Another New Member

[David Smith]

Thanks for all the interest in my screaming engine. Didn't realise there are so many XM enthusiasts.

Vehicle has been recovered by local Citroen agent who have always dealt with it (Holland-on-Sea, Essex). Haven't heard from them yet - will keep you posted.

I can confirm that there was no apparent existing problem with the turbo - no black smoke. Dip stick showed normal oil level with no apparent pollution. The over-revving occurred briefly twice on the journey - first time I thought my foot had slipped off the brake onto accelerator. There was also a brief mechanical grating noise at one stage. Second time, I knew foot hadn't slipped but both times revs were moderate and it recovered. Third time I was prepared and switched off ASAP but it had still reached screaming pitch with cloud of 'blackish' smoke but engine did stop. The guy who recovered it said possibly it was consuming engine oil but in that case it would not have stopped when switched off!

Thanks for your interest'
David

[CitroJim]

If it stopped on the key David it was unlikely to have been consuming its own oil..

Will be most interested to hear what the garage finds...

[Dieselman]

Black smoke would indicate a fueling problem.

[David Smith]

News from garage - dismantled turbo and found it full of diesel! Drained and it started and ran OK but refilling with diesel 'like a tap running'. They said there is a valve somewhere that is not working. Apparently still available and waiting on delivery.

[David Smith]

Hi just to let you know the outcome of the problem with the screaming engine on my XM. Pleased to say it is fixed. The garage report says:

Inspection revealed diesel fuel in the intercooler unit - removed intercooler unit, drained and flushed out. Found fuel back feeding from injection pump via pipe from bottom of pump due to internal fault [faulty valve?]. Relocated pipe back into fuel system and blanked intercooler pipe to prevent a repeat of this fault. Pump will require overhaul or replacement for permanent fix.

Don't understand the details but it seems to run OK.

Thanks for your interest.

[citroenxm]

Ahhhh, yes, thats the Over Fuel Device sensor, it has a diaphram inside it.

Basically, it senses the Turbo Boost from the Intercooler, and adjusts the fuel up for the Turbo Pressure increase.

Without the pipe connected to the intercooler, the car will be flat as the pump cant supply the Extra Fuel for the boost from the turbo...

Thats the bottom of it. Pleased you found the fault. I cant remember if this was a Bosch Pump or Lucas Mechanical Pump on your car..

[David Smith]

Regret I don't know the make of pump. The turbo indicator on dash doesn't move very much. I will run it for a bit to see performance but not worth a new pump I guess!

[citroenxm]

You wont need a new pump. Im not CERTAIN, others will know, but its not a hard thing to swap on these.

I can find out for sure for you if no one else comes up..

[Dieselman]

As long as the diaphragm inside the boost compensator is intact, there is no reason you should need a new pump.

You need a new boost compensator, which screws on from the outside.

The pump is a Lucas DPC.