Low oil pressure @ idle - 93 Honda Accord

[EricG]

On the way home last night I noticed my oil light flickering at idle. A touch of throttle and it's gone, so I drove it home and checked the level - it's about halfway between the dipstick marks, so I add about 1/2 a quart. On the way in to work this a.m. I see the same thing again. At idle - maybe 700-800 RPM the oil light flickers or sometimes stays on steady.

First - does anybody know if this light indicates level or pressure? Or maybe both. I'm guessing it must be pressure since it's correlated with RPM.

Any suggestions? There's no obvious leak - parked it over some clean snow last night and didn't see anything in the morning. I should try letting it run awhile in the same place. It's not really using much oil though - last change was about 4K ago, Valvoline 5w/30

FWIW it's a 1993 4cyl manual with approx 170K on the clock.

 

[pb4ugo]

The light relates to oil pressure.

Change the oil.

Hopefully the sending unit is bad. If that doesn't correct the problem then you need to hook up an oil pressure gauge to see what the actual pressure is at normal operating temps. With 5w-30 & 170k, you might want to consider a heavier wt oil if pressure is low. Good luck!!!!

 

[EricG]

Ok, I'll look into that. Do you think a bad sending unit would respond to RPM that way though? My previous experience with bad sensors is that they just fail completely, fail randomly, or fail correlated to engine temp.

 

[pb4ugo]

Ok, I'll look into that. Do you think a bad sending unit would respond to RPM that way though? My previous experience with bad sensors is that they just fail completely, fail randomly, or fail correlated to engine temp.

No, I'm just hoping for the best. Sometimes they will leak if they are bad. The alternative is gloomy. Oil pump hopefully, worn bearings etc.
Thicker oil might get you by. You really need to put an oil pressure gauge on it to see what the pressure really is. On old American cars the light comes on somewhere around 4 psi, IIRC, which is not good.

 

[EricG]

Ok - looks like it's going from bad to worse. Went out to a lunch meeting and noticed that the light doesn't come on when it's cold - even at low idle. Same thing on the way back - sitting for 1.5 hours, and the light didn't come on for about 5 miles.

There was an autozone across the lot so I went in there and got a new pressure switch ($3.99) - you're right, just one wire so it must just short to ground. I also picked up a bottle of CD2 Oil Detergent ( Turtle Wax - Oil Detergent) - a guy at work suggested that there might be a sort of check valve in the oil pump that is gunked up or otherwise stuck, so I should try some sort of engine flush. Note - this is not a flush product that you dump in and run for 5 minutes just before an oil change. It's an additive that you're supposed dump in and leave in.

Anyway, driving back to the office about 5 miles. No light until I'm about to pull into the parking lot. But now it's not just flickering at low idle. It's flashing on and off at any RPM - flashing regularly - not flickering. At low idle it still does the flickering bit.

So ... any further ideas? I'm more then a little concerned about driving this 20 miles home tonight.

The temperature bit is strange - viscosity related? I may try stopping at a jiffy lube just up the road and having 10w30 put in.

I'm thinking oil pump also. Price on the pump itself is around $250 and you have to drop the pan to get at it. That's alot of $$ & work for a car I only paid $2K for.

 

[Hottrod81]

Worn main bearings possibly. Try a thicker oil like stated above. My 22R would do the same thing after warming up. Had no oil pressure hardly at all at idle. My 22R finally blew up a couple of weeks ago. This would be your worst case scenario of course.

 

[EricG]

I stopped at jiffy lube on the way home (yea, I know - just didn't feel like laying in the snow) and got an oil change. Put in 10w30 vs. the 5w30 it had. No significant difference. I'm going to try to swap out the switch tomorrow.

Any way to tell if it's the bearings vs. the pump? Though I'm guessing either may be the death knell given the age & value of the car.

 

[EricG]

Worn main bearings possibly. Try a thicker oil like stated above. My 22R would do the same thing after warming up. Had no oil pressure hardly at all at idle. My 22R finally blew up a couple of weeks ago. This would be your worst case scenario of course.

Did your engine make any noise when it was running such low pressure? I would think I should hear something - valve clatter, knocking, etc. - if the pressure is that low and everything is oil starved. I remember a chevy 305 I had that sounded awful if you started it with a dry filter after an oil change. But this sounds smooth as silk.

 

[Hottrod81]

I didn't have any noise until it was too late. But a toyota 22R is different from a Honda motor. I wouls swap out the switch before anything.. Hopefully it is just a bad light . The diffence between a 305 and a honda motor is that the 305 is a pushrod motor and is more likely to make noise.

 

[EricG]

Ok, I replaced the sensor, and no light!! My only concerns now are that the boot over the connection was very hard and brittle and broke/tore to get it off. And the actual electrical connection is not very substantial - isn't on the old part either. So without the boot to hold it in place, I don't have alot of confidence in it staying on.

Plus, I don't know what the behavior will be if it does come off. Will it light up - or silently not work? Engine is to hot right now, but I'm going to pull the wire tomorrow and see.

 

[Hottrod81]

Right on.. It sounds like you found your problem.

 

[AJP]

1993 4cyl manual with approx 170K on the clock.

why don't you treat it to 2 hours at a Honda dealer for it's 15th birthday....maybe they can secure the pressure sending harness ...

seems like the least you can do for the old bus after what sounds like pretty good service