V70 resonant vibration

tomg · Post by **tomg** » 20 Oct 2003, 13:54

I have driven my 2000 manual 140hp 2.4 'new' V70 since it was new. It has the B5244S2 engine. A few months ago an annoying resonant vibration became noticeable. It occurs when accelerating under load through the 1900 - 2100 rpm band. It sounds like engine vibration causing something to resonate at its natural frequency. Having found no obvious sources of the noise when the engine is revved in neutral, I gave the V70 to my local Volvo dealer who adjusted the catalyser heat shield which gave just a little improvement. I gave the V70 back to the Volvo dealer, having done a road test with their senior technician who confirmed the noise. He suspected the catalytic converter. However, he changed the flexible section of the exhaust down pipe which made no difference apart from the dropping resonance rev band from 2000 - 2200 to the current 1900 - 2100. The Volvo dealer gave up at this point and told me to live with what is probably induction noise. I don't accept this story as the noise was not noticeable from new until a few months ago and it does not feel like induction noise. I found a few references to V70 noises/vibration in other web sites, including a reference to resonance in the exhaust system. Before I go the expense of changing the exhaust system, does anyone have similar experience or advice ?

Post by **matthew1** » 20 Oct 2003, 16:03

Are your engine mounts worn?

tomg · Post by **tomg** » 21 Oct 2003, 14:12

There is no obvious sign of wear in the engine mounts. The V70 has clocked only 30,000 miles and most of this mileage is gentle driving on motorways (highways).

Tsquared · Post by **Tsquared** » 21 Oct 2003, 16:32

To check to see if your mounts are worn when they appear to be ok, you need someone behind the wheel while it is in park. Raise the hood and have your friend gun the engine a few times. If the mounts are worn the engine will tourque and rock inside the compartment - it will be fairly obvious which mount is shot. If the engine moves very little you are ok - you might see what else is causing the vibration when the revs are up...

Good Luck

tomg · Post by **tomg** » 26 Oct 2003, 06:43

Matthew, Tsquared, thanks for your advice.

BTW, a contributor to the UK Volvo Owners' Club web site with the same problem suggested changing the spark plugs, because that worked for him. Unfortunately it did work for me.

Ian Stone · Post by **Ian Stone** » 23 Feb 2004, 02:23

Got exactly the same problem. Mine is an automatic so all the engine load work is done around 2000 rpm. It was like it when I bought is second hand at 46000 miles.
I improved the situation by stopping the heat shield hitting the body but is was still there. I have noticed a rattle from the exhaust as it there was something in there. I am going to attack the problem in the warmer weather. I have also noticed the air filter assembly is not that sound so will strip this down in the better weather. My first guess was the inlet ducting.