automatic gearbox oil

[hellas]

Hi, Is it easy enough (for a mechanic) to check and possibly change the automatic transmission fluid in my Bongo.?
On a motorway drive doing a steady 60 it jumped out of gear into a lower one. I stopped and let it cool down a bit
and then drove OK. BTW I have a LPG/petrol van, which I gather runs hotter than a Diesel.
Any advice?
Thank you.

[Muzorewa]

Are you sure you have a problem, has it done this more than once? The autobox is supposed to change down if the road speed and throttle position suggest it should, or you inadvertently knock the 'hold' button.

[mikeWalsall]

I would have thought a compression ignition (diesel) engine would have run hotter than a petrol engine ..

Accidentally pushing the 'H'old button in as .. Muzorewa .. seems a good bet ..

Have you checked the condition (smell) .. colour (cherry red) the fluid level (with the engine running and box in 'P') ..??

[hellas]

Are you sure you have a problem, has it done this more than once? The autobox is supposed to change down if the road speed and throttle position suggest it should, or you inadvertently knock the 'hold' button.

It only did it once and I am sure I did not knock the hold button. I was doing a steady speed on the motorway. I thought it would be wise to check the transmission fluid. Just to make sure. Good idea?

[wonkanoby]

yes as if not done before you will find sump full of crud

[hellas]

yes as if not done before you will find sump full of crud

Interesting! Will get it done as I don't think it has been done before. Thanks everyone for your advice.

[scanner]

I would have thought a compression ignition (diesel) engine would have run hotter than a petrol engine ..

No they don't, as they are more thermally efficient (indeed just more efficient) and convert more of the heat produced to useful energy. So less heat has to be dissipated by the cooling system.

Basic physics.

[mikeWalsall]

Diesels always seems to be the ones suffering overheating / cracked heads .. but thanks .. I wish I understood more about thermodynamics than I do ..!!

On Motor Bikes when tweaking the engine it's usual policy to 'up jet' .. not purely for performance gains .. but petrol acts as a coolant so it is 'kinder' to the engine ..

[scanner]

Diesels always seems to be the ones suffering overheating / cracked heads .. but thanks .. I wish I understood more about thermodynamics than I do ..!!

That isn't the RUNNING temperature, that is overheating, another thing altogether.

Overheating occurs when the heat produced (however much or little) cannot be properly dissipated due to inadequacies in cooling of whatever kind. With diesels it is usually because the cooling system has not been correctly bled or the system has obstructions to flow.

On Motor Bikes when tweaking the engine it's usual policy to 'up jet' .. not purely for performance gains .. but petrol acts as a coolant so it is 'kinder' to the engine ..

You cannot "up jet" too much or the engine will exceed it's stoichiometric ratio and run too rich and it is the evaporation of petrol in the inlet tract that cools the incoming charge of air and so cools the engine (slightly). That cannot happen with a diesel because ..
1 Diesel does not evaporate.
2 The fuel is injected under very high pressure directly into the combustion chamber where it combusts.

[The Great Pretender]

12.5/1 was aimed for when power tuning with petrol Mike.

Stoichiometric ratio.
This is something I ponder, as older cars ECU’s running closed loop try to keep the mixture at “stoichiometric ratio” is the car running hotter and using more fuel?
Modern fuels have up to 10% ethanol if the ECU keeps the ratio to14.7/1 the engine is running lean. Ethanol has a stoichiometric ratio of 9/1 so you have a hotter running engine producing less power.........

[mikeWalsall]

On the older cars especially with SU or Stromburg carbs the best thing I use are Colour tunes ..



To balance the air flow on twin carbs a 'bit of tube in the ear' is OK .. but for bikes I use vacuum gauges ..

[The Great Pretender]

Just been there Mike after modifying a set of Suzuki GSXR throttle bodies to fit on my Kawasaki ZZR 1100.
Older carb engines respond well to colortune but modern management systems provide real time response by data logging exhaust gas (oxygen contant) in milliseconds.

[mikeWalsall]

I have always dabbled with bikes and cars .. the 'glass' colour tune is great for fixed jet carbs like on the old minis .. Sprites .. and the likes .. tends to get them spot on .. I have a set of four .. saves burned fingers 'cos they get very hot ..!!

I used to have a Gunsons carb balancer .. but to be honest .. un bolting the linkage .. and listened to the 'suck' with a bit of tube works as well ..

Thinking about it .. I had another type that 'pulled' liquid up scales .. dunno what happened to that .. (that's having kids / grandkids with bikes)..

My No2 son (our Ade) is into Ducatis now .. at the moment as a couple of very nice 996s and a CCM ..





Son in law (Martin) R6 track bike ...



No1 son (Tony) TY250 mono (as kids they had a twin shock Ty175) ..

[mitch]

Being the least techie bloke ever!
Is it worth having the oil changed in my 2.5L turbo auto box as she has done nearly 100K miles and what kind of oil do I need???


Thanks

[mikeWalsall]

Loadsa recent posts on auto box checks / re fills ..

if you don't know when it was last changed .. then yes it is worth while ..

The normal autobox fluid is Dexron2 .. but most opt for the later / better Dexron3 ..

The same fluid can be used to top up the power steering as well ..