Engine Noise

[GSSPORT]

Hi All,

I was wondering whether you can help?

I have a GS300 MKII (2000) which has 120k miles (motorway miles & FSH). I have noticed a slight knocking noise coming from the top of the engine nearest to the radiator.

The noise is a knocking noise which is present most of the time. It is most vocal when the engine is hot and increases with the revs but can't be heard over 2000 revs.

Could this be a sticking valve or a the water pump (can anyone also tell me where the water pump is situated?).

Has anyone encountered a similiar problem

[IanCornwall]

Hi there

I have a 95 GS300 and had the same knocking sounds really rough at tickover then disspaears when the revs climb a bit

Mine was just a fan belt clicking way but sounded like a metallic cclick and bump as it went around

Hope yours is the same fault dead easy to change when you work out the knitting pattern for the belt

[GSSPORT]

Hi

I don't think it is that, as I changed my cam belt and fan belt a couple of months ago.

I'm wondering whether its a sticking valve (hopefully) or the water pump.

Thanks for getting back to me though.

[paulgoodall]

Hi GSSPORT I have just bought a 1999 with 120000 with fsh and have a similar noise but it seems to be coming from the rear of the engine. I too disappears over 2000 rpm, if you get any feedback let me know thanks.

[WilliamJ]

GSSPORT

Couple of suggestions for you:-

With the engine idling, does the noise increase if you turn the air con on? Decrease with it off?

Try taking off the serpentine belt - is the noise still there? If not then it may be one of the ancillaries (water pump, steering pump, air con, alternator).

By the way, the water pump is on the right hand side of the engine (if you are facing forwards), low down at the front of the block.

If the noise is still there without the serpentine belt then it could be a number of things:-

A sticking valve......if you mean valve in the cyinder head, I doubt it.

It could be a large valve clearance. Valve clearances tend to stay pretty static unless it has been overheated or run low on oil. It is not a five minute job to check these!

It could be a broken valve spring but you would get some misfiring to go with it.

It could be something in the bottom end of the engine but these engines are very strong - so that is unlikely.

Again with the engine idling and making the noise, does the noise reduce if you engage drive? If it does and the noise also increases with the air con running, it possible it could be the torque converter drive plate breaking.

If the noise goes away entirely when the serpentine belt is removed then check the four ancillaries and check the serpentine belt tensioner.

I have a 99 GS 300 sport and I chased a noise like this a couple of months ago. The noise was really hard to pinpoint even using a stethoscope. It sounded like top front at first and gradually got louder and moved rearwards over a couple of weeks. I was told it was cams - no it wasn't. I was told it was timing belt tensioner - nope. I was told it was the VVTI mechanism. I got fixated on that and eventually stripped it apart (yes, I know it says you cannot but that is a big lie) and it was perfect. I tested the oil supply pressure to the VVTI and the electronic control of said supply, nope. So I realised it probably wasn't that. I checked the knock sensor as it sounded like detonation for a while but it was fine. I checked a few other things as well

Eventually I found a man who knew nothing about Lexus cars and he came up with the torque converter drive plate suggestion and he was spot on.

Good luck.

Bill