2003 1500 RAM VAN whistle
Help!! Ihave a 2003 1500 ram van with the 5.2 magnum. Bought used with24k on the odometer. Right from the start I've been plagued by a high pitch whistle that only occurs in the cold weather. Whistle is intermittent and can occur at any speed, and doesn't matter if engine is up to temp or not. Give it a little more or less throttle and the noise goes away. ( will fade in or out like an air whistle being throttled by a 1/4 turn ball valve) Whistle almost always appears while maintaining a steady speed. Tried disconnecting all the vac lines and plugging them at the manifold - still whistles.( even tried it with brake booster disconnected and capped - scary! ) Changed throttle body and gasket, tried driving with air cleaner assembly off, checked for restricted exhaust, cleaned IAC, tried unlit propane torch trick around manifold, T.B.,& vac lines. Checked intake manifold for oil on the plate- it was pretty clean, not surprised as I wasn't using any oil.Took the van to my local garage, they did a "smoke test" and found no vac leaks, did a test drive with the scanner hooked up and everything checked out normal. Convinced it was a vac leak , I installed a vac gauge- @100 KMH it only runs about 10" Take it out of O.D. and the vac runs 18" to 20" and I'm getting about 18MPG. With the O.D. on with the lower vac reading I get 12 to 14 MPG. Out of desperation I took it to the dealership (now at 58K). After checking it out, they told me the whistle was the PCV valve and hose, but the engine had so much blow-by, they were going to change the motor under warranty. ( excess blow-by without oil consumption?) Was told no motors were available in the system,I'd have to wait awhile. While I waited (about a month) I tried driving the van with the PCV valve removed and the line capped- made no difference-still whistled. When I got the call the motor was in, I was told it was a 2 day job ( sounded about right) 1 month later I got my van back just as the weather was warming up so it didn't whistle at this time. This is after they installed a re-man factory short block, new water pump, serpentine belt and clutch fan. Now it's cold again and the whistle is driving me nuts, and I don't always remember to disengage the O.D. so the mileage really sucks. ( I was told by the dealership the overdrive can't be defeated without opening up the tranny and then I'd have to ignore the check engine light) On a side note, when in overdrive and maintaining a constant speed ( by foot or cruise) the heater controls will only switch modes once or twice , then won't work until you back off on the throttle to bring the vac up again ( the vac reservoir must be not leaking) If the van is driven out of O.D., the heater controls all work properly. I'm all out of ideas and really flustered.I've talked to anyone who'll listen , both backyard and proffesional mechanics who are all stumped-nobody seems to have an answer for me. Anybody out there with an answer ?