bad knock on start up

[TomG401991]

on starting up there is a brief crunch/knock everytime

what could this be   im worried its expensive 

[G40supercharged]

Depends what the noise is like. If it's a single bang from under the car it's probably the exhaust hitting part of the bodywork. When you first start the engine it rocks more than normal and the exhaust will move about with it. The most common place is where the exhaust goes past the tunnel brace (under the gearlever). There is a join here and you have to place the clamp properly to stop it hitting. If it's an engine knocking that goes after a few seconds then your oil pump is probably on the way out. This would tend to happen first thing in the morning when the car hasn't been used for a while. If you stop and then restart a few seconds later you shouldn't get the knocking.

[samg40]

Oh, mine does this. Sounds like a toothed belt that has stripped teeth. Would you akin that to the oil pump sound? Not sure it stops when you restart it, I think it still does it although for a shorter time.

[G40supercharged]

The engine noise I mean is the big end bearings knocking if there is no oil on start up. I had a coupe S that did this due to a worn oil pump. The stripped belt type noise sounds like you mean the noise the charger makes when you first start - my G40 does this and I think it's normal.

[samg40]

Well it never used to do it. I'm under the car this weekend so will try and investigate. Something to bear in mind though.

[TomG401991]

its like a grinding noise (sounds like gear crunch but alot quieter)

happens a second after start up everytime       hot or cold

[GSBellew]

Sounds like it could be the starter motor sticking, like its not disengaging properly at first

[TomG401991]

sweet I'll give it the old technical tap if you know what I mean

[eliseu]

hi there

my car used to do that. check the oil level,if its to low it will do those noises. it can be from that. its not a new car so you will have to constantly ckeck the oil. i do it and it stoped.
hope its some help

[SpikeyG40]

Sounds like it could be the starter motor sticking, like its not disengaging properly at first

Had this issue on my old 1 litre also!   Most certainly the starter motor.

My G40 had a strange noise when i bought her, thought it would the bearings in the charger, but the noise went when she warmed up a bit and when lightly reved.   Turned out to be the cambelt slapping against the cam belt cover.   The belt had 6 teeth missing and serveral more on they're way! My G was very very lucky!