1994 Mercury 40hp 4 cyl wrong crank case sealant

[paulywally]

Trying to figure out my problem on a 1994 Mercury 40 hp 4 cylinder. I replaced a piston and got all the cylinders honed by a reputable machine shop. I put it back together and used "loc-tite high flex form in place gasket maker" http://www.henkelna.com/product-search-1554.htm?nodeid=8797881860097

So it ran great for about 5 minutes on the muffs. Checked compression and had an even 130 psi across all 4. Took it out on a little fishing excursion and after 5 minutes under load it died. Took it home checked compression and compression was between 80 and 100 psi uneven across cylinders.

Now I know this sealant is an anaerobic sealant which means it won't unless there is an absence of oxygen. I do have uncured sealant on the outside of the cases and I did allow sufficient drying time.

So compression is low, at first I thought it was a fuel problem but I took the carbs apart and they are working properly. spark plugs aren't wet, and have spark.

So will a failed crank case seal cause low compression? I'm having trouble remembering my two stroke theory properly to figure it out myself.

Any words of wisdom?

Thanks.
Paul

 

[paulywally]

No one has ever has their crank case seal leak?

 

[racerone]

Volunteers provide you with answers but you have to show some patience on here.-----No the wrong sealant has nothing to do with compression in the cylinder.-----The wrong sealant can however have too much filler in it.----The joint on the case is a metal to metal fit and the correct filler will almost all squeeze out.----That is needed to get proper clamp-up of bearings and reed valve assemblies.----And did you correct the problem that caused the failure of the piston ? ----Did you replace the waterpump impeller ?---Running with 50:1 oil mix ?

 

[paulywally]

Ya I know I'm being impatient. This thing is just frustrating me. Yes I fixed the problem that caused the failed piston. Yes I was running a 50:1 mixture, and yes I redid the water pump impeller.

Tonight I'm going to try a different compression tester and if that doesn't work I'm going to pull the power head.