[steamship]

Originally Posted by MikkiJayne

The manifold pods might actually be a clue - if one of them has a split diaphragm it could be making a noise as its leaking. Possibly it could be a leak in part of the SAI valve system which reduces the vacuum such that only one pod can activate. Possibly something around the throttle body boot / oil separator.

I would first try disconnecting the vac pod solenoid valve, just to rule those out. It will throw a code but thats easily cleared. If that doesn't affect it, have a good look around the back of the engine with a torch looking for split hoses.

Just an update on this. Disconnected both vacuum pod solenoid valves and took it for a short run as well as doing a few errands, but noise was still apparent. I also checked both diaphragms on them and no apparent splits or holes.

I had a look at the pipe coming from the SAI pump and that is fine. I'll check all the vacuum pipes tomorrow when the engine is cold, although I had replaced the majority of these a couple of years ago.

There are two of the vacuum pipes that I'm not sure where they go. Each goes from the front of the engine to either wing, seems to connect to a stiffer plastic pipe and then disappears up towards the bulkhead. Any idea where these head off to?

I'll also get it up on ramps and check that heat shields and anything else lurking around is firmly secured.