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By 62bigwindow - 6 Years Ago
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What would be the cause for low oil pressure at idle. Its went from 20lbs to 7-10lbs gradually over the course of a few weeks. I still have good pressure(40 lbs) at cruise and around town. The engine only has about 3000 miles on it so I dont think it's a wear issue. I will ad that when cold it has 20+ idling.
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By charliemccraney - 6 Years Ago
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Low oil level, loose inlet tube nut.
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By 62bigwindow - 6 Years Ago
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Oil levels good. Just did an oil change. I'll check the tube tonight. Thanks Charlie.
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By 62bigwindow - 6 Years Ago
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Nut was loose but didn't do much to improve it. I'm getting 10 psi at idle and 45 psi anything above idle speed which is 700 rpm.
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By MoonShadow - 6 Years Ago
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You can increase it by removing the nut on the oil pump, where the spring is, and adding washers to tighten up the relief valve. But only if you don't have another problem causing the drop. Is that idle in gear or neutral?
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By oldcarmark - 6 Years Ago
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62bigwindow (9/23/2018)
What would be the cause for low oil pressure at idle. Its went from 20lbs to 7-10lbs gradually over the course of a few weeks. I still have good pressure(40 lbs) at cruise and around town. The engine only has about 3000 miles on it so I dont think it's a wear issue. I will ad that when cold it has 20+ idling.
Have You verified that the Gauge is in fact Accurate?
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By 62bigwindow - 6 Years Ago
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Car is a 3 speed manual so idle is in neutral. I plan on trying another gauge but I wasnt sure that was the problem because of the gradual change. But with the poor quality of aftermarket parts lately its definitely a possibility.
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By MoonShadow - 6 Years Ago
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Any change in oil brand or viscosity?
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By dbird - 6 Years Ago
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I'll be looking forward to seeing if you find a solution to this. I've been having the same problem on my 55 'Bird for years. The first time I noticed it, we had just traveled about 100 miles in hot weather and the idiot light came on at the first stoplight after I pulled off the freeway. Putting my automatic in neutral was enough to turn off the light. Since then, reinstalled the cheap under-dash gauges, which showed it wasn't the sender. Replaced the oil pump, changed out the semi-worn main bearings, tried different seals on the pick-up tube, installed a higher quality oil pressure gauge, finally resorting to 20-50 wt oil which helped, but not enough.
Charlie mentioned a loose pick-up tube nut, I thought I read that it's possible to over tighten the nut and collapse the tube. is there a guideline for how tight to go?
We're off for about a 250-300 mile run this weekend and I sure would be nice if I didn't have the problem
Don
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By 62bigwindow - 6 Years Ago
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I did change oil viscosity. I was using Penn 20W50 and am now using Penn 10W40. But it was the same with both grades.
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By 62bigwindow - 6 Years Ago
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Overtightenin the tube is a interesting thought. If that is true then that may be a problem. Is it possible for the pressure relief in the pump to be faulty? If it was stuck partly open could that produce the low pressure?
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By charliemccraney - 6 Years Ago
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The relief valve can be faulty but it seems like it would be low pressure at all RPM, not just idle and immediately jumping to 45psi off idle.
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By KULTULZ - 6 Years Ago
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"What would be the cause for low oil pressure at idle. Its went from 20lbs to 7-10lbs gradually over the course of a few weeks. I still have good pressure(40 lbs) at cruise and around town. The engine only has about 3000 miles on it so I dont think it's a wear issue. I will ad that when cold it has 20+ idling."
What was the reading(a) at break-in?
Interesting Read - http://www.eatonbalancing.com/2014/09/19/hi-volume-oil-pump-for-the-y/
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By MoonShadow - 6 Years Ago
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Just a thought but could the end of summer and onset of cooler weather be a factor? Would multi viscosity oil show a difference at idle in colder weather?
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By Dave C - 6 Years Ago
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Years ago when I wrenched for a living, Pontiac's were semi notorious for the relief valve sticking in the open position. Idle pressure went to zero but cruise pressure was normal.
