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Oil Pressure Gauge

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healeygal

Jedi Warrior
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Help! We've got a '64 MGB that's acting like my Healey, and giving a hard time! Switched over to the screw-in type oil filter head, changed the oil, and then when you start the engine, it idles at 20, but once you hit the gas pedal, it goes up to 40 and stays there until you shut the engine off.

(The low oil pressure is a whole other issue - this is the car that had been sitting for 18 years until re-awakened last year.)

Sharon
'64 MBG
 
You have installed a spin-on adapter? Are you certain the proper filter is now attached? Avoid Fram like the plague. Use either K&N or Napa Gold.
 
Could be it is just a fluke with the gauge or the line leading up to it. I had some trash clog up my flexible line going up to the gauge once. I got kind of freaked out since my gauge nosedived to 0 while cruising down the road. Once I got her home, I detached the line from the gauge, started the engine up ( you would be surprised how much oil comes out really fast). It took a few minutes to move the junk out, but after that I had no problems at all.

I have never heard of others having this problem, so it may be one of those things that never happens, but might be worth looking into.
 
Good point. It's always reasonable to suspect the gauge first. Double check the readings with a hand-held pressure gauge if possible.
 
Thanks for the quick response!

Steve - yes, the filter is a Napa Gold.

Ron - thanks for the suggestion. A friend thought it might be a clogged line also - won't be able to check it 'til Tuesday, will report back.

In the meantime, a few questions, as this car is new to me. My sister is driving it, but being less of a "car guy" than me, I get to ask the questions. The car is back on the road after sitting for 18 years, as compared to the Healey, which I've had for 30 years. So here goes - what plugs are best to use? It's got Champion RN9YC gapped at .025 right now. What about the oil - Castrol 20-50?

I think maybe second gear is wearing out - sometimes it engages just fine, and sometimes there is a slight "crunch" when engaging. Then other times no noise, but it doesn't engage smoothly. It's more like a two-parter - it goes into gear, then have to pull a little more, otherwise seems like it might grind, but don't want to let out the clutch to test it! Checked the transmission oil level, and it's OK. Would Redline MT 90 help? (I've heard lots of Healey folks say it makes shifting smoother).

Is taking off from second gear a no-no? (I'm used to doing it in my Healey because of the low first gear.)

The turn signal doesn't self cancel, handbook says it should. Is it an easy fix?

Did the '64 come with windshield washers? I don't see them mentioned in the handbook, but the car has them.

Oil pressure (when the gauge was working) read 40 when running, 20 at idle, down to as low as 10 at idle when warmed up and running for an hour - should I be worried? Is there a pressure relief valve spring that can be replaced, as on the Healey, to bring up the pressure?

Sharon
 
The plugs and gap are correct, assuming all is stock.

You may have a weak second gear syncro. I would drain the oil and check for metallic deposits. A little is ok but if there is a lot, you may have more serious issues. Early gearboxes are cheap and easy to find used but you have to remove the engine to change it out. The best oil is either 20W-50 or straight 30-weight. If this is an overdrive model, try 30-weight non-detergent. Be sure to clean the overdrive filter. Depending on the type of overdrive, you may have to drain and fill the main gearbox and the overdrive module separately.

Starting in second is fine. It's a low gear and the engine is all torque.

The turn signal is canceled by a small nub on the steering column. It comes around and bumps the stalk of the switch, knocking it back to center. If you remove the plastic cowl behind the steering wheel, you will see the nub. It should be obvious what the problem is. Either it isn't aligned with the switch or it's missing. Move the switch until it lines up and works properly. It's also possible the switch is broken or worn out where it's supposed to catch the nub. In this case replace the switch assembly. If yours is a factory original, it is worth attempting a repair. Current reproductions are of very poor quality and don't last that long.

Windscreen washers are standard for all MGB. There should be two individual jets.

Oil pressure sounds low, but not terminal. A new engine will show roughly 25 idle, 70 at speed. Some people shim or uprate the pressure relief valve, but this isn't really the proper fix. So long as you're getting 40 or higher at speed I wouldn't worry too much about it. Be sure to run 20W-50, especially in the Summer.

If you're up in my area, feel free to swing by to test the pressure gauge.
 
Steve,

Wow, thanks for all the answers to the questions that have been popping up as we tinker with the car! Yes, it's stock, and a non-overdrive car, but sure wish it had it! Will add checking transmission and fiddling with turn signal assembly to the list of things to do on Tuesday. Sticking kind of close to home with the car for now, but thanks for the offer to check the gauge!

Sharon
 
On my 65, 1st gear was shot (my fault), and I used 2nd gear to start off for years until the car would not go in reverse. I then got another box, but force of habit kept me starting out in 2nd gear. I have not seen any ill effects from this, at least for the short time I was driving on the new box before I put the car up on jack stands.

