Oil Light Flickers

[joelittel]

Started taking everything apart today. So far, nothing too out of the ordinary, however I didn't plastigauge the bearing clearance yet... need to clean off all the oil first.

I did find a leak on the flywheel side of the block that would have driven me crazy had I left it. So, if nothing else, my loss of oil pressure is going to help fix an oil leak that I otherwise may have chosen to live with. Win win.

No slipped/spun bearings so that's good news. The shot below is what my worst bearing looks like. Some of the others weren't scuffed at all and some were scuffed lightly. I'm hoping that's "normal wear and tear" you see on the bearing surface. Any opinions?

The other picture is the oil pan, circled in yellow is a thick milky collection of goo that was in there when I took the pan off. What is that stuff? It was thicker than the rest of the oil in the pan, like a thin mucus. I didn't see anything like that coming out when I drained the oil (which I saved for further inspection because it seemed a little dark for only having been in the car for one weekend).

All moving parts seem free of any binding or drag, which is good and bad. I was hoping my problem would be obvious and only require a parts swap.

Next up will be to clean and measure the bearing clearance. My fingers are crossed that I'll discover an obvious fix and be happily motoring along in two weeks or less.

[beater]

You know sometimes engine rebuilding can be a funny thing. I had mine rebuilt by the shop teacher at a school I worked at several years ago. The only reason I went for a rebuild was because it smoked bad on decceleration/downshift but ran fine and did not seem to use any oil. Upon disassembly the bearings looked much like the one in you picture so we honed the cylinders, put in new rings and seals and put it all back together with the old bearings. Like I said that was years ago and it has run perfectly since then and I don't drive it easy. I guess my point is sometimes you can be incredibly careful and anal with a rebuild and it doesn't work out and other times just do what needs doing and put it back together and you can be fine. Luck of the draw I guess!
Forgot to mention my light never came on or flickered but my oil pressure with the stock gauge has always read low before and after the rebuild. I hooked up a "manual" gauge with an actual tube leading from the sending unit output to a aftermarket gauge and it showed excellent oil pressure so you definitely don't want to rely on the electric current gauges output.

[DieselSpider]

Hard to tell from the pics with my old eyes but it looks like bearing material in the bottom of the pan from here. What does the crank pin look like at the scuffed bearings location? Might be just tight enough to bind when everything is hot.

[joelittel]

Thanks for all the advice, you guys have been very helpful to me.

Diesel your probably right, everything turns easily now because it's cold. I hadn't thought about that.

The crank looked normal to me (no marks or scouring), but it was still covered in oil so I could have easily missed something.

One night this week I'll clean it up and plastigauge the whole thing. Then I'll compare it with my other crank and put the better of the two in the block on fresh bearings. I assumed this was the better of the two cranks because it had gone to a machine shop and received a clean bill of health.

Now that my oil pump is out of the car how could I test it? Could I submerge the pickup head in a tub of oil and spin the spindle with a drill to see if it's moving and oil?

[Turbofiat124]

The oil light on my Brava started to flicker one day but only at idle when at normal operating temperature. When cold at idle or going down the road at normal operating temperature no light either.

I rigged up a mechanical gauge and verified I had around 15 PSi of oil pressure at 190F. I think I read 15 PSI was acceptable for idle.

I tried about three used sensors with the same result. I finally found one (I think from a Yugo engine) that operated normally. Light on with key on but engine not running then would go out when the engine was started.

[joelittel]

Today I'll measure my bearing clearance and test the oil pump.

Hopefully I find something that identifies the problem so I can fix it.

The weather in Illinois has been colder than normal, so at least I'm not missing good driving days but I am starting to miss having the car on the road.

[joelittel]

I think I'm making progress.

My main bearing clearance was .003" or higher. The connecting rod clearance was .002" or higher.

My manuals put these measurements at the high end of bearing tolerance. Looks like I'll be going up a bearing size.

I still want to test the pump, although I see the logic in just replacing it now while everything is easily accessible.

So far I'm happy enough with my findings. I was worried that I'd have some mystery problem on my hands that I couldn't solve.

The below image shows two of the mains with the plastigauge strip after torquing to spec. They were all about the same.

[joelittel]

Another interesting find. The first two main bearings do not have grooves in them. The other 3 do. When I installed these bearings did I do so in the wrong order (photo is from nose to flywheel perspective)? Should the grooveless bearings be on the ends? I'm embarrassed to say that I didn't even notice this detail when I installed these bearings a few months ago.

I now feel very lucky that my oversights did not render my engine useless.

[joelittel]

Just an update for those who may have a similar issue.

My main bearings were not installed correctly. Two of the bearings do not have an oil groove down the center, while the rest do. These two bearings are to be installed in/on the center journal and cap. I had mine both at the front of the engine (not sure why, other than I wasn't paying close enough attention when installing). Because of the position of those two bearings I believe my crank was off kilter and eventually caused a problem. Luckily for me I was at home and idling in the driveway when it happened so nothing of significant value was ruined.

I had to measure the bearing clearance twice and was surprised to find an uncomfortably wide range in measurements... turns out that plastigauge is dramatically effected by temperature, so make sure you aren't using it in cold weather.

I'm happy to report that everything is back together now and waiting to go back into the car.

While I had the engine out I took the opportunity to make a few upgrades that should help down the road.
1.) Ishihara-Johnson crank scraper because I like to drive fast and high into the RPM range.
2.) Mechanical oil pressure gauge to help me keep an eye on any future oil pressure issues.

[joelittel]

Fired it up for the first time since the incident. All is good so far, love the pressure gauge.

I hope to be back on the road within the week.

[RRoller123]

Excellent!