Nearly ready to put my engine back together and I was wondering what liquid sealer works best on the crankcases where its required? Also its going to be a long rebuild process so I was wondering what oil would be best to use to prevent any surface corrosion during the build phase.
I spent a couple of hours researching this question so here goes-
Engine case sealers- There are 2 types of case sealers -
Anaerobic sealers which are solvent based. They cure quickly roughly 20 minutes from the time of initial application until fully cured.. Put the sealer on 1/2 of the joint (they don't tell you how or supply an applicator), put the 2 halves together and torque to final required torque. You can then add your fluids and crank her up. Sealants in this category are 3 Bond 1100 series , Yamabond and Hondabond and for the record the Yamabond and Hondabond are 3M 1100 series sealant packaged by 3M for Honda and Yamaha. The prices I found for all 3 range around $40 CDN per tube. (Not cheap)
Permatex also makes an anaerobic sealant they call Motoseal and their advertisement states it's specifically for 2 stroke and 4 stroke crankcase sealing. It also has a cure time of 20 minutes (identical application as the previous three sealants ). Motoseal sells for $13 CDN a tube (Canadian Tire)
Moisture cured sealers - This category of sealers initiate the curing process by exposure to the humidity in the atmosphere. The instructions tell you to apply a bead of sealer to 1 half of the joint, then install and tighten down the fasteners until you see the sealant start to squeeze out of the joint and then stop tightening. You then have to allow the humidity in the air to initiate the cure. They suggest that it will take about 2 hours for this to happen and you need to check the sealant that's squeezed out of the joint and see if it's tacky. If not wait longer. Once tacky, you can then tighten down your fasteners and torque up. You must then allow 24 hours for the sealant to cure before putting in any fluids. An example of this type of sealant is Permatex Ultra Grey Sealant. It's also $13 per tube.
As far as how much sealant to use- Think about it. Once assembled, the 2 halves will be tight together so for the most part, if you cleaned your case halves properly, there will be less than .001" to fill in with sealant and more than half of the sealing faces are less than 6mm wide, so how big a bead do you need to apply? I'll suggest that a bead of 1.5 mm (.060") or 1/16" is more than ample. the crankcase is not under pressure so as long as there's no skips in the sealant bead, you'll have more than enough to seal this joint.
So bearing all this in mind I've decided to go with the Permatex Ultra Grey Sealant If I were to use one of the Anaerobic Sealants like 3m or Hondabond or Yamabond when looking at the surface to be sealed and trying to imagine painting on the sealant with a brush, I think first how consistent could I be with the thickness of the sealant with a brush because the last thing I want is excessive sealant squeezing out of the joint and ending up in the crankcase which will break off and end up in the oil pump strainer screen.
Second, with a cure time of 20 minutes, I'll spend half of that just putting the sealant on the joint, then as the case halves go together, you have to engage the shifter forks into the gears on the secondary shaft and the final drive shaft, then once the two halves are together, install and torque 37 bolts on the lower half then flip the engine over and install the remaining 10 bolts and torque. I fear that some of the sealant may cure before I get the assembly all torqued up.
The Permatex Ultra Grey sealant requires you to lay a bead on one half and I feel that I can lay a bead of about 1.5 -2mm in diameter along the face that's to be sealed and I'll be able to tell if it's too thick or too thin before assembling and have time to fix it if I have to. then I have 2 hours minimum to get the 2 halves together and install all the bolts on the lower half and get it assembled just enough to start the squeeze. A couple of hours later, finish torquing the bolts on the bottom then flip it over and install torque the 10 top bolts. I'm in no rush to fill the crankcase and fire it up so I want to be able to take my time and get it right the first time.
Second question - What oil to assemble with to prevent surface rust.-
I pulled my engine apart last week after it had been sitting in the garage with the cylinder head off for the past 5 years. I feared that the pistons might have stuck in the bores during that time but everything was fine. I had had the cylinder block off about 8 years ago and after a hone, reinstalled the cylinder block and at that time, knowing that I would be using Shell Rotella T6 engine oil, I assembled the cylinder block by wiping the bores with Rotella T6 and installing. I also had dumped the original engine oil and left the drain plug out for a week to get all the oil out of the crankcase after which I reinstalled the drain plug and dumped 4 liters of oil into the crankcase and rolled the engine over several times to wet everything inside. I had to move houses a year later which meant packing everything up and moving, so at that time, I dumped the engine oil again so that I wouldn't have to worry about a mishap. Bottom line- After this engine had been open to the atmosphere for the past 7 years, everything in the crankcase looked brand new. Not a spot of surface rust anywhere.
So my advice here is to assemble your engine with whatever engine oil you plan to use once you fire it up and not worry about the possible surface rust that you think may happen. My experience here is that it's a non issue.
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