Problem Description and Possible Solution
On 3.9L V6 and 5.9L V8 engines, the intake manifold gasket may leak and cause increased oil consumption and a spark knock during acceleration; the gasket should be replaced.
Average mileage: 146,500 (63,000–230,000)
12 people reported this problem
Van had an extended period of idle storage, but upon bringing back into service, at roughly 63,000 there was a noticeable increase of sound similar to a vacuum leak near front grill area of intake tube. Also had a major mysterious oil consumption, didn't leak onto ground or smoke badly, but worked out to a qt for every week with daily use. On inclined roadways, a noticeable loss of power to climb and bogging down effect when worked harder with very apparent valve-train noise.
I purchased the Dorman gasket repair kit with all gaskets for intake area (my only complaint is a weak thermostat came in the kit which I would not recommend...I would've been better sticking with factory). My BIGGEST piece of ADVICE is to get an aluminum plenum cover to replace to stamped steel plate from the factory before doing the repair...the gasket set alone will only provide a temporary fix compared to swapping it out. (Apparently the thin steel coupled to aluminum creates a poor seal due to "walking" of the gasket material because the two metals heat up and disperse heat differently creating a weak gasket in a relatively short period of time.)
Mine was fixed at 69,000 and holding well and now I have used a 1/4 of a quart of oil in the weeks since 72,500 (roughly 1/12th of what it was doing previously). I can also now hold speed climbing up normal hills on the highway, unlike before. One of the first major repairs done on this van, but one of the best I could have opted for. Now, as a result of this failure of design, I need to address a misfire in cylinder 8 and check on the health of the catalytic converter and oxygen sensors (only showing P0308).