Oil pressure on BN6

[bighealeysource]

Hey all,
Once my BN6 warms up and I'm cruising at 55 to 60, my oil
pressure runs at 50 psi which is about right. However,
after running at that speed for about 25 minutes, I stopped
for about 15 minutes and on the trip back, oil pressure would
not go over 40 psi at same speed. I am working on minor
over heating issues - installing a Texas cooler this weekend-
so it seems that when things are nice and warmed up to 190
running temp, maybe up to 200 if I get caught in some traffic
or at a light, the oil pressure just won't go over the 40 psi.
I have read everything I can about oil pressure and used
Norman Nock's tech bits book ( he is missed already ) and
with a newly rebuilt engine, I'm a little concerned. I am
not sure what oil was put in and getting ready to change
it out as got about 500 miles on rebuild now. I could have
10w30 in there but don't know so should I put in 30 wt. Shop rebuilt it about 2 years ago and it was run in on a test stand but then sat until I bought it as a roller to finish. Cold is not a factor down here in South Carolina, heat is, so
maybe the high operating temp is thinning it down too much ?
Should I check the oil pressure relief valve?
Thanks,
Mike

 

[TimK]

Engine temperature (ie. oil temperature) definitely affects oil pressure. I use 20w50 oil and have a well worn engine and get 40 lbs. after a long warm up period. I put a new radiator core in and it keeps the oil pressure up much longer running at about 180 deg. than when the temp went over 200 regularly. 40lbs. pressure will not harm your engine. Try the heavier oil and get your water temp down before trying anything else.

 

[twas_brillig]

I had oil pressure problems on our BJ7 - turns out it was the oil pressure relief spring. Here's a compendium(?)of earlier posts on this
(check: https://www.britishcarforum.com/bcforum/u...f_Va#Post531756
for the whole thing, including advice from others plus additional links)

Doug

****************************************
We have a 62 BJ7 that has about 65000 miles on it and has been stored since the mid-70s. Oil pressure is a bit below 20 psi at idle (using 20-50 Penrite, if memory serves).

I ordered a replacement relief spring and relief spring cup from AH Spares in the UK, based on the possibility that the engine was losing pressure due to oil bypassing the spring cup (due to a weak spring or worn cup). Order placed Dec. 15 and received the 23rd (via air letter).

The Haynes "Austin Healey 100/6 and 3000 Owners Workshop Manual" (date of publishing unknown) that I have advises that the minimum length for the spring is 2.87 inches. THe Bentley reprint of the original Healey workshop manual doesn't mention this dimension.

My 'old' spring is about 2 11/32 (2.344) inches long; the new one is about 2 5/8 inches long (2.625), so I've gained a bit more than a quarter of an inch, but am still a quarter inch shorter than the Haynes reference.

The angle of the 'cone' on the new cup appears to be slightly more tapered (ie more shallow; less blunt) than the original; the base on the original has a slight chamfer that is missing on the replacement - I think I'll smooth the resulting 90 degree edge a bit with a whet stone.

I'll install the new bits and advise if there's any change in my oil pressure.

And hopefully I haven't betrayed any etiquette by mentioning brand names.

***********************
Eureka!

Installed the new spring and cup last night; re-installed the spin-on oil filter assembly (had removed it to ensure that the gasket lined up etc; had to use the tap and die on the bolts and the block; used a magnetic pickup to pull some of the debris out of the block bolt holes); fired her up with some paper over the rad to get the temperature up (we've got about a foot and a half of snow on the ground and temperatures to match) and...

oil pressure at idle of 600 rpm and temperature of 195 to 200 F was 45-50 psi; at 2500 rpm, it was 55 psi.

Looking forward to confirming these numbers this summer.

Quite happy about this pretty cheap fix, as I don't have the skills Bob has. Greg -thanks for the note regards the other thread also.

 

[Marvin Gruber]

40 PSI warm is not bad. Like Tim, I run 20-50W Castrol in all my LBCs for 25+ years, some had about 10 PSI warm.