What's the mystery noise???

[gatecrasher]

My dear friends I have no other option then to ask your help to solve this mistery noise that has started about 3 weeks ago after the cambelt was changed.

Its a metally tapping noise that is coming from the engine but only when its running on the road and not when stationary. I went back to the mechanic to see if he could make any sense, we drove together for a while but he couldn't come out with any idea, the only thing that he could think of was that there is something loose on the bottom and when its running at speed its making the annoying noise.

Thing is I don't think its something underneath but something inside the engine that's making the noise as its of coming from the head not so loud but you can hear it. It wasn't there before the changing of the cambelt and now I'm wondering if its the timing wrong or some other problem that can escalate to more serious damage.

So if you've had the same problem please let me know.

Thank you

Alex

[Tur80]

If it's only started doing it since the cam belt was changed, I think you need to get the cam belt timing checked ASAP.
Sounds like the valve heads hitting the pistons once it's under load!!!!!!!!!!!!!!!!!!!

[Simon Jones]

I would have thought the valves hitting the pistons was an unlikely scenario. If the timing was wrong, they would collide the moment the engine was turned over on the starter. Unless an engine is fitted with a variable valve timing system, then there is no connection between load / engine speed & valve timing. Technically, at very high revs you can get valve bounce where the springs do not open & close fast enough to be able to keep up with the camshaft, but that's proper high performance stuff. I've had a cambelt slip a tooth on a diesel Fiesta at under 5 mph & it took out 3 valves straight away.

It was mentioned it only happens when driven on the road: what sort of engine revs & does it get faster as the revs increase? When you rev the engine to the same point when stationary, is there any sign of the noise? Does it only happen under load, or can it be heard when cruising or decelerating?

Other things like the water pump, air con compressor & alternator would have all been disturbed while changing the cambelt, so there are other options to consider.

[lee13]

i didnt pick up if it was diesel or petrol but valve lash adjustment is my answer make sure they have done it as diesels dont have hydrolic lifters like the petrol engines
regards Lee13

[Northern Bongolow]

this is going to sound really dumb but here goes.
press the trip/oddmeter thingy make sure its engaged right!!!

[gatecrasher]

Thanks for your replies...and thanks to Simon for the feedback on what else it could cause the noise.

Went to the mechanic yestarday and explained once again my concern and also mentioned that I've just come back from Wales and done around 1000 miles since the chance of the cambelt and he litterally discharged the possibility of wrong timing on the cambelt explaning me that for a valve to hit the piston you have to be out 4 tags which is a lot and the engine would not perfome well from the start and also by now it would have blowned! So that was a relief also we went for a new run to try to figure out where the noise is coming from and aggreed to bring back the van next week for a full investigation...the story continue and will keep you updated.

Thanks again

Alex

[missfixit70]

this is going to sound really dumb but here goes.
press the trip/oddmeter thingy make sure its engaged right!!!

definitely worth checking that, more than one person has been caught by that one, chasing spurious noises

[gatecrasher]

I don't even know what and where is this thing...lol...anything goes to be honest with you that noise is driving me crazy.

[Tur80]

"Unless an engine is fitted with a variable valve timing system, then there is no connection between load / engine speed & valve timing. "
I appreciate there is no connection, and wasn't suggesting the timing was changing. My suggestion was unlikely, however, it happened to my wife's escort (probably similar to your fiesta engine) . the camshaft pulley was slotted and had moved the equivalent of about half a tooth. Under hard acceleration or high RPM there was a metallic noise. It turned out that the pistons were just kissing the valves. I had 4 replaced (and the cambelt ) It was explained to me as Compressive and Tensile Inertia, that the pistons could exert enough force to stretch the conrods a tiny amount to allow piston/valve contact.
Only trying to help from previous experiences

[missfixit70]

I don't even know what and where is this thing...lol...anything goes to be honest with you that noise is driving me crazy.

The little tripmeter button on the bottom of the speedo, if it's not depressed fully, it can catch halfway as it's trying to turn the numbers over, sounds a lot more serious than it is, had me worried for an hour or two not long after I got mine & there was another couple out caught by it a few months ago. Just give it a good firm push to check. & make sure the numbers zero properly.

[Simon Jones]

"Unless an engine is fitted with a variable valve timing system, then there is no connection between load / engine speed & valve timing. "
I appreciate there is no connection, and wasn't suggesting the timing was changing. My suggestion was unlikely, however, it happened to my wife's escort (probably similar to your fiesta engine) . the camshaft pulley was slotted and had moved the equivalent of about half a tooth. Under hard acceleration or high RPM there was a metallic noise. It turned out that the pistons were just kissing the valves. I had 4 replaced (and the cambelt ) It was explained to me as Compressive and Tensile Inertia, that the pistons could exert enough force to stretch the conrods a tiny amount to allow piston/valve contact.
Only trying to help from previous experiences

Useful info there - not something I'd come across before. Most of the cambelt incidents you hear of are fairly catastrophic, but I guess even a slight stretch in the belt, or the tensioner slackening off could be enough to take it just out of sync too.

Fingers crossed for a simple solution to gatecrashers problem

[lee13]

if its diesel its tappet adjustment or valve lash im sticking to that

[bigdaddycain]

Having never replaced the cambelt personally...(a local garage did mine) Has the tensioner been replaced? Do the crank pulley's have to be pinned whilst tightening the tensioner? Does the tensioner have a pointer mark on it to ensure it's aligned properly? (sometimes they can slip on tightening).