While the 847typeM sealer is a great sealer, it is truly tough to work with and dries super quick. I wish they would package the stuff in smaller tubes. The OMC gel seal (or 3M equivalent) is much easier to work with, but requires proper prep or it won’t seal properly. I wouldn’t use just any sealer for this job, it is a super important process that is easily messed up. Imagine firing up a freshly rebuilt powerhead only to see bubbles coming out of the crankcase halves….Now the engine has to be split apart again. Once again, the prep is the real important factor here. If the halves are not properly cleaned/prepped, the block halves will be “shimmed apart” just slightly creating crankcase leaks. It might be a good idea to bolt the crankcase halves together “dry” before assembly and check the various flanges for fit with a small feeler gage.
Please forgive me, don’t think I read the original post carefully, thought it referred to sealing crankcase halves….. Seems like we are speaking about clamshell split gearcases…
In that case, my response was partially in error. Never use OMC gel seal on clamshell/split gearcases!
The beauty of the 847 sealer in this application is that it is strong and dries quickly. Keep in mind that the sealer helps keep the spaghetti seal in place during reassembly. In this case, unlike crankcase sealing, it is helpful to lay a very thin bead (yeah I know, tough to do) in the spaghetti seal groove, then quickly install the spaghetti seal and let it dry in place before trimming the ends. The spaghetti seal loves to pop out of the groove, especially during installation. Again, it would be so helpful if they packaged this stuff in smaller tubes making it easier to apply without making a big mess.
I laugh when folks claim that sealing up one of these split gearcase is relatively simple, HA-HA! Sure, most can probably get it back together ok, but sealed up properly, well that is another story. And god forbid you find a leak during pressure testing after assembly, now you must pull it all apart and spend considerable time cleaning out that darn 847 sealer that works so well!
