Gremlins in my 93 johnson!

[Greg Lawrence]

Ok I have a 1993 Jhonson Pro Tracker Series 60hp that was overhauled and got new fuel and water pump, new pistons, sleeves. ditched the oil injection so i mix my gas, heres the problem. runs fine on the water hose, put it in the water, it runs great, open up the throttle to WOT, then i back off some, the motor starts losing power and the rpms sound like im at 1/4 throttle even thought the controls are WIDE open. pull the spark plugs the first time this happened, there was a small puddle of water next to the piston, i check my gas, and theres water all in my tank.. so i get a spare tank fill put in a gallon of fuel and run that small amout of water out in the drive way... so i figure it was my fuel was contaminated and dirty.. ok, so i dump and flush my tank with methanol, and put in some fresh gas and mix it a little rich. put it in the water today, and it loses power after wot,same symptoms. however there is no water in my fuel tank this time.. like i said it runs great on the water hose with no water pressure around the motor.. could water be getting in somewhere? could water be getting in the head somehow? i know it is not comming from the fuel.. i know it is nto the same on the water hose as it is in the water, i wouldnt put it in gear on the water hose.. heh anyone have any suggestions?

 

[Hooty]

Re: Gremlins in my 93 johnson!

Yo Greg,<br />Do you have the factory-recommended plugs? If so,when the engine does its slow-down thing, shut it off IMMEDIATELY and pull the plugs, keeping track of what plug came from where. Are the plugs wet or dry. Are they real clean or are they tan or black or what. The plugs will tell the story. Let us know what they look like.<br /><br />c/6<br /><br />Hooty

 

[BKool68]

Re: Gremlins in my 93 johnson!

Your carb bowls may be full of bad gas still. You might want to yank them and clean them out.

 

[Greg Lawrence]

Re: Gremlins in my 93 johnson!

oh boy... just pulled the plugs and got out the ole compression tester, top has 140#, middle has 105#, bottom has 140#, so evidently i lost compression on the middle cylinder and water is getting in there.. could it be a head gasket? the water had nowhere to go except blow out the head gasket? surely it hasnt cracked the head or the cylinder walls? are the heads on a boat the same as a car where the water jacket surrounds the head? and as is common with ford 302, you blow from a cylinder wall to a water jaket? being that is the thinnest point? never been into a boat motor, my experience is with ford v8's and stroker motors! wish i could put on o those on my little aluminum boat! he he! anyways back to the boat! help!

 

[Greg Lawrence]

Re: Gremlins in my 93 johnson!

oh forgot to mention, i just put my air compressor to the line comming from the fuel pump and blew out all the gas in the carbs and lines, then i put the air blowing like one blows over the mouth of a coke bottle and the fuel came flying outta the carbs in a fine mist, to bad no one was around to light up a cigarette at that oppurtune moment! so i guess the bowls are where the fuel comes outta the bottom of the little straw lookin thing?

 

[Greg Lawrence]

Re: Gremlins in my 93 johnson!

oh yeah, this motor ran perfect for a year, till now, i had run 25:1 for probly 10 hours! and i did a "real" break-in. that puttin along and not runnin wide open sort of breakin, that suxors. anyways. it all started when i filled up at that **** texaco.

 

[Hooty]

Re: Gremlins in my 93 johnson!

One more time.What did the plugs look like??<br />If your getting water ia a cylinder that plug will look different than the rest. It will be real "clean" lookin'.<br /><br />c/6<br /><br />Hooty

 

[Greg Lawrence]

Re: Gremlins in my 93 johnson!

yeah the middle plug was a little cleaner than the rest...

 

[Joe Reeves]

Re: Gremlins in my 93 johnson!

Greg..... Water could enter that center cylinder via the head gasket or the exhaust baffle plate. However, due to the compression drop on the center cylinder, the most probable cause would be:<br /><br />1 - A uneven or flawed block sealing surface.<br />2 - A warped cylinder head.<br />3 - A faulty head gasket.<br /><br />The faulty head gasket is usually caused by not torquing the cylinder head properly to 18/20 foot pounds in the proper sequence (the bolt holes are numbered).<br /><br />Running that engine will just make matters worse. Remove the cylinder head and look for the cause.<br /><br />If someone else rebuilt it, Let them do it under warranty.

 

[Greg Lawrence]

Re: Gremlins in my 93 johnson!

ok heres an update, pulled the head, not a blown head gasket. odd thing is there is carbon buildup on three pistons. BUT there is no carbon buildup on the head, none on all three chambers? the motor has been run maybe 15-20 times last year, what the heck is goin on! can water enter anywhere other than the head surface? Yeah the guy who rebuilt it pulled the head, he going to try it out tommorrow with a new gasket, we drained the bowls and flushed the gas in the lines again, caught it all in a bottle, no sign of water... hrmm.

 

[DJ]

Re: Gremlins in my 93 johnson!

Greg,<br /><br />Water leaks into the combustion chambers are sneaky sometimes. The gasket may look good, yet a new one with proper torque fixes the problem.<br /><br />One thing that very few people do on a new engine or rebuild is re torque the head bolts after the first run cycle. A lot of head gasket problems could be avoided if folks would do that.

 

[Greg Lawrence]

Re: Gremlins in my 93 johnson!

wouldnt you be able to see where the water was leaking thru on the head gasket? yeah nothing was retourqued... hrmm.being aluminum what the max tourqe i could put it at?<br /><br />Thinking about my compression. the only things that i can think of that would cause a drop like that is a gasket, or a cracked cylinder? but if it had overheated, wouldnt the pistons show scars and melt? the pistons are the same as day one. with minimal carbon buildup is what gets me.<br /><br />tommorrow were going to do a new gasket and see what happens.. do compression after the gasket to see if that helps.

 

[Greg Lawrence]

Re: Gremlins in my 93 johnson!

BTW how much can you mill off a head to bump up the compression? whats the max psi you can run? as always im always trying to find a way to squeeze out some extra horse power. i wonder how strong the stock rods are. i know some jetski racers mill off .080 and run 185psi - 205psi... think i could bump up to 160 on the motor? or would that be beyond the limits??

 

[Joe Reeves]

Re: Gremlins in my 93 johnson!

Greg..... The head bolt torque is 18 to 20 foot pounds. The bolt holes are numbered for the proper tightening sequence.

 

[Hooty]

Re: Gremlins in my 93 johnson!

Yeah, and Greg, if you're gonna run pump gas, better stick to the stock compression ratio. <br /><br />c/6<br /><br />Hooty

 

[DJ]

Re: Gremlins in my 93 johnson!

Greg,<br /><br />I had a V-4 that popped the gasket and I could not find the leak point. I probably could have fixed by retorquing, but I decided to replace the gasket instead.<br /><br />Forget about milling the heads. There's more to a performance boost than that.

 

[fireman 757]

Re: Gremlins in my 93 johnson!

Milling those heads will cause you more problem in the long run. If you want more horsepower then buy it. If you stay with your factory specs and treat it halfway decent this engine will last you a long time. Look at Joe's replies, he really helped me and I think it's great that a 30+ year OMC man is on this site. That kind of experience at the dealer costs you 65.00 an hour.

 

[Greg Lawrence]

Re: Gremlins in my 93 johnson!

when i pulled the head, it looks like the ring might have been damaged? there are some light scratches on the cylinder wall that will need to be honed out.. guess it has to get pulled apart. Those fish sure are lucky. this will spare them another week..