Help - P38 diesel, black smoke, won't idle, after head gasket repair

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petetid

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Hi All,

I'm new here and desparate for some help. My 1999 P38 diesel has just had the head gasket repaired by my local garage. When they put everything back together and tried to start her up they were struggling to get her to start. After some trying they eventually got the engine to run but with a big cloud of black smoke and it wouldn't idle, it would stay running if you keep the revs up at about 1000 but let the throttle off and it stalls . The car ran completely fine before they took the head off, I've never had a problem starting it nor have I had any black smoke. It drove to the garage for the head gasket repair without any problems.
The garage that has it are scratching their heads about it. They're talking about replacing the injector pump but I can't see why there should be an issue with that, as I say the car ran completely fine before they started the head gasket repair. Can anyone suggest a trouble shooting sequence that I can work to with this? Or anything that the garage may have missed off or not tightened/sealed properly while putting the head back on? Any help will be greatly appreciated.

Pete
 
black smoke is poorly burnt fuel ie not enough air or too much fuel,pumps dont fail by mechanically by throwing in more fuel ,it will be poor timing or some mistake theyve made, you would expect a cloud after trying to start and engine and it taking some doing as your burning off excess fuel created whilst turning engine over
 
Classic symptoms of the injector pump being slightly out by a tooth on the timing - fuelling no longer matches the cylinders now which is critical on a diesel engine. Yes after a strip down of a head some crap will likely burn off once it's run the first time but the injector pump doesn't need renewal unless they've dropped it during removal...
 
The injection pump does not need removing to change the head gasket nor does it's timing need to be disturbed. Only thing that should need timing when the head is put back on is the camshaft. Have they had the pump apart? Sounds like they have made a mistake somewhere along the line. Maybe they are scratching their heads because they don't have a clue what they are doing.
 
wammers said:
The injection pump does not need removing to change the head gasket nor does it's timing need to be disturbed. Only thing that should need timing when the head is put back on is the camshaft. Have they had the pump apart? Sounds like they have made a mistake somewhere along the line. Maybe they are scratching their heads because they don't have a clue what they are doing.
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Not many garages these days seem to know what they are doing, most are only happy changing old for new parts and don’t want to know why it failed or how to repair
 
JohnnyCrash said:
Not many garages these days seem to know what they are doing, most are only happy changing old for new parts and don’t want to know why it failed or how to repair
Click to expand...

Sounds like they don't have a clue what they are about. If they have not had pump apart or off, injection and cam timing needs checking first off. But would they know how to do that? Maybe they have turned engine backwards and jumped a tooth on the crank sprocket. All speculation though not knowing exactly what they have done.
 
Thanks for the replies.

I did have the FIP timing at the top of my list of suspects but didn't think it was necessary for them to disturb that. If they had got the cam/crank timing off by a tooth would they be able to get the engine to fire up at all? or would the timing be too far out?

Are there any hoses or breathers that are not obvious if they've missed one when reassembling?

Ideally I could do with a list of things to check to give me a process of elimination if anyone can help? Also can anyone think of anything else that could have been disturbed while remiving the head?

Thanks
 
petetid said:
Thanks for the replies.

I did have the FIP timing at the top of my list of suspects but didn't think it was necessary for them to disturb that. If they had got the cam/crank timing off by a tooth would they be able to get the engine to fire up at all? or would the timing be too far out?

Are there any hoses or breathers that are not obvious if they've missed one when reassembling?

Ideally I could do with a list of things to check to give me a process of elimination if anyone can help? Also can anyone think of anything else that could have been disturbed while remiving the head?

Thanks
Click to expand...

It has nothing to do with hoses and breathers believe me. I have already said what may have gone wrong. Check the pump and valve timing if it has jumped a tooth everything will be out. You need special tools for these motors if they haven't used them and winged it they are idiots.
 
Last edited:
wammers said:
It has nothing to do with hoses and breathers believe me. I have already said what may have gone wrong. Check the pump and valve timing if it has jumped a tooth everything will be out.
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and if it has count yourself lucky the piston didn't meet the valve!

I'd start with the FIP you suspected it before the head gasket, so why would it still not be knackered?
 
JohnnyCrash said:
and if it has count yourself lucky the piston didn't meet the valve!

I'd start with the FIP you suspected it before the head gasket, so why would it still not be knackered?
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We need to know WHY the gasket was changed what was the problem? If they have had the pump apart? And what tools they had to retime the engine if any. These are not things you can wing must be done correctly. If it ran ok before, they have done something wrong that much is obvious. Not enough info at the moment.
 
Saint.V8 said:
Surely wouldnt start with crank sensor missing!!
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It certainly wouldn't tick over with it missing. Below a certain throttle potentiometer voltage idle switch is active, idle is controlled by crank sensor readings via ECU and fuel quantity servo. If RPM falls fuel is increased, if it rises fuel is decreased. But non of that should have been touched changing head gasket. So unless you are in the know about what exactly has been done by the garage and why it was done in the first place, all from where i am sat is speculation. If i could put hands on the car i am sure it would not take long to find out what the problem was. Garage seem incompetent to be honest.
 
cheongthong said:
if the flywheel sensor is out of not connect it will start but will not idle for this diesel engine
Click to expand...

We know that, but why would you touch crank sensor to change cylinder head gasket. But as i said we don't know what the garage has done. Another thing for the OP to check. We can't do it for him.
 
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