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Engine Rattle At Idle. Worried!!


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I have a 2001 Mk3 Mondeo petrol that has done nearly 70k. It is in great nick but..... about a week ago I have noticed a rattling coming from the engine ONLY at idle and ONLY when the engine is hot (not mildly warm, but hot). The rattling is irregular and sounds kind of like you are shaking a plastic box with a coin in it. The rattle doesn't seem to be contributing any vibrations. As soon as you gently press the accelerator the rattlings stops.

On closer inspection with the bonnet up, it sounds like it is coming from the belt area (to the left of the engine). These symptoms suggest a possible belt tensioner on it's way out or the more worrying scenario of the inlet manifold butterfly flaps breaking loose!!

I took the car to a mechanic yesterday and suggested these two possible scenarios. I got the car back today. The mechanic said there was excessive play on the tensioner so he fitted a new one. I was relieved and very thankful........only to come home just now and hear exactly the same rattle as before. The problem is not fixed and now I am very worried it could be the manifold flaps, even though I have spent money on getting the tensioner replaced!

So I have put it to this forum. I have tried to be as detailed as possible with the symptoms. Do these symptoms present themselves as a manifold flap problem in people's experience, or could it be something else?

I commute 120 miles daily on a round trip to and from work. Is it wise to continue this until I can get the car booked in for a weekend? (This weekend is too late).

Thanks in advance

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this is most definitely the crank pulley but they are known to take out the tensioner too so replace the full lot - kits are available from eBay (gates make the original parts for ford so source a gates kit)


is it a petrol or diesel? i automatically jumped to it being a diesel

EDIT: just read your post again and realised its got the dreaded flaps in the manifold so a petrol it is then

ignore what i said above

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Its very difficult to diagnose audible problems from written descriptions, for example a member described "knocking" from the front suspension of his car, which sounded like a description of a broken spring, and turned out to be tha tracking out, (which would have made a different noise, including "scuffing" under lock and posibly even tyre squeal under heavy cornering

The noise may just be the noise the valvegear (cams/ followers) makes when the engine warms up, or another belt or pulley or the waterpump, or lots of other things

It may be if you change the oil (for fresh oil/ and a high quality oil, like Magnatec) and a new oil filter (genuine Ford or quality replacement) that the noise goes away or gets quietsr (if its the top end/ valve gear making the noise)

The butterflies in the inlet manifold were badly designed and can break up dropping little parts into the engine, later cars were revised to prevent this, i think, and many cars were retrofitted or the butterflies removed and the holes blocked off by the cars' owners, if you are concerned about this, you should get it checked, if the butterflies were removed you should be able to see where the holes were blanked off on the inlet manifold (eg - aroldite) or you may be able to tell from the cars' manufacturing date/ vin/ reg if it was one of the "problem" cars and if it was recalled/ modified by Ford/ a dealer

Ive just read stef123s post, im not familiar with the petrol engined aux belt/ pulley design, but on the deisel the crank pulley has a crank damper built into it, which should be replaced together with the belt/ tensioner, also "cheap" pattern ones can give problems, better to stick to Ford but the gates ones are ok, personally i fitted a genuine Ford crank pully and gates belt & pully kit

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Unfortunately, it is a "problem mondeo" ie 2001 petrol. Funnily enough when I took the car to the garage it was due an oil + oil filter change so I got that done too. Unfortunately, the sound still persists.

Due to my lack of tools i'll have to pay a garage to take apart the manifold and have a look at the butterflies. This is my hunch....

Just wondered whether the fact that the rattling comes ONLY when the engine is hot may be a significant tell tale sign of whether it is a manifold problem or not

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I don't know if the rattle when warm is the manifold flaps but apparently the flaps can rattle

Taking the manifold of is a relatively "big" (expensive/ "fiddly") job, and the inserts and seals have to be replaced before fitting, the flaps are close to the head, and a rod runs through all 4 "inlets" on the manifold, if the flaps were previosly removed, you will be able to see the (horizontal) rod without taking the inlet manifold off,

If the rod is still there, if it was my car i would just remove it/ get it removed rather than see if its there/ falling to bits or not because its allegedly an "achillies heel"/ ticking time bomb on these engines,

What some people have done is buy a secondhand inlet manifold cheaply off eBay and remove the flaps/ rod off it, then block the end holes with aroldite (regular aroldite has to be left overnight to set) then swap the "new" manifold for old (perhaps someone can supply ready- modified manifolds?)

Certainly if you like/ intend to keep the car it must be worth doing/ getting done

ive never owned or worked on a 4- pot petrol mk3 Mondeo, (i run a diesel myself now) so a lot of this info is 2nd hand, from other forums etc, mostly i try to comment on repairs/ modifications ive done myself, as ive been "caught out" before, but i think its genuine

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My Mk3 Mondeo died with this!

I was bombing down the M11 and the butterfly flaps came apart and disappeared into my engine, leaving me with a totalled car on the side of the road.

To make matters worse, I had a car full of band gear and the AA bloke wouldn't tow me because of the load. I had to get a mate to rescue my gear so the AA could tow me.

So yea, word to the wise. Sod the cost, get the manifold done or find yourself without a car! It was nice that this known issue was flat-out denied by Ford Customer Services.

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how ever if u look near throttle body just behind that theres a little damper try popping off link arm into damper that will stop the buttlerfly flaps moving loads as temp fix,i did it to mine 4000 miles ago but still gotta get car sorted.i brought another manifold and stripped out the butterflys on that and sealed ends up ready to fit.but am looking out for newer car lol

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