late oil pressure

F

fast fredy

Senior Member
On my stock 55 272 my oil light stays on for about 45 seconds , seems to be since colder weather . Is it possible my oil is too thick ? I think its 20 w40 once it seems to start to warm up its fine 45 seconds plus seems an eternity when your waiting for oil pressure thanks Fred
 
Yikes! I'd throw a gauge on the line to verify oil pressure. Problem with the sender or pump.
 
thought a bit heavier might do well in an older engine . I had checked earlier in the summer and had 40 lb , but will put a gauge on it in the morning. thanks Fred
 
Not only take the pressure at idle but the car has to be driven with the gauge so it becomes fully hot (tape it to windshield).

Is it a high mileage engine?
 
oil pressure

I haven't much luck with the standard issue parts store replacement oil light pressure senders, they seem to last about as long as the brake light pressure switches, that is not very long.
,
 
The specified oil grade to use is 10W-30, although many now are using 15W-40 diesel oil in Y-blocks to get the benefit of zinc content in the oil (which you need for the solid lifters). Other types of oil with up to 1200 ppm of zinc are being used as long as viscosity is up to snuff.
On another note, if engine has been setting for years, the oil pressure sending unit diaphragm will harden, leaving contacts open and won't light the idiot light. To my knowledge you can't save a good older sending unit by taking it out and cleaning it, or by trying to store it in a cup of oil. Either way, they become compromised but the old units (pre china parts invasion) will last practically forever as long as the engine is run regularly.
If you do end up having to buy a new sender, keep your fingers crossed, the chinese made electrical and control parts are of lousy quality and may not last long.
 
The '64 shop manual for its part specs "35 to 55 psi HOT @ 2000 RPM" and this would be using something like 10w30.

"Good" oil pressure is ... good, of course. But the goal isn't simply high oil pressure just for the sake of high oil pressure. Excessive oil pressure causes problems, too.
 
The stock original Y block in my '54 has the light stay on for about 3 seconds after it starts, but I typically don't run the car in the winter or late fall much...and cold stiff oil is part of the reason why. I only try to start the car at 40 deg. F or higher. It's never stayed on 45 seconds, though, at any temperature. Keep in mind that since the car isn't run that much and the carb is also original, I have to crank it a bit to get it started...and this can help boost oil pressure prior to it firing up. Can't remember exactly what weight I use, but I think it might be 10w 40. I have pretty decent oil pressure at normal oper. temp. Also, I have no idea how widely accepted it is, but I'm of the opinion that STP oil treatment helps protect an engine at start up.
 
Last edited:
The OIL light has always extinguished immediately at engine startup. I never paid much attention to any of it, other than the light itself and regular oil & filter changes. The "rebuild" I paid good money for some years ago left a lot to be desired. The rocker arms and shafts were trashed and should have been replaced as part of the rebuild process. Anyway I started paying closer attention to upper oiling, and oil pump pressure and that kind of thing. Remember please oil pumps don't produce pressure, they produce flow. Y-Blocks like any engine need plenty of flow to carry away engine heat from internal parts not served by the cooling system.

Yeah, the replacement pressure senders are not too good. Had one fail just the other day. Had to make a judgment call at the time, since oil was full on the stick and it wasn't making any protest noises I went ahead and drove it anyway and finished my errands. I've a new sender but want to track down a NOS spare.
 
Could be some odd sender problem, but it sounds more like a drain back problem to me. What happens when it’s warm and you shut it off and immediately restart it.? Instant pressure, or another lag? I’ve seen some odd problems with the oil pick up tube to the oil pump sucking air without showing a leak, too. I can’t imagine why any of that would be ambient temperature related though.
 
we had a SBF in our '41 and we were on a ride 100 miles from home and oil pressure dropped to 0. stopped and listened to the engine. was OK. kept an eye on the temp and it stayed normal. got home and replaced sender twice from local parts stores. both were not correct. ground crimp off original sender to open it up and found a piece of trash in the orifice. cleaned with a needle, tack welded the sender back together and it lasted for years. was still on the car when we sold it.
 
heres an update . Put oil pressure gauge on this morning and 0 on the gauge till it started to warm up , then gradually rose to 35 - 40 .. I think I was wrong on what oil I have in it , pretty sure its 10 -30 ( i found the latest jug) The other day I had it jacked up on its right side to do something and its after that I noticed the oil pressure problem , thought it was coincidence ,but possibly air lock . But if it was air lock it should have been fine after it picked oil up .. After checking this stuff this morning I tightened up the tube that goes into the oil pump but I guess I wont know if that helped till the next cold start ..even this morning , oil gauge reads at least 20 imediatley every time I start it. Do you think it could be the oil pump , I have a few leaks but dont think those should cause this Fred
 
I tightened up the tube that goes into the oil pump but I guess I wont know if that helped till the next cold start ..even this morning , oil gauge reads at least 20 imediatley every time I start it.
Click to expand...

Most likely just suction loss in the pickup tubing. Keep an eye on the pressure.
 

Attachments

  • Oil Pump - 1955- Gear Type w Hex Drive.jpg
    Oil Pump - 1955- Gear Type w Hex Drive.jpg
    43.6 KB · Views: 9
  • Oil Pump Assy - Rotor Type _2 - Threaded Pickup Tube.jpg
    Oil Pump Assy - Rotor Type _2 - Threaded Pickup Tube.jpg
    57.5 KB · Views: 9
Last edited:
Ordinarily oil pressure starts out pretty high when cold, higher than the spec, maybe 70 or 80 lbs and decreases as things warm up. That's one reason the spec is listed and checked when engine is "hot". What they mean by that is oil temperature, not coolant.

I'm not sure what specific oil pressure at the sender will cause the light to illuminate (or ... go out) but it isn't very much. Not trying to be a debbie downer but it's worth investigating. A defective oil filter can also cause some weird stuff, also oil pump bypass stuck open, air leaks at the gland nut etc.

The nice thing here about a Y-Block is it's easy to drop the oil pump without doing much of anything else (like having to drop the oil pan) as is necessary on most engines. If you want to do that we can walk you through it.
 
You must log in or register to reply here.
Back
Top