After fixing many different issues on my tbird, I wanted to address the low reading of the oil pressure. I did a search on the forum and found a gentlemen with similar issues. I replaced the sending unit and still have same readings. Others that replied to his post said to check battery voltage to be 14.5 volts, I will check that tomorrow, but it's a new battery and regulator.
All other gauges seem to operate properly. I noticed that the oil pressure at idle is near the left edge of the bracket on the low side, but once I put the car into drive the oil pressure drops to the lowest reading. I'm not sure if that is normal but it remains there even when I increase rpm.
It also has new oil filter and oil is fresh; i previously cleaned oil pan, oil pump, and screen. But this reading has always been low as long as I've had the car.
Thanks in advance for the advice!
low oil pressure
Moderator: redstangbob
low oil pressure
1955 Thunderbird
There are 2 different sending units. One is a flat unit that is intended for use with a light and one is cone shaped. The cone shaped unit is for use with a guage. This is true with a 64. Dont know for sure about a 65. Maybe someone else with a 65 could provide that answer.
'64 conv. black on black red interior
64 hardtop parts car
'94 lx 4.6
VTCI # 12001
64 hardtop parts car
'94 lx 4.6
VTCI # 12001
The ideal thing is to hook up a mechanical oil gauge and line to the fitting where the oil pressure sender is, and get readings with that at various rpm/temps. That is the best way to prove what the problem is.
If you can't do that, you could try a new CV to be sure the voltages are good to the gauges. There is a factory calibration screw (IIRC) on the oil gauge that you could adjust if you prove your pressure is really OK, but the readings are off due to drifting of the original factory set-up calibration of the oil pressure gauge. Maybe someone here can tell us typical oil pressures for the 390 at normal driving conditions. At full warm temp and running about 50mph on the highway, my oil gauge needle is about 2/3 scale to the right...at idle the needle falls to about roughly 1/3 scale to the right at full warm-up.
If you can't do that, you could try a new CV to be sure the voltages are good to the gauges. There is a factory calibration screw (IIRC) on the oil gauge that you could adjust if you prove your pressure is really OK, but the readings are off due to drifting of the original factory set-up calibration of the oil pressure gauge. Maybe someone here can tell us typical oil pressures for the 390 at normal driving conditions. At full warm temp and running about 50mph on the highway, my oil gauge needle is about 2/3 scale to the right...at idle the needle falls to about roughly 1/3 scale to the right at full warm-up.
Last edited by BrianC on Sun Jul 27, 2014 9:48 pm, edited 1 time in total.
'66 Ragtop, 77k miles. Antique bronze. Brought from original owner. Fully documented.
Hi Mick,
are you sure the 'real' oil pressure is correct? What I mean is, have you installed a mechanical oil pressure gauge in the sender location and made sure the pressure is within specification?
Yeah, stating the obvious but .... you did not say if that was done
Graeme
are you sure the 'real' oil pressure is correct? What I mean is, have you installed a mechanical oil pressure gauge in the sender location and made sure the pressure is within specification?
Yeah, stating the obvious but .... you did not say if that was done
Graeme
1962 Hardtop - in Melbourne, Australia
The CV is Constant Voltage regulator which supplies a floating 5.5 volt average to the oil gas and temperature gauges. If you other gauges are with in range it likely is not at fault. The regulator is very small and is located on the rear of your instrument panel not easy but can be replaced by going through the clock pod.
Take the wire off you oil sender unit then turn the key to run position and ground the wire to a good ground point, if the needle moves to the top your gauge and wiring are good next make sure that the sender unit is grounded through the mounting point if there has been lots of teflon tape used on it the ground may be poor causing a low reading.
If it still reads low get a mechanical gauge installed temporarily to check the reading on it.
Take the wire off you oil sender unit then turn the key to run position and ground the wire to a good ground point, if the needle moves to the top your gauge and wiring are good next make sure that the sender unit is grounded through the mounting point if there has been lots of teflon tape used on it the ground may be poor causing a low reading.
If it still reads low get a mechanical gauge installed temporarily to check the reading on it.
