4200 Knocking when cold

GeoffCapes

GeoffCapes

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I've come across a 4200 which looks like it's reasonably priced, however, the owner has advised me that there is a slight knocking when the engine is cold.
He has been informed by his garage that it is the manifold, and is a 'common' issue that causes no problems.

Hoyle Fox in Maldon Essex, have assured him that it is nothing to worry about.

Has anyone had this issue? And what is the fix? Anyone know anything about HF?
 
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D Walker

D Walker

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If it is the manifold you can here it straight away, I've heard one but it was more of a rattle, vibration than a knick.

Edit: knock!!
 
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GeoffCapes

GeoffCapes

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D Walker said:
May have been confirming my statement Mark, but any unusual knock, rattle is obviously something that needs sorting!
Click to expand...

Obviously any knock or rattle needs investigation, but if Hoyle Fox are saying that it is nothing to worry about, and having looked at what they do, I would imagine they know what they are talking about.
Should it be a car I buy I would want it fixing asap, and want to know how much it will cost to fix, however, if the knocking is knackering the engine, I won't even bother looking.
 
CatmanV2

CatmanV2

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If it's what I think they are talking about it's because the manifold (or I thought it was lower down the pipe) is double skinned. The welds holding them separate and the inner skin can knock against the other (or vice versa). It can stop when warmed up as everything expands.

The official fix is to replace. The un-official is (if I recall) that you can use a punch to drift the the two together so prevent movement.

It has no impact on performance. But I'd also not think it would sound like a knock. Deffo a rattle. Trying to recall who had it here. I think maybe MAF?

Cheers

C
 
conaero

conaero

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The manifolds are twin skinned and what happens is the welds fatigue and the inner skin rattles against the outer when cold. As the engine warms up, the metal expands and the rattle stops.

Yes it's a well known issue and yes it's more of an annoyance than anything else to worry about.

To remidy, you can obviously replace with a new one but the engine has to me jacked up off its mountings to gain the necessary access to remove them and they are stupidly expensive. Alternatively I do know Autofiscina can drill, plug and weld them in situ to stop this happening for a few hundred quid.

What you have to be sure of is that this noise is the manifold rattle and not something else like variator failure or oil starvation due to failed oil accumulator.

If you descided to proceed further with this, get it checked out first.
 
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rossyl

rossyl

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The manifold is double skinned. Often the inner ski nnseperates from the outer. When cold this causes a rattle. Once warmed up, the inner skin expands and no longer rattles.

It should not be a knock. The noise shouldn't be too loud and shouldn't last very long.

You can put in welds to try and connect the two skins. But its not guaranteed to work.

Little concern with this one.
 
Contigo

Contigo

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Manifold if it goes when warm but it could be Cam Variators or have even spun a conrod bearing/shell.

The one I bought was knocking like a ******* and didn't go when warm.

There is a fix for the manifold and it involves punching the first skin and spot welding then together.
 
FelixV

FelixV

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Thanks to all for clearing this up as mine does this for a minute or so when warming up or a few seconds when driving off after a short while stationary.
 
GeoffCapes

GeoffCapes

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The owner has confirmed that it has been diagnosed as what you guys have said it is.
Just waiting for a date/time when I can go see it.
 
rossyl

rossyl

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Contigo said:
Not the best idea, Manifold rattle sounds pretty awful and would put me off buying any car, charachter or not.
Click to expand...

I would take a more considered approach and go and listen to it myself and then make a decision. Either it sounds terrible and you cannot stand it, in which case walk away, or it is minor and you barely notice it, in which case it might be a contender for to be bought and an issue to haggle the price over.

That said, Geoff has a pacifists approach to pulling the trigger
 
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