Oil Light Flickers

[joelittel]

My oil light started flickering yesterday.

The dipstick shows the oil level to be right at the full mark and the oil pressure sending unit is new.

I checked the wires and they all look like they're plugged in and in good shape. I was going to run the car for a few minutes and then check to see if oil was getting into the cam towers by taking one of the covers off (after I stop the engine of course).

What else can I do to diagnose my problem?

[DieselSpider]

My oil light started flickering yesterday.

The dipstick shows the oil level to be right at the full mark and the oil pressure sending unit is new.

I checked the wires and they all look like they're plugged in and in good shape. I was going to run the car for a few minutes and then check to see if oil was getting into the cam towers by taking one of the covers off (after I stop the engine of course).

What else can I do to diagnose my problem?

Get a $15 oil pressure gauge and verify the exact pressure. You do not want to mess around with low oil pressure. The gauge will tell you if your pressure is bad or if the new sending unit is simply defective.

[joelittel]

DieselSpider I agree with you, I do not want to mess around with low oil pressure. I think I'll pick up a pressure gauge before the weekend rolls around.

Where does the oil pressure gauge get connected, in the same place as the sender unit? Would I have to take the sender unit out and put the gauge in it's place while I test?

I did notice that the sender unit was leaking oil at the spade connector, and that doesn't seem right to me.

I've got a fuel injected '80, is there any value in replacing my clock with a pressure gauge like the older models had? I've read that the gauges aren't all that accurate, but at least it would be giving me data I could monitor.

[124JOE]

and normal pressure is??

[DieselSpider]

and normal pressure is??

According to the 1975 thru 1982 service manual at 212 Deg F (100 Deg C) it's 50 to 71 Psi (3.5 to 5.0 Kg/sq. cm)

[joelittel]

So anywhere between 50 and 71 is within spec. Seems like a wide range.... but who am I to say

I picked up an oil pressure test kit via the interweb
and am looking forward to seeing what I've got going on in there.

[narfire]

Does it flicker while the car is level or just going around corners? I'd guess you would know if you have wacked the oil pan. The oil pick up can break off and at level still pick up oil fine but as the oil sloshes going around a corner it can suck air giving a low pressure signal.

[joelittel]

This is all on level ground.

Oil pan is in great shape.

The spade connector on the sending unit shouldn't leak oil, correct?

I'm really looking forward to blaming the sending unit for all of this... but at the same time, am now very curious about my actual pressure numbers. My engine is a fresh rebuild with only 100 miles on it, so there's an excellent chance that I've done something wrong, like not having the correct sized bearings on my crank journals etc.

Because this intermittent issue just came up and wasn't an issue for the first 95 miles I don't think I've got an oil pressure problem, but... I'm going to test everything to be sure.

I'm tempted to let it run with the oil cap off, as mentioned previously, but I don't want to clean up the oil spray that should get all over everything should it turn out to be working correctly.

[RRoller123]

Shouldn't leak through the connector, I think you have found the source of the problem right there?

[joelittel]

Ordered an oil pressure test kit but haven't received it yet.

So, like any good home mechanic I hoped for the best as I rushed in and changed my sending unit, and fired the car up.

This time the oil light stayed off while the car was warming up so I thought I was in the clear. Once the temp was up and the cooling fan kicked on my oil light came back on as well.

So I thought that I might as well change the oil and the filter while I wait for the pressure test kit. I thought that maybe the filter was packed full of assembly goo and hopefully the cause of my problems.

Oil came out looking dark but I figured that is to be expected due to the liberal amount of assembly lube I used while putting the engine together.

Filled it with oil, (including filter) and fired the car up. This time it was making a nasty rubbing sound that I seriously hope was just a belt. It's cold and wet here today. So I shut it down quickly.

Checked oil level and tried to start it again. This time it didn't want to fire up right away, which is very odd for this car. When it did start it made the same uncomfortable grinding/rubbing/dragging noise so I immediately shut it down.

I feel my good luck easy breezy rebuild has turned against me.

Letting it sit now and will go back to check my oil level later. I'm not sure how changing the oil and filter could have caused these symptoms.... it's not as if the block had gone bone dry before my attempts at restart.

[So Cal Mark]

the warning light will illuminate at approximately less than 5-9psi, so a flickering light indicates loss of pressure. 50-70 psi would be at a much higher rpm than idle. The grinding noise is troubling, was cranking speed noticeably slow? You may have spun a rod bearing. During the rebuild did you measure bearing clearance?

[joelittel]

I did not measure bearing clearance.

I bought the block and crank from someone who had taken them to a machine shop. The block got bored but there was no record of anything being done to the crank. I even called the machine shop and asked.

This is where I'm hoping I didn't make a mistake...

I assumed standard size bearings were the way to go because my "dry fit" seemed to fit/sit fine...

Now I'm really wishing I had measured the bearing clearance for myself.

My next move will probably be to disconnect the battery, take the plugs out and crank it by hand. It used to be really smooth yet with some resistance. If I've slipped a bearing I'm hoping I'd be able to feel it.

[124JOE]

use a stethiscope,hold it on the area of the bering

[joelittel]

Stethoscope is a good idea.

Cranking speed didn't catch my attention as being slow, but it could have been slower than normal.

Usually the car fires right up like 1-2-broooom.

If I have caused a problem I'm very fortunate to have done so with the car at home, so I've got that going for me.

[joelittel]

I took the cylinder head off today, and so far I'm just more confused.

With the head off I rotated everything (independently of course) and I can not reproduce the grinding noise I heard the last time the car was running.

I wasn't able to rotate the cams more than a few degrees because they're still in the towers which is connected to the head.

Everything, crank, auxiliary pulley, cams tentioner bearing rotates silky smooth.

Tomorrow I'll pull the block and check my bearing tolerance (like I should have done before it went into the car) but so far there is no obvious source of my grinding noise.

Like everyone always says, it is actually easier the second time