My new Z has a rather strange knock coming from the engine which is fairly random. The noise has been apparent ever since the previous owner bought the car, and it hasn't got any worse probably in 8000 miles.

 

The car went into Zedworld and Jamie listened to it and agreed it was bottom end and suggested it would only last 1000 miles but that was over 2 years ago!

 

The knock is no worse now than it was 2 years ago and the knock goes away as soon as I start putting my foot down. The knock is more noticeable at low speed then goes away at faster speed.

 

If the car is idling at a standstill you can bring the revs up slightly then the noise will start but then seems to clear.

 

The car still drives perfectly and is very quick, so it doesnt appear to have any symptoms other than the noise?

 

I assumed that if the bottom end was knackered then it would do it all the time? Any ideas or suggestions would be greatfully received, cheerZ :scooter:

As I said on the other thread? Slightly goosed oil pump? When did it last have a water pump or some sort of pully knocking? Its all down that area. Surely if it was a bearing issue it would have let go long ago!

i remember when this car was sold the first time, if it still going strong after all this time it sounds like its not an internal issue to the engine, could be somthing like a broken engine mount/loose bracket etc.

 

you could try working around the engine with a stethiscope trying to pin it down a bit

as i said aswell check for a loose pulley

just break it mate, you will get to the route of the problem on the way lol

lmao don't tell him to do that, because he will!

thanks to the guys that also replied on the other thread, I wanted a seperate thread so I can see all the ideas together and have a big brainstorming exercise :lol:

 

I will have to check for loose pulleys and broken mounts. Quavey - what do you mean about the oil pump, I mean how would that create a knocking noise?

 

When you start the car and it sits at idle it sounds lovely from the HKS system, and the engine is perfectly quiet. You bring the revs up and it starts its knocking/clattery type sound. I haven't got a stethoscope but I'll try a long screwdriver and listen to see if I can find the source. :thumbup1:

Is it a knocking or a tapping?

kind of a knocking mate

Go and get some STP engine flush and some replacement oil and filter. Run the engine up hot, turn it off, add the Engine flush, run it at a fast idle, around 2K rpm for 15 minutes, see if it actually goes away whilst you're doing that. Of course then you need to drain the oil and re-fil, and of course replace the oil filter, but sounds to me, if it's been there for that many miles, it may just be something silly like the oil feed pipe out from the sump being clogged up when you pick up the revs, causing airlocks when sucking the oil up etc. Don't drive the car on load with the flush in, not good :D

 

Only a theory, but possible. Lots of people don't use engine flush on an oil change, but I've done it on just about every car I've ever had and it almost always makes them run better, so it's a good thing to do anyway, even if it doesn't cure the problem.

Yeah thats not a bad idea. Surely if it was damaged bottom end it would do it all the time? and not particularly just under load?

 

 

i remember when this car was sold the first time, if it still going strong after all this time it sounds like its not an internal issue to the engine, could be somthing like a broken engine mount/loose bracket etc.

 

 

Do you remember if it was for sale on the forum? would love to find some old pics of it. :thumbup1:

Well thats what I'm thinking mate, I doubt it's a loose bracket or anything, because it doesn't do it on idle but it does do it when stood still. Roses VR4 had a nasty knocking sound, but only when moving, turned out to be the arch liner was only being held on by one bolt and was flapping at speed.

 

I reckon yours could be a really simple fix matey. If it sounds like bottom end, but it hasn't let go yet, it's either a VERY stubborn bearing, or something silly like I suggested.

what about shells? could it be tthem

usually a shell will make that noise when it gets above a certain rev range and stay there as its making the conrod into a oval at the bearing end. eventually it will give putting a rather large whole somewhere when it throws the conrod about the engine.

 

Might even be the oil pick up knocking one of the balance arms on the crank, have you checked for dents in the oil pan baz?

thanks to the guys that also replied on the other thread, I wanted a seperate thread so I can see all the ideas together and have a big brainstorming exercise :lol:

 

I will have to check for loose pulleys and broken mounts. Quavey - what do you mean about the oil pump, I mean how would that create a knocking noise?

 

When you start the car and it sits at idle it sounds lovely from the HKS system, and the engine is perfectly quiet. You bring the revs up and it starts its knocking/clattery type sound. I haven't got a stethoscope but I'll try a long screwdriver and listen to see if I can find the source. :thumbup1:

 

Sorry baz, my total lack of knowledge showing here! I assumed it would be a rotary pump with moving parts that can bang around depending on the load. But after reading up about it I presume a zed would have a gear pump which looking at cant really make a noise through wear, it would just stop working.

 

(Pumps on steam engines whih is what im a bit more used to tend to knock and bang a bit depending upon whats happening :) )

no not checked for dents or anything yet, will get it jacked up later and have a nosey.