White cab 3cx (bmc engine) shuttle box leaking

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Benweatherley
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White cab 3cx (bmc engine) shuttle box leaking

Post #1 by Benweatherley » Wed Jun 14, 2017 10:33 am

Hi everyone. This is my first post but I have been lurking here for a while.

I've just bought myself my first JCB. it's a 1982 white cab with the bmc 498/nt engine. I have picked it up for reasonable money due to it leaking fluid from the shuttle box out in to the bell housing which I assume is the main shaft seal on the torque converter? The leak is fairly bad so this needs to be my first job to get her in to a useable condition. Looking for a little advice on how I would go about this job on this model. Do I only need to split it at the bell housing to engine? Or will I need to split the 4 speed box off the back of the shuttle too?

Any advise, pictures, diagrams very much appreciated. Especially from anybody who has done this job on one of these before. Thanks. Ben


Dross432
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Re: White cab 3cx (bmc engine) shuttle box leaking

Post #2 by Dross432 » Sat Sep 07, 2019 6:23 pm

Hello. Just bought an 1984 and its doing the same thing. The question is raller than taking it all apart even though i hate the idea of a bodge. Just slap abit of weld around the leaking bit for now? Or best doing the strip down and replacing the oil seal?


agrimax
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Re: White cab 3cx (bmc engine) shuttle box leaking

Post #3 by agrimax » Sat Sep 07, 2019 10:17 pm

Er...what are you thinking of welding??
It's likely the seal in the middle of the transmission oil pump that's leaking. Needs split at the bell housing and the transmission slid back out of the TC to give access to the pump.


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Re: White cab 3cx (bmc engine) shuttle box leaking

Post #4 by Dross432 » Sat Sep 07, 2019 11:32 pm

Put the oil into it to get it too move. Onlt took 5 litres but was enough to move her to a better location. Its leaking from a pry hole so i was hoping it was just a small seal and i could have just run a weld ovee the hole and sorted it. But as im only nee to this stuff im starting to think its gona be alot more work.
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Re: White cab 3cx (bmc engine) shuttle box leaking

Post #5 by essexpete » Sun Sep 08, 2019 12:09 am

When we did a similar transmission in an earlier powertrain we jacked up on the legs and placed two suitable cut sleepers between the lower rear cross rail and the jack feet. Lower down to pinch wood. The prop shaft was removed then the gearbox and shuttle was supported on a trolly jack with cup made to fit the sump of shuttle. The engine was also supported with blocks of wood under the sump. At this stage all the controls, pipes and wires were disconnected. The shuttle and gearbox were removed by unbolting the bell housing and removing the mounts then sliding backwards to leave the torque converter on the engine end. Agrimax will have more idea of what to do next.
On reassembly the tricky part was sliding the shuttle on to the converter.


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Re: White cab 3cx (bmc engine) shuttle box leaking

Post #6 by agrimax » Sun Sep 08, 2019 12:56 am

IIRC,I just used a floor jack below the engine and a trolley jack below the transmission on my own white cab.It was probably around 18 yrs ago,although I did remove a later synchro shuttle a few months back but it had to come right out from below the machine for a rebuild. I think I was able to pry out the old seal from around the shaft in the middle of the pump and tap in a new one.You must ensure that everything is well lined up for reassembly as the seal is so easily damaged when the TC is remated withn the pump.(Says he that had to start all over again the next day!!)You would be well advised to check the TC for cracks as well in case that is the cause of the leak but it's more likely the seal.


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Re: White cab 3cx (bmc engine) shuttle box leaking

Post #7 by Dross432 » Sun Sep 08, 2019 1:06 pm

So gota do it the hard way :/ any recomendations on sorting anything else while in that far? Also wheres best for replacement parts?
Thanks


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Re: White cab 3cx (bmc engine) shuttle box leaking

Post #8 by agrimax » Sun Sep 08, 2019 5:50 pm

Assuming everything else is working and pushing power is good,you should only need a seal(and oil). Any bearing stockist should be able supply you. I'm nearly sure the one I fitted is red rather than black and think it may been a Viton seal. Better heat resistance amongst other things!


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Re: White cab 3cx (bmc engine) shuttle box leaking

Post #9 by Dross432 » Sun Sep 08, 2019 9:02 pm

It was pushing really well until it started given up the power and clearly looseing oil. But there was quite afew attempts to get her to move in all gears front and back before giving up. Im more inclined while im in that far do i just replace afew more things save any hassle in the future?


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Re: White cab 3cx (bmc engine) shuttle box leaking

Post #10 by agrimax » Sun Sep 08, 2019 10:08 pm

When mine was leaking from that seal,it was still pushing and driving as normal. I'd say you might have a TC and/or transmission pump problem. TCs aren't cheap.........
If you look in the download section of the forum,go to JCB and the last download on page 2 covers your machine.There's a section on pressure testing the transmission(before you remove it).Section 6,page 8-1.
Make sure you have the machine lifted high enough for the box to come out from below....


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