gasket problem

[Aquanut1]

My 1990 150 johnson has a small leak under the power pack on the crankcase.The leak is about a quarter of an inch long and the only reason I saw it is because when it coughs it blows a small puff through the hole. The marina where its being looked at now says that I will blow the motor if I don't fix it...is that true? Ofcourse they'll have to split the powerhead to get to the gasket. Im being told that it's going to be $1000.00 or more in labor. That sounds like a milking. My question.... Is that a high pressure area? and can I seal that from the outside with marine tex or liquid steel?

 

[angus63]

Re: gasket problem

Are you talking a crack in the block? A hole on the block? Or an existing thru the block fitting that is leaking? Can you better pinpoint the location for us. What gasket are you referring to? How did the marina explain the cause of this?<br />I think you'll find that a weld, braze or JB Weld may be a viable and much less expensive solution. Please provide a picture if possible.<br />Good luck

 

[Aquanut1]

Re: gasket problem

I was told it was the crankcase gasket and it's leaking on the starboard side under the powerpack. It's in an easy place to repair if I could do it from the outside. I didn't know if the crankcase has pressure to stop me from doing and outside repair seal. The boat is at the dealer now so I cant send any pictures but it's on the same lateral line as the lowest spark plug..I know opening up a 15 year old motor will bring in a whole new bunch of problems and money.

 

[R.Johnson]

Re: gasket problem

It sounds like you are discribing a leak between the crankcase halves. This is sealed with a gasket type sealer, not a gasket. The puff of smoke you see is a lean fuel spit-back affecting #5 cylinder. To repair this,the engine must be split at the case halves, all surfaces throughly cleaned, and resealed. You would not want to tear an engine down to this point without checking all other components, as the engine will be in a state of almost complete disassembly. That is where the $1000 cost came from. A leak of this type is very hard to seal from the outside, as the leak seem's to just form a new channel. I won't say it can't be done, I just have never seen any success with it. A lean condition to a clyinder can cause damage. Have you notice'd a backfire with this engine? The reason I ask is because I'm wondering what caused this seal to blow out.

 

[Aquanut1]

Re: gasket problem

Havn't had the boat long, been out 10 times on it. It's a 1990 nitro 2000 w/ GT 150 and since i've had it I had only heard cough/sneeze at idle. How can it run lean from a crankcase gasket?<br />I never had a backfire on it. Could that mean the rings might be bad? Thats the only time i've seen pressure in a crankcase. Im new with boat motors but good with cars. thx for helping guys

 

[angus63]

Re: gasket problem

C:\Documents and Settings\Administrator\My Documents\My Pictures\two-stroke_c.gif<br /><br />This, if it works, will demo how the crankcase is charged with air/fuel/oil mix. A leak will draw in excess air which yields a lean mixture, hence the coughing/sneezin.<br />If the .gif doesn't work, post an email address and I'll send it to you. Blowby in the rings doesn't really apply in two-strokes like four strokes.<br />You can get a manual at www.theoutboardwizard.com that will illustrate the whole motor.<br />As far as sealing the motor, It's a gut-check call. You can prep and JBweld and it may hold. Or it may fail and burnup a cyl. You can tear it apart but be prepared to dump your wallet on the counter after 15 yrs of worn parts are inspected, and you do'nt wanna do that twice!!!!<br />Maybe some others with more experience will chime in.<br />Good luck<br /><br />Edit: Post did'nt work, I'll try again later when the darn phone stops!!!!!!

 

[Dhadley]

Re: gasket problem

One outside chance thing to look at. <br /><br />Look at the by-pass cover. If that gasket leaks it'll sometimes fool you into thinking its the block halves leaking. Trust me.<br /><br />One other thing -- look at the cast in number on the cover itself. Then look at another cover that exactly like the one that is near the leak. There will be 2 types of covers. Ones with threaded bosses and ones without any bosses. Compare numbers on 2 that are alike.<br /><br />What we're concerned with is the motor sucking air and leaning out a cylinder and damaging a piston.

 

[Aquanut1]

Re: gasket problem

The dealer says that Jonhson hads problems with this sealant used to join the halfs. I looked in a Clymer manual, it is the crankcase halfs union. I was hoping I could seal the leak,keep an eye on it and use it for a year or 2, then a new/rebuilt powerhead. I get more info and confedence from you guys than the machanic working on it. thx all

 

[Dhadley]

Re: gasket problem

We've not seen any problem with Gel Seal other than if someone left the cap off for 6 months and then used it without testing it.<br /><br />Look real close at the by-pass cover before you go dumping a bunch of money into something thats not needed. And theres a reason for looking at the casting numbers too.