Jim Mills
VTCI # 8071
VTCI 1964-66 Technical Editor
2002 Thunderbird
1965 Convertible
1962 Convertible (in progress)
1959 Ford Retractable HT
Many parts cars
VTCI # 8071
VTCI 1964-66 Technical Editor
2002 Thunderbird
1965 Convertible
1962 Convertible (in progress)
1959 Ford Retractable HT
Many parts cars
Re: low oil pressure
How many miles on this engine? I've got a Y-block in my 62 truck with who knows how many miles on it. No smoke and doesn't use oil, but the oil pressure at the mechanical gauge is low like you describe (40 psi max, less when warm and at idle.) Since I know the gauge is accurate, the only thing left is worn bearings in the motor. You may have a similar situation.After fixing many different issues on my tbird, I wanted to address the low reading of the oil pressure.
~Steve
Quick note. This guy is talking about a 66 truck-built 390, but says his manual notes a normal pressure in the range of 35-55 @ 2000 rpm with the engine warm:
http://www.ford-trucks.com/forums/11987 ... ssure.html
~Steve
http://www.ford-trucks.com/forums/11987 ... ssure.html
~Steve
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Mich 66 Bird
- Posts: 61
- Joined: Sat Apr 30, 2011 7:35 pm
Ive been very dissatisfied with the Chinese replacement
for the Ford IVR...
Here are some suggestions for the IVR:
http://squarebirds.org/Electrical/CVR/S ... eRetrofit/
but, there was a company in Ohio selling "adjustable" regulators
that were made for models and robots. These were rated for
3 amps so much better than using a 7806 (good for 1 amp)
I can't put my finger on the link , but that is what I put in my '66 T Bird and
is working fine.
As for the oil pressure,
When the engine get hot, it is common in the FE for oil pressure to
drop when the oiling passages in the upper end of the engine are plugged.
I'd also inspect the oil pump after testing the pressure with a "wet" gage!
for the Ford IVR...
Here are some suggestions for the IVR:
http://squarebirds.org/Electrical/CVR/S ... eRetrofit/
but, there was a company in Ohio selling "adjustable" regulators
that were made for models and robots. These were rated for
3 amps so much better than using a 7806 (good for 1 amp)
I can't put my finger on the link , but that is what I put in my '66 T Bird and
is working fine.
As for the oil pressure,
When the engine get hot, it is common in the FE for oil pressure to
drop when the oiling passages in the upper end of the engine are plugged.
I'd also inspect the oil pump after testing the pressure with a "wet" gage!
66 T-Bird 428 4V Q-Code
So I tested the battery when car was running and I was receiving 14.59 volts, and we. I grounded the oil sender wore the needle on gauge went all the way past the high mark.
There are 77,778 miles on the engine and I believe this to be accurate based on condition of the original interior, etc.
I did inspect the oil pump when I replaced the oil pan gasket. I took the oil pump and screen off and cleaned them both. I used gas to clean them and I operated the oil pump in the gas to see that it was still functional. I looked into replacing the oil pump with a high volume pump sold from advance auto.
One thing I will mention is that when I replaced the oil pan gasket, the oil pan was dented from the bottom, so when I got the pan off I was able to use a r u be mallet to reform the pan. I assume that when the pan was initially dented the oil screen dome was dented upward as well. I also manage to bend the dome back flat without any damage to the tube. I once and again tested it in the gas and I didn't observe and leaks from the tube or dome from where it was bent. I wanted to replace the oil screen but couldn't find one, maybe one of the thunderbird parts books has one.
Since all else seems to work I guess that the bearings are worn, I wanted to wait a few years to rebuild the engine as I have never been able to drive the vehicle on the road besides around the neighborhood, and don't really have the funds to rebuild it at the moment.
As I have pretty much fixed and tuned everything thus far, I was in the midst of getting insurance so that I can finally try and take the car on the road. The low oil pressure is the last task for now, but I wanted to address the issue. Will I ruin the engine by running it periodically to car shows with this low oil pressure or should I install the high volume oil pump and see if pressure increases.
Oil pressure at idle in park
oil pressure in drive sitting still
There are 77,778 miles on the engine and I believe this to be accurate based on condition of the original interior, etc.
I did inspect the oil pump when I replaced the oil pan gasket. I took the oil pump and screen off and cleaned them both. I used gas to clean them and I operated the oil pump in the gas to see that it was still functional. I looked into replacing the oil pump with a high volume pump sold from advance auto.
One thing I will mention is that when I replaced the oil pan gasket, the oil pan was dented from the bottom, so when I got the pan off I was able to use a r u be mallet to reform the pan. I assume that when the pan was initially dented the oil screen dome was dented upward as well. I also manage to bend the dome back flat without any damage to the tube. I once and again tested it in the gas and I didn't observe and leaks from the tube or dome from where it was bent. I wanted to replace the oil screen but couldn't find one, maybe one of the thunderbird parts books has one.
