Diesel Knock / Chatter

[adam03031980]

One of the guys at work said it sounded like my car had diesel knock on friday now i know its very chattery when cold but goes away when warm to me diesel knock is a lot louder has anyone had any experience with this mines the 2.0 hdi 90

[gumby6371]

I'd be surprised if you had a diesel that didn't sound knocky in this weather, mine sounds like a tractor when I first fire it up but calms down after a few minutes when it warms up a bit.

If it sounds normal once it's warm I wouldn't worry about it, it will idle high anyway with the cold start keeping the revs up to help warm things up.
Always worth leaving it ticking over for a few minutes in this weather before driving it.

[lozz]

+1

Injector noise is common, itl be this frosty weather no doubt,

[adam03031980]

One thing i have noticed is that when started it will idle fine but after several minutes the revs drop as if its cutting out and it throws out black smoke then revs back to normal and it will do this consitently every 20 seconds or so until i drive off in it but once warm sits and idles fine

[gumby6371]

Sounds like it may be related to the cold start mechanism shutting down the fuelling to far then having to push extra fuel through on the anti stall causing the smoke, mine being an old school XUD it's controlled cogs and pulleys and bits of string not sure how it's controlled on a HDI but it probably involves that new fangled electrical magic.

Somebody from this century will be along to confirm or deny soon I'm sure.

If you've got the patience try holding the revs between 1100 and 1200 for a minute or so with your right foot.

[lozz]

Cutting out, Blacksmoke,

those couid be symptoms of a Blocked E.G.R valve,
give it a dose of wyns egr cleaner or simalar,

[trufflehunt]

Some years ago, I owned an old 1980's Mercedes diesel.., a W123 240D. These engines are reputed to be
able to run on just about anything. I'd occasionally add some vegetable oil from Tescos.

What I really did notice was that with the veggie in.., the diesel clatter virtually disappeared. Not talking
about load of veg oil..., I never had more than about 25% veg in the tank.

I understand that modern common rail (?) diesels like the HDI are not quite so tolerant about what goes into the
tank...?

[rwb]

couid be symptoms of a Blocked E.G.R valve

i.e., stuck open. Get it blanked

I do get noticeably more "head noise" when it's cold. It takes more cranks to start these days (although I did have a cheap battery in two years ago), and cranking is definitely slower wen it's cold.

I understand that modern common rail (?) diesels like the HDI are not quite so tolerant about what goes into the
tank...?

Nothing but diesel will do for the HDi I'm afraid. Once had a tankful of bio in mine and it was not happy; that caused the one occasion on which it nearly let me down.

There's nothing like the sound of an XUD on a cold morning

[Busman]

Don't you just love the sound of a xud on a cold morning?

[jonsowman]

Yep, mine sounds fantastic when it's freezing cold.

Still starts absolutely on the button though

[madmadmax]

xuds sound nicer when running on old gearbox oil no clatter or knock just chug

[lozz]

xuds sound nicer when running on old gearbox oil no clatter or knock just chug

Surely thats Hazmat stuff,

[madmadmax]

na its classed as an alternative fuel so it's fine just don't use more than 2,500l per year, never put power steering fluid in the tank did that once and got dipped the next day trying to explain that was hard.

[lozz]

theres one chap up here who runs his transit
on the oil out oiled filled radiators and transformer oil,

he rekons its better than pump diesel