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Kohler Magnum Vertical Knock/tick Teardown

7921 Views 35 Replies 7 Participants Last post by  Grand Sierra
As some may have read in my other thread in the craftsman forum. My Kohler Magnum Vertical has/had a knock. I tore it down expecting to find alot of wear on the rods. Rods and pistons look good. As does the bore. Everything I can see looks good, Other then finding some goo in the sump. Any suggestions on what to do? It also backfired always when reving down from WOT. bad enough that flames came out.

Chips in cam shaft normal?

See the goo?

It did this to the muffler

Compression test was 50PSI both sides

Vavles were checked and they were within spec as far as the tappets go.
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50 PSI compression?!? I'm amazed it started! Walk us through your equipment and testing proceedure... if it has compression release that could explain such low readings.
I think i found the source of the knock/ting, Look in pic three. See the wear marks where the connecting rod goes? Looks like its been rubbing.
I believe the Magnum did come with an automatic compression release, but 50 psi still seems pretty low. Were the valves seating fully? Are the heads slightly warped?

I am impressed that you are tackling several projects at once. I try and stay with one at a time.
On the K, the only thing I can think of that would allow the piston rod to slap the housing would be worn crank bearings, or a worn connecting rod. Do either seem loose?
Erm, This is a MV18 Larry :p The K is in the other thread for my John Deere. For the time being though. i am putting this engine to rest. Going to put it back togeather so no parts are lost and store it.
If i reassemble, Will it damage any parts? Or should I leave it in parts until I get time again?
If you are talking about the 'shiny spot' on the surface to the left of the cylinder bore, that is not from the connecting rod, but is 'grind marks' from the casting plant where the flashing was removed. Generally, when the castings are poured, the parts that delimit molten metal flow allow some seepage, leading to 'flashing' that is thin metal that must be removed. If the connecting rod had been banging on the surface, it would look more like hammer marks. If that is indeed what you are pointing out...
You can clean up the journal with a rag, and the bearing surface in the connecting rod, and assemble it {with the piston not installed in the cylinder} and use some "Plastigage" to measure the bearing clearance. The extruded wax(?) is of a specific diameter, and will deform when the connecting rod is in place and torqued to spec to indicate bearing clearance. A quick, inexpensive way to determine "what's what" inside an engine. You want to keep side loadings to a minimum to insure the most accuracy possible, so don't hang the piston on the rod and don't let the piston 'lean' on the crankshaft(or vice-versa) in the horizontal position. In other words, lay the crankshaft and piston/rod on the bench to minimize weight effects.
You can re-assemble without damaging anything if you are careful. The piston rings have to be compressed to fit into the cylinder, and that has to be done very carefully to avoid breaking the rings or damaging the bore. Your cylinder walls still show the cross-hatch of the original manufacture, which is a good sign. You can use a micrometer to measure the bore at the top, middle and bottom to determine tape, but it sure looks like there would not be much to measure. You can use a single piston ring, squared in the bore by the piston inserted 'wrong way', and measure the end-gap as above to determine both the gap and the taper. You must use standard size pistons and rings unless you overbore the cylinder.
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Well, Got around to having some monies for this and the time. Took out the valves and cleaned them and put them back in, The seats looked fine and were not lose. Mesured ring gap, and its way out of spec -_-. Maybe I did my math wrong, Here are the pics to follow. Priced new STD rings and they are out of my range for this month. 79.99 plus 20.00 shipping
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Ring end gap on Jug #2

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Jug #1


Ring end gap Jug #1



Should mention I used the same ring on both sides. So the ring end gap should really be the same no?
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I would have done a leak down on it to find why its compression was so low, how was the head gaskets?
Headgaskets were due for replacement as they had been removed about 3 times before
The bore needs to be uniform, and if not mistaken a little tighter at the bottom. A quick check would be to tale the top ring from the piston and measure the enn gap from the top, middle, and bottom of the cylender. The manual should give the spec.

Here is how I did mine.
Does this have the non-adjustable valves like the Briggs? These can be a bear to get set right. If the valve is too tight (from valve seat lapping) you need new ones "valves". and those have to have the stems ground down to bring into spec's
I'll check to see if the gap changes between the bottom and top. If not I guess a honeing I go? What should I do next? I don't really want to cut corners but am tight on funds. Can't afford the rings so I am gonna reuse em if they come good.
Checked ring end gap in top,middle and bottom, seemed to get tighter as it went down the cyl. Got some pictures of the pistons and pins and crank shaft. Opinions? will post in a few

Is this nick bad?

Nicks above oil ring, Is it fine?

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So, Opinions on what I should do next?
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