Engine Noise

[billgatesisaconman]

Hi guys, my Rx 400 has developed an erratic mechanical rattle somewhere near the oil filler cap, it's only when the engine runs ... any idea's hat it could be ?

[Verbout]

You don't get many rattles on cars when then don't run.

Loose dip stick, loose engine cover, missing engine cover rubber mount, oil filler cap not on correctly, small rodent or pet stuck under the bonnet.

[billgatesisaconman]

Cheers Garry, I had narrowed it down to the timing belt tensioner pulley or water pump ... turns out it was the water pump,

Lexus did the timing belt a couple of months ago ... now it might be a coincidence but if the the timing belt was over-tensioned it could have caused the water pumps failure, so I'm a bit worried now about the tensioner pulley as they don't change it with the timing belt ...

[Gliderpilot]

From what I've read on here, it's always best to change the water pump when you do the cam belt!

[billgatesisaconman]

I agree Peter, I had also read some owners are on 150k + without changing it, so I thought I would chance my arm ...but that hasn't worked out so well ... lol

it seems its standard deaer practice to not change the tensioner with the timing belt, a friend had the the tensioner fail after a timing belt change at a Vauxhall deaer & it wiped his engine out ... there is a lot of conflicting info as to whether or not the rx 400 is a non-interference.engine ?

[Verbout]

Pays your money and takes your chance with the water pump, but not replacing the tensioner when replacing the belt is negligent.

[billgatesisaconman]

Pays your money and takes your chance with the water pump, but not replacing the tensioner when replacing the belt is negligent.

... according to Lexus it isn't part of the schedule when replacing the timing belt & isn't even mentioned... neither was the water pump ...lol