M18 Oil Pressure issue

[Gompers]

Originally Posted by ol'George

I can't tell you if the last Kt blocks were the same as mag blocks as I don't have a late kt block to compare to a mag block.
I do know they eliminated gaskets and went to RTV sealant,and caution that if the pto cover had a gasket, to reinstall with one.
That would indicate the .020 or so gasket thickness, was taken care of in the cover, not the block.
I personally don't think it is critical as far as the cover with or without a gasket.
I think the series 2 had the thick webbing but can't swear to it.
Don't disrespect a series 2 block without an oil filter provision.
Production went to many manufactures that didn't request/require it so it was not provided by Kohler.

The jugs on the late mags went to a *30 valve & seat angle.
Also the right & left jugs were different in at least 2 ways.
One for a magneto mounting, also a hardened valve seat for the exhaust valve.
So while the jugs will bolt on, they would not have the correct valve seats and the mounting holes for magneto mounting.
IIRR also the camshaft has a different part number for the *30 valves
it is covered in the service manual.
But again I don't see why either cam will not work in either magnum block.
other than the mag cam has no lobe for ignition point activation if installed in a kt block.



.

Currently sitting on about 10 complete KT17s. 2 series 1s and 8 series IIs.

I have about 50/50 oil filter blocks and non-oil-filter blocks for the series IIs.

I just snagged a KT a couple weeks back that has a 1997 serial number on it (oil filter block), so they must have made both the M18 and KT17 at the same time for quite a while. It doesn't look any different than my other KT SII oil filter blocks, but I'm not going to tear it down to find out since it allegedly runs really well. Just seems like it would be a waste of resources to keep two different castings around if you're making basically the same engine.

I seem to recall in the M18 service manual that the jugs were swappable until the 30* valve change. The bosses are on even the KT jugs for the magneto mount, but they'd need to be drilled and tapped obviously .

[mobermiller]

Thanks so much for the interesting discussion on the KT series and magnum series engines.

After a closer examination for crankshaft side play, I discovered that both sleeve bearings have excessive play in them. This is most likely where most of the oil pressure is escaping from.

If I had only had a low oil pressure light I most likely would have never have discovered the low oil pressure at idle because the light barely flickers. Thus I'm wondering how many other high time engines keep going, going, and going with low oil pressure.

Here is a couple of pictures of the screw dent on top of the piston and on the head. I thought you all might be interested seeing this

[Gompers]

That’s pretty crazy.

There are different sized thrust washers you can get to take out the end play. There is usually very little wear on those bearings though. There were .010 and .020 bearings available but I don’t know how hard they would be to find.

[J-Mech]

Originally Posted by mobermiller

After a closer examination for crankshaft side play, I discovered that both sleeve bearings have excessive play in them. This is most likely where most of the oil pressure is escaping from.

Ok..... so I'm going to call BS on this. An engine bearing has about .002"-.003" running clearance. If it is loose enough that you can literally rattle the crank in it.... the seal would be leaking and you would likely not have any oil reaching the rear bearing. It would have to have a horrific amount of clearance for you to be able to "feel" it. My bet is when you jerked on it, you felt the crank end play, which is normal. If the main bearings were wore enough that you could actually feel the movement in them, you better be looking for another engine because that one may run a couple more hours.

Originally Posted by mobermiller

Here is a couple of pictures of the screw dent on top of the piston and on the head. I thought you all might be interested seeing this

Hopefully you still have the head off. A dent like that will cause hot spots on the piston and the head. You need to take a die grinder or a dremel with a grinding wheel on it and smooth out the dents. Don't make them any deeper, but wider is fine. No sharp/thin spots. Nice smooth sides into the crater. That will keep them from making hot spots and causing pre-detonation. It will be fine with the divets but they need smoothed out.

[ol'George]

On another note, It appears someone has used scotch brite pad on the head.
Not what I like to see for a good seal for the head gasket.
Be sure to use sandpaper on a surface plate or flat glass to restore it flat.
I will not use a scotch brite pad on any machined surface,
I've seen a few surfaces ruined.

[mobermiller]

Originally Posted by J-Mech

Ok..... so I'm going to call BS on this. An engine bearing has about .002"-.003" running clearance. If it is loose enough that you can literally rattle the crank in it.... the seal would be leaking and you would likely not have any oil reaching the rear bearing. It would have to have a horrific amount of clearance for you to be able to "feel" it. My bet is when you jerked on it, you felt the crank end play, which is normal. If the main bearings were wore enough that you could actually feel the movement in them, you better be looking for another engine because that one may run a couple more hours.

Yes, the crank seals were leaking and leaking really bad. I do see severe SIDE play on this crank on both bearings. It's not end play that I'm seeing. This engine is shot. You yourself J-Mech have said in several other posts that magnum engines are not worth overhauling because of the extreme cost of the parts. You have said that they are a disposable engine. I considered buying .010 over pistons from baktforkids on Epay, but when I found the play in the sleeve bearings, I decided no more! You're right, this engine is on it's last leg and may only last a couple more hours. That's why I'm putting it back together and not spending anymore money on this engine.

It's time to lick my wounds and move forward. I got taken on this engine. It was always my intent to find a super and put a command engine in it with the CV joint drive-line. I guess I'll be doing that sooner than expected. In the meantime I'm going to find out how much more this engine can take. If it goes boom, then I still have my 3000 series with a 60" deck to fall back on.

[mobermiller]

Originally Posted by ol'George

On another note, It appears someone has used scotch brite pad on the head.
Not what I like to see for a good seal for the head gasket.
Be sure to use sandpaper on a surface plate or flat glass to restore it flat.
I will not use a scotch brite pad on any machined surface,
I've seen a few surfaces ruined.

I used a wire brush on a bench grinder and also a rotary wire brush on a drill. I'll keep this in mind for future reference. I've always cleaned with wire brushes and haven't had any ill effects from doing so, so far.

I sure thank you for the advice!

[mobermiller]

I wanted to post a follow up to my oil pressure problem.

I had a low time MV14 engine that I had robbed the cylinders off of. I decided to check the sleeve bearings on this engine and found them to be in good shape. I cracked the case on my M18 and found the crank in good shape.
So I replaced the sleeve bearings and checked the rest of the engine. I found the cam in good shape. The governor gear had some play in it so I replaced it as well as the rotor set in the oil pump.

I put it back together and ran it today. When hot I now have 50 psi high speed and 25 psi at idle. Major improvement from almost zero!

We'll see how it holds up over time. Thanks so much for all the help!

[Gompers]

Excellent news. If I recall, there is a slight difference between the jugs on an MV and an M. I can't remember exactly what it is, but I'm sure someone else on here knows.

Also, there is a TSB to "pin" the governor stub shaft. Don't know if you're worried about that or not, but it's something I like to do on my M/KTs.

[ol'George]

The vertical jugs have an oil drain back hole drilled in the spigot, or mounting base if you prefer.
Since the horizontal block is not drilled for a matching hole, there will be no problem.
But if horizontal jugs are used on a vertical engine,(no hole)
the drain back holes will need be drilled in the spigot, or the oil will pool in the valve spring chamber causing too much lube oil remaining in there.