Weird kncoking sound from a B200k

Post by **Chris_C** » 22 Jun 2006 06:38 pm

Hey all, when I was causing oil slicks round Nicks house the other day, I had a listen to his car, not sure how much you can get from this, it's a really tinny recording

http://www.ecs.soton.ac.uk/~clc202/nick.mp3

Any clues?

Post by **Carl** » 22 Jun 2006 10:37 pm

Hard to tell from that, but could be the bottom end knocking. Which would probably mean a new engine!

Post by **SteveP** » 22 Jun 2006 11:28 pm

Bottom end knock?!

It'd have to be pretty special to have a bototm end knock on a N/A redblock, with what I remember to have rather low mileage?

Post by **Carl** » 22 Jun 2006 11:42 pm

The strongest engine in the world will still detoriate if the person driving it doesnt look after it (not talking about Nick or Mick there)!! All it takes is one owner with no mechanical sympathy at some point in it's life!!

Post by **Chris_C** » 23 Jun 2006 01:09 am

Yeah, it's not making as much of a noise as Kar was when it was fully rattling, but I'd say the noise wasn't too different to what Kar makes now, with no stuff floating about in the pistons.

Post by **Nick C** » 23 Jun 2006 09:03 am

To elaborate slightly on what Chris said - it only makes that noise when it's cold, as soon as it warms up it disappears.

Post by **mac** » 23 Jun 2006 10:36 am

Very hard to tell from an mp3 but on a B220K I would look at the fuel pump first. (sounds a little hollow for pump knock though).

Certainly doesn't sound like bottom end (that would get worse as the motor warmed up anyway).

Piston slap will go away as the engine warms - but red blocks don't suffer from it (unlike B14s !!) - and slap is more of a tap.

If you can get hold of a stethoscope (automotive type) have a listen to the pump first.

The mp3 actually sounds like an exhaust gas recirc. valve 'flapping' - but I dont know if Nicks car has it fitted.

Anyway - somthing for you to think about. Mac.

Post by **redline** » 23 Jun 2006 12:30 pm

We put a brand new fuel pump on it before Nick bought it ,
she always did rattle a bit on start up but as has been said it clears once warm ,
Chris hasn't said where the rattle appears to be coming from i.e. front back , top or bottom of the engine that may help ( I never bothered to investigate it as I was having too much fun driving it once Pete and I got it going )

Post by **pettaw** » 23 Jun 2006 06:10 pm

I have to respectfully disagree with Mac on this one, the low friction redblocks (B2xx) are notorious for piston slap when cold. In later designs they redesigned the engines with piston oil squirters to direct oil at the piston skirts so they wouldn't overheat and skuff the bores causing the excess wear and knocking on cold startup.

Having spluttered all that....I don't think this sounds like it to me. I had pretty bad piston slap on my blue car before I rebuilt the engine and I have it slightly on the red one. This sounds more like something in the top end, possibly the camshaft rattling slightly, or possibly the exhaust knocking against something. Its very difficult to tell tbh.

Post by **mac** » 23 Jun 2006 08:22 pm

Oh dear I'm not doing very well today am I ?

Still, quite happy to be corrected Pettaw - my only defence is that piston slap was never a real issue with the redblocks (I agree that the B2xxs being a short skirt design were candidates) in the way that the Renault engines were.
At least not insofar as 'new' cars were concerned.

With my old '84' 340 you could tell the outside air temp by how long it took for the pistons to shut up from cold. (With the B14 it wasn't wear that produced the slap, but the short skirt piston 'rocking' in the bore until the piston and liner temperatures equalised ! (partialy cured in about 88ish. with 'Duotherm' pistons, which had a steel band in the skirt - to change the expansion rate).

If indeed as Pettaw says the redblock slap is a product of scuff wear in service it's possible that it never cropped up as a warranty issue (my department was largely involved in examining product problems during the first 3 years or so).

Grovel, grovel, grovel Mac.

Post by **pettaw** » 23 Jun 2006 08:42 pm

Ahh right, I only have experience of a B14.4E from 1989 model in our family and that had no slap at all on a cold start. Interesting to know.

Don't think it sounds like slap though do you? The frequency is too low, that's why I'm guessing something cam related, cos of the speed.

Post by **mac** » 23 Jun 2006 08:55 pm

Definitely doesn't sound like piston noise at all - it's very distinct above the injector clatter isn't it ? Sound almost 'hollow' - It's one for the stethoscope I think. It's way less than engine speed though (from the injectors, sounds like
engine was about 900-1000 or so but the noise (havn't counted it) cant be much more than 250 - sticky valve or lifter perhaps ??

Mac.

Post by **pettaw** » 23 Jun 2006 09:07 pm

Shouldn't be any injection clatter. Its a carb engine AFAIK

Sticky valve is a distinct possibility. A good dose of engine flush followed by a top quality oil might help.

Post by **mac** » 24 Jun 2006 10:11 am

So my 'injector clatter' is valve clearances! Blame my ears (or the mp3).

Pettaw is quite right - if it is a sticky valve a good 'flush' may well help. Could be just a build up of carbon on the stem (unleaded is not as clean in some ways).

Pettaw - have you come across any valve guide issues on redblocks that could give this problem ?? I don't know of any myself. If it is a valve it sound like it's only one.

Mac.

Post by **redline** » 24 Jun 2006 10:25 am

Mac and Andy , you got all that from an mp3 recording

is all I have to say (we dont have a smiley taking his hat off to you )
it is indeed a cab model

Weird kncoking sound from a B200k

Weird kncoking sound from a B200k

Noise