Correct Oil Pressur

[Pikey]

Can someone confirm the correct oil Pressure on a 1098cc. The only reason ask is that about 5 years ago I rebuilt the engine with 30 thou o/s pistons new oil pump etc. I had the crankshaft measured by a professional machine shop who confirmed that I could use standard bearing shells, so I replaced all main and big ends with standard. I have an oil pressure gauge fitted. When started from cold I have a good 60ish PSI and when cruising (hot) at about 40 mph in 4th and hot its about 45/50ish PSI, tick over when hot is about 30ish PSI. I think these readings are fairly healthy. But recently when restarted from hot, the oil pressure guage takes about 5 to 10 seconds to register any pressure at all. Is this normal wearing in, dodgy oil gauge or something more serious.

[ndevans]

60psi sounds ok to me. I think it will take a few secs for the pressure gauge to reach a stable reading.

[Pikey]

Forgot to mention the oil light never comes on at any time and always goes out when cranking on the starter (takes milliseconds to go out), whether hot or cold, which is why Im questioning the pressure gauge.

[dalebrignall]

sounds like your engine is in perfect health,only start to worrie when you get less than 35 psi doing 60 when hot

[Stig]

Is your pressure gauge an electrical or mechanical one? I'd expect an electrical one to be slow to change reading.

Do it take it that the gauge used to jump up quite quickly and has recently become slow?

[dunketh]

Mine pops up straight away but takes ages to go down.
The only way to get a reliable reading is to tap it every now and then.

I wander if its possible to pump some solvent into it? Perhaps de-gunk it?

On the same subject - mine reads around 70psi cold then normally 50 when warm and sometimes 40 ish after a damn good thrashing. Is this OK? Its a 1275 midget lump.

[Willie]

The designed pressure on the 1098 is 60 psi running hot. i.e. apart from a cold start when the pressure will slightly exceed 60psi and running below 30mph in top when hot the needle should be glued to 60. This is on a perfect engine. The max pressure is controlled by the oil pressure relief valve which has a spring which should be of a specific length
(2+55/64" or 72.63mm). There is not much point in increasing the pressure especially since the rear oil seal arrangement is so poor.
As ever the A series engine is extremely forgiving regarding pressures and will work fine for thousands of miles below the designed pressures.

[Packedup]

The Midget reads about 35 - 38 even at 40mph+ after a good long thrash.

I would worry, but I've got to cure the high speed overheating on my daily driver before I stress too much - There's no knocks or rattles at that pressure so though I'm not happy, I'm not distraught.

It's better than the 10psi or less I've had on Triumphs at hot idle!

[bmcecosse]

Pressure should be 60/70 psi when cold - and even when hot it really needs to be 10 psi for each 10 mph in top gear. Ideally - it will stay at 60 psi almost all the time. I wouldn't worry about the sluggish gauge - the readings are good enough. The 1275 engine readings are a bit low - and would benefit greatly from an oil-cooler installation - BMC fitted one as standard on the 1275S Mini and the MG Metro had one too - it helps quite a bit during hard motoring.