CS6 Overhaul

[Oldfart]

I see the Listeroid spares only advertise an iron piston for a CS6. Ours has an alloy piston, would fitting an iron piston be OK? Would the crankshaft/conrod have to be rebalanced with an iron piston?

The bore looks pretty good with only a lip of about 5 thou or so at the top of the ring movement. I think it's a cast iron bore being part of the cast cylinder.

Bore still has cross hatching visible on the wear area of ring movement.
Is it worth going the hole hog and putting in new mains and seals with big end, piston and rings?
The engine will be used as an occasional charger and support for a solar system with batteries so it probably won't be worked too hard for too long.

[38ac]

Hi again, Yes it would have a noticeable affect on balance to change piston materials but a 6 HP engine would have had an iron piston originally so it has been apart and changed previously. 
Standard bore pistons (Indian) are readily available in either material. There are certain things that the Indians can and o make well and Pistons is one of them, nothing to shy away from.  Check with Diesel Electric first if in the states. If Gary doesnt have aluminum they are available here http://www.stationaryengineparts.com/Lister-CS-engine-spares/ 

 You need to be sure of the bore surface, if chromed you need different rings than plain iron.

I would consider .006 to be iffy at best for re-ringing a work engine. for display you can get away with it as long as you cut the ridge out of the top. As an aside should you decide to bore it oversized  cast iron pistons and rings in two over sizes will be available through either  DES or  my shop by Spring 2014. 

[dieselgman]

Both piston types readily available... http://diesel-electric.us

dieselgman

[Tom]

Usually crosshatch and ridge are not possible on the same cylinder. Perhaps your "ridge" is really just a carbon buildup. If it were mine I would take one of your existing rings, put in the bore near the top and measure the end gap. Then move it down near the bottom of the bore and measure again. Similar measurements mean your bore is straight and not worn. If the gap at the top is no more the .020" I'd reuse the rings.

[38ac]

Usually crosshatch and ridge are not possible on the same cylinder.

Sure it is, but not in the same place in the cylinder.

 Unless run for many hours with terrible maintenance there is seldom much wear at the bottom of the bores or even at the bottom of ring travel. The last cylinder I bored had hone cross hatches still visable at the bottom but did not quite clean up at .020" at the top and I had to go .030 over. The most wear in a used bore will always be in the top inch of the top ring travel.

Butch

[Bottleveg]

I wonder if it’s been fitted with an 8/1 piston?
8/1 pistons have 4 rings and 6/1’s have 5.
If it’s a Dursley made piston it will have the part number stamped into the crown.
If it is an 8/1 piston it would be worth checking to see if it’s been fitted with 8/1 governor weights. I think there’s a photo on here somewhere that shows the differences. 

[Tom]

Well Butch perhaps I should have phrased that a bit more accurately. Usually cross hatch and a ridge are not found right next to each other as they are in the pic in this thread.

[Oldfart]

That's the bottom of the bore in the piccie. I will be heading out to look at the engine/gen tommorrow so I'll pull a ring and have a look at the bore. The piston has 5 rings, one at the bottom. I hadn't thought wether the bore was chrome or not, come to think of it there was a crazed sort of a look about, again I will have a real good look tommorrow. Thanks for the replies fellla's.
The piston has an errosion on the top, if it was a petrol engine (I've had nothing to do with diesels) I'd say it was detonation marks so I will be replacing the piston and might as well bore it at the same time.

[38ac]

Well Butch perhaps I should have phrased that a bit more accurately. Usually cross hatch and a ridge are not found right next to each other as they are in the pic in this thread.

The confusion lies in you are'n't looking at the top, That's the bottom of the cylinder in the pic I had to look three times to be sure myself.

[Tom]

Oh! I see said the blind man as he picked up his hammer and saw. That's not the ridge, it's the bevel on the bottom of the cylinder.

[38ac]

I hadn't thought wether the bore was chrome or not, come to think of it there was a crazed sort of a look about, again I will have a real good look tommorrow.

If un dinked with the chromed bore cylinders had a small brass plate on them that said "Listard" or "Listhard" Cant remember how it is spelled.

[Oldfart]

Had a closer look today, the piston is cast iron. Do they normally get this sort of errosion on the piston top?

The ring gap just under the top of the ring movement was about 100 thou. I didn't measure it but it looked just under an 1/8 of an inch.

I can't get any movement out of the bigend apart from a bit of sideways movement. Is there any point in just doing the top end and not doing bigend and mains? Do I need to plastigauge the bigend? What are the shims I read about for bigend, can you shim movement out?

[38ac]

Pitting like that on the piston tops is common. Biggest piston problem I see is wear in the top ring land which is critical. It is possible to have the ring lands machined square and to some oversize for which there is a spacer available.  With new replacements being very affordable I don't spend much time on old pistons unless outside factors make it mandatory. Yes by all means you need to refresh the big end shells and personally I have never seen a small end bushing good enough to reuse and if there is decernable wear in the wrist pin it should also be replaced.
Shims or not is determined by measuring the individual engine. Most of the time they are not needed with slightly worn cranks and stretched big end caps. When I have cranks reground or welded and the rod big end reconditioned I just send the inserts along and tell them to size it for no shims, problem solved. The only time I have used shims that I can remember is when "rebuilding" a new Indian CS clone.
 

[bschwartz]

Is that pitting on the top of the piston just carbon build up, or is it in the cast iron itself?  I'd scrape it/clean it off for a closer look myself.

[Oldfart]

The pitting is into the head of the piston, looks like errosion or detonation. Do you get that in diesels?