Timing belt

fastandfurryous · Post by **fastandfurryous** » 14 Oct 2006, 14:26

People seem to be talking at cross-purposes here.

The HDI engine has two pumps. The first is an Electric "lift" pump. it's a low pressure pump that simply lifts fuel from the tank to the engine.

The second pump IS mechanical, IS driven by the cambelt, but DOES NOT have any form of timing. It simply generates high pressure fuel for the common rail system. You can do anything you like with the orientation of this pump.

If ( as has been suggested ) that the camshaft timing was a tooth out, then I don't think the engine would run very well at all, simply due to the valve timing being wrong. The injection timing would match the valve timing, but neither would be correctly in sync with the pistons. I doubt it's this.

More likely is that while someone was changing the cambelt they have severed a cable, or smacked a sensor somewhere. The thought by MikeD that it may be the temperature sensor believing that the engine is at temperature when actually it's cold is much more likely.

But then also as malcolm says, if it's only done it since you had the belt changed... take it back to them and complain!

citronut · Post by **citronut** » 14 Oct 2006, 17:43

ok i have not had any thing to do with the HDI lumps yet,and i did think they had and electric pump insted of the ususal mechanical pump,i also would think that it could be posible to have the cam timming out by one tooth,i have in the past found a diesel BX with the cam belt out by four teeth and it did still run
regards malcolm

JohnD · Post by **JohnD** » 14 Oct 2006, 19:11

[quote=" it could be posible to have the cam timming out by one tooth,[/quote]

I agree! If the old belt had been removed and the new one fitted without loosening the three camshaft sprocket bolts, the valve timing could be very slightly out.

citronut · Post by **citronut** » 14 Oct 2006, 23:06

what i have seen which causes this is people dont bother peging the flywheel,so when the tensioner takes up the slack it also moves the cranck sproket slightly
regards malcolm

curly · Post by **curly** » 19 Oct 2006, 04:58

Thanks for all your input into the subject .Just to confuse this subject abit more if the timing was out say by one tooth and when starting from cold (left over night for 12 hours say) the engine runs rough but when the engine has warmed up would it still run rough or would it be harder to detect the problem as once my engine is warm it seems alright?

JohnD · Post by **JohnD** » 19 Oct 2006, 09:55

If the timing is slightly out you'll have rough running all the time. But probably at its worsed on starting up.

curly · Post by **curly** » 15 Nov 2006, 04:29

Hi everyone sorry I haven't been back sooner and thanks for all the info . Anyway took my car back last week and left it there for 4 days when i rang the people I bought it off they said there mechanic could not find anything wrong with the car

so I have decided to take it to the mechanic I use and get him to check the cambelt to see if it has been fitted propely .I have the feeling when it was changed the sprocket pegs where not used and the cam is very slightly out from the pistons ,could this be the problem and do you think it has damaged the engine .
P.S if this is the problem I shall send the bill to the people I bought the car off

alan s · Post by **alan s** » 15 Nov 2006, 04:51

curly wrote:Hi everyone sorry I haven't been back sooner and thanks for all the info . Anyway took my car back last week and left it there for 4 days when i rang the people I bought it off they said there mechanic could not find anything wrong with the car so I have decided to take it to the mechanic I use and get him to check the cambelt to see if it has been fitted propely .I have the feeling when it was changed the sprocket pegs where not used and the cam is very slightly out from the pistons ,could this be the problem and do you think it has damaged the engine .
P.S if this is the problem I shall send the bill to the people I bought the car off

I'm fast coming to the conclusion that these later generation engines, both petrol & diesel are particularly sensitive to the way the belt is fitted or more correctly, the way it's retained whilst it's fitted.
This is what's happened to me in the past couple of days.

http://www.frenchcarforum.co.uk/forum/v ... hp?t=20723

Haven't been able to get back to sort it yet due to having been battered around a bit in a severe storm this morning and now have water to get out of the garage before I can recommence hostilities.

If there's been no clangs and bangs in the engine, I'd imagine it should be OK once the valve timing has been sorted out.

Alan S

curly · Post by **curly** » 22 Nov 2006, 03:35

HI back again just heared from the mechanic he says the timing belt is fine but there is a problem with the engine. He says it could be a valve gone but if his is right then wouldn't the engine be rough all the time not just when cold .He is going to look further into it today to see if he can find the problem (more money) I'm beginning to think it is one of the sensors which I hope it is as this has got to be cheaper than having a valve replaced

sods law it will be a valve

citronut · Post by **citronut** » 22 Nov 2006, 13:19

maybe if the garage you bought the car from fitted the belt slightly out,and realised there misstake then corected the belt,but the first atempt cliped the edge of a valve,now if a valve is very slightly damaged it might close up more when the engine warms up,do you know if the engine had been warmed up before you saw the car when you say it seemed to be running ok,becuse they might know there is a fault that they were covering up to start with
regards malcolm

jeremy · Post by **jeremy** » 22 Nov 2006, 14:29

Could even be something highly technical like air getting into the fuel when the thing stands. This isn't so likely on a HDi as there is a pressure pump at the rear - so rather than air getting in as on XUd's fuel would get out.

I would have thought that a valve would have shown up as a rhythmical pulse or roughness - as 1 in 4 cylinders would be affected. I would also have thought that some smoke might be visible but HDi's have filters so that may not happen.

curly · Post by **curly** » 22 Nov 2006, 15:13

yes it has this filter on exhaust so any smoke does not show .So am i right in thinking if valve has gone the engine will be rough all the time not just when cold

jeremy · Post by **jeremy** » 22 Nov 2006, 17:44

Yes basically.

XUD's can suffer from valve sinkage problems which close up the clearance between the cam and the valve/tappet - preventing the valve shutting fully. As the engine warms the alloy head expands more than the steel valve gear and the valve seats properly. - So it misses when cold and seals when warm (which can be quite quick)

If your HDi has hydraulc tappets I would have thought that this problem wouldn't occur as they weould adjust to the proper clearance.

curly · Post by **curly** » 23 Nov 2006, 04:52

Thanks Jeremy. I sorry to keep picking your brain but it seems you know a bit about this so if it is this problem is it a big one or can it be fixed by a good mechanic and do you think it will cost alot to repair

curly · Post by **curly** » 05 Dec 2006, 04:51

Hi again got my car back last week took it to my mechanic who check it out and told me it was not the timing belt but I did have a problem somewhere .The tappets are hydraulic so he said its not that so he is at a bit of a loss as he has not had much to do with these engines.I told him when I bought the car part of the throttle body was broken (A long bar with a plastic elbow joint on the end ) which has been replaced ,could this be the problem does this have to be set up propely and would this make the engine judder when cold

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