Gas oil mix leaking from block halfs bad???

[Keaten]

My 1986 merc 150 has gas oil mixture leaking from the block halfs.. I've cleaned it before a run and 10mins later it's back again..
My motor some times bogs down after running around 5000rpms.. is that leakage causing lost compression or vacuum for the fuel pump on block or power in general. .. every time I fix one problem another one shows up... but this could be the root cause....

[vnemous]

It needs to be re gel sealed JMO

[Keaten]

Ok sounds good do you think it's a problem like it is... because it doesn't like to run over 4500rpm very long then it bogs down but will run 3000rpm all day..

[TEXAS20225]

well yeah:rolleyes: they are or supposed to be a sealed crank case maybe even left the cork out:eek: fix it it aint nothing but a thang

[albypine]

Mine leaked because someone used a dull chain saw to clean the two 1/2's:leaving:

[capnzee]

The block halves need to be sealed. If they are leaking, you are losing what is called "base" compression. It is the base compression that forces fuel through the intake ports and into the cylinders to be compressed, etc. etc. This same base compression is what is forcing the fuel/oil mixture out between the crankcase halves instead of forcing it into the cylinders. This compression leak will also weaken the effectiveness of the fuel pump. Take it apart, clean the surfaces completely, use the proper sealer and put it back together using the proper torquing technique and engine should "wake-up" if all else is in order. While you have it apart, you might check the reeds for proper sealing.

[Keaten]

Ok thank you very much capnzee6000 that sounds great I want to put some Chris carson or boyesen reeds in anways...

[capnzee]

Chris Carson reeds=probably a good move! Just make certain the surfaces of both the block and the intake manifold have no scars from previous tear-downs and that the surfaces are spotlessly clean.

[Keaten]

Ok will do ..... dum question the power head has to come completely of the mid..or can I just take the front off piece by piece

[capnzee]

I have always told my kids, if there are two ways of doing things (which in this case there aren't) do it the hard way and most likely it will be the right way. This may not be always true, but..the powerhead must be removed, that means pulling the flywheel (requires special tool), then the electronics (stator etc.) then the top and bottom end caps. At this point you can get ready to split the case. TAKE PICTURES-TOP, BOTTOM, SIDES, BUY A MANUAL, CHEAP INSURANCE WHEN YOU START FINDING EXTRA PARTS.

[flabum1017]

crankcase leaks can also cause a lean run and melt pistons............

[mn808gade]

p/head has to come off,top and bottom caps should be removed and THEN front half can be removed/cleaned/resealed and reassembled w/new reeds

[Keaten]

Ok thanks to all.... I've looked it over and took lots of pics and I got it just about ready to pull power head off I've got all the electronics off I've got a flywheel tool all ready...it's just a bare motor now... hope to get it done soon

[FMP]

you might want to take an even couple thou off the front case surface.

[capnzee]

Taking a couple thou off the front case surface will not only ensure a perfectly flat sealing surface but will also increase the base compression which will in turn force more air/fuel into the cylinders. I don't think you will notice any performance change from this modification however, every little bit helps.

[Keaten]

O ok sounds good maybe get the heads shelved a lil bit to I don't know how much to remove

[capnzee]

You can take the heads down to 26cc's safely. Can't tell you how much to take off to get there however.

[Keaten]

I would love to make some more hp but ill whait till i get a 200hp motor ...Ok so I need a new cork kit and what is the best gel sealant is it loctite red gel gasket maker

[flabum1017]

Loctite 518 or OMC Gel-Seal etc......