As for the canceling turn signals, Moss has the parts to repair the problem. On mine, the spring that cancels the signal had fallen out somewhere, and the plastic cam broke. I was able to pick up a new unit on ebay for fairly cheap.
 
Progress report - Disconnected the oil line, and oil came out in a steady stream with no gunk. Wanted to clear out the small line between the gauge and the flex line. Couldn't get the oil pressure gauge out of the dashboard to undo the line even though we loosened the two nuts and pulled the bracket backwards. Gauge wouldn't loosen up and come out - it is firmly in place! Put everything back together. As before, gauge responds OK at idle and up to 40 pounds pressure, but then gets stuck at 40 lbs. Tap on the glass, but it stays there. Even if increase the rpm's, stays at 40. Shut off engine, goes to 0.

Turn signal - a small spring and another little metal piece were lying in the bottom black plastic casing around the turn signal mechanism. Also a 1" piece of the white plastic casing holding the turn signal lever, etc. broke off and was in there too. Looks like we're going to need the whole assembly.

Didn't get to the transmission oil.

Sharon
 
Sounds like a bad gauge. It should come out of the dash easily, but if there is an old o-ring between the gauge and the dash, the rubber could be hard and stuck like glue. Rock the gauge back and forth from behind and it will likely break free of the rubber. The dash and gauge are both metal so there is little chance of damaging anything by applying some force. Just be careful with the chrome trim ring.
 
Steve_S said:
Just be careful with the chrome trim ring.
Click to expand...

Key words there! I was beginning to get a little bit concerned, so we quit! Will give it another go in a couple of days, along with the transmission oil.
 
Still haven't gotten around to pulling the oil pressure gauge - been dealing with Healey issues. In the meantime, started the MG up one day, let it run a bit, then shut it off. A few minutes later, there was a large puddle of oil under the car. Turns out the oil flex line from the block to the oil gauge pipe is cracked and leaking. Fiddling with it the other day probably caused the problem - the car had been sitting for 18 years. Anyway, would this item be available at NAPA, or does it have to be ordered from one of the LBC suppliers?

Also, still haven't gotten to the transmission oil change. It's a non-overdrive car, so 20-50 detergent oil is OK? How many quarts? And where does it go in - thru the dipstick opening??

Sharon
'64 MGB
 
Hello Steve,

your figure of 70 psi oil pressure at speed sounds too high.
My memory tells me 45 to 50 psi for A and B series BMC engines?
I have only known one car which ran such oil pressures which was the Tadek Marek six cylinder Aston Martin, which had rather critical crankshaft bearings.

Shimming the pressure relief valve to up the oil pressure is usually just a waste of power and can increase oil leaks. (And of course does nothing on a worn engine as there is too much clearance in the bearings for the oil pump to get to regulation pressure)

Alec
 
70 PSI at speed is where all my MGBs have always run. This is using 20W-50 Castrol GTX motor oil. On a hot day the pressure may drop to 55-60 due to thinner oil. On a cold morning I have seen it as high as 80. 65-70 seems to be the normal reading.
 
Yup. /bcforum/images/%%GRAEMLIN_URL%%/iagree.gif Always been at the same readings here with MGB engines.
 
I currently run the same readings (same as what Steve indicated) in my '76 B. Though, on hot days after the car has thoroughly warmed up the idle pressure tends to be around 50psi.
 
Hello Steve,

I still feel that is higher than the original specification at normal operating temperatures, unless American versions were set a bit higher to compensate for higher ambient temperatures?

Alec
 
Pro'lly more to do with the designation of oil 'weights' than anything. "Back-in-the-day" when I ran straight 30W non-detergent (!) oils in MGB's, the pressures were the same. After a fully run-in engine was run hard the pressure would drop, but only everso slightly. Idle would be 40-ish, high in the range of 55~60.

Sharon said:
Also, still haven't gotten to the transmission oil change. It's a non-overdrive car, so 20-50 detergent oil is OK? How many quarts? And where does it go in - thru the dipstick opening??
Click to expand...

5.6 PINTS total, 20~50W Castrol will be fine, Sharon. And thru the dipstick hole, yup... it has marks on it for level check, too. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

A piece of 1/2" ID fuel line tubing and a funnel are helpful for this job.
 
DrEntropy said:
5.6 PINTS total, 20~50W Castrol will be fine, Sharon. And thru the dipstick hole, yup... it has marks on it for level check, too. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

A piece of 1/2" ID fuel line tubing and a funnel are helpful for this job.
Click to expand...

Thanks for the reply! Was a little worried there, as the responses got a little side tracked from the question!

Sharon
 
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