Re: IML: Should I believe the gauge?

[randalpark@xxxxxxx]

The sending unit is located on the top of the back of the engine close 
to the firewall, beneath the intake manifold. It is a pretty good 
sized, almost bell shaped unit, with a wire connecting to the top of 
it. It may also be leaking it if is going bad. They do fail, but 
usually they leak first.

The suggestions about having the pressure checked manually under the 
hood is excellent advice. My thought is that if the oil pressure gauge 
shows high when the car is cold, and little to nothing when it is warm 
and at idle, it may be doing its job. That job is to tell you that the 
engine is worn and needs to be rebuilt. As bearings for the cam, crank 
and connecting rods wear, the clearances increase resulting in a 
decrease in oil pressure. When the oil is cold, it is thick and would 
read high, but at operating temperature, it will drop significantly, 
with little to nothing at idle. The post about hearing lifter noise 
first when warm, at idle, and after a little bit of time has past is 
quite correct. Serious low oil pressure starves the lifters and they 
usually protest the most.

This type of bearing wear can happen prematurely as a result of 
continuous prolonged pre-ignition or spark knocking, caused by 
incorrect ignition timing and today's low octane fuels. That causes the 
most stress on the rod bearings, but will effect the crank shaft 
bearings in the longer term as well. I also should be remembered that 
even under the best of circumstances, engines wear out. A 1968 440 
should be fine in this respect for around 200,000 miles with normal 
wear and tear. Considering the cars age, this could be the case.

Check the pressure manually under the hood. It should read between 10 
to 20 pounds at idle to be safe, but any is better than none. At least 
you will know the truth. Even with 5, I wouldn't be too concerned as 
long as the car is tuned properly for today's fuel and meticulously 
maintained. If you start hearing the lifters clattering you will know 
the rebuild is overdue.

Paul W.




-----Original Message-----
From: Steve B. <Imperial59@xxxxxxxxxxxxxxx>
To: mailing-list@xxxxxxxxxxxxxxxx
Sent: Sat, 14 Jul 2007 6:51 pm
Subject: Re: IML: Should I believe the gauge?


> Aloha, 
> I'm trying to decide whether to worry about something or not. For the 
> past couple of months, >the oil pressure gauge in my '68 LeBaron 
drops to > nothing after the engine is warm and I stop >for a light or 
at idle. 
 
Replace the sender first. If the pressure still reads low connect a 
manual gauge and see what the pressure really is. You may find that 
there are two senders under there... one for the sentry and one for the 
gauge. You can pull the wire off one at a time to figure out which is 
which. 
 
  Steve B.  
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