1990 V4 90HP Johnson finally ready for crankcase cover assembly

[havoc_squad]

I've finally was able to get all connecting rod caps properly aligned and 100% torqued to factory spec, the crankshaft moves with no binding or weird anomalies that I could see/feel.

The delay was mostly because I got overly concerned about not doing anything to put a mild port edge chamfer on the vertical areas (600 gentle hand sanding the edge a small amount) and had to re-do everything (clean the block, re-insert crankshaft and pistons, etc). Then life got in the way to add to the delay.

The cylinders are all used with factory/std bore and might have not needed chamfering or was less of an issue than a bored/oversized cylinder.

Anyways, here are the following questions that the service manual does not address that I want to make sure are correct:

1. Is the attached photo a correct pattern for the gel-seal? (Marked in red) If not, please provide a revised image with the correct placement.

2. Just to confirm, the taper pins are tapped/pushed into place from the top of the crankcase cover down towards the block, with the fat end of the pin up and the narrow end to be driven in?

3. Is there anything extra I should keep a look out for when the cover has been properly installed per service manual? I did see a section that says when checking the crankshaft after the cover installation is done, to hit the top of the crankshaft with a soft mallet up if binding is experienced.

I think that's all the questions I have until I get the powerhead 100% sealed up properly.

 

[racerone]

Did you replace the wee check valve for the center main bearing ?----I know it is expensive but ?

 

[ct1762@gmail.com]

on the check valve... i've always just blown into it to make sure its clear with a 1/8'' hose or a hose attached to a syringe. is there some reason it should be replaced?

 

[havoc_squad]

Did you replace the wee check valve for the center main bearing ?----I know it is expensive but ?

No, I did not. I do not believe it was listed in the items to replace (must replace) when I asked here previously about a checklist of things not mentioned in the factory manual for putting the powerhead together.

This motor was running when taken apart for the purpose of resolving stuck piston rings, not major damage to cylinder, pistons, bearings, etc.

Cylinders were in spec, they just needed new piston sets, de-glazed cylinders, and the normal changed items.

All the factory service manual said regarding that was to blow low pressure compressed air (less than 25 psi) after cleaning the block. I did with 15 lbs of air pressure and I don't remember hearing any air escape.

If I understand that main bearing check valve correctly, that's it's job. Allow it in but not to escape out correct? Any way to check it without removal?

Even the re-circulation system servicing section does not cover anything about this part in the fuel section.

Although the center bearing cap was not removed for inspection, there was no warning signs shown of bearing damage. (movement noise/friction/discoloration).

Regarding this overall, I'm getting very frustrated getting burned by the factory manual with no documentation for testing/diagnosing this center bearing check valve to determine whether it needs replacement and no data on the tools required to remove it and replace it.

This will be the 3rd re-work I have to do to take this apart and keep wasting more money because I keep getting bad data or omissions on what it takes to get it done right.

 

[racerone]

And why did you not remove the center main bearing ?-----You remove the spring clip and the bearing falls off the crankshaft.----Just as easy to put it back on too.

 

[havoc_squad]

And why did you not remove the center main bearing ?-----You remove the spring clip and the bearing falls off the crankshaft.----Just as easy to put it back on too.

Several reasons:

1. Top crankcase cover/crankshaft bearing and the crankshaft surface for that bearing looked and moved excellent with plenty of oil, no excessive wear marks, no noise, no slop, and no corrosion. Looked almost textbook perfect for a used motor when I pulled the cover off the top of the crankshaft.

2. Center main bearing when crankshaft was removed had plenty of normal looking two cycle oil that came out and looking via the indexing dowel hole showed no signs of rust or overheating

3. Bottom bearing housing was not removed for inspection, but bearing behavior was like the top and center.

4. The motor never exhibited ANY symptoms when running of sounds of a worn out or damaged bearing.

All those points gave me reasonable confidence that there was no need to take off the center bearing or separate the bottom bearing housing from the crankshaft.

If I must revisit that matter about the center bearing, I will.

However, could I please have a detailed answer about the center main bearing check valve diagnostic procedures and the tools required for removal and replacement.

The more details and visibility about it, the better.

Where the flow of oil comes from, right and wrong behaviors of it, symptoms of it not working, etc, etc. etc. (I know where the top and bottom bearings get their oil from, but not the center)