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Topic: marshall pistons (Read 245 times) |
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powershaft
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marshall pistons
« Thread started on: Nov 3rd, 2009, 10:57pm » |
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could some one keep me right about pistons with3or4ring.which is the detter
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J V P
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Re: marshall pistons
« Reply #1 on: Nov 4th, 2009, 08:14am » |
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Hi Powershaft - Is your Marshall fitted with a Leyland or Perkins engine? - JVP
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powershaft
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Re: marshall pistons
« Reply #2 on: Nov 4th, 2009, 9:22pm » |
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Sorry Leyland4/98TT
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J V P
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Re: marshall pistons
« Reply #3 on: Nov 4th, 2009, 11:20pm » |
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Hi Powershaft - Pistons, rings & liners are a minefield. The 4/98 TT engine should have a 4 ring layout, turbo 4 ring pistons, 'Short' 'Plateau honed' liners and stengthened con-rods with a larger small end bore. Old non-turbo tractor engines should have 4 rings, an empty 5th groove and 'Long' 'Diamond' honed liners. A 5th ring was sanctioned in cases of oil consumption but you can't fit a 5 ring set up into a 'Short' liner, the ring comes out of the chamfer at the bottom of the liner, nor should you fit a turbo piston with 4 rings into a long diamond honed liner. Later non turbo tractor engines received the later turbo pistons, liners and con-rods.
Since the last engine was built 24 years ago you may now find anything fitted and almost any combination of the above. Add to this the fitment of non original parts! A number of engines have been seen with piston and ring combinations that should not have been factory fitted!
Anyway to answer your question, a four ring pack should be fitted, don't delete any compression rings. -JVP
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rickcobley
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Re: marshall pistons
« Reply #4 on: Nov 5th, 2009, 07:35am » |
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Hi, Years ago when I had far less knoledge I built up an engine with 5 ring pistons and short liners and as JVP said the bottom ring came out so I left it off only to start burning oil 2000 hrs later. I later fitted fresh pistons with the 4 ring pack and it is ok now.
The 4 ring pack is different rings it is not the 5 ring pack less the 5th ring .
Regards Rick Cobley
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leirdalen
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Re: marshall pistons
« Reply #5 on: Nov 5th, 2009, 5:21pm » |
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Is it possible to get som more information about Plateau and Diamond honed liners.
Regards
Andrias Leirdal
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| « Last Edit: Nov 5th, 2009, 5:21pm by leirdalen » |
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J V P
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Re: marshall pistons
« Reply #6 on: Nov 5th, 2009, 9:12pm » |
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Hi - The easiest way to explain the difference between 'Plateau' and 'Diamond' honed liners is as follows:-
A diamond honed liner has a surface finish which, when you look through a microscope, looks like a series of 'V' shaped grooves with sharp peaks.
A plateau honed liner has the top of the 'V' shaped peak ground off leaving a flat surface but still leaving the rest of the groove.
For information, the honing tool is moved up and down as it rotates leaving a swirling pattern on the inside of the liner.
These grooves in the liners are very small with many hundreds per cm. Why the two types? Diamond honed liners retain oil in the grooves for lubrication and fast 'Bedding in' of the rings, but the 'down' side is premature ring wear. 'Plateau' honed liners provide a compromise of oil retention, quick bedding in and long ring life.
As I mentioned in my earlier posting, and I quote; "nor should you fit a turbo piston with 4 rings into a long diamond honed liner". I didn't explain why. The reason is the 4 ring pack, turbo piston and the earlier diamond honed liner are not compatible, although they are dimensionally the same (Apart from the small end diameter) the composition of the rings are different and the piston has the oil return holes below the oil control ring deleted. - JVP
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