Oil Light 1964 Riviera-Any Ideas?

The problem I am having is the oil light comes on, but only after I have been driving on the freeway and then slow down. It does not come on while I am driving on the freeway. And it does not come on unless I have been driving on the freeway. And I can let the car idle for 20 minutes and it won't come on. Odd, right? Any ideas, other than the oil pump? I notice that OldBuickParts.com has an Adjustable Oil Pressure Regulator (OPR600-4). Does anyone have any experience with this part? Any ideas? I am going to replace the oil pressure switch. Thanks again!

How old is the oil pressure sending unit and have you checked the connector and inspected the wiring?

Are you sure that you indeed are losing pressure?

Thanks Marty. I am going to replace the sending unit--which I called the pressure switch in my post. I will inspect the wiring when I do that. I honestly don't know for sure that I am losing pressure, but I actually don't think I am. I appreciate your help.

Thanks Marty. I am going to replace the sending unit--which I called the pressure switch in my post. I will inspect the wiring when I do that. I honestly don't know for sure that I am losing pressure, but I actually don't think I am. I appreciate your help.

It could be the sending unit.....change it and see what happens. If it doesn't fix it the next logical step is to put

an oil pressure tester gauge on the engine and go out and drive it on the freeway for a while then pull over and see what the pressure

is. If it is really low, then the most likely explanation is sludge in the oil pan clogging up the screen at high speed, then when you slow down at low RPM the oil can't get through the clog, then later the sludge falls off. This is assuming the engine hasn't been rebuilt recently. If it has it could be the oil pump or perhaps something like a spun cam bearing. Take off the oil cap and look for sludge inside

the valve cover.....if you find some that could be the culprit.

That is very helpful. Thank you.

Thanks Marty. I am going to replace the sending unit--which I called the pressure switch in my post. I will inspect the wiring when I do that. I honestly don't know for sure that I am losing pressure, but I actually don't think I am. I appreciate your help.

Billy,

Had I read the last line fully, I would have seen and understood your reference to the pressure switch.

Seems we are both on the same page, while it could be an actual pressure drop, I, like you lean more towards a faulty sender switch.

Very inexpensive, so why not start simple?

I also wonder if the wire is being tugged by engine movement.

Just to be safe, check your movement at the motor mounts.

Usually that would happen on acceleration, but it could be getting pulled the other way.

Keep us posted!

That is very helpful. Thank you.

One more thing, if it does turn out that you have a sludge puppy of an engine causing your problem, there

is an old Farmer's trick that will fix the problem without tearing the motor apart. I've used this trick on several occasions at my shop

when I had a sludged engine sending the oil pressure to zero with a clogged screen and it worked every time. What you do is drain out all the engine oil and fill the crank case with diesel fuel right up to the top of the valve covers, then let it sit for about 4 weeks. After

that time , drain all the diesel out of the pan, put in fresh oil and filter and then remove the spark plugs and turn the engine over to get all the

diesel out of the cylinders for about five minutes, reinstall the plugs then change the oil again. The last step is that you have to run it for about an hour to get the exhaust to quit smoking like a mosquito fogger because a lot of diesel will get into the exhaust system.

If, after you've looked at everything mentioned thus far, the problem still persists, you may what to check to see if there's a DASHPOT mounted at the carburetor linkage. If it is supposed to be there, and is missing or is out of adjustment, when you decelerate the linkage will snap your throttle plates closed too far, causing engine RPMs to drop far enough to momentarily cause a low oil pressure condition. Let us know what you find.

OK Billy: I am running for the most unpopular Riviera person ever (on this forum at least).

1. Put an oil gauge on the block. Right rear of the valve cover.

2. Check the oil pressure with a PROVEN oil pressure gauge. It's OK to be hopeful but let's first be scientific. This will tell you if your engine is producing oil pressure. If it is then check for continuity.

3. Let's be realistic. Your car is 50 years old. If the gauge says low drop the pan (not that hard) and inspect everything. Go from there. There is an excellent chance your engine is tired and will need a complete rebuild. If you get lucky....I got lucky once. It happened so quickly that I didn't know whether Lady luck was good looking or ugly. Mitch

Years back I had an unusual problem with my first '63 Riv. The oil light came on only after a few miles, and after checking the usual things I found a cause that I have'nt seen since on all my Rivs and nailheads. The "idler shaft" in the oil pump backed out enough where I had oil pressure up to about 25 pounds and the light would come on at low speed and cold.

kaycee

Tools, gotta have tools.

Bernie

Extremely helpful. I am going to start with the sending unit. Easy enough and cheap and it is 50 years old after all. Might try some Seafoam in the oil and then an oil change, which I have had good luck with in the past to get some sludge out. Hope I get lucky! If not, I'll put the gauge on. (You all know I'll test the pressure regardless.). Just in time for a Thanksgiving weekend project. I really appreciate the advice I just got this car BTW. I have had other classic cars but never a Riviera. I have always wanted one, and happened upon this one and couldn't resist. Interior is excellent, body is straight and paint is decent. Generally unmolested. Super happy with it what a fantastic car--even if I do have to rebuild the engine.

Billy,

I certainly do like the idea of a gauge, but why not just add a permanent one?

Or at least put one in for a few hundred miles of driving, just to confirm all is well!

I never liked idiot lights by themselves.

Great to have to grab your attention immediately to alert you to check a gauge, but not just the darn catastrophe light!

