on Thursday a 52 plate mondeo diesel is coming in, it has a strange rattle which starts a second or two after the engine fires, it sounds external and belt end, not entirely regular but similar to a noisy tappet. I haven't heard one before but my bet is the crank pulley.
Anyone want to have a guess in advance?
Aux belt tensioner or idler.
How does the sound change with the revs?
it increases in frequency, but it is does not seem to be in direct sync with engine speed. it is irregular and loud.
My Rover had me worried with a similar noise once. Then I found it was just the bonnet stay vibrating against the air cleaner box. Anything loose on this Mondeo?
I'll see tomorrow, but on the brief listen I had it really didn't sound like a loose bit of trim or whatever, it sounded very mechanical and serious, but clear, as though it was not an internal engine fault, but outside, belts, pulleys, air con, alternator etc.
First thing I'll do is have a better listen from underneath, then remove the auxiliary belt, hopefully that will stop it and limit the number of bits to inspect, otherwise it is going to get dirty and expensive and I hope not.
Silly bit is that before christmas I gave the car a valet and fixed up some odds and ends as the owner was going to p-x it!! She left it too late!
Well it turned out that it was the crank pulley, the give away was the way the noise increased with electrical load and it was possible to see that the pulley wobbled about along with the tensioner moving noticeably.
Pulley retail at 88.69 inc vat.
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