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Ford Focus TDDI knock

I have a knock on my '99 Focus TDDI (Endura-D engine) Ghia, which appears to be at half engine speed. It is considerably worse when cold and *almost* imperceptible when fully warmed up, but I can just about hear it.. It is worse when pulling away and inaudible or at least masked when driving. My local mechanic has had the car for a couple of hours and has reassured me that it is not bottom end failure as the engine otherwise sounds very sweet, especially for a TDDI, and sounds normal when revved. It's not rumbly or particularly clattery. The exhaust is smelly though, but I realise these are fairly dirty and unrefined engines to start with.

The car has a full service history and has been serviced at the recommended intervals. It has 81K on the clock. My mechanic says that it's likely one injector is worn/leaky and causing excessive knocking, which sounds plausible enough. Can anyone back this up as a possibility please? He has bunged in some injector cleaner and told me to see what happens over the next few days.

However, I'm concerned that if it persists that excessive strain is being put on the conrod bearings, like a pinking petrol. Need I worry?

Looking at the injectors it looks a fairly trivial job to replace them- undo the pipe retaining bracket, undo the pipe from the injector with a spanner (taking precautions for pressurised fuel), pull off the rubber pressure relief pipe or whatever it's called, undo the single bolt on the retaining plate which holds the injector down, lift the injector out. Reverse procedure to fit new injector. Is it really that simple or am I missing something?

Is there any point in replacing the single faulty injector or should I replace the set? Would I be better off getting aftermarket injectors or genuine Ford parts?

All opinions welcome, thanks in advance.

Morse

Reply to
Morse
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i'm not sure which type of injectors yours are, some have to be programmed/calibrated to the PCM but i think this is only for the TDCI's look for an eletrical connection on the side of the injector. if its not there then it should be an easy job as you said, dont forget to change the copper washer at the bottom good luck

Reply to
ford_technical_

Thanks for your reply, Dave. They're the purely mechanical ones, no electrical connections- just the metal diesel feed pipe and the fabric-covered rubber pipe.

Morse

Reply to
Morse

In terms of cost, it'll be cheaper to get the injectors removed and overhauled, but finding somewhere with the proper equipment to overhaul them may be hard. I'm sure at that age, it'll be dual stage injectors (is it a fly-by-wire injection pump?), which can't be tested with conventional injector testers. Have look in Yellow Pages under Diesel Fuel Injection, and then phone some companies for prices.

If you remove the injectors yourself, you'll need to completely remove (or at least slacken the injector pipes) from the injection pump to get the injectors out. You should never bend diesel injector pipes.

Reply to
M Cuthill

Ah, I take it these are expensive parts?

I'm not very experienced with diesel engines so I'm not sure what dual stage injectors are- does that mean solenoid operated? AFAICS it's a mechanical pump with simple injectors operated by the pressure of the fuel pump. There's no ECU or electrical control of the injectors themselves, does that help?

Thanks, will do.

I thought that might be the case. The pipes look a bit awkward to get to on the pump but not that hard. Once they are loosened or removed can they just be reattached without changing any seals etc?

Cheers.

Morse

Reply to
Morse

Yes. Overhauling (where possible) is always the far cheaper option.

I'm sure at that age, it'll be an electronically controlled pump. There are no electronics in the injectors, but the pump is all fly-by-wire, and I'm sure it'll also have two stage injection. Any decent injection specialist will soon tell you if they can test/overhaul the injectors or not.

Ford did recommend that once disturbed, that you should replace the pipes, up until it was costing them too much in replacing injector pipes under warranty whenever they had to be disturbed to do a warranty repair. So they relaxed the guidelines saying they could be reused once, but provided they don't leak once you've got them back on, I wouldn't bother replacing them. On a Focus, they're pretty accessible, so taking them back of to replace them isn't a major job, unlike a Mondeo/Transit where you've got to dismantle quite a bit to uncover the pipes.

Reply to
M Cuthill

My mechanic added a dose of injector cleaner to the diesel and it seems to be getting better all the time.. Hopefully I'll get away without spending any money for a while!

Thanks, I'll keep an eye on it and see what happens. Hopefully I won't need to take it any further for a while.

I found a tip on a couple of websites that to find the knocking cylinder, one has merely to pack round the injectors with rags and slacken the pipes slightly one by one to reduce the diesel pressure enough to prevent the injector opening, and when the knocking stops the bad injector has been found.

Didn't really seem to help isolate the bad one, but made a bit of a mess in the process! However, the pipes seem to have re-sealed perfectly- I won't bother pushing my luck and trying it again!

Morse

Reply to
Morse

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