Oink ! Stag grunts like a pig

[mattsay]

Hi All,

I recently had some work done on the car including extensive engine work. I was still running the car in (done less that 100 miles) when I noticed this strange noise like a horse trotting or even a pig grunting! I hope the link works, this is my first attempt at "you tubing".

Any help from anybody that might know what it is would be greatly appreciated

Thanks, Matt

http://www.youtube.com/watch?v=76ld_ekMTaM

[martin]

From the sound of it, and the hunting, it could be a large air leak. Martin.

[mattsay]

Hi Martin, I thought you might be first out of the blocks - cheers mate.

Anywhere I should start looking and what is actually making the noise? As you can hear it is quite a rattle / clonk.

Matt.

[mattsay]

I was trying to recollect what I might have changed just prior to the noise starting. I know this process is recommended by many wise heads to point to where a new fault could have arisen from.

The only thing I can think off was, the pipe from the thermic valve / sensor was previously blanked with a small bolt. I removed the blank and fitted it (the pipe) to the manifold where it should be. However having had the tip from Martin about a possible air leak, my mind went to breather / vacuum pipes etc. Is there any chance that this could cause the noise and hunting (i.e. if the thermic valve / motor / flap wasn't operating correctly and so had been blanked off)? I found an old thread about thermic sensors and some guys (nib and sheepdip and I think Julian - jleyton was included) referred to a clacking noise, which could be another description for my grunting sound?

I know it would be easy to check by re-blanking the pipe, but I haven't started / driven the car since the noise began for fear it was a significant mechanical issue. Some kind words of encouragement would again be appreciated.

Cheers,

Matt.

[Bob Heritage]

There is a valve in the manifold/pipe that you are talking about,I wonder if it has been removed in the past. Try re-blanking off the pipe to see if the noise disappears, then you will know your answer.

[singapore stag]

Horse trotting, Pig grunting, clacking (like Duck?).... sounds like old Mcdonalds farm to me....

[mattsay]

In my case it's more like Billy Smart's Circus !

All i want to hear is the burble for a change.

[jbuckl]

its possible to trace an air-leak with an areosol spray such as carb cleaner etc.
with the engine running spray around likey leak areas, list for engine note to change.

did you set ign timing to 12 degrees static / 0 degrees advance at idle?

[mattsay]

There is a valve in the manifold/pipe that you are talking about,I wonder if it has been removed in the past. Try re-blanking off the pipe to see if the noise disappears, then you will know your answer.

Thanks Bob, I'll give it a go. To be sure though do I blank off the air box end (using a bolt/plug in the pipe) and leave the manifold vacuum pipe / stub as it is (i.e open to the elements with nothing attached) ? Cheers, Matt.

[mattsay]

its possible to trace an air-leak with an areosol spray such as carb cleaner etc.
with the engine running spray around likey leak areas, list for engine note to change.

did you set ign timing to 12 degrees static / 0 degrees advance at idle?

timing is set at pretty well bang on 12 at around 700-750 rpm using strobe. Thanks for the tip on tracing for air leaks. Cheers, Matt.

[jbuckl]

Is it possible to post another youtube recording?

longer / clearer?

[mattsay]

http://youtu.be/0OHY29ObOfQ

http://youtu.be/APEKJdKOvI4

http://youtu.be/9vtOyB5pZHw

Not sure these are any better - I took them at the same time as the first one. Will try to get better / longer clip tomorrow perhaps.

Cheers,

Matt.

[wilf]

Are you sure this isn't an exhaust blow?

[martin]

Hi Matt, blank off the pipe at the manifold. As Bob says, there's a valve in that screw in connection, it's just a ball but make certain it's there, the fibre washer is known to break up so have a new one handy. Try the carb cleaner / WD40 round the base of the carb pedestal and the inlet manifold where it joins the heads. It may also be worth checking the breather pipes for splits and blockages. Martin.

[martin]

Just a thought, prompted by Wilf, the join between the exhaust manifolds and the down pipes can make some odd noises, the nuts have been known to undo themselves. Martin.