308QV Mondial engine "clatter" at 2500 revs

For starters, I would think the oil is too thin. On the 3.0 QV, factory spec is synthetic 10W50 AGIP. Some forum members will go with a synthetic xW40 (eg Mobil1 0W40, Pennzoil 5W40), but I don't believe anyone recommends or runs a xW30.

 

Something is loose? Heat shield, exhaust manifold shielding, sampling tubes, belt cover, muffler, cat, Etc. Also an exhaust leak can sound similar.


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I use valvoline VR1 20/50

 

We gotta remember here, the cam belts were replaced and the oil was not touched. If the issue did not exist before the belts were changed and suddenly started AFTER the belts were changed, chances are: something got screwed up during the process.

Lets start from the top...
Did you have the belts replaced professionally? or by yourself?

Was the service performed engine out? or in the car?

 

The PO said he also change the the oil with Shell Helix HX7 5w/30

 

I just changed my belts. The number of things you disassemble in the process left me wondering why more things don't clatter so I am going with a loose or misaligned part.

Can you get it to clatter in the garage? If yes then get a friend to hold the throttle at the clatter speed and use a stethoscope to pinpoint the clatter. My guess is the intake tunnel, ac hoses, gas tank breather canister or heat shields.

 

I would think after a belt change the Clatter could be from the AC belt or Alt belt... mostly the AC belt. or if you don't have the right amount of spacers in the bracket.

if you used a belt that is still stiff from being on the shelf you can get some slap... just need some belt conditioner.

 

Maybe a loose exhaust heat shield? I had that problem. Would rattle at about 3000rpm.


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Clatter? I think we need a little better description of the noise...

 

I was just in Surrey for a Wedding 1.5 weeks ago. was at the Surrey Town hall... would have loved to lend you a hand.

 

It normally helps if I read the whole post, but the first sentence and last usually get me by

 

Keith
Where in Surrey are you? I could try and pop over to have a listen

 

A/c hoses may have been disturbed and now resonating against metal? Try isolating them with some short sections of radiator hose, split, wrapped and zip tied around the area near where the hoses pass into the body enroute to the front of the car.

Mine sometimes resonate around those revs and its quite metallic.

 

Hi Keith, is this a 'new ' sound after the cambelt change you mentioned ?

 

Did you certify that cam timing was correct after the belts were changed? If one or both intake cams was advanced a tooth is it possible that you could be hearing a pre-ignition knock under load due to advanced ignition timing? Just throwing this out there.

 

Can you get it to clatter just running the motor and not driving?

 

+1. Check where the cross the fiberglass air tunnel. I used rubber tape on mine to stop some noise.

 

+1. Check where the cross the fiberglass air tunnel. I used rubber tape on mine to stop some noise. I also have a fuel check valve that hits the ac bracket silenced with rubber tape.

 

This seems inconsistent with the observation that it occurs "under load".