upper bypass passage gaskets leaking?

[jriegle04]

1985 Johnson 150GT J150STLCOH
I have what appears to be gas/oil mix on the engine block. It looks like it is coming from the upper bypass gaskets on the port side. Is this a reasonable assumption? I have been noticing a performance decrease with a lot more than expected gas oder coming from the engine after a WOT run. I have also been having a lot of sluggish acceleration. I just rebuilt the carbs, upgraded from VRO to OMS, replaced the stator, power pack and 1 coil on that side and all spark plugs. I can't seem to figure out what is going on. Compression is all within 10% all being above 110psi.

 

[Dhadley]

Re: upper bypass gasket leaking?

Re: upper bypass gasket leaking?

It's not unheard of for a bypass cover to leak but certianly not common. When you pull it off just make sure the block is still straight so a new gasket will seal.

 

[jriegle04]

Re: upper bypass gasket leaking?

Re: upper bypass gasket leaking?

could this cause the engine to suck air and create the previously stated symptoms?

 

[Dhadley]

Re: upper bypass gasket leaking?

Re: upper bypass gasket leaking?

If the air leak gets bad enough it can cause piston damage on that cylinder. Yes, it can lead to bad idle and sluggish acceleration. Just depends on how bad the leak is. Any leak is too much.

 

[jriegle04]

Re: upper bypass gasket leaking?

Re: upper bypass gasket leaking?

new gaskets are on their way. i will be taking it apart tonight. i will be looking cylinders over for wear marks. any ideas on how this happened?

 

[jriegle04]

Re: upper bypass gasket leaking?

Re: upper bypass gasket leaking?

i have removed the top bypass passage cover and it is definitley where the fuel on the block is coming from. it looks like the bottom 2 are the real leakers. i was going to remove all the covers on the port side then i decided i should wait until the new gaskets come in so i dont get any contamination on the crank. i put the other cover back on and will be patiently waiting for the gaskets to get here. i had never heard of this problem until i discovered the fuel leak. any input on this would be great.

 

[Dhadley]

Re: upper bypass passage gaskets leaking?

Were these covers ever changed?

 

[jriegle04]

Re: upper bypass passage gaskets leaking?

they are still painted white and the gaskets have the Johnson white paint on them also. the starboard side still looks good. the engine did get a rebuild before i bought it. i know the rings were replaced but not sure what else was done.

 

[emdsapmgr]

Re: upper bypass passage gaskets leaking?

Was there any evidence of gasket sealer on the cover gaskets?

 

[jriegle04]

Re: upper bypass passage gaskets leaking?

i am not seeing any. i have only removed the top cover. i will be removing the other 2 on that side wednesday when my gaskets come in. should i use gasket sealer on it with the gaskets when i put it back together? i always thought the gasket was enough.