Perkins 4108 cylinder bore tolerance
- Thread starter pcatterall
- Start date
<152587>
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How much to bore/ press the old liners?
How much to press the new liners?
How much to preheat the block and freeze the liners to achieve a 0.0015 to 0.002 thou Interference fit?
How much to bore the liner to achieve the piston fit?
How much the possibility of screwing the block whilst achieving the above?
PaulRainbow
Well-Known Member
Nothing. The old liners can be pulled out with a simple tool. No presses needed.
Nothing. The new liners press in by hand.
Nothing. No need for heating and freezing. In fact, if someone was stupid enough to heat the block they'd no doubt bugger the seals up for the liners. Doh!
Erm.... Once again, nothing. The new liners come pre-finished.
If you were doing the job, looks 100% certain you'd screw it up. If a half competent amateur, with the aid of the manual, was doing the job, 0.0%
Here's the key thing though, which really shows how little (zero) you know about these engines.......... you cannot rebore the liners on the marine engine and you cannot fit oversize pistons to them. Now might be a good time to stop digging.
<152587>
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Get your nurse/carer to explain the difference between wet and dry liners, sure she has vast experience in wet ones.
I will let you into a big secret now if you promise not to tell anyone.
Perkins 4.99 and 4.107 had wet liners you are quite correct in your method of replacement. However the 4.108 is a dry liner and as such can be rebored
I will let you into a big secret now if you promise not to tell anyone.
Perkins 4.99 and 4.107 had wet liners you are quite correct in your method of replacement. However the 4.108 is a dry liner and as such can be rebored
RichardS
N/A
The liners in the parts photo do look like dry liners as they have no top flange but I might be wrong in assuming that all wet liners have a flange.
Richard
Richard
PaulRainbow
Well-Known Member
PaulRainbow
Well-Known Member
They are dry liners Richard, but Perkins say you can't rebore them.
Besides, why would anyone want to rebore an engine when you can buy new liners, pistons etc for £375 ?
pcatterall
Well-Known Member
Interesting ( and sometimes informative) to follow the little difference of opinion going on.
yes, my 4108 uses dry liners but I thought I had to take them somewhere to have them pressed in ?
Also once pressed in I understood that they had to be bored to size and honed ( quoted £50 each for pressing and honing)
What about any requirement to 'top' the new pistons or could they be 'prefinished'?
Pauls comment that the supplied liners were prefinished was interesting as I have chums who could help with the pressing
( I wonder if you can buy an off the shelf circular plate sized to press the liner?)
Instinct tells me that if needed then the kit is the way to go so limiting the cost of specialist workshop involvement would be great!
Thanks again for the advice, sorry if I have stirred anything up!!
yes, my 4108 uses dry liners but I thought I had to take them somewhere to have them pressed in ?
Also once pressed in I understood that they had to be bored to size and honed ( quoted £50 each for pressing and honing)
What about any requirement to 'top' the new pistons or could they be 'prefinished'?
Pauls comment that the supplied liners were prefinished was interesting as I have chums who could help with the pressing
( I wonder if you can buy an off the shelf circular plate sized to press the liner?)
Instinct tells me that if needed then the kit is the way to go so limiting the cost of specialist workshop involvement would be great!
Thanks again for the advice, sorry if I have stirred anything up!!
D
Deleted member 36384
Guest
A friend has a press that he purchased to push bearings out of old Harley Davidson cranks. It was bought from machine mart: -
https://www.machinemart.co.uk/p/clarke-csa4b-4-tonne-hydraulic-bench-press/
They have larger models with deeper throats. There are loads around and I am sure you could take the block to a press and do this yourself.
https://www.machinemart.co.uk/p/clarke-csa4b-4-tonne-hydraulic-bench-press/
They have larger models with deeper throats. There are loads around and I am sure you could take the block to a press and do this yourself.
pcatterall
Well-Known Member
Stop press !! ….. informed by the kit suppliers that the Liners do need boring and honing after pressing in. Apparently the liners are quite thin and may be distorted in the parent bore so do need boring,
in which case I can let them press out the old ones and in the new ones.
Question about piston topping remains please!
in which case I can let them press out the old ones and in the new ones.
Question about piston topping remains please!
<152587>
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Wet liners do come prefinished and are sealed to landings in the block casting. They may be pressed in by hand assuming you have sufficient strength to overcome the resistance of the bottom seal, usually o ring. The wet system can fall into disrepute due to corrosion in badly maintained engines letting water into the sump.
Dry liners on the other hand are shrunk fitted to an already present boring in the casting, thus no contact is made between the coolant and the wall of the liner unlike wet liners. The operative words here are shrunk fit. The liner is retained in place by an interference fit. That means that the outside of the liner is a few thousandths of an inch larger than the bore they fit into. Because of the interference fit some distortion is going to be present so the liner is finally finished to ensure piston clearance.
As you may appreciate in my comments I talk of occasionally, very occasionally this can go all wrong due to the forces necessary to achieve the result.
You would be not advised to attempt this yourself unless you have access to an oven large enough to warm the block and a method to freeze the liner. A large hydraulic press is also required.
Motor_Sailor
Well-Known Member
The limits for the tolerance between the top of the pistons and the top of the block are in the manual.
One engine I did were within limits, the other needed topping.
Perfectionists top them all to ensure they are all exactly the same.
Perfectionists don't go sailing.
<152587>
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Google Foleys.com and closely read tech tip#32. Could save you a lot of money possibly.
pcatterall
Well-Known Member
Intrigued but can only find 'foleys' the landrover specialist and no tech tips there!