I've not known a dephaser failed completely on one of these
I would agree with that usually even a really noisy pulley doesn't actually show much signs of wear when dismantled like this one. The outer part of the pulley rotates a few degrees around the centre and there are 8 veins which prevent full rotation. It's not dissimilar to a hydraulic vein pump except the centre doesn***8217;t fully rotate. All the parts are an extremely good fit looking to me as though they are precession ground.
However I bought a 2002 1.8 F4P engine from a breakers recently (uses the same dephaser pulley as the 2.0 F4R) which was supposed to be a good runner. At £110 it was very cheap for a Renault 16 valve engine. When I got the engine in the car and running the upper engine noise was terrible worse than I've ever heard before. On dismantling the dephaser I found one of the chambers was totally smashed and bits of debris I only found 7 of the 8 veins and also found a piece of metal jamming up the dephaser solenoid. This must have worked it***8217;s way back through the
way. The dephaser couldn***8217;t return to it***8217;s
position and it was only the 2 unbroken veins which were preventing the pulley centre from completely rotating and totaling the engine
. The cam shaft bearing adjacent to the dephaser was also badly scored and under size by at least 0.2mm that I could measure. I have repaired the cam shaft bearing surface and de commissioned the dephaser and the engine is now nice and quite. I have to say the car goes like s1ht of a stick with no dephaser function.
I bought the above car from a Polish guy as a non runner. I'm not sure whether he really was an idiot or just playing dumb? Though in fairness he did say it needed a new engine but was very vague as to what was wrong with the engine his mechanic had taken it apart and put some of it back together again?
Towed the car a mile or so down the road and had to stop and found one of the wheels was loose!! I guess what can expect from a bloke who puts a plastic supermarket bag on his head when it starts to rain!
Once home found the inlet cam shaft had snapped but no signs of the dephaser pulley ? but virtually no damage to the rest of the engine. I didn***8217;t take the valves out but a quick leak test only showed 2 to be leaking very slightly. So why did the shaft snap ? a badly rattling dephaser pulley? Or maybe it got broken by some ham fisted polish monkey trying to remove the pulley with a crow bar?
In the photo below an inlet cam shaft on the right which is 6mm longer than exhaust cam shaft and has extra
holes in it to feed the dephaser pulley.
Dephaser pulley on the end of the inlet cam shaft you can see the
cross holes in the shaft where the other inlet cam shaft has sheared.