Engine Noise

[Roady]

Hi Everyone,

 

Just wanting some diagnosis help.  I have a feeling it may be a leaky valve but thought I would ask for some fresh ideas before I start pulling things apart.

 

I can only hear it at idle and originally I thought it was an air leak from the carbys or exhaust.  Kind of a "squishy" noise.  Then I tracked it down to cylinder 1.

 

Now as I honed in it sounded a bit metallic so I thought perhaps it was contact in the engine.  Pulled the spark plug lead and the noise stopped, so therefore not the valve/piston contact.  Swapped spark plugs, leads and distributor cap, same noise from cylinder 1.  So I am happy it is not an ignition issue.

 

I presume that am I only hearing it from when the spark is firing because of the increased compression?  My current thoughts are potentially a leak from either valve, manifold gasket or possibly cylinder head gasket (but coolant levels, oil etc all appear to be normal).  Sound appears worse on manifold side of engine. 

 

As Gav suggested I have uploaded a video - I have intentionally let the car only just idle which is when the noise is clearest.

 

All ideas welcome

 

Cheers

 

Engine.wmv

Edited November 11, 2015 by Roady

[gav240z]

If you have the capability a video of said noise would probably be far more helpful.

[Roady]

Great idea Gav, I have tried about 6 times to upload it now, the file size is about 10mb but everytime it fails to upload saying "no file selected"

 

 

[gav240z]

Are you trying to upload the video to this server or to Youtube? You should probably try Youtube and then link to it from here.

[HKSZ]

take the rocker off and check your valve clearances

[Cozza]

Try a compression test or even better, put compressed air into the cylinder and listen for a leak.

Good luck

Mick

[Roady]

Video uploaded to original post

[dat2kman]

take the rocker off and check your valve clearances

Yes, this.

Check lash on other cylinders as well, for comparison.

 

Kinda thinking you have an issue with valve seats, or a slightly bent valve head, only takes a thou, and seat wont seal.

Removing plug lead and running engine on the comression>fire stroke, its either getting expanded out of either valve.

 

Do you know f someone has played with camshaft timing, or, has it had a big rev moment?

[gav240z]

Video uploaded to original post

 

Ok I didn't think it was possible to upload video to the forum, but you obviously have. I don't know if we have enough space for frequent video uploads and certainly bandwidth could be an issue. Hence why I said Youtube was probably a better option.

 

 

Here it is for everyone else.

 

It sounds like some kind of valve train issue. I agree it could be a bent valve, sounds like a leaky chamber. Compression test would reveal for sure...

[C.A.R.]

Exhaust manifold leak, head gasket leak or it's dropped a valve seat (generally they sound worse though).

[Roady]

Thanks for all the info guys at least I know I'm in the right area.

I had reset all the valve clearances around 1000km ago and it has driven fine this far not making this noise and no big rev moments (last time I tracked it would have been 400km ago). That said I will check the clearances as the last thing I really want to do is have to pull the head off.

I was also going to stick an inspection camera into the chamber and have a look around but as has been mentioned it could be only a tiny bit out and not obvious to the naked eye.

 

My only follow up question is, if I compression check it, how will I tell the difference between a leaky valve vs a leaky head gasket?

Edited November 11, 2015 by Roady

[Yamahacam]

^{You should be able to hear through the manifold (intake or exhaust ) where the leak is coming from.}

[Linton]

like lurch said the manifold gasket is leaking, you can hear it because of the cylinder misfiring, you will not hear a head gasket leaking, a compression test is the first thing you should do, if its low add about a teaspoon of oil and check it again, if it stays low it is the valves, It might  be also the intake leaking at the gasket causing the miss fire. either way the manifold must come off, but make sure you do a compression test first

Edited November 12, 2015 by Linton

[Roady]

Thanks for all the ideas, I will thoroughly check all the suggestions and report back what the final problem was in a week or so.

Cheers

[Roady]

Hi everyone, thanks very much for your help.

 

As some of you picked - the magic noise is the manifold gasket!! (exhaust)

 

Inspection Camera - OK

 

Compression checked - OK

 

Traced the leak - Slight "burning" look where it is leaking out of the gasket from number 1.

 

 

Thanks again for all the suggestions