A65 Oil Pressure Help

Mar 8, 2015
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Need some help after I have now ruined a fresh rebuild on a 68 Lightning. Bought as a basket case and no history on the motor.

I rebuilt the motor- new standard bearings, 20 over pistons etc. Timing side bushing looks good and measures right at the max tolerance. It did not have much play with the crank installed, so decided to run with it for now.

Got the engine running great and put about 20-30 miles on it and noticed a knocking. Decided to tear it down and both connecting rod bearings are now ruined along with scoring on the crank. Seems like low oil pressure but can't find a reason why. I had oil returning to the oil tank. The OPRV is the piston style that has the external pin that moves showing pressure. While cold the pin was out like expected and went in almost all the way when warmed.

Sludge trap was cleaned during the rebuild. I can blow air through the crank from the bushing side through to the journals. No restrictions. I used the original oil pump that I fed with oil while spinning to test. It spins and gurgles and seems fine. I took apart the OPRV and it seems fine. Spring has lots of resistance and the piston moves freely in the bore.

With the oil pump off, I blew air through each of the holes to confirm the passages were clear.

I'm totally lost as to why this happened. Without having a cause, I'm thinking about buying a new oil pump and OPRV and hoping this does not happen again. Any other ideas that I'm not thinking of?
Is there anywhere you can put a pressure gauge , so you can see some pressure ? , instead of return oil .
Well , This is Your Lucky day ! :rolleyes:

A65 Oil Pressure Help
A65 Oil Pressure Help

ASIDE FROM THAT . Checking the pump - flooded - a finger blocking the outlet - one assumes - would be dispaced whilst turning the pump over .

OIL PUMP & IGNITION are prime A1 1000 % Tip top Ship shape requirements on old pommy rubbish .

END FEED ( Thru crank end ) is sorta not to bad a set up , for a A 65 . The other stuffs dressing / Hi Po .

Aluminum Bronze bush wasnt a bad idea . ANY deterioration in the surface of a old grey iron bush is detrimental .

The Oil Pump - Pressureised - sort of a Leak down - test might tell you something .

a NEW Hi Capacity PUMP would be a start . The British were never renowened for their oiling ( other than externally )
or there cooling , out here in the colonies . The avro Lanchesters death knell . Tho Land Rovers enjoyed tortures and horrors .

A65 Oil Pressure Help
A65 Oil Pressure Help

Tyres were another thing .

A65 Oil Pressure Help
Standards are slipping .
A65 Oil Pressure Help
A65 Oil Pressure Help

Er B.S.A. Right . . .

Any Oil Seals need to be PRE LUBED copiously . As in you drench them , so the seal area is fully coated entirely - and the shaft . A drip will not do .

AND ANOTHER THING : https://www.classicbritishspares.com/blogs/news/the-bsa-a65-oil-pump-journal-1962-1972

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As your bike is a '68 it I think it has a 1/8" NPT port for an oil pressure switch. If it has you can connect an oil pressure guage. Also, you say that the OPRV has a tell tale. This sounds more like a Triumph type & is not the correct part. Are you sure that it has the same dimensions as the BSA item, as it could be showing pressure but dumping most of the oil to the return side. Just a thought. The only other thing I can think of, apart from a defective pump, is the main bush has moved partially blocking the oil way. Even if the rod big ends were out of round, which is very common on all ally rods, it wouldn't grind to a halt this soon.

Thanks guys. It does not have the port for an oil pressure switch unfortunately. I just checked the dimensions on the OPRV vs the case and everything looked like it should work. I will probably order a new one for peace of mind. I triple checked the main bush dimension vs the crank journal and the clearance is .0017" which seems good to me.

I have another oil pump that I will use just to eliminate a variable. I did re-use the aluminum rods during the rebuild. They seem very good and I can still see the machine marks on the big ends so they are not beat up. I cant confirm they are perfectly round but they must be close. Maybe worth taking to a machine shop to size them again?

The crank is at the machine shop now getting sized for 10 under bearings. I will take apart the sludge trap again when I get it back. With the tube bolted into the crank, I can't imagine a way that the tube could block the journals but I'll double check.
Hi , a better way is to get your big end tunnels measured up , if they are all ok to spec fit the bearings to the rods and grind the crank to suit , i:e .0015" etc .
Bush Mechanics trick is cut a steel dowel , slight radius ends . trim till a light push fit , & rotate . OBVIOUSLY if its the same all round its the same all round . Within Reason .
Why ,
ALUMINUM Oil Pumps WEAR . Olde 4.1 L Falcons , low oil pressure - The Iron Body Mellings pump -> 250.000 miles and still NEW pressure .
Original Alumn. might be fitted to get people to buy new cars as the oil pressure goes low at 100.000 . When theres still NO WEAR anywhere else .
( With regular oil & filter changes ) Theres also the differential expansion trip - when stinking hot .

A65 Oil Pressure Help

LARGER than LIFE . 2 inch diameter . 52 m.m. ! actual .

theres These , Oil Pres. & water ( OIL ) temp. 2 inch. Guages .
Capillary lines .
Gave one to a A 65 owners , but he never fitted it .

No doubt a Elec. Wired'd fit less fumblingly - But these are ' period '
Mk 1 Cortina , Lotus , and other contraptions .

( Throw the Temp. Bulb in the Oil tank & a ' T ' at the oil switch .
Itll fit up tween the dials - no worries . And look sophisticated . ;)

( to look REALLY sophisticated , you might ' black ' over the ' water ' script . )

A65 Oil Pressure Help