high oil pressure

Post by **fsk658** » Fri Jun 09, 2006 5:14 pm

I have just got back from france after a 1,700 mile trip. On the journey the oil light came on at tickover, thought faulty oil switch but the engine became more noisey not big ends. I suspected main bearings or loose flywheel. When I got back I fitted an oil pressure guage. The oil pressure with hot engine 45psi @ tickover if you rev the engine it will go upto 75psi. I have changed the guage for another one and is within 2psi of the first guage. The guages have also been checked for accuracy. I have removed the pressure relief valve no problem with that, not sticking and the length of the spring is correct. The reconditioned engine was out of a scrap moggy I bought. I am baffled as to the high psi any suggestions.
Thanks John

Post by **Packedup** » Fri Jun 09, 2006 8:56 pm

Blocked oilways (quite possibly crank/ mains)?

Would explain endy noises but high pressure maybe.

Post by **bmcecosse** » Fri Jun 09, 2006 11:10 pm

Oil pressure is excellent! Faulty pressure switch. Noise in engine must be something else - certainly not big ends/mains or the oil pressure would be nowhere near as good.
Ps - it's a gAUge !!

Post by **minor_hickup** » Fri Jun 09, 2006 11:17 pm

It doesn't seem far off what mine shows, considering my engine is 68,000 miles never rebuilt. Mine shows 40-45 psi warm idle and 65-70psi whe revved, running fast up to and over 70psi

Post by **RogerRust** » Sat Jun 10, 2006 9:52 am

exactly the same as mine 40- 45psi tickover 65-75psi at speed

Post by **bmcecosse** » Sat Jun 10, 2006 10:09 pm

Must be fast tick-over! Normally would expect ~ 25 on a good engine at a slow but adequate tick-over.

Post by **chrisd87** » Sat Jun 10, 2006 10:17 pm

The ever-helpful 'Techincal Tips' section on this website says:

"A good engine will read 40 psi at idle and 60 psi at normal running speed with the engine HOT. If it is below 30 at idle it is rather worn. Below 20 it is badly in need of a rebuild"

http://www.mmoc.org.uk/technicaltips/Engine_Health.html

Post by **Willie** » Sat Jun 10, 2006 10:39 pm

The designed oil pressure of the Minor engines is indeed 60 psi running which
should be regulated by the oil pressure relief valve. The spring length is critical but if that doesn't bring the pressure back to spec then the relief valve
cup is probably worn too. A higher pressure wouldn't do too much harm except that,on the Minor, the rear main bearing arrangement for preventing
the oil from escaping from the crankcase is not particularly good(an Archimedes Screw) so excess pressure would tend to lead to more oil leakage from the rear end.. Regarding the 'below 20 psi tickover means a
badly worn engine' that could well be true but when my engine gave these
low readings but seemed otherwise very healthy I renewed the oil pump and
now have 40 psi on tickover!

Post by **bmcecosse** » Sun Jun 11, 2006 9:41 am

For a road-runner, oil light flicker (~ 15 psi) at tick-over is not a problem.

Post by **Willie** » Sun Jun 11, 2006 10:34 am

The oil pressure warning light should illuminate at approx. 8lbs psi.