Chums

Car is driving fine but one thing I've always had is a sort of rattle/mechanical type noise under load at speeds 25-35mph usually in 4th gear. Giving it 3/4 pedal in 4th at these speeds and I get an almost industrial cog whirring sound. Giving it the beans in lower gears and not a problem.

It doesn't sound like loose tinware and seems more forward of the engine around the tranmission area (front drive shafts?).

Any clues?

 

Zingers, could be your labouring the gearbox and getting noise from the lay shaft. My dad's 2.7 used to do this all the time unless you were a little bit more revy. I'm sure someone more knowledgable than me will be along in a mo....

 

I have the same, its just a c4 thing i think, i've always had it. I had a couple of pros listen to it over the years all said "some of them do it - its fine". Its most noticable when "lugging" the engine, but when your ear is really tuned in you can hear at motorway speeds sometimes.

 

I know this is not an answer to your question, but WHAT are you doing in 4th gear at those speeds, and especially under load.

 

Yep, totally normal (all cars will do it) and if you have an RS clutch and lightweight flywheel it's even more noticeable. Just use lower gear!

 

Thanks guys. Yes I know the addage of labouring the engine but sometimes I get it when moving 3rd to 4th around 40 mph. I suspected it was a C4 thing/lay shaft.

crg53 I hear ya. Believe me it went like stink this afternoon on a run. What impresses me is the way the front end is so planted at high speed and not like my 993 C2. Sticking like **** to a blanket.

Next job is to put the de-cat pipe on which I picked up off eBay for £16.99

Actually its the cat pipe with no cat inside it so hopefully it will give me a little deeper sound

 

I agree with the comment abt going those speeds in 4th gear. I rarely drive mine under 3k rpm. Seems to like 3k+ a lot more and I get less carbon buildup. Also in my case, I have a single belt conversion, and so I have to spin the engine in order to get proper spark. Not as much amperage under 3k rpm. There was a comment here somewhere on rennlist abt the importance of spinning these motors a little faster than other cars. I tend to agree. Mine definately likes to be living in the middle rpm range, where my Audi loves 2000 rpm all day long...

 

I have a similar sound sometimes and I'm thinking its the engine "pinking" or pre-detonation which sounds like the rattling noise you have described.

Anyone else get this??

Cheers

Mark

 

What I'm talking about is somewhat louder than pinking, almost like something metal is loose and rattling around.

 

OK I think we have different symptoms - mine is almost certainly pinking - I think I must have a knock sensor issue or something like that. Or c**p fuel which is likely the most probable cause.

Cheers

Mark

 

check dist belt...