White smoke

Hi peeps I have just had my head gasket changed finally after the overheating problem.
After driving it for about 30mins there is now a loud ticking/tapping noise coming out of the engine ive been told that it may be one of the injectors; there is also white smoke coming out of the rear this was not a problem before the work was done as the engine was pretty sweet any ideas please
Thanks

RR P38 BMW 2.5 diesel 1998

White smoke is generally unburnt fuel. As long as your sure its not steam?
Sometimes injectors knock, if so its easy to find which one, slacken each injector pipe in turn with the engine running and listen to any difference in engine tone and noise. Whats does it drive like? is it down on power?

thanks; yea we did that but didnt seem to be a difference the drive is really bad the engine shakes and lacks power

is it possible the valve timing could be out slightly? has it done it right from when the head gasket was renewed?

yes it was a slight ticking then after driving it for about 30mins about 70mph it became louder and the loss of power feels it wants to stall; valve timing could explain more on this please

Did you do the headgasket yourself?
If you remove the cylinder head you have to remove the timing chain to the camshaft. Obviously this has to be timed back up correctly. I had it before on a different diesel engine where the camshaft was a tooth out. the enhine was able to run but white smoked and run roughly. I am not sure if these engines would run a tooth out as i never got the timing wrong to be able to fnd out. There must be someone in this forum that knows the answer to this question though..........

no i didnt but how would u time it up; thanks for your help

you use timing pins to lock the crank via the flywheel at TDC on no 1 piston.
Then you would use a locking tool on the camshaft.
Have you taken the car back to the person or garage who did the work yet?

Yea i have taken it back to him; just wanted to get a better understanding of what could of gone wrong. Thanks is that timing procces an easy one to do.

yeah sure thats fair enough. I would say theres a few possible explanations. White smoke means unburnt fuel. Its could be an injector not atomising the fuel properly, it could be incorrect valve timing( valves are opening at the wrong time and letting unburnt fuel out the cylinder before its been fully compressed)
It could be a dead cylinder due to low compression or head gasket leaking.
When you slackened off each injector pipe and listened to the engine, If the cylinder is in order the engine would die down or sound rougher/less balanced. If an injector is knocking and you slacken it off on the injector pipe, then the knock will cease.
If the valve timing was incorrect or has slipped then it would cause these symptoms. Usually you take the camshaft gear off, which is on a taper fit. So it would be possible to have it slightly out.
Was the head pressure tested or skimmed? Also was the camshaft and hydraulic tappets removed?
One thing is if you remove the hydraulic tappets they expand and when you refit them your meant to leave them for a period of time to relax, other wise they can open the valves to much and cause contact.

Its not too complex to time up these. just one timing pin in the crank and then a tool on the camshaft.
As your only timing the camshaft to the crank. The injection pump wouldnt of been touched or disturbed.....hopefully!

Spoke to the garage today and one of the valves broke they replaced it and it now wont start it turns over though; there is fuel reaching the injectors; and they did take the head off again to find this; i think that they are to correclty puttng the crank shaft along with the cylinders hence the starting problem can you shed any light: Really appreciate the help so far mate:

so it had a bent/ broken valve? means that the timing was out or they didnt allow the hydraulic tappets to relax before turning the engine over. Basically there has been piston/valve contact i would imagine.
Have they actually given you a reason why they say the valve broke?
your welcome.

irpbath said:

so it had a bent/ broken valve? means that the timing was out or they didnt allow the hydraulic tappets to relax before turning the engine over. Basically there has been piston/valve contact i would imagine.
Have they actually given you a reason why they say the valve broke?
your welcome.

Click to expand...

i guess but there wasnt a problem until the work was done: i thought as much is was the timing the TDC right: they said i drove the car to hard after the work was done

Driving the car too hard?? you could drive that car as hard as you like and it wouldnt break a valve. For it to break a valve in my oppinion the timing must of been incorrect. Its got a timing chain which is far superior to a timing belt in terms of strength and they last far longer. The purpose of which is to keep the sequence correct. ie valves opening at the correct time for the pistons sequence. TDC means 'top dead centre' When you time an engine you use TDC on n.o 1 piston as the start of the sequence. Then you have to correctly time the camshaft to the crankshaft.
But its only as good as the person who times it up.

i totally agree with you the car is built to cope with that kind of drive im going to go and watch over them tomorrow: and make sure they time it prperly ive got RR cd so should have all the information there: i saw him postion the TDC on the head before he fitted it on the block: so i guess that where the mistake happened he should of done it when it was onn the block thats why its not startting now as it out completley

yeah true, u set the piston at tdc on the compression stroke and then check the cam lobes on no 1. they should be flat and facing the same way, to clarify it more theres a tool that goes on the cam it also locks the cam up. If you got the rave cd then i am sure it tells you everything in great detail on there. good luck and hope you get it sorted.

yea i have ok mate will let u know i get on thanks for all your help

irpbath said:

yeah true, u set the piston at tdc on the compression stroke and then check the cam lobes on no 1. they should be flat and facing the same way, to clarify it more theres a tool that goes on the cam it also locks the cam up. If you got the rave cd then i am sure it tells you everything in great detail on there. good luck and hope you get it sorted.

Click to expand...

I would check your pump timing, when on TDC on the correct stroke there should be a little black dimple visible on the top of the pump sprocket (look down from the top with the chain guide rail out).

The pump and cam turns once to the cranks twice, so you could be one revolution out!

Did they use a new cam sprocket bolt when they rebuilt it?
this is a stretch bolt and can only be used once, the sprocket sits flat against the end of the camshaft, no taper, no keyway, ect, so the only thing holding it all together and in time is the tension of this bolt!!