33 replies to this topic

[GaryK]

I have noticed recently that if I put my foot on the accelerator slightly, to give it a tiny amount of 'gas', a tapping noise comes from the engine bay. I've uploaded an mp3 below:

 

http://picosong.com/6rkM

 

You can hear the tapping at seconds 4-5 or so.

• The tapping doesn't happen if I have my foot on the clutch
• The tapping doesn't happen on idle - only when lightly accelerating
• I can't really tell if it changes with revs because if the noise is there, it gets drowned out by the engine as soon as the revs are increased.
• I think it might be getting louder, but that might just be in my head...

Any ideas? Thanks!

[GaryK]

Small update: I noticed this evening that it only starts making the noise once the engine's warmed up...

[Judderman]

cracked manifold? 

[GaryK]

That's it alright. Dammit. Thanks for the quick diagnosis 

 

[The Batman]

That's not a crack When was the timing chain last done?

Edited by The Batman, 10 November 2015 - 12:25 AM.

[GaryK]

Ah, OK... Couldn't see anything else, even hairline, but can't see much by just pulling the heat shield back. Chains were done by Vocky in June 2010, just over 10k ago.

[The Batman]

Look in the middle of 2 and 3 exhaust primaries that's usually where it cracks

Like this:

[vocky]

Sounds like piston slap, if you lift the clutch pedal up to the biting point and rev the engine with the handbrake applied you should be able to replicate the noise

Edited by vocky, 10 November 2015 - 08:15 AM.

[Sutol]

Sounds like piston slap, if you lift the clutch pedal up to the biting point and rev the engine with the handbrake applied you should be able to replicate the noise

thought you only got that when the engine was cold??

[GaryK]

I can't see anything wrong with the manifold by pulling the heat shield back. I picked up the car in June and it's entirely possible the noise has always been there as it's quite subtle and I've only recently had the roof on. Another possibility is that I had it serviced a couple of months back and went with a thicker oil (10W50 I think). Any chance this could have something to do with it? Or loose plugs, maybe... I will have another check over this eve.

[vocky]

 

Sounds like piston slap, if you lift the clutch pedal up to the biting point and rev the engine with the handbrake applied you should be able to replicate the noise

thought you only got that when the engine was cold??

 

 

can also be caused by a cracked piston if the noise appears when hot

[vocky]

10w50 is not that bad, many owners use that type of oil

[phippsy]

I had a tapping noise on cold start up, thought I had a cracked manifold but turned out to be exhaust gasses passing the gasket between exhaust manifold and head.

As I had bought a new manifold and gaskets I fitted them anyway, possible you have a similar problem.

 

Id whip the rear clam off and do a bit of investigating if I were you. Much easier to see what's what once its off.

 

Edited by phippsy, 10 November 2015 - 08:37 PM.

[GaryK]

I appreciate the help everyone. I already have my dad coming over weekend of the 28th to help strip the suspension for a refresh, so it was gonna be off the road for a while anyway... may as well have the clam off at the same time. His first thought was gasket. Fingers crossed that's all it is.

[james_ly]

Haven't seen the video but I had a (quiet) tapping noise from my engine. I tightened up the bolts on the exhaust down by the passenger wheel. I think it's where the U bend meets the backbox, but not sure. The reason I did this was I noticed some water below it which I think was condensation from the exhaust when you start it up.

[GaryK]

Another good suggestion. I've recently had the backbox replaced and pretty sure I only noticed this after...

[GaryK]

I started the stripdown last weekend for suspension refresh. Took my dad out for a spin first, and now he's convinced it's not a blow. He asked whether the speedo cable is mechanical?

 

Anyway, on taking off the rear clam, I found this! Should be worried?

 

 

The location of the above...

 

Edited by GaryK, 07 December 2015 - 11:24 AM.

[techieboy]

No speedo cable. It's all electronic, driven by the ABS sensors in the wheel hub/bearing.

[mbes2]

Above photos oil from head breather?

[GaryK]

I think so, yeah... I'm assuming this amount of oil isn't normal. FWIW, there's no gunge on the oil cap.