Weird Knock From Engine

[VenomX]

Noticed this odd knocking noise couple of weeks back from what sounds like the front, probably near the alternator or belt..

any ideas what it could be ? You will hear an intermittent knock/clunk noise.

It started a couple of days after doing the spark plugs. But they are all fine, and the car drives perfectly.

 

[KennyN]

Quick test would be to remove the belt and start the vehicle for a brief time , knock gone something external , knock still there something internal.

If the knocking noise is gone then you can start checking the components that the belt drives and look for a bit of lift in the tensioners or roughness of bearings.

FWIW it sounds like a failing bearing on something external.

K

 

[VenomX]

OK thanks. I will remove the belt when I get a chance and give it a go.
Is it possible it is just the belt itself ? Personally, I think it's one of them cogs that spin round has a bit of play in it, as it does seem to be outside the engine itself.

 

[M80]

Check the auto tensioner with a 17mm 12 point socket. It should move freely against the spring tension.

I'm assuming they have similar to the diesels, and on a 203 there's every chance it's tight with corrosion.

 

[rifiki]

If the tensioner is old or original change it.
They can and do let go without warning, have had this problem with CLK, M272.

 

[VenomX]

Car has 33K miles on it, so very low mileage.

I took the belt off, noise disappeared.

This, however had some play in it... circled in white.
Anything I can do to either adjust or replace ? This is around the area the knock is coming from so the most likely culprit. I did try tightening the four silver bolts but didn't make much difference.

 

[KennyN]

Is that the water pump ?

If it is are there any signs of a water leak from the drive shaft ?

K

 

[VenomX]

Is that the water pump ?

If it is are there any signs of a water leak from the drive shaft ?

It

Here’s the part number..

A1122020110

Yes it is something to do with the water pump by googling it.
No sign of any water leaks at all

 

[KennyN]

That is the drive pulley for the water pump , not much can go wrong with that as it just bolts onto the water pump drive shaft.

If there is any lift in the pulley and the bolts are tight then the play will be in the shaft of the actual water pump itself , cant be that bad or it would be leaking past the shaft seal.

How is the idler pulley / alternator pulley for lift ?

FWIW i would be looking at the idler pulley as they are pretty cheap to replace and unless totally knackered may seem fine until the belt tension is on it.

At least you now know that the noise is external which should be less expensive to repair than an internal knocking noise.

K

 

[VenomX]

If there is any lift in the pulley and the bolts are tight then the play will be in the shaft of the actual water pump itself , cant be that bad or it would be leaking past the shaft seal.

How is the idler pulley / alternator pulley for lift ?

Thanks for the helpful info, lots learnt today.

As far as I could see, the only thing with a bit of play once the belt was off was the water pump pulley.
Good shout on the idler though, when I get a chance I will have another look. Seems as though they are cheap and easy to replace.

In regards to the water pump pulley, are the four bolts supposed to be completely tight ? They were tight but not fully.
Before buying a water pump pulley, would it be an idea to take off the pulley and see if there is any play behind it ( on the water pump drive shaft itself ) ?

Thanks

 

[KennyN]

Thanks for the helpful info, lots learnt today.

As far as I could see, the only thing with a bit of play once the belt was off was the water pump pulley.
Good shout on the idler though, when I get a chance I will have another look. Seems as though they are cheap and easy to replace.

In regards to the water pump pulley, are the four bolts supposed to be completely tight ? They were tight but not fully.
Before buying a water pump pulley, would it be an idea to take off the pulley and see if there is any play behind it ( on the water pump drive shaft itself ) ?

Thanks

Normally the pulley bolts onto the water-pump shaft which is an integral part of the water-pump. If you want to eliminate the lift on the shaft the entire water-pump assembly would need replaced , the pulley would probably never need replaced in normal circumstances.

You get the idea of the component buildup from this eBay listing , you can see where the pulley bolts onto.

Pardon our interruption...

K

 

[VenomX]

Normally the pulley bolts onto the water-pump shaft which is an integral part of the water-pump. If you want to eliminate the lift on the shaft the entire water-pump assembly would need replaced , the pulley would probably never need replaced in normal circumstances.

You get the idea of the component buildup from this eBay listing , you can see where the pulley bolts onto.

Pardon our interruption...

K

OK thanks When I get a chance I will check out both pulleys ( idler and water pump )
Can an idler pully make a clunking/knock as in the video above ? I heard they make more squeaking noises.

 

[KennyN]

Can an idler pully make a clunking/knock as in the video above ? I heard they make more squeaking noises.

Bearings that are on the way out can make all sorts of weird noises , the bearing in the idler / tensioner pulleys will be sealed but a wee squirt of instant maintenance (WD40) may silence them for a bit which will point to the faulty one.

K

 

[AndySlade]

Don’t spray WD40 into bearings, it is a silicon spray not a grease or oil. It cleans the surface and can allow them to gall with one another.

 

[VenomX]

Will have a look tomorrow to confirm if the waterpump is the culprit. Going by what I've seen on YouTube then unfortunately it most likely is, as it definitely had play in it when I checked yesterday

There is no way a water pump should have play in it at 33K miles surely ? How has that happened ?

 

[M80]

The pump has a bearing, that shouldn't have significant wear.
But the rubber seal is likely to have deteriorated with age.
I would be replacing it anyway.
If your coolant is original, then replacing that is another advantage.

 

[VenomX]

Ok thanks.
I took the pulley off the water pump and there is slight play in the shaft mechanism which the pulley bolts on to.

The idler pulley has a slight grinding noise when spinning so I will replace that first.