The sounds of a P6

[Dave3066]

Hi guys and gals

I wasn't sure which category to post this thread in as it relates to engine and gearbox noise so I've dropped it in the engine cat.

I'll start with the engine first. That V8 'burble' that everyone talks about, I think my exhaust might have a slight leak and I really need to get under the car and have a good listen (once the weather allows) but I'm not sure if the noise is simply the engine. It sounds very throaty at tickover but ok at cruising speeds. Is this normal or do I have a leaky exhaust?

Gearbox now. I know gearboxes on old cars have a tendency to generate noise. I once had an Allegro and its gearbox used to have a distinctive whine which was normal for this car. When I move up through the gears on my P6 the noise in 1st, 2nd and 3rd sound like someone blowing down a large tube. When 4th is selected the noise goes away. Is this normal or is my gearbox heading for trouble?

I'm hoping to go to my first regional meet in Edinburgh this month so I'll get someone with more experience of P6s to listen to it. In the meantime any advice on what the engine and gearbox should sound like would be much appreciated.

cheers

Dave

 

[Tor]

Hi Dave,

Depending if the throat sounds sore or not... it could be you've a holed system. With the engine idling, grab a rag and block the tailpipe with it. If you press hard enough achieve a good seal you should only hear a faint murmur and the engine should choke and even stop after a little while. If there is hissing or other ungainly motor noise heard from under the car you've got a hole.

If the system is holed, jack up the car and crawl under it. With the engine idling you'll be able to locate the leak. First, go by ear. Then inspect the various joins on the silencers and pipe by moving your hand around close to the metal, almost touching, to feel for gases escaping.

My 'S' sort-of sings a bit in low gears, but doesn't whine. Look for threads describing oil types and try to determine how old your gear oil is, then change it first of all.

 

[chrisyork]

Sort of throaty sounds like intake noise rather than exhaust. Have you got a standard air cleaner fitted and if so does it have a paper element in it?

I'm afraid the gearbox sounds very like a layshaft bearing. In top geaer the drive through the box goes directly through the mainshaft, so no problems there. But in 1st 2nd and 3rd the drive is diverted into a parallel shaft (the layshaft) before returning to the mainshaft via a choice of gears to give you the 3 lower gears. Thus if the noise is only in the lower gears then layshaft bearings are the obvious diagnosis.

Chris

 

[harveyp6]

Thus if the noise is only in the lower gears then layshaft bearings are the obvious diagnosis.

Chris

That is true, but it can also be the imput shaft bearing, because it's straight through in top, whereas driving through the layshaft in first, second and third, the helical cut on the gears puts a side loading on both the bearings.

 

[Dave3066]

Gents

Thanks for the advice.

Chris, yes it has a standard air cleaner fitted, haven't had a chance to check the element but I will thanks.

I'm presuming layshaft bearings is a fairly major job so I'll change the oil in the gearbox when I change the engine oil this weekend and see if it makes any difference.

I'll let you know how I get on

Dave