Dave
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By 62bigwindow - 6 Years Ago
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Right now I'm leaning toward putting a new pump on it if the gauge checks out. Hopefully that cures it and I can get back to driving it. It seems like every year something comes up and I have to park it early for winter.
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By Lou - 6 Years Ago
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Every y-block I've owned (20) had low oil pressure at idle, as long as there is some pressure at idle there usually is no problem.
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By 62bigwindow - 6 Years Ago
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Maybe I'm worried about nothing. It was just a little concerning since it started out around 20 at idle and now its 10. I know 10 psi is sufficient at 700 rpm. I'd just like to get it back to where it was for peace of mind.
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By charliemccraney - 6 Years Ago
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A sudden drop like that is something to worry about.
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By 62bigwindow - 6 Years Ago
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What brand of oil pump would be reccomend? I'm thinking of getting a Melling.
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By Talkwrench - 6 Years Ago
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Im thinking that its wearing in, and unless you did the engine yourself and are exactly sure of bearing clearances, maybe a little too much. I know with my Flathead Ive just rebuilt when I started hot idle was a good 30+ now after a few hundred miles its down and settled at 20.
keep an eye on it .
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By PF Arcand - 6 Years Ago
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D Bird: In your case, if your light is coming on at hot idle, your pressure is at 5 lb or less! There's something seriously wrong there. I wouldn't be driving long distances in Hot weather like that..
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By dbird - 6 Years Ago
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Paul, thanks for your concern, which i share. After going to a heavier weight oil, I haven't had an issue with the light, though the gauge barely reads 10 at a hot idle in drive, so if it's going to idle any length of time, even a red light, it's in neutral. I will note that the first time for the light was over six years ago and the engine's still going strong. Of less importance, it's not the original engine so it's not like I might be ruining the originality of the car.
Don
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By 62bigwindow - 6 Years Ago
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I'm going to change out the oil pump in hopes that that fixes the problem. How tight does the tube nut have to be?
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By Gene Purser - 6 Years Ago
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I'm no authority on this and have no specs, but I just replaced the pump drive rod in mine. I put the rubber sleeve on the pick up tube for the install. I could feel the resistance of the rubber as I tightened the nut. Finally, it felt like the nut ran out of threads and I didn't push it any more. I know the nut wasn't very tight when i removed it. It just takes enough to push against the pump body and squeeze the rubber around the tube.
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By 2721955meteor - 6 Years Ago
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my 292 has a few miles hot idea is15psi at 650 hot. i would look at oil to rockers if you have groved cam and cam bearing the rockers will bleed of oil pressure ,especially with return tubes. in my case i block the tubes off completely. with the cam that has holes the oil is metered,i would still block off the drain tubes. if rockers and shafts are good you will find better oil pressure at idel. if engine is fresh like previous poster noted check the relief have, possible debree holding valve of seat, or sticky valve due to debree.
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By charliemccraney - 6 Years Ago
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From the Torque limits section of my trucks shop manual, 10-12 ftlbs, real easy to overdo.
Invest in a shop manual.
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By Gene Purser - 6 Years Ago
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Hard to put a torque wrench on that nut, but from my feel you would have to bottom out the nut to get that much.
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By charliemccraney - 6 Years Ago
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If you bottomed out that nut, then you have overtightened it. There are torque adapters and crows foot wrenches if you want to get a wrench on it.
I just snug it, start the engine to make sure there are no anomalies. If pressure is good, I make sure oil doesn't drip out of that nut after being shutdown a while. If it does, I tighten it a little more.
If pressure drops, then the nut is possibly too loose and air is being pulled in. Tighten until pressure is normal or it seems to be getting tighter than should be required without fixing the problem.
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By KULTULZ - 6 Years Ago
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Just a thought here-
If this discussion is BIRD, then maybe the pressure is dropping because of engine heat (small engine compartment - overheat due to BIRD WP positioning).
