Don Terrill’s Speed-Talk

I today dismantled friend's old Hyster propane forklift engine (due of horrible mechnical noise).First idea were that valve has dropped but when I get the head off it was clear that the #4 piston was completely destroyed (and bent and twisted conrod) So,since the forklift is not in production use and the remaining 3 cylinders offer more than enough power to occasional use we think that just cut the exess of the bent rod so it rotates freely and leave pushrods off the damaged cylinder.Creating oddfire 3-cylinder.
How desperate move that will be;no hope or just go for it?
Finding decent engine for such old forklift sure is cost prohivitive and in personal use the ugly running don't matter.
The engine had run fine exept some ticking before the catasthrope happened.

my first thought about this, it will not cost much to try your idea and it may be just fine for the usage you described. I "think" cut the rod beam off leaving only enough to clamp the bearing around the journal. "OR" just use a hose clamp to fasten the bearing around the journal. It will be way out of balance without the piston so may not matter about the rod piece.

I once dropped a valve in a 4 cylinder diesel but I did not know.
It just stopped far from home with water dripping out of the tail pipe.
So I took my Charger of the trailer bed and drove it home and returned next week with a upper gasket set.
One valve sat upside down in the piston and there was agaping hole in the head when I took it off.
So I went to a gas station and bought some Plastic Padding tank sealer and thinner to clean with.
I repaired the hole and took the injector and push rods out, put a hose on the fuel line to a Jerry can and drove home.
40 miles from home and the truck was definitively not faster on 3 cylinders but I got home.

Another time we where on our way to Finland with a Chevy crew cab with 454 and one piston disintegrated.
We drove off at a service station and pulled one head and the sump.
We did what you suggested, sawed the rod off and took the remains of the piston out but left the valve gear in.
It also took us home without problems so go for it.
It might vibrate a little bit more though.

Erland

Yes,the idea was to fix it very cheap and see will it be usable;just some gaskets and work.Unbalanced it will be and fear is that since engine is solid mounted will it shake itself apart.But running 2000;2500 rpm max does it matter..

weld some weight to simulate the rod piston assy on to the rod. it should at least reduce the imbalance.

Maybe put something behind the bearing on the cut off rod so it won't spin freely. With that flopping around in there it may have a variable balance. You could make a round weight the would bolt onto the journal like a rod split in half so it would be heavier than just a piece of the old rod but still seal oil. Would the oil still flow through the crank or should the bearing shell or bolt on weight be grooved to allow oil to flow to the next bearings in line?

Plug the oil hole or use the cut off rod. It might shake like a big wet dog, but will run as you want.

And do report back re how it works!

Tap & plug the oil feed hole, weld some weight onto the end of the rod that's left to get close to the mass that you lost and then weld the rod to the journal and also the counter weight cheek if you can, even if you need to span some metal to do it.

Leave the valves out and Epoxy closed the ports.

Oh, and please report back if you get it running!

It is desided that we try that 3-cylinder solution.If it don't run well enough;well the engine is shot anyway!
Nex week forklift will be rised to get the oilpan away and deside what strategy we will go with.
Will report how this end..

You need to thread the oil hole on the big end and insert a grub screw with lock tight. Remove the rod completely as you don't need it for balance as is suggested. Remove push rods and the motor will run very happy. A straight 4 crank is in balance with out counter weights.
So how do I know this I had a 6 cylinder Subaru motor that I converted to 3 and I rev it to 6.500 rpm. It has no rod on 3 of the big ends on one bank and has grub screws to block the oil gallery.
Here is a video of the motor on my home built dyno. I use it for intake testing etc. The crank comes from a motor that through a rod so a damaged bigend.
https://www.youtube.com/watch?v=a8_kv-Y7lwI