Engine Knock

jimmymarsbar · Unread post by **jimmymarsbar** » 17 Jul 2016, 17:47

Set off for a day out with the missus today, arrived at our destination after an hour of smooth, pleasurable motorway driving, realised that the event we wanted I go to wasn't all that it meant to be and left to find something else to do.

After about 2 minutes at 40mph down an A-road, a flapping noise suddenly appeared, followed by a heavy knocking which could be felt through the whole car.

So, I pulled over and popped the bonnet, the engine was bouncing all over the place, and it sounded as though the piston was smashing against the valve or something.

Got the car recovered home and took a video of the engine for you helpful folks to cast your eyes and ears over.

My first thoughts were that the timing belt (which was changed only a month ago) had jumped a tooth or two and the crank and camshaft had fallen out of sync. But, PP2000 says that they're still in sync.

So, what are your thoughts? is it a case of a broken/bent arm, knackered piston....?

ken newbold · Unread post by **ken newbold** » 17 Jul 2016, 19:54

First thought is injector knock

jimmymarsbar · Unread post by **jimmymarsbar** » 17 Jul 2016, 20:00

Would that cause the whole engine (including intake manifold and air box) to rock back and forth, and make the car judder? I'll check the injectors and see if there's any sign of them being loose or sunk.

The live data showed that the injector correction rate was slightly higher than normal - there is usually a range between -2 and +2, whereas this afternoon I had it at -5 to +5

Unread post by **myglaren** » 17 Jul 2016, 21:44

The engine in my first C5 decided to leap around like a mad thing.
There was no knock but it turned out to be a dud injector.

chinkostu · Unread post by **chinkostu** » 17 Jul 2016, 22:01

A buggered injector will do that, or no combustion in a petrol. It might be buggered or just blocked, PP not showing any codes?

jimmymarsbar · Unread post by **jimmymarsbar** » 18 Jul 2016, 06:51

No codes whatsoever, the only "anomaly" was the injection correction rates - all 4 showed that they were injecting, but the correction was covering a larger range.

The missus has pretty much said that it's time for a new car, and I'm gutted to say that I'm beginning to agree with her. Bought it as a shed, nursed it back to health only for something else to appear....

I'll have a look tonight and try work out which injector could be to blame - a brief inspection last night found everything to be secure, no signs of leakage. Are there any ways of identifying which injector could be the culprit?

Gibbo2286 · Unread post by **Gibbo2286** » 18 Jul 2016, 09:32

jimmymarsbar wrote:No codes whatsoever, the only "anomaly" was the injection correction rates - all 4 showed that they were injecting, but the correction was covering a larger range.

The missus has pretty much said that it's time for a new car, and I'm gutted to say that I'm beginning to agree with her. Bought it as a shed, nursed it back to health only for something else to appear....

I'll have a look tonight and try work out which injector could be to blame - a brief inspection last night found everything to be secure, no signs of leakage. Are there any ways of identifying which injector could be the culprit?

With the engine ticking over and the knock present crack open each injector pipe (just undo the most convenient pipe nut) one at a time, good ones will make a difference to the running a bad one won't, same as shorting out a spark plug on a petrol engine.
Make sure you cover the injector with a cloth before undoing that pipe or you'll get a diesel shower.

jimmymarsbar · Unread post by **jimmymarsbar** » 18 Jul 2016, 12:10

Cheers, I'm hoping that it's something that can be quickly fixed, as I'll be looking to get rid soon!

Unread post by **Peter.N.** » 18 Jul 2016, 12:35

Does sound like an injector, if its not providing the correct amount of fuel it will cause the engine to rock as the power will be down on that cylinder. I assume that its an 8 valve engine, if so injectors rarely fail consequently they are very cheap, I got a complete set from ebay for about £25.00 and they are not difficult to fit, you can get new seals from ebay for not a lot of money. You can probably do the job in half an hour to an hour.

Have you looked at the live data on the lexia? I would have though it would have thrown up some anomaly between the injectors.

Peter

jimmymarsbar · Unread post by **jimmymarsbar** » 18 Jul 2016, 13:25

Thanks Peter, PP2000 didn't throw any fault codes up, which is probably why I'm a bit confused/perplexed.

The live data showed that all 4 injectors were squirting away, although the correction from the expected flow rate was more than normal. Instead of being a 4 point range (normally between -2/+2) there was about a 10 point range in the correction (-5/+5).

I'll have another look tonight and study it in more detail.

I had a look at injectors at GSF and Euro CP on the way to work this morning, and 1 injector at ECP was about £450, and a Bosch from GSF was £225.

The knock is loudest at the gearbox end, so I guess this will be a good place to start.

Hell Razor5543 · Unread post by **Hell Razor5543** » 18 Jul 2016, 14:07

People quite often avoid ECP, as it is not unknown for them to have old, used parts in the box.

jimmymarsbar · Unread post by **jimmymarsbar** » 18 Jul 2016, 15:17

Would unplugging the electrical connector on each injector help identify which injector is at fault? Or is it a case of connecting the fuel pipe on each?

Unread post by **Peter.N.** » 18 Jul 2016, 16:58

http://www.ebay.co.uk/itm/PEUGEOT-206-3 ... SwAvJXBt8R

The ones I bought or £25 were fine. I would have expected one injector to show an error on the live data.

I can't see a problem myself with unplugging the injectors but I have never tried it so can't guarantee the outcome. You can do a leak off test fairly easily with four containers and some plastic tube.

Peter

Unread post by **RichardW** » 19 Jul 2016, 12:31

Don't disconnect an injector when it's running on a CR engine - that is a very bad idea.... I think it also says don't unplug an injector when running as that can ruin them. Check that the crank pulley hasn't disintegrated - when this lets go it can make some very bad noises!! Does this engine have a DMF - does it make any difference if the clutch is pressed?

jimmymarsbar · Unread post by **jimmymarsbar** » 19 Jul 2016, 13:57

The clutch was swapped for a single body flywheel before I bought it - however I had the clutch replaced and since then there was a noticeable vibration when starting off from standing, and it was particularly bad when facing uphill.

The mechanic said that the judder was probably because the new clutch kit needed to "bed in" to the flywheel, and, coupled with an ageing driveshaft caused the judder when starting off. I was always dubious about this diagnosis, but gave him benefit of the doubt and told to allow the clutch to settle.

So, it would seem plausible that the crank/drive system is at fault. I'll test the clutch tonight (if I ever get time

).

My first instincts were that it was something moving internally, rather than injection, but I'm still aware and considering everyone's advice on the injectors

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