2002 4.4v8 gearbox problem

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GullH

New Member
Posts
129
Location
Leeds
Hi all,

It's been a while since I have been on here.....had no issues till now....lol

Just been for a drive in the old beast this morning on the motorway and all was fine on the short outward journey of 20 miles.

But on the way back home, I noticed that it won't change up to 4th gear. Even in manual mode it would not change up to 5th.....was doing 70mph and it was stuck in 4th at 3500 rpm.

Then came off the motorway and it came down in gears, but then it wouldn't change up past 2nd gear. Ended up driving it home stuck in 2nd gear at 30mph and 4000rpm.

Is this a major issue or will a gearbox oil change sort the issue?

The car is a 4.4v8 with a Prins LPG system. It has done 140k miles and has been serviced regularly. I understand from the previous owner that the gearbox oil was changed at 75k miles.

Any advice would be greatly appreciated.

Cheers guys.

Gull
 
Sounds like the box has gone into its cooling stratergy.

If the gearbox oil gets above a certain temp, the ECU holds lower gears to allow the pump to push more oil through the cooler to try and keep it at a lower temp.

Mine started to do this so i changed ghe cooler, gearbox cooler stat snd backplate and now no more issues since.

It could also be silted up from an old radiatir as coolant to the cooler is from the bottom of the rad. If this is blocked there will be no cooling to the gearbox oil.

When was the fluid changed last? Old fluid will clog up the cooler.

Read my how to!!
 
Sounds like the box has gone into its cooling stratergy.

If the gearbox oil gets above a certain temp, the ECU holds lower gears to allow the pump to push more oil through the cooler to try and keep it at a lower temp.

Mine started to do this so i changed ghe cooler, gearbox cooler stat snd backplate and now no more issues since.

It could also be silted up from an old radiatir as coolant to the cooler is from the bottom of the rad. If this is blocked there will be no cooling to the gearbox oil.

When was the fluid changed last? Old fluid will clog up the cooler.

Read my how to!!
Thanks for the reply Ant
Gearbox fluid was last changed at around 75k miles.
I had the water pump and stat changed around 500 miles ago.

Is it worth getting a laser thermostat and checking the temps on the cooler and the gearbox after a short drive?

If so, how do I use the laser thermostat??:D

And would you change the gearbox fluid and filter first and then re-asses to see if the problem reoccurs?

Cheers
 
Not the main stat, there is another one mounted on the cooler.

Not sure if a laser temp on the sump and cooler would give an accurate measurement of actual oil temp, but worth a go.

If you are on 140k and the last gb oil change was 75k then ot is well past due and needs to be done.

ZF reckon on 50-60k miles but id say 24-30k miles or two years whichever is sooner.

Could change oul and filter then flush the cooler and hope for the best!
 
Not the main stat, there is another one mounted on the cooler.

Not sure if a laser temp on the sump and cooler would give an accurate measurement of actual oil temp, but worth a go.

If you are on 140k and the last gb oil change was 75k then ot is well past due and needs to be done.

ZF reckon on 50-60k miles but id say 24-30k miles or two years whichever is sooner.

Could change oul and filter then flush the cooler and hope for the best!

Cheers Ant,
How do I flush the cooler? And is this best done before changing oil and filter or after?
 
Cheers Ant,
How do I flush the cooler? And is this best done before changing oil and filter or after?

Drain fluid, take out the cooler, flush cooler through using a a solvent based cleaner- akin to a safteyklean fluid...failing that a solvent that is aluminium friendly - brake/carb cleaner will do!, leave to dry....whilst drying, remove sump, remove filter, replace with new FILTRAN filter and new O ring, clean sump, replace sump with new gasket, ensure cooler is dry and refit, fill with new oil as per RAVE or my How To, job done!
 
Drain fluid, take out the cooler, flush cooler through using a a solvent based cleaner- akin to a safteyklean fluid...failing that a solvent that is aluminium friendly - brake/carb cleaner will do!, leave to dry....whilst drying, remove sump, remove filter, replace with new FILTRAN filter and new O ring, clean sump, replace sump with new gasket, ensure cooler is dry and refit, fill with new oil as per RAVE or my How To, job done!

Nice one Ant,

Sounds like a plan....gonna get the parts this coming week and get it done at the weekend. Will it be safe to run the car till then?

My thinking is that I only do 30 mins to work. If the gearbox problems only arise after it heats up, I might get away with taking it to work. Then it will be cold again in the evening and I could get back home again safely.

What are your thoughts on that?
 
Nice one Ant,

Sounds like a plan....gonna get the parts this coming week and get it done at the weekend. Will it be safe to run the car till then?

My thinking is that I only do 30 mins to work. If the gearbox problems only arise after it heats up, I might get away with taking it to work. Then it will be cold again in the evening and I could get back home again safely.

What are your thoughts on that?

You *should* be fine.....if it starts happening regularly then something is blocked or the oil is getting cooked....cooked gearbox fluid is something you want to avoid, as when it gets hot, it thins out so much that all is friction modifiers and 'oily-ness' properties give up and it is not much better than water !!!!

Also, hot fluid will no longer be cooling the clutch friction plates causing hotspots on the plates and potential warpage or loss of friction material which eventually kill the box....

Not scare mongering, but if in your 30 minute drive it starts to happen, then time to do something about it asap....mine only started doing it after a couple of hours driving in Summer....

Remember to check your main radiator too, as if it is old, it could be silted up at the bottom.....stupidly, BMW put the bottom hose a few inches up from the bottom of the rad, so the last few inches do get silted up, the gearbox oil cooler is plumbed in below the bottom hose, so if the rad is silted up, flow to the cooler could be restricted.

640.jpg


The GB Oil Cooler is plumbed in to the small fitting near the bottom of the rad on the right!

Check the gb oil cooler stat too...I have had one fail already and has been replaced twice (once when I did the gb oil cooler and again when I was getting an airlock)
 
As ever, you are the man, Ant. Well done and thanks for the excellent advice mate. Will keep you posted....
 
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