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BJ7 Oil Pump
- Thread starter Mac
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<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by stever:
What oil pressure should be maintained in a sound engine by the pump? Thanks!<hr></blockquote>
Steve--
Bruce Phillips at Healey Surgeons always likes to say that it should be a minimum of 10 psi per 1000 rpm's. Personally I would find that to be scarily low and I have 40 to 50 psi at cruising speeds, though I have heard folks say that Healeys don't need oil pressure over 20 psi ("Weeee don't neeeed no steeeeking oil pressure!!)
What oil pressure should be maintained in a sound engine by the pump? Thanks!<hr></blockquote>
Steve--
Bruce Phillips at Healey Surgeons always likes to say that it should be a minimum of 10 psi per 1000 rpm's. Personally I would find that to be scarily low and I have 40 to 50 psi at cruising speeds, though I have heard folks say that Healeys don't need oil pressure over 20 psi ("Weeee don't neeeed no steeeeking oil pressure!!)
Hello Mac,
Yes they can be rebuilt but whether that is worthwhile is down to the replacement costs. In the UK, oil pumps are relatively cheap.
Refer to the workshop manual which gives the clearances, and if your pump exceeds those or there is obvious signs of wear or scoring then it is up to the relative costs as to what action you take.
I would not judge the state of oil pump wear on oil pressure. Check all clearances, (even on a new pump) and go from there. Nothing worse than sticking an unchecked pump in and running the car to find poor oil pressure.
Alec
Yes they can be rebuilt but whether that is worthwhile is down to the replacement costs. In the UK, oil pumps are relatively cheap.
Refer to the workshop manual which gives the clearances, and if your pump exceeds those or there is obvious signs of wear or scoring then it is up to the relative costs as to what action you take.
I would not judge the state of oil pump wear on oil pressure. Check all clearances, (even on a new pump) and go from there. Nothing worse than sticking an unchecked pump in and running the car to find poor oil pressure.
Alec
John Loftus
Darth Vader
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I have heard that 15 lbs of pressure @ idle is low .. time for a rebuild and 20 lbs @ idle is the minimum with 60 lbs @ 3000 rpm with 20-50 wt oil and completely warmed up motor.
First you need to make sure your oil pressure gauge is accurate .. best to use a test gauge. There is a procedure to test just the oil pump with a test rig .. I think I heard about this from the Nocks at British Car Specialists... does anyone else know how to do this?
The oil pump may be working fine but it is the wear of the engine bearing surfaces that causes the pressure to drop. When the bearings are tight the pressure is high as the oil is forced through the small openings (like holding your thumb over the end of a water hose).
There is a procedure for checking the oil pump clearances for both oil pump types in the workshop manuals. There is also a high volume pump avail. (eccentric rotor type) which is good for everything but racing (I'm told). Although you can rebuilt or adjust the pump it is good insurance to replace it when you do an engine rebuild.
Cheers, John
First you need to make sure your oil pressure gauge is accurate .. best to use a test gauge. There is a procedure to test just the oil pump with a test rig .. I think I heard about this from the Nocks at British Car Specialists... does anyone else know how to do this?
The oil pump may be working fine but it is the wear of the engine bearing surfaces that causes the pressure to drop. When the bearings are tight the pressure is high as the oil is forced through the small openings (like holding your thumb over the end of a water hose).
There is a procedure for checking the oil pump clearances for both oil pump types in the workshop manuals. There is also a high volume pump avail. (eccentric rotor type) which is good for everything but racing (I'm told). Although you can rebuilt or adjust the pump it is good insurance to replace it when you do an engine rebuild.
Cheers, John
Thanks to all who replied. The reason I brought the subject up was that my BJ7 runs at about 10 pounds when at idle and warmed up and maybe about 20 at cruising speed (double nickel). The person I bought the car from said he had rebuilt the engine with new bearings, etc., (not that I took it apart to check) but since the car has a kazillion miles on it, I'm guessing, and doesn't burn oil and runs strong, I suspect it has been rebuilt. So I'm thinking the oil pump may need an upgrade. Mac
tahoe healey
Yoda
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Before you go to any expense, loosen the nut behind the pressure gauge and bleed some oil out to be sure there is no air bubble in the line. A small amount of air would give a lower reading. A big one like I had gave no oil pressure reading and I thought the gauge needed replacing. You may be compressing air instead of oil. It's like bleeding brake lines.
Rich
Rich
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Someone previously referred to Bruce Phillip's comment that 10psi at idle was ok. From talking with other experts that's very close to right. But 20psi at crusing speed is not real good. My BJ7 carries about 45 to 50psi at 55mph. Using straight 30wt. Smoky Unick who built american race engines back in the '60's always said that you only wanted 10psi per 1000 rpms at the rockers. I've always wondered why British engines seemed to want so much more oil pressure than American engines. Most American V8's only run about 30 to 35lbs at speed. My 350cu in Vette only runs 35lbs at crusing speed. And idles at about 20. I would suggest that if your engine seems stronge, doesn't have piston slap or a knock and your gauge is showing 20psi at speed then I believe your guage is faulty or has a restriction in the line/gauge. If you've got 10 at idle you should gain at least 20 more when you wind it up.
Also you can check your rocker arm play like Norm Nock (of British Car Specialist) says. You do lose a certain amount of pressure there and It is an easy fix. I had an MGA awhile back that had a pretty poor engine with piston slap and knock when cold. It maintained about 10 to 15 psi at idle and about 25 at speed when hot. It ran for many years that way. Took it on many day junts but honestly would not have driven it across country.
Ways to check an oil pump, as has been said there is the technical way which you will find in most any shop book where-by you get the spec and use a feeler gauge etc. But apon inspecting the pump look for any ware pattern on the inside surfaces and any deformity in the impellers. Any scuff marks or scratches or gouges. If any of that stuff is present it must be corrected. A new pump is the easiest. On a high mileage pump just chuck it. If it's low mileage and shows no marks, run it.
Good Motoring,
Dave.
Also you can check your rocker arm play like Norm Nock (of British Car Specialist) says. You do lose a certain amount of pressure there and It is an easy fix. I had an MGA awhile back that had a pretty poor engine with piston slap and knock when cold. It maintained about 10 to 15 psi at idle and about 25 at speed when hot. It ran for many years that way. Took it on many day junts but honestly would not have driven it across country.
Ways to check an oil pump, as has been said there is the technical way which you will find in most any shop book where-by you get the spec and use a feeler gauge etc. But apon inspecting the pump look for any ware pattern on the inside surfaces and any deformity in the impellers. Any scuff marks or scratches or gouges. If any of that stuff is present it must be corrected. A new pump is the easiest. On a high mileage pump just chuck it. If it's low mileage and shows no marks, run it.
Good Motoring,
Dave.
bighly
Jedi Knight
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Just a quick note on low oil pressure. I experienced great pressure until warm-up then about a 15-20 PSI drop. This was caused by worn a rocker assembly. It was corrected by having the rocker assembly rebuilt. I personally get thrown off by symptoms and sometimes end up replacing and rebuilding things to find it was not the end cause.