leyland 4.98 engine damage why?

[si25]

i've just pulled the head of my jcb, which ran very well (on 3) to find the crown of number 4 piston smashed to bits. looks like impact damage, certainly from the top, thing is, the head looks in perfect order. no damage at all. i've not yet checked the valve seats and guides but there is no impact damage equal to that of the piston crown.
this is really puzzling me?
any ideas?
cheers. si25

[MrF]

Seized at the bottom of the stroke on that pot then destroyed by the conrod? That usually makes a mess of the piston/liner though, which will be really apparent when you extract the piston.
The only other thing that springs to mind is if its new to you, someone opened it, seen the carnage inside maybe after it dropped a valve or something and just buttoned it back up quietly, maybe fitting a spare head in the process...

Someone on ebay does "kits" for the leyland 4/98's, pistons, liners, gaskets etc. Havent bought one so cant vouch for the quality of it, but know I have to do the same for my 3c some point in the near future as its breathing like its been on 100 woodbines a day for 40 years...

http://cgi.ebay.co.uk/LEYLAND-NUFFIELD- ... 1|294%3A30

[si25]

...The only other thing that springs to mind is if its new to you, someone opened it, seen the carnage inside maybe after it dropped a valve or something and just buttoned it back up quietly, maybe fitting a spare head in the process...

thats what i decided upon. whcih is odd, as it would seem that it was put together with a degree of care. it all seems "right" but majorly not right. dropped the oil today, no major metal in it? it must have been taken apart and partially repaired?

[spod]

si25,sorry for your trouble doesnt sound good I guess its a case of buyer beware....theres some treacherous people about I hope youve alerted others on ebay with your feedback others need to be warned!

[innes]

i've just pulled the head of my jcb, which ran very well (on 3) to find the crown of number 4 piston smashed to bits. looks like impact damage, certainly from the top, thing is, the head looks in perfect order. no damage at all. i've not yet checked the valve seats and guides but there is no impact damage equal to that of the piston crown.
this is really puzzling me?
any ideas?
cheers. si25

I'm not familiar with this engine but if its direct injection I have seen injector nozzle tips coming off and damaging the piston crown and with no valve damage,
Innes

[gamble.greg]

I have to agree with Innes, I have seen countless engines with the same damage as you have described and it was all due to injector tips falling off.
For the most part it will not affect the running of the engine, in a machine that is used for farm work or not in a commercial sense it would be fine to leave it as it is, if you use the machine in a commercial way, then the best thing is to run a full kit thru it, do the pump and injectors at the same time and start off fresh. Do yourself a favour and fit a new oil pump to it at the same time. All the best..........greg.

[si25]

si25,sorry for your trouble doesnt sound good I guess its a case of buyer beware....theres some treacherous people about I hope youve alerted others on ebay with your feedback others need to be warned!

cheers for all your input, had another real good look at it today. injectors look alright, they are at least all there and complete. now got the offending piston out. it was a valve that did the damage, i can only guess that it must have been partially repaired prior to me getting it.
fortunately, i only paid half of scrap value, and it was sold with the pretense of being a non runner.
non the less, i will be repairing it, cheaply, despite this being against my mental rules, (i dont want to fork out to find the block is scrap) and will be fitting a replacement piston with rings. i will be using the old liner as it appears to be in very good condition. once i have it fully running properly with no major problems, as part of the restoration i will more than likely pull the engine out, apart, and re-build it properly.
si25

[martyn williams]

I have come across this fault before.Its caused by the injector,the nozzle becomes defective,then injects too much fuel,this effects the lubrication of that cylinder the end result is excessive ring wear/broken rings then piston damage.If you remove that piston you may find vertical grooves on it Someone's just done a head replacement and did not fancy doing any more work to it.
Martyn