block. one side(the outside as facing the motor) is flush like it is supposed to be but the inside from about 1 o'clock to approximately 6 o'clock gradually protrudes to .011 at highest point above the deck. i intend to try and shave that off down to flush as it should be. assuming that is where the water is getting in and the combustion pressure is getting into the water system; the new seals should solve the high water pressure problem. if it does not then where else can combustion/exhaust pressure be getting into the water system? is the interference between the sleeve and the block considered to be air/water tight sealed? maybe the head gasket is bad and on the up stroke the piston pushes cumbustion gas past the seal and the down stroke creates a vacumn and pulls some water into the cylinder? is that possible? just searching for some ideas here. i know it has to come apart but taking it apart for new rings and to reset the sleeve may not cure the problem if it is an unseen crack in the block somewhere. is there a way to determine if the block is solid? any help is greatly appreciated. thanks.

[fscott1520svx]

update. i pulled the head and shaved the sleeve in #6 so it is perfectly flush with the block. installed all new head gaskets and the outer seal. lifted the powerhead up and installed a new gasket under it, installed another new exhaust divider plate gasket. installed another new poppet valve kit. cranked the engine on muffs and water pressure still high. all i get out the tell tale is spits and sputters of water mixed with lots of air. i pulled the spark plug on #6 and cranked the motor and a steady spray of water is coming out of the spark plug hole on every compression stroke. how is it getting into the cylinder?

[leonreno]

If you had to shave part of the sleeve off my guess is it much more damaged than can bee seen. I would maybe some type of penetration dye to see if you can find a crack in the sleeve or the head or block.

[EuropeanAM]

You have poor adhesion between the sleeve and the block (parent casting). Surrounding that sleeve are intake ports, and above that is a COOLANT port.

Somewhere in the circumference, there's a LEAK. Otherwise, it would HAVE to be a fracture in the sleeve, over the water jacket.

You need to a get a machinist that's well versed with these 2-stroke blocks/sleeves to pull that sleeve and inspect for the problem (and what might be able to be done to correct it).