Hello jtdwannabe welcome to AO
I picked up a high milage JTD earlier this year - albeit the small one, so my comments will be based on the 1.9, a cylinder less and more tractor sound
. Sound and tourque apart, they are quite similar though...
1) Are there any people on here with high milage 2.4 JTD's (ie 125,000 miles+) and what problems have they had (if any).??
Front suspension - especially the upper wishbones. First thing I changed - not expensive and well worth it. The rubber bushings tend to wear, leaving a knocking noise and the possibility of more wear to the front tires. Why oh why did I move on to a street with speedbumps...
Radiator/Fan. Mine looked fine the day I bought the car - while in fact the fins were well corroded and the fan had seen it's day. Took about 5 years and 160k km to wear out the radiator on my 156. Had them both changed during a full service for ~800 EUR with a few new hoses.
And my favourite
- the knob for adjusting the mirros keept breaking off. Fix: 2 EUR bottle of superglue. Then a 4 EUR bottle of slightly fancier glue. Then an 8 EUR bottle of something with pictures of a Rhino and since then - not a problem.
2) timing belt intervals??
Officially quite long intervals... Previous owner broke his at 102k km. New engine. Mine is scheduled for a visit to the garage at ~70k km for stone chips and belt/tensioner. This is already plenty for me...
Still good at 170k km. No slippage at all no matter how much I try. The extra grunt from the 2.4 may reduce the life a bit though - it probably would for me
4) common/known problems/things to look for on test drive.
Klunks, rattles and powerlosses in the rev range. Most of these can be fixed easily and not too costly.
Fluid levels - before EVERY drive
Tire wear, paint and alignment of panels...