Since all else seems to work I guess that the bearings are worn, I wanted to wait a few years to rebuild the engine as I have never been able to drive the vehicle on the road besides around the neighborhood, and don't really have the funds to rebuild it at the moment.
As I have pretty much fixed and tuned everything thus far, I was in the midst of getting insurance so that I can finally try and take the car on the road. The low oil pressure is the last task for now, but I wanted to address the issue. Will I ruin the engine by running it periodically to car shows with this low oil pressure or should I install the high volume oil pump and see if pressure increases.
Oil pressure at idle in park
oil pressure in drive sitting still
1955 Thunderbird
My sense is that if the engine needs a rebuild, you can hardly ruin it by driving it a little while longer in moderation.
My gauge rests between the O and I in park, just above the low mark in drive at idle. Best guess on my engine is about 35k since the last rebuild.
Don't know if it's possible to rebuild the bottom end with the motor in the car, but if rings and valves are good, it might be something to consider. Has anyone here ever attempted that?
~Steve
My gauge rests between the O and I in park, just above the low mark in drive at idle. Best guess on my engine is about 35k since the last rebuild.
Don't know if it's possible to rebuild the bottom end with the motor in the car, but if rings and valves are good, it might be something to consider. Has anyone here ever attempted that?
~Steve
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Joe Johnston
- Posts: 2638
- Joined: Tue Aug 19, 2008 3:34 pm
- Location: Sunny FLORIDA
I agree - I drove a Pontiac 350 for years as a go to worker that had 0 oil pressure at idle in drive (verified by different mechanical gauges). At just a few rpm more in Neutral I did have a couple of pounds pressure. In my normal work commute I could usually pace myself through the stoplights, but shifted into N if I had to stop for very long. Didn't hurt a thing for about 2 years of daily driving. I would drive the car in moderation being fully aware a rebuild is in the near future, but enjoy it a while as it is while saving up for a full rebuild.My sense is that if the engine needs a rebuild, you can hardly ruin it by driving it a little while longer in moderation.
PLEASE invest a few bucks and buy all the shop manuals for your car. Definitely will save you much time and be an education.
55-57 VTCI Forum Moderator
57 Inca Gold-Colonial White
63SR Silver Mink
55-57 VTCI Forum Moderator
57 Inca Gold-Colonial White
63SR Silver Mink
MickMan
Your test grounding the oil pressure wiring has proved that there is nothing wrong with your gauge or wiring I would now check the body of the oil sender unit to ground with a V.O.M. to make sure the ground is good.
Your test grounding the oil pressure wiring has proved that there is nothing wrong with your gauge or wiring I would now check the body of the oil sender unit to ground with a V.O.M. to make sure the ground is good.
Jim Mills
VTCI # 8071
VTCI 1964-66 Technical Editor
2002 Thunderbird
1965 Convertible
1962 Convertible (in progress)
1959 Ford Retractable HT
Many parts cars
VTCI # 8071
VTCI 1964-66 Technical Editor
2002 Thunderbird
1965 Convertible
1962 Convertible (in progress)
1959 Ford Retractable HT
Many parts cars
Re: low oil pressure
Found this thread, this is exactly my issue as well.
1966 Town Landau with 390.
- checked gauge, getting power.
- new oil sender.
- new oil and filter
- new oil pump
- new battery and new alternator (1 wire)
- other gauges work fine (except fuel, but thats another issue)
I have a bought a compression gauge, going to try and remove steering pump to get access and screw it in and see what she reads. Did anyone figure out what the reading should be? Im assuming i do that while parked? try it in neutral and then in gear?
1966 Town Landau with 390.
- checked gauge, getting power.
- new oil sender.
- new oil and filter
- new oil pump
- new battery and new alternator (1 wire)
- other gauges work fine (except fuel, but thats another issue)
I have a bought a compression gauge, going to try and remove steering pump to get access and screw it in and see what she reads. Did anyone figure out what the reading should be? Im assuming i do that while parked? try it in neutral and then in gear?
Re: low oil pressure
Well, the "general rule of thumb" for a vintage V8 is 10 lbs of pressure for every 1000 rpm. If you're in that range, you should be fine (as long as you keep the car off the oval track).
I would definitely not test the pressure (or anything else, really) with the car in gear.
~Steve