Mechanical oil pressure gauge . Too much pressure ?

[maxdog]

Hi
Wasted a rainy afternoon installing a mechanical oil pressure gauge which I found in my junk box . A real PITA of a job !
I needed a tee piece 14x1.5 mm connection for the warning light switch with side connection for 1/8 copper pipe to the gauge . I eventually found this on the UK Holden Vintage site
You have to remove the oil filter before you can get at the existing pressure switch . Wrap the filter body with rags to avoid oil dripping into your eyes ,long after the filter is removed .
My pressure switch has a strange size hex head ., no metric or A/F wrench will fit it . I found that an offset 1/2 inch British Standard Whitworth ring spanner worked best !
I now have a working oil pressure gauge in place of the clock . The gauge shows a nice 40 psig at tickover ,
But the pressure increases dramatically with engine revs to 60/70 psi at a decent cruising speed .
This seems to be very high Can I damage the engine , blow a seal ,with such high pressure ??
Is there a relief valve some where which should control the oil pressure ?
Where is it?Is it adjustable ?
Is there a blockage in the lube system . The oil filter and oil were both changed 350 km ago
Am I worried about nothing ?
The engine runs like a sewing machine, I was a happy camper before I installed the gauge .
""When ignorance is bliss - - - - -etc !""
Maxdog

[AndyVAS]

The seals and gaskets that you need to worry about are the cam towers. They were a problem from day one. That said, if they haven't blown out already you're probably fine.

[SteinOnkel]

AFAIK 99% of all engines have such a pressure relief valve inside or close to the oil pump. I've seen it fail exactly once. All it took was one good rev under load to 4k rpm and the engine bay was completely filthy.

I don't think your gauge is very accurate. 40 psi on a hot idle would be a good value for a brand-new, fresh off the line engine at a modern automaker's factory.

On a 40 something year old motor I would expect to see around 15 psi at hot idle and 40 psi around 2500 rpm.

On my other toy car the sender is inside the head (no clue why VW does it this way on new-ish engines) and stock was an idiot light that would come on below 4.5psi. It's engine rebuild time if that light ever goes on under load. So I swapped it out for one that comes on below 16 psi. Sitting at a light in the middle of summer and you kind of lug the car a little bit, it does flicker sometimes. Bottom end has 120k miles on it, it's fine.

Cheers
Steiny

[18Fiatsandcounting]

Maxdog, what weight motor oil are you using? Something like 10W-30 or 10W-40, or heavier oils like straight 30 or 40 weight, or 20W-50? If the latter, and especially in a cold climate with the engine not up to full operating temperature, I don't think your psi numbers would be all that unusual.

To answer your specific questions, yes, there is a pressure relief valve in the oil pump housing internal to the engine, and no, it is not adjustable (unless you change the spring, which I wouldn't recommend).

When I rebuild the engine in my spider, I would get about 60 psi when revved up, and 30 psi when idling, when the engine was relatively cold. With the engine fully warmed up, I would get about 45 psi when revved and 20 psi when idling. Everything seemed fine.

So, to make a long story short, I think your oil pressure sounds fine, although you may want to consider different oils depending on your climate and the time of year (winter vs. summer).

-Bryan

[maxdog]

Thanks
That sounds reassuring . I'm using 20W 50 oil now that Montreal temperatures are above freezing !
Maxdog

[18Fiatsandcounting]

20W-50 might be OK for Tucson in August, but for Montreal, I'd go with 10W-40 or even 10W-30.

Be assured, Maxdog, sounds like your oil pressure is fine.

-Bryan