4/98 leyland engine swap between JCB3CMk2 & Mk3?

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jcb3cmkdeux
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4/98 leyland engine swap between JCB3CMk2 & Mk3?

Post #1 by jcb3cmkdeux » Thu Feb 08, 2024 11:36 pm

Hello folks, i'm still to find time to explore the cause of water in the engine oil of my JCB 3C Mk2, however if it transpires that the cause is a showstopper are Leyland 4/98 engines in JCB Mk2 interchangeable with those in Mk3's?
thanks
Mike


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Re: 4/98 leyland engine swap between JCB3CMk2 & Mk3?

Post #2 by agrimax » Fri Feb 09, 2024 1:36 am

Yes they are. A few internal differences in the last of the MK3 Powertrain engines but still interchangeable.

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Re: 4/98 leyland engine swap between JCB3CMk2 & Mk3?

Post #3 by Billy26F5 » Fri Feb 09, 2024 11:26 pm

Depends a bit on the years as to how difficult it is. Even the earliest 3CX's use the 4/98, more similar to the Powertrain 3CIII than the normal ones. A few changes did occur over the years, Julian Carder got most of them in his book (which is on the forum). The biggest differences are probably the lack of balancers on Powertrain engines and possibly the flywheels too. You can work without a balancer but it does vibrate a fair bit more. Beware of lorry engines as they rev more too making the lack of balancer seem worse.
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Re: 4/98 leyland engine swap between JCB3CMk2 & Mk3?

Post #4 by jcb3cmkdeux » Fri Feb 09, 2024 11:55 pm

Thanks for the replies guys, i was asking because i was going to Gregsons used machinery at Uttoxeter today to pick up a bucket for my manitou and while i was there i had a look at the engine in the 3C Mk 3 they have for sale. The engine number was abit obscured with muck but i'm fairly sure it read 4/98. It was just a good opportunity to see the differences between Mk 2 and Mk 3 in real life.
cheers
Mike


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Re: 4/98 leyland engine swap between JCB3CMk2 & Mk3?

Post #5 by MrF » Mon Feb 19, 2024 5:25 pm

I've gone the other way even further, my 3c3 with a 4/98 had liner issues and I had no time to dig right into it, and I got a really wrecked 3c2 with a 38dt in it. Its now in my 3c3 currently and I have the 4/98 stashed swearing to rebuild it properly one day and run it up on a dyno for a few heat cycles when I have time.
Although the person I bought the 3c2 donor off said it was running perfect before the accident that destroyed it, the sludge in all the filters and mixed up injector bolt + bleed union on the pump said otherwise & it seems to vibrate more, probably becaues it was ran on 3 cylinders because of the injector bolt mixup, its now using water too, and its not as powereful and smooth as even my poorly 4/98 but its better than a dead jcb.
I think I'd probably have been better off just persisting fixing my 4/98. Better the devil you know and all that...
Some 4/98 are rumoured to have a inline pump (the 38dt is like this too), but mine had the dpa type.

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Re: 4/98 leyland engine swap between JCB3CMk2 & Mk3?

Post #6 by Billy26F5 » Mon Feb 19, 2024 8:49 pm

If it vibrates a lot you could be missing the balancer, it makes a big difference. The 38TD was never as powerful as the 4/98, there are many differences between these engines. The early 4/98 did have the minimec inhereted from the 38TD, it was later replaced with the DPA in around 72 or so.
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Re: 4/98 leyland engine swap between JCB3CMk2 & Mk3?

Post #7 by essexpete » Tue Feb 20, 2024 1:42 am

MrF wrote:I've gone the other way even further, my 3c3 with a 4/98 had liner issues and I had no time to dig right into it, and I got a really wrecked 3c2 with a 38dt in it. Its now in my 3c3 currently and I have the 4/98 stashed swearing to rebuild it properly one day and run it up on a dyno for a few heat cycles when I have time.
Although the person I bought the 3c2 donor off said it was running perfect before the accident that destroyed it, the sludge in all the filters and mixed up injector bolt + bleed union on the pump said otherwise & it seems to vibrate more, probably becaues it was ran on 3 cylinders because of the injector bolt mixup, its now using water too, and its not as powereful and smooth as even my poorly 4/98 but its better than a dead jcb.
I think I'd probably have been better off just persisting fixing my 4/98. Better the devil you know and all that...
Some 4/98 are rumoured to have a inline pump (the 38dt is like this too), but mine had the dpa type.

The last 4/98 turbo that we fitted, sourced as obsolete stock, had an in line pump. With the turbo the engine ran very clean as well.


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Re: 4/98 leyland engine swap between JCB3CMk2 & Mk3?

Post #8 by aussiecat » Tue Feb 20, 2024 10:06 pm

I haven't dealt with that exact issue, I've heard swapping engines between JCB models isn't always straightforward.


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