Jim Grant's Tech Tips
93
Lincoln Towncar, Smokes When Idling
Q: My ‘93 Lincoln Towncar smokes after it sits at idle, but only after
it warms up. When it is cold (engine) it doesn't smoke. As soon as the
water heats a small amount and the temperature switch senses this the
check engine light comes on and the smoking begins. Whenever you sit at
a light and then accelerate there is a large cloud of blue smoke which
comes from the tailpipe. The engine uses about 2 quarts of oil every 400
miles. I tried reading the engine codes and the closest I can come up
with is the EGR system. This problem just started a few months ago and
I'm stumped. The last time I had a problem was poor running and a thermactor
code. It cost me $400.00 for a new mass air flow sensor and a cleaning(
I think I got the cleaning ) of the EGR system. Any help would be appreciated....Rick
A: Something
isn’t adding up here. First, 2 quarts of oil every 400 miles is a major
oil consumption problem! It’s unlikely any computer codes are going to
give you an answer to that. I would not recommend spending much money
on that vehicle until you know why the engine uses so much oil. The way
you describe the problem brings back some memories of problems we’d see
with older vehicles. Of course I was very very young at that time.
Here’s what
would happen. Because of poor oil quality, lack of proper maintenance
and/or driving habits the oil drain back passages in the cylinder heads
would plug up with deposits. This condition would cause oil to become
trapped in the valve covers of the engine. As a vehicle is driven, oil
is pumped up to the top of the engine to lubricate the push rods and rocker
arms (in your application) that operate the valves. This oil is suppose
to drain back down into the engine. When oil cannot drain back, it collects
at the top of the engine in the valve covers. Once the oil reaches a high
enough level the valve seals are overpowered with oil and eventually the
PCV valve, which is designed to remove vapors, would have liquid (oil)
available. Needless to say this condition would cause oil consumption
to jump resulting in a marked abundance of blue smoke out the exhaust
after a vehicle had been run a short time. This condition would also raise
havoc with the vehicle emission controls, which could cause the computer
to send out a desperate plead for help (check engine light on).
An easy way
to check for this possibility is by inspecting the oil level in the morning
after the engine has set overnight. Then drive the vehicle until it starts
smoking good. Shut the engine off and check the oil level. If the oil
level has dropped in that short of time then it is very likely that oil
is trapped in the valve covers of the engine. The fix is removing the
valve covers and cleaning the drains.
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