How did you conclude that number 4 was at fault :* It's more than likely that you saw an increase in fuel on that injector. The ecu is probably fuelling that cylinder with more fuel to try and keep the engine running smoothly and in reality its probably an injector showing the least fuel. The other option is that one of the other injectors is having a dribble so it may pay you to pull all the injectors and have them checked as a matched set, its also possible that the recon injector is out of tolerance as I've found in the past and there not as good as they are made out to be.

 

Festa,

Thanks for the reply.

After advice given from diesel engineers and garages they all pointed to a faulty injector that the solenoid sticks and stays open - so I bit the bullet and bought a re-con one hoping it would solve the problem and would be put to bed.

I do believe that there is extra diesel being dumped in that cylinder as when you look through the intake manifold and compare to others it looks very clean compared to the others, which would in theory explain the low compression in that cylinder as the diesel may have washed away the coating of oil to the cylinder block/pistons.

Is there any other way of testing the injectors/delivery of fuel i.e on a computer or VW programme prior to having to strip the injectors and have them sent away.

Thanks

 

If the compression on cylinder 4 is low that will cause the white smoke, when the cylinder warms the smoke will reduce - clear. A cylinder leak down test will help diagnose the fault as to wether the piston rings are broke or valves worn by the direction the leaking air takes. Had something similar with a Volvo truck white smoked at start up but cleared after a couple on miles enough to pass the mot checks but I wasn't happy with it. Performed a leak down test and found two cylinders were lower than the rest and air was escaping through the bottom of the engine rather than the cylinder head. Took the pistons out to find the second rings on both pistons were broke. Had caused no damage to the cylinder bores so was lucky

 

Faulty injectors can not affect the compression of a cylinder. Piston rings, pistons, cylinder head gasket and valves affect the compression of a cylinder

 

You would probably want to rethink that statement... all the 5 pot engines show signs of cracking through the injector entry to the combustion chambers on the head, this intern spreads to the exhaust and inlet ports and travels behind the valve seats into the ports. The washing of fuel in the inlet ports is the diesel from the high pressure side of the injector breaking through and washing off the oil from piston ring blow by. The exhaust side suffers as well as you would get white smoke with the diesel igniting in the exhaust side with the heat as it wouldn't be full combusted.
I've just documented on here that very problem on the head I had removed off my sick engine back in January and I have just finished a full rebuild with a few more parts that vw didn't fit
Yes a leak down test would test the rings but the compression test would test the whole chamber. A pressure test on the fuel rail would confirm a problem with that area from the tandem pump.

 

^8)tCoK*1u

 

Thanks for the information provided Chris.

I did get mixed messages regarding the injectors not being related to compression but I wanted it too be the injectors as I have had nothing but issues with the van since I have owned it.

I think I am going down the route of a cylinder leakage test see where we stand and prepare for the worse!

Do you have any information on how I know I am at TDC on number 4?

Thanks

 

Ok should have included cracked cylinder head but op has already checked for that so didn't include it. Similar problem that the older LT engines suffered with cracking between valves. A leak down test should identify a crack in the cylinder head as water bubbles in the cooling system

 

The disign of the head and the location of the cracking doesn't appear to go anywhere near the water ways. The op did state that he checked for injector bore wear and as said cracking...Can't see cracking from the top side unless it's been inspected when the head was off.
Not heard of a 5 pot head warping only when overheated but you can get away with a 0.1mm discrepancy across the head.
I've also cut up a couple of heads to see what's going on before porting mine. I've also had head lift which damaged the head gasket between 4/5 but only because of the extra combustion pressures I was running.
Leak down on the head would have been easier to do with the head off

 

Guys,

Great feedback much appreciated.

Festa - do you have the link too your post regarding your issues ?

I will have too do some more tests over the weekend which will no doubt mean stripping the engine down 'the joys'

Keep you posted and thanks again

 

Think my build thread is getting a bit long now as it started with a larger turbo and progressed into something else and is over 2 years Some of the pictures got deleted when the new forum owners took over but you may get the jist of it.
http://www.vwt4forum.co.uk/showthread.php?t=437685

 

TimmyT5 from what you have described u have the exact same issue, did you ever work out the cause to all the smoke?