Hello all,
I am new to this forum.
I am going to recondition the gearbox and transfer case on a 1997 Discovery 1 300tdi.
I am planning to upgrade the transfer case to 1.4,
and make the 5th gear in the gearbox high.

Should I change the oil pump in the gearbox as well ?

At times, lot of heat is coming in the cabin, right hand foot well, gearbox side.
I looks to me like the gearbox may be overheating.

Thanks in advance for any advice.

 

Regarding overheating, on petrol trucks I would suspect the catalytic converter, possible over fueling, and make sure the heat shields are good and in place between the gear box and exhaust.

 

It is a diesel, 300 tdi

 

Of course, I know what tdi means. Just brainstorming with you.

 

Welcome to the forum.
Heat - my first thought is exhaust but the tdi exhaust on the left side - right hand footwell should be opposite exhaust side. For a manual to produce that much heat seems odd. Could be a hole in the fire wall via rust or rotted out grommet letting in engine heat? Go for a drive then get under the vehicle and see how hot the tranny really is.
From my experience when a manual transmission is low on fluid, its first felt in the synchronizers - hard shifting/grinding when engaging. If bearings are bad it will pop out of gear and make noise - especially under load. A friends 96 with R380 had 3 rebuilds by the time it hit 125k miles (V8 model) - FYI.
I would first change the fluid and check for metal shavings - there should be no more then a 'dust' layer on the drain magnet (assuming the drain has a magnet like the transfer case).
My rebuild policy is to replace everything -except gears in this case, I would do the pump, synchronizers and all bearings at a minimum. Also would take the gears to a reputable shop to determine gear wear/reuse.

5th gear high - I would really research this as it may be fine on flat land but force you into 4th on any up hills.

I too have considered the t-case upgrade to 1.4 but I dont do much of any hardcore off-roading and my t-case is in great shape so I rather leave well enough alone for now - just my opinion.

Input shaft wear - I cant speak to manual transmissions (I have a 98 V8 auto) but I know they wear as they were not provided with oil passages properly. I believe there are replacements that have oil passages - may be worth double checking the input shaft since it will be apart.

Good luck - let us know what you find and how it goes.

 

Thanks for your explanation.
Thought of the firewall because by age it is possible to rot out.
Is it available to buy ?
Low on fluid is not my thoughts because it is well serviced and in time, and it works nicely.
By the way, I always work in a shop, I am not the mechanic actually.
Going for the rebuild of both boxes is because the t case is leaking oil pretty much and it has to be sleeved, so I’m opting for an upgrade. Considering a lot of uphills in my country, a lot goes for the 1.4 option and the 5th high gear for long flat roads.
Surely will let you know about the outcome.

Thanks.

 

I dont know if the firewall is available - but I patch welded rust holes in mine - 10yrs ago - done properly it has lasted. Check where the front inner wings-wheel well mates to the firewall - especially under the brake booster. Leakage from brake fluid eats the paint=rust. That's where the biggest hole was. To replace the firewall would be a massive job, likely windshield out, engine tranny out - just patch weld it. FYI there are a lot of replacement panels available from various aftermarket vendors in the UK.
My t-case (like all) leaks too but its not that bad and I keep a regular eye on it. Can you explain 'it has to be sleeved' - I haven't heard that before. Just curious for my own personal knowledge.
Im not a mechanic either but I have some experience - these vehicles are easy to work on - just takes patience and the right tools. This forum is a great help.

 

Good morning,

Regarding where to be sleeved,
The hole that supports the head of the intermediate pin in the LT230 casing is prone to wearing, and the pin elongates the hole so that it is out of round.
Ashcroft has the sleeve for it.
The T case has to be machined

 

You mean there are aftermarket panels for the D 1 available ?

I don’t need at the moment but it’s good to know about the availability from whom.

 

that's good info on the LT230 - was not aware of that - do you know if that is exclusive to the manual or auto too?

IRC Europe requires vehicle inspections, in which rust cant fail the inspection and I believe the manufactures are required to keep parts available for several years after production ends either OEM or aftermarket......

here are some sites:
https://rimmerbros.com/SubCategory--Discovery-1--m-78
https://britcar.com/
https://www.paddockspares.com/parts-...nd-panels.html