A new knock after a engine clean..read on

**DirtyDawg** · 2nd July 2006, 08:34 PM

I was cleaning the Pig (98 Def 300TDi) with degreaser and water hose when I started motor there was a distinctive semi rapid knocking noise from the front of engine bay, gave the area a quick spray of WD40 noise dissappeared.(bizzarre but after water I thought might be moisture related)
next morning same noise, most audible from front of Radiator grill, used stethoscope on head,waterpump, timing cover,injector pump,alternator I cannot for the life of me track this noise down. All bearings spin freeley and pulleys appear balanced whilst in motion even went to the trouble of removing aircon belt to isolate problem, viscous fan turns ok and balanced.
the noise is loud enough to be heard over the tractor sounding diesel.
Anyone had a similar problem maybe point me in the right direction.
Its due a timing belt change soon, I might advance the change and that should sort it out.
Well if you dont ask you'll never find out..TIA
DD

**one_iota** · 2nd July 2006, 08:46 PM

Chances are:

Auxiliary belt tensioner bearing or the main belt tensioner bearing.

We are talking about a $10 part and labour.

Use a big screw driver as a stethoscope to isolate the origin of the racket

**DirtyDawg** · 2nd July 2006, 08:53 PM

Mahn,
Ive got a ridgee didge Stehoscope which is usually excellent at isolation of noises and the tensioner bearing isn't the culprit. thanks for the input though.

**DEFENDERZOOK** · 2nd July 2006, 09:05 PM

why dont you just spray the WD40 while the engine is running.....
on one thing at a time till the noise stops....?

should be easy to do......then you can use the stethoscope to pin point the noise.....

**DirtyDawg** · 2nd July 2006, 09:31 PM

Thanks Tony,

I have removed the auxilliary belt and aircon belt..too late to start car tonight will do in the morning should isolate noise either engine or bearings...

By the way tony the fan makes it a bit hard to Wd40 individual Items and there is enough residual from yesterdays fun to cancel out that suggestion. cheers anyways.

**DEFENDERZOOK** · 2nd July 2006, 10:05 PM

hold the fan......the engine is cold......the fan wont need to spin......

if the noise is there......it doesnt matter how much WD40 is there....
when you hit the spot you will know where the noise is coming from.....

did you start it without the belts....?
it shouldnt make any noise without the belts as all the internals of the engine werent degreased.....
the bits that were are run by the belts......just dont run it too long without the belts
cos the water pump wont be circulating the water.....

british4wd · 3rd July 2006, 10:05 AM

It is just water on one of the belts

**barney** · 3rd July 2006, 10:44 AM

was the engine hot when you hit it with the hose?

**DirtyDawg** · 3rd July 2006, 06:44 PM

well I found it a 5am this morning. removed the aux and serp belt and tracked the sucker down, the fan pulley had a slightly loose bolt. turned pulley by hand and every rotation there was a slight knock and I could move the pulley off axis by about 2mm. Tightned the bolts, turned again no knock. put all together started...yum yum just the tractor noise no added knocks... thanks for all your input.

**Cruiser** · 3rd July 2006, 09:29 PM

How does water loosen bolts?

Hope you don't do many river crossings

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