If you do decide to replace the pump, consider a MELLINGS HV with an ARP shaft.
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By KULTULZ - 6 Years Ago
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- INVALUABLE TECH ARTICLE -
http://www.eatonbalancing.com/2014/09/19/hi-volume-oil-pump-for-the-y/
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By 62bigwindow - 6 Years Ago
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I've read that article. The engine is in my '56 wagon.I highly doubt its anything internal. Tim Mcmaster built the engine so I'm confident all is good with the clearances.I'm thinking its something in the pump itself. As far as the Melling HV pump where do you get them? From what I've read here they are not available anymore.
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By KULTULZ - 6 Years Ago
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"As far as the Melling HV pump where do you get them? From what I've read here they are not available anymore."
You're correct. I did not know that and is why I posted the EATON article on a fabricated pump.
If Tim McMasters built the engine, he should be your first inquiry.
Please get back with what you find.
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By 2721955meteor - 6 Years Ago
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the good thing with the Yblock is the oil pump can be removed in 10 min. open it up check the relief valve piston as well the condition of the pump. even if it is new new means nothing especially if it comes from abroad .any engine that is rebuilt ,or new is never completely clean,first place for tiny debree is the oil pump,then the filter.
so those who are hobey mechanics, first find a tradesman discus issue and then search a site for further advice,sharing the trdesmans vew.
just my slant re endless posts over a problem with no feed back re solutions work
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By 62bigwindow - 6 Years Ago
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I'll definitely post what I find. For insurance I ordered a new pump. After the swap I'll open the other one up to see what is going on.
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By 62bigwindow - 6 Years Ago
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I got the old pump off today and it looks good inside. I'm confident it was the seal on the pickup tube. It was the style that has a metal ring around the rubber seal. I dont think it was able to completely compress and allow a good air tight seal. I'm going to put the new pump on any just to be safe. Are there any tricks to getting the oil pump drive shaft to stay in?
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By 2721955meteor - 6 Years Ago
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62bigwindow (11/12/2018)
I got the old pump off today and it looks good inside. I'm confident it was the seal on the pickup tube. It was the style that has a metal ring around the rubber seal. I dont think it was able to completely compress and allow a good air tight seal. I'm going to put the new pump on any just to be safe. Are there any tricks to getting the oil pump drive shaft to stay in?
did you remove THE RELEAF VALVE IF SO ANY MARKS OR BERS ON THE VALVE INDICATING STICKING.
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By 62bigwindow - 6 Years Ago
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Yes. I didn't see anything but there was a slight rough spot. It didn't seem to bad though. Does anyone have a trick when putting it back together to hold the pump drive shaft in place?
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By charliemccraney - 6 Years Ago
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I just put the shaft into the pump gear or rotor and work it into place. Pointy end up and the retaining washer goes on the oil pump end.
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By PF Arcand - 6 Years Ago
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Re low oil psi at idle; Often this has to do with improper seating of the grommet according to a Tag I have here from a pump. The instructions are to install the pipe, jam nut & grommet as a unit into the pump . Forcing the pipe into the grommet when already in the pump, is not recommended. Ensure you do not cause rubber to be peeled off the grommet. It will cause an air leak or worse jamb the pump rotor causing a driveshaft failure. Also, one of the pump
mounting bolts must not exceed 1-1/4" in length or it will damage the pump housing which may also cause a drive failure...
N.B- Often when oil psi problems come up here, it leads to enquiries about Hi Performance pumps.. That' s not going to solve the problem & is just a waste of time & money.. All things in the engine being otherewise correct, Y-Block pumps are more than adequate for virtually any application..
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By 62bigwindow - 6 Years Ago
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I finally got the time to swap out the pump. Now I'm getting 15 lbs at idle and 60 lbs at cruising speed. I'm pretty sure the problem was a bad tube nut seal. One thing I did find out was when,putting in a pump in a 56 passenger car,the oil pump drive shaft has to be installed in the distributor first. I got it to stay in the the dizzy by putting wheel bearing grease on the shaft.
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