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Burning Engine Oil

I am the proud owner of a '99 Dodge Durango with 82K (now 72K) miles on it. Last month I noticed the oil pressure guage “dancing” up and down on the dial. Experience has tought me that I am about to lose an engine rod, which I did. After $2500 and a new engine in my vehicle I have a burning question. When the rod was going in my vehicle, how come I could not smell any burning oil?

The oil pressure is created by the pump pushing oil against a system without significant spaces for the oil to flow through. That pressure then forces the oil between the bearingas and their corresponding wear surfaces.

Loss of oil pressure from wear occurs because the spaces between the bearing surfaces wear to too large a space for the pump to maintain pressure. It’s sort of analogous to trying to maintain pressure in a balloon with a hole in it.

The oil flowing through these larger spaces between these worn surfaces just goes through too readily, making it impossible to maintain that pressurized fluid seperation between the metal surfaces, and the metal seizes. The oil does not go into the cylinders and get burned.

The reason “oil burning” is associated with this in people’s minds is that usually when an engine is worn to that point its cylinders and rings are also worn out, its oil rings have lost their spring tension, and it’s allowing oil to pass into the cylinders and be burned. Both oil burning and loss of sufficient oil pressure are manifestations of a worn out engine, but they’re actually different failure modes.

However, I’d be negligenet if I did not add that having worn out more than one engine in under 100,000 miles either indicates that you do all local driving or you might want to take a close look at how religiously you’re maintaining your vehicles. No disrespect intended.

Does this experience “sour” you on Chrysler products?

Some more info would help.
First off, define new engine. New as in rebuilt/remanufactured or new as in salvage yard and new to the vehicle? I only mention this as I’ve seen countless people refer to a salvage motor as being new, a head gasket job meaning a “rebuilt” engine, etc.

Have you considered the possibility the dancing oil pressure gauge is possibly caused by a faulty oil pressure sending unit? Replace it or check the pressuer with an external gauge to verify it.

A rod bearing that is going will not cause a burning smell unless you’re running the engine out of oil, and if that’s the case the vehicle is not at fault.