17 replies to this topic

[Ginge620]

Anyone got any ideas of what this noise is. Only happens when there is no load on the engine, for example reving in neutral or driving while lightly pressing the throttle. Noise goes away when you accelerate or decelerate with you foot off the pedal in gear.

The tapping noise still happens with the clutch depressed or not.

The noise is a lot less noticeable within the first 10 minutes of driving. Once to normal temp you get what's in the video.

 

Here is a video, the noise is more noticeable when the engine revs then slows down. The tapping at 0:39 - 0:42 is one of the more noticeable.

https://onedrive.liv...thint=video,mp4

 

A few engine details,

998 +40

12G202 head, slightly modified

266 Kent cam

Double valve springs

duplex timing chain without tensioner

 

I have just done the head gasket today due to blowing between 2 and 3. Here a couple of photos after a quick clean. Note the noise already occurred before the head gasket and still does after the new one. Compression was fine before i did the head gasket, i havent checked since the new one. Just for information i have switched from a copper head gasket to a composite type.

Cylinder walls show no scoring or damage. You can still still faint marks from the honing process.

 IMG_20160323_174748.jpg   60.45K   27 downloads

https://onedrive.liv...thint=photo,jpg

 IMG_20160322_193403.jpg   36.53K   18 downloads

Edited by Ginge620, 24 March 2016 - 11:59 PM.

[nicklouse]

Sounds like your idler gear.

[Ginge620]

Sounds like your idler gear.

That has crossed my mind. But the noise still persists even the clutch is depressed. Wouldnt that stop the power going through the gears?

[nicklouse]

Ok just listened the whole way through. And maybe not the drop gears then.

[MRA]

It sounds very tappity are you sure you have adjusted them correctly ?  I l know worn pads play a major part in tappet rattle as adjusting it out is a bad idea...  maybe that is what you have done ??

[Ginge620]

All set to 12 thou. My phone makes it sound more tappy than it actually is but it's the noise that comes and goes that sounds like a small hammer knocking on the side of the engine block. Im thinking worst case at the moment is excessive play in the little end bearing on one of the pistons maybe.

[MRA]

All set to 12 thou. My phone makes it sound more tappy than it actually is but it's the noise that comes and goes that sounds like a small hammer knocking on the side of the engine block. Im thinking worst case at the moment is excessive play in the little end bearing on one of the pistons maybe.

 

Check your exhaust is not contacting the engine block in certain modes....  I stripped a brand new engine down some years ago for a knock in the engine at the time I was inexperienced and listened to my next door neighbour, of course I found nothing wrong so rebuilt it and it worked fine, but still had the knock, i eventually traced it to the exhaust just touching the block, took it off bought a new Maniflow unit perfect from then onwards.

[Ginge620]

 

All set to 12 thou. My phone makes it sound more tappy than it actually is but it's the noise that comes and goes that sounds like a small hammer knocking on the side of the engine block. Im thinking worst case at the moment is excessive play in the little end bearing on one of the pistons maybe.

 

Check your exhaust is not contacting the engine block in certain modes....  I stripped a brand new engine down some years ago for a knock in the engine at the time I was inexperienced and listened to my next door neighbour, of course I found nothing wrong so rebuilt it and it worked fine, but still had the knock, i eventually traced it to the exhaust just touching the block, took it off bought a new Maniflow unit perfect from then onwards.

 

I wish it was as simple as the exhaust. Doesn't seem to be that. The tapping/rattle is defiantly internal. Looks like I'm going to have to find some time to pull the engine apart again, 6 months since rebuild. Suppose it gives me a reason to get the spare 1275 metro lump rebuilt to swap in,

[Ginge620]

Been reading about on the internet and come across this webpage http://www.southernw....com/Dec-08.htm

 

The section regards to Rod Bearing seems to be the issue I'm currently having. If the fault is with one of the pistons or rods i should be ok to just replace the one component/s?

[MRA]

Been reading about on the internet and come across this webpage http://www.southernw....com/Dec-08.htm

 

The section regards to Rod Bearing seems to be the issue I'm currently having. If the fault is with one of the pistons or rods i should be ok to just replace the one component/s?

 

Who fitted the pistons to your conrods ?

[Ginge620]

 

Been reading about on the internet and come across this webpage http://www.southernw....com/Dec-08.htm

 

The section regards to Rod Bearing seems to be the issue I'm currently having. If the fault is with one of the pistons or rods i should be ok to just replace the one component/s?

 

Who fitted the pistons to your conrods ?

 

Foxwood Engineering.

[MRA]

I cannot hear what you want us to listen to, I can hear the video but the noise you mention ?  I can hear what sounds like gears rattling, try to depress the clutch and then select a gear, keeping the clutch depressed, as this will stop the idlers from turning if they are, ie if it has a sticky clutch for example.

[Ginge620]

I cannot hear what you want us to listen to, I can hear the video but the noise you mention ?  I can hear what sounds like gears rattling, try to depress the clutch and then select a gear, keeping the clutch depressed, as this will stop the idlers from turning if they are, ie if it has a sticky clutch for example.

Clutch engaged, clutch disengaged, in gear or out of gear, car moving or not moving, doesn't change anything. Listen shortly after 38 seconds on the video, that knocking/tapping is louder. Once you tune into you can hear it.

[MRA]

Ok heard it, it doesn't sound like little end or piston contacting head, too rattly for piston ring damage, if it was the other end I would say timing chain, but even that isn't quite right...... how about a bent push rod

 

Do you get it under load ? constant rpm ? or on up rev /down rev ?

 

Did you try 4th gear stationary ?

Edited by MRA, 17 April 2016 - 02:50 PM.

[Ginge620]

Ok heard it, it doesn't sound like little end or piston contacting head, too rattly for piston ring damage, if it was the other end I would say timing chain, but even that isn't quite right...... how about a bent push rod

 

Do you get it under load ? constant rpm ? or on up rev /down rev ?

 

Did you try 4th gear stationary ?

The noise goes away when under load. So say when i'm driving any speed, any rpm, any gear, the noise happens when i lightly press the throttle pedal. Noise also happens like in the video when revving, tends to be when the revs slow down. Gets louder/happens more when the engine gets up to temp and/or driving for 20mins at 70mph. Hope any of that makes sense.

Also i checked the push rods when i did the head gasket recently. All clearances are set correct.

I should be able to find answer to this soon anyway, i have a 1275 lined up to go in next month then ill be able to tear it down.

Edited by Ginge620, 17 April 2016 - 08:22 PM.