Still hope it is the sensor!

But as someone pointed out, hope is not a good strategy.

You are right Marty. I am going to add the standard 3 gauges or at least oil and temp. Looking for gauges that will look good and trying to decide where to put them. Found some 1.5 inch I might be able to fit above the heater controls.

Take your pick

http://www.egauges.com/Gauges-Senders-and-Accessories-s/13.htm

OK Vermont: DO NOT use Seafoam. It is an excellent product but can be really a kiss of death in you application. If you indeed have low oil pressure drop the pan and inspect. SEAFOAM WILL ONLY DISTURB THE SEDIMENT IN THE PAN IT CAN EASILY CAUSE YOUR OIL PUMP TO BE CLOGGED UP, THUS STARVING THE ENGINE FOR OIL.

Re-read my original thread. Mitch

Well, I was able to get into the pan enough to see there is no sludge in there. The guy I bought the car from told me the 47K miles on the odometer are original, not 147K, and I have seen no reason to doubt that yet. So I did try the Seafoam (thanks for the words of caution, Mitch), drained the oil and refilled it, this time adding about 25% Lucas Oil Stabilizer, which I have used in other cars. I also found the sending unit, and cleaned the wire connection point, which was all dirty and greasy. The oil is so clean now that it is hard to see it on the dipstick, the engine is noticeably quieter (I had a little lifter noise before), and no more oil light. My guess is that the oil light was a result of a bad connection at the sending unit wire. I am still going to install a gauge, however, and in that regard wanted to let you all know about IEquus.com, because they have 1.5" gauges. I think I can get the 1.5" size to fit above the heater controls, below the vent that is below the radio. If you are interested they have them in black, part #6100, and aluminum part #8100. Put the part number in the search box. Unfortunately, they don't have the 1.5" size in chrome. I know this kind of modification is not for everyone. One member here told me he put an oil gauge where the clock goes, but my clock works, believe it or not. Really like this car! Thanks again.

If you think about it, the forward and back momentum of the car accelerating and braking could have made the contact at the sender loosen up a bit and give you a false light. You'll never know but perhaps just cleaning and tightening the connector at the sender might have been the ultimate solution.

I had a temperature light on my hot rod El Camino that would sometimes give me an instant hot reading. That turned out to be a wire on which the insulation was burned off. When I accelerated, the wire would touch the header and instantly give me a hot reading.

Ed

The loose connector theory does not make sense. The oil light switch circuit goes to ground, or completes the circuit, when there is no oil pressure. A loose connection is an "open" and the opposite situation from completing ground. Ed`s header situation is an example of completing the circuit to ground by a bare wire shorting, or going to ground, against the header. A loose or open connection will not cause the light to illuminate. There is another variable that has changed and was the cure, or the issue is intermittent and will return. Was the original switch swapped out for a different one? Is it possible the old oil was diluted with fuel or a different viscosity? As a tech I would not be satisfied with the loose connection theory....BTW, I agree with Mitch in regard to using cleaners or "flush" for the lube system. I have seen engine knocking develop immediately after using these products

The diesel fuel reference brought back some memories. When I was a young boy my best friend`s Dad would run diesel fuel thru the motor as a cleaner when changing oil...NOT under a load but just idling. He disposed of the waste by pouring it around the foundation of the garage to keep the weeds at bay! My, how things have changed....

Tom Mooney

Hi folks-put gauges in your cars=cheap and good insurance. Dan Mpls. Mn.

Hi folks-put gauges in your cars=cheap and good insurance. Dan Mpls. Mn.

I like driving my car with only what was available from the factory/dealer years ago. Did Buick offer a dealer installed gauge package in 1964, even if not really meant for a Riviera?

Years back I had an unusual problem with my first '63 Riv. The oil light came on only after a few miles, and after checking the usual things I found a cause that I have'nt seen since on all my Rivs and nailheads. The "idler shaft" in the oil pump backed out enough where I had oil pressure up to about 25 pounds and the light would come on at low speed and cold.

kaycee

Russ martin mentions this in his web site. I think he also says that this condition causes a knock that sounds similar to a bad bearing.

arnulfo

If the cause is a worn engine, but it runs well, you can put a can of STP in it.

The tip-off is the oil light comes on at idle after driving on the highway. Classic symptom of worn engine bearings. Most likely 147k miles on the car. The oil light won't come on until the pressure drops below about 5 psi which is nothing. Put a gauge on it to know for sure. I don't know for sure what causes the pressure to get so low after a highway run but then come back up after driving in town, but I have heard it is because the bearing tolerances increase slightly at higher speeds due to heat but decrease shortly after the high speed driving is over. Oil viscosity breakdown also contributes to this. If the pan is still loose take it all the way off and remove the main bearing cap closest to the oil pump. This affects pressure the most. The rod bearing farthest from the pump will have the most wear. If there is wear on these bearings, you need an engine. The advice to add some STP will buy some time as it will thicken the oil and raise pressure which is good, but it will slow down the flow, not good. As mentioned a spun cam bearing will cause low oil pressure too.

Oil pumps really don't make pressure. They make flow. The bearing clearances make the pressure. However pressure and flow are related which is why a higher volume oil pump will increase pressure because it can keep up better with the leaking clearances than a stock pump.

My car had this exact problem. I rebuilt the engine and now it has good oil pressure at idle.