SPGTi 2 Posted May 2, 2008 After much searching I have found the following information : XU10j4R started life in the Citroen XM in 1993, but has seen some evolutions of the engine within this model, even though it is still marked as the XU10j4R (RFV). It seems that in 1996 the cylinder was modified along with camshafts, camshaft bearing casings, the dipstick was modified and also the piston / rod assembly. Cylinder head : reduction of the width of camshaft lateral bearing (bearing no5 gear side) from 24mm to 23mm. Apparently there are 3 possible combinations for the piston / rod assembly : 1. early - pistons had a chamfer on the skirt 2. for only a few engines - introduction of nozzles 3. new cylinder block without nozzles, but improved surface condition of cylinders .Pistons had a better skirt design. Drilled rods and upper bearing half shell assembly (to replace nozzles) The changes are referred to by R.P.O numbers : cylinder head from 6779 Dipstick from 6793 piston/rods 1. prior to 6769 2. 6770 to 6944 3. 6945 on This info was taken from XM information, I am presuming that it follows for all engines across the model range, Citroen and Peugeot. Anyone aware of any later evolutions of the XU10j4R ? What exactly are the R.P.O numbers and are they marked on the engine or VIN plate ? If an engine is out of a car and these R.P.O are not marked on the engine, without dismantling, is there any way to tell these evolutions apart ? Is the latest evolution the best ? Or would fitting the nozzles into the latest evolution block be worthwhile ? cheers Steve Share this post Link to post Share on other sites
welshpug 1,661 Posted May 2, 2008 (edited) RP number is the build code, usually painted in in similar positions to the Paint code (I.E strut tops, usually left), Peugeot started using Build codes around 94. Engine numbers may get you somewhere, not sure if there would be any sequence or record of them though. The changes mentioned seem to coincide with the introduction of the GTi6 engine. Edited May 2, 2008 by welshpug Share this post Link to post Share on other sites
Hilgie 16 2 Cars Posted May 5, 2008 agreed with the above....and additionally I would choose the early version with oil spray nozzles. Share this post Link to post Share on other sites
SPGTi 2 Posted May 6, 2008 agreed with the above....and additionally I would choose the early version with oil spray nozzles. Ok, so how would I relate these build numbers to an engine that is more than likely out of a car ? I don't fancy having to whip the sump off every time and then check the size of the camshaft bearing. Steve Share this post Link to post Share on other sites
Hilgie 16 2 Cars Posted May 7, 2008 early 406es should be fine, but I still would take the sump off as Peugeot liked to put in the cars whatever they had in stock 1 Share this post Link to post Share on other sites