pajero high rpm

[canuk99]

new to this site, needing a little info from those who may know.
I recently imported a 91 pajero into Canada, the problem is at 100km/h the engine is reving at 4000 rpm. It has a 2.5L diesel with an auto trans with overdrive. When it shifts into o/d the rpm only drop 200. I have checked all the obviuos things tyre size, gear ratio (5.28). There is a valve on the trans. I believe it is for the o/d. These vehicles a not very common here yet and it is hard to get any good info on them. Any advice would be great. thanks

[-Scott-]

It should drop more than 200 rpm when shifting into overdrive. I'd guess that you're only seeing the torque converter lock (does it lock?) and not o/d.

NFI what you do about it... Guess I'd start with coolant temp sensor - if the trans thinks the engine is cold it might not use o/d? What else would cause the trans to lock out o/d?

[klrevo]

if it helps anything at all, mine has 5.29 centres as well, but it also has 35" tyres, and it still does 3000 @ 100km/h, so if youve got standardish sized tyres this wouldnt surprise me, though auto and o/d should be more effective than that,

dean.

[NJV6]

Sounds like it is not getting 4th gear.

From stop, take off and count the changes.

[canuk99]

I checked out the shifting. It is not engaging into O/D. Found three temp. sensors, one for the fan, the other single pronge for the temp. light on the dash (I believe),third has two pronges and I think that might go to the computer to engage theO/D. If anyone can tell me if I am on the right track I would be happy with the input.