Vaccuum leak on M60?

[Sherman]

I have a 94 M60a that has started to whistle. It's very high pitch, and only happens when driving... which makes it awfully hard to locate. My mileage has dropped off in the past couple of weeks, but I think that's more related to my coilover install and running a bit more toe in the rear (until my Kmac bushings arrive).

I'm going to hook up a vaccuum guage and monitor while driving, but are there any common leak points on these cars? I've also read that this may indicate a pending tranny demise... Any truth to that? Are these really non-serviceable trannies?

Any thoughts on what to look at would be appriciated... though I know I'm giving much to go on.

[kalevera]

First, I would inspect the intake boot (between the MAF and throttle body) as they tend to crack. If nothing is evident there, get a can of carb cleaner, with the engine idling, spray at the base of the intake (where the runners meet the heads) and also along the areas where the throttle body meets the intake and where the PCV plate meets the intake. The idle will smooth/even out if there's a leak. Could also be the valve cover gaskets/nut grommets.

[Sherman]

Thanks I'll have a look. She runs smooth as silk and doesn't whistle when at idle.