gbmarc

I have this nice looking 2002 3.0 B6 with 187,000 miles.
I have no history on it as the previous owner purchased it in an auction and then couldn't get it running.
The engine cranks over but doesn't start.
I'm getting codes P0347, P0342, P0392 and P0367 (Crankshaft Position Sensor Circuit Low) for all four of the sensors. Obviously all 4 sensors have not simultaneously gone bad, so this obviously means something else.

The timing belt looks OK and every now and then the car makes a very weak attempt to fire up. Any ideas?

Prospeeder

possibly the timing belt was attempted without the special tool? I would also pull valve covers and look at everything. they did have some camshaft problems, like siezing bearing and broken cams. Might have broken and just the cam pulley and half a cam are turning. You done a compression test yet? Does it sound normal cranking?

gbmarc

Yes, the cranking sounds normal. The problem with the broken camshaft theory, is that all four cams would have to be broken as the "Circuit is low" error occurs on all 4 sensors.
I have ordered the timing belt kit and tools and was going to do that anyway, but it would be nice to get an idea what's going on while the engine is still together.
In some other posts I read about the timing belt jumping a couple of ribs. I can't see how that would happen unless the timing belt ribs are destroyed. I guess I could rotate the engine while inspecting the belt all around.
If the timing belt was set incorrectly by a previous change, how can it be verified now? Are there exact alignment marks on each camshaft when the crank is at TDC?
I haven't done a compression test yet.

lyleswk

Not familiar with V6's, but do you really mean 4 Crank position sensor failures or Cam position sensors. If it is the crank, there should only be one. What you describe sounds like like a 1.8t with a bad crank sensor (G28).

Another comment is does the immobilizer light come on?

One other comment and again, not familiar with the 3.0, but if some of the cams were moving, wouldn't you have pistons and valves clashing?

Prospeeder

there are special cam lockdown tools, and you just line the balencer up with the mark on the timing cover.

gbmarc

So I dismantled further and took the timing belt covers off. I went to rotate the engine and the cams didn't move!! Not a good sign I discovered all the ribs on the timing belt down by the crank had disintegrated. So now I am trying to see if any valves are bent. Not sure if this is possible with the heads still on, but right now I'm carefully rotating the camshafts and inspecting the valves to see if they are coming up properly. Now and then I also have to rotate the engine a bit to avoid any valve/piston collision. If anyone has a better method to check for bent valves I'd like to hear it. Otherwise, if it all looks OK, I'm going to reset the timing on each bank with the camlock tools, put a new belt on and test the compression.

Prospeeder

valves ARE bent, dont waste time seeing if they are.

ddillenger

If you tried to start it with the belt slipping, pull the heads. There is no chance that all the valves are fine. The valves that were open will be damaged, and attempting a repair without removing the heads could turn the job from a simple head job, to a complete longblock.

gbmarc

Ahh, so all doom and gloom, or I suppose bitter experience from wiser heads than mine. One other discovery I made: I hand rotated each Camshaft, taking care to position the pistons so there was no interference, and all the camshafts turned easily, (flopping around faster as they reached their point of least contact on the followers) all except for the passenger intake shaft. This one was uniformly very stiff, even when reaching the point of rotation where none of the cam lobes were depressing the followers. I suspect that if this camshaft was this stiff then its no wonder the timing belt lost 6" of ribs. It simply wouldn't have been able to turn it.

gbmarc

OK, so what's the best procedure on doing the heads? I pull both heads and then send them off to someone (any recommendations?) to get rebuilt?
Will the shop also be able to fix the stiff camshaft?
Do they provide new valves and followers, or should I source those?

Mark