Sealing rings at top/bottom of cylinders

[RalphWiggam]

Not much to update. Finally got my idiot light working. I think the bulb in the dash was bad. Found some new ones locally. Ordered a new single terminal oil pressure sender. Swapped it in place of the dual terminal warning/pressure sender that I found in my dad's stuff. Hopefully that will take care of my low readings when the oil is hot. Got a new voltage gauge installed in the dash as well.

Changed the oil at 100 miles. Poured a little bit out on a piece of glass so I could inspect it.

Doesn't look too bad to me. Way cleaner than what came out at the first oil change. It's been raining a lot so I haven't been driving the bus. Hopefully this weekend I can get some more miles on it.

[RalphWiggam]

Alright folks, got some questions.

Took the bus out this morning for a spirited 25 mile drive. Did about 15 miles on the highway. With the new oil pressure sender I am still only getting about 25psi at 3500rpm when the oil is hot (220). When I pulled off the highway and was waiting to turn around the idiot light started flashing and came on. This is a new idiot sender and should come on around 3-4psi. Scared the crap out of me and I gave it a little gas to get the pressure up.

The whole drive oil temps never went above 225. CHT never went above 310. What the hell is going on with my oil pressure? Is this break in oil just not meant for regular use? Should I switch it out for some straight 40wt?

I really don't know what to do. Am I doing damage to the engine driving it like this?

Maybe it's the 18" sender extension I have running from the idiot light port throwing my readings off?

[Tcash]

You cannot trust the idiot light. The oil pressure switches are known for being all over the place.
You need to qualify the switch by hooking up a mechanical oil pressure gauge.

Oil Pressure FAQ

Good luck
Tcash

[SGKent]

break in oil is 30 weight. While it will show slightly lower pressure than a heavier oil, unless if is 80 to 100 F outside your low pressure is oil. You can swap in a 10-40 up to 100F and see what happens. Frankly it sounds like something else is going on. You do need to put a mechanical gauge on it because at this point both the idiot light and the gauge are agreeing that pressure is a little low. At 220F after a freeway drive my oil pressure is still about 15 PSI per 1000.

When you rebuilt the engine did you change the o-ring on the oil pickup tube? Did you replace the over pressure valve with the same style one that came out of it or reuse the old one? They come in slotted and non-slotted depending on the style case you have (single relief or double relief).
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[raygreenwood]

[SGKent]

[raygreenwood]

[RalphWiggam]

I had a dual pole sender in there and I swapped it out with a single pole sender thinking that may have been the problem. Readings are about the same on either one of them.

I did use a new o ring in the oil pump and lubed everything generously before installing. The gears looked very nice. The oil pump installed into the case pretty tightly. I used no gasket on the outside, just loctite 518 and it is not leaking. I also used a new o ring on the oil pickup tube and lubed that before installing.

I am going to hook in a mechanical oil pressure gauge and try and remove any air that might be in my extension line.

[Busstom]

I may have missed it earlier on within this thread, but I wonder if you know what this engine was producing before you rebuilt it, or if you only had the idiot light.

In the end, you may end up just having to live with it the way it is. Ideally you'd have 4 or 5 pounds min at idle...that's not highly uncommon...sure, I realize it doesn't conjure warm fuzzies, but flickering oil lights are fairly common in these old cars. I know people are gonna say I'm fulla shit and you gotta go to the ends of the Earth to get to the bottom of this, but I'm just sayin' you may not fully resolve it to your satisfaction or meet this 10/per spec bandied about.

Do some Internet searching, many people with various engines in various vehicles have survived with low idle pressure.

[RalphWiggam]

So I rigged in my dad's old mechanical oil pressure gauge...

I know I shouldn't leave it like this because it will break off. I figured a few runs would be fine. I took my daughter to pick up breakfast this morning and got the oil temp up to about 200f. We when got back I had my wife help me watch the mechanical gauge in back...

The mechanical gauge seemed to read about 8 psi higher than the electric one in the cab. Mechanical would read about 40psi at 4000rpm.

I went for a highway run later and think the mechanical gauge is destroyed. It spins in circles when I rev it. I guess I will leave it and order another mechanical gauge just to check it again and make sure. I don't know if I should trust it's earlier readings. Decent news though....

[raygreenwood]

[SGKent]

be aware that mechanical gauges soray oil if the line fails. Those around the race track know this, some folks who've lost an expensive engine when a line cracked or chaffed thru won't use them again. Personally, I won't have anything to do with them. Oil pressure is not the kind of thig that requires perfection. You either have enough and are in the broad window or not. Besides, anyone who was chasing better regulation in oil pressure would be running a dry sump, and maybe a windage tray as well although the scavenge pump somewhat negates the need. This constant need to chase perfection in this thread is like trying to make a beauty queen from a bow legged buck toothed redhead with freckles. Run what you have with a slightly thicker oil and monitor it, or tear the engine apart. If you didn't replace the pressure valve(s) on the case with the correct kind, you should.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Abscate]

Unless you pay beacoup bucks for a high end pressure gauge I bet you will find the error on this stuff is in the 5-8% full scale range.

We found this in testing this stuff for industrial customers.
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[TomWesty]

[RalphWiggam]

[busdaddy]

Personally those numbers don't really get me all that worried, play with viscosity and find the happy spot and then put some tape over all the gauges so they won't distract you as you drive. It's making oil pressure, isn't getting crazy hot and hasn't siezed up solid, clueless surfer hippies cross continents with fewer checks in the win column than you have going on.
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[SGKent]

I can't answer that. On my 1971 dual port type 1 case, the slotted screw style plug was what was used for both plugs. On my 1977 there is one plug only - slotted.

When rebuilding the plugs should come out, be cleaned, inspected, and the spring rate tested. You can test the spring rate with a bathroom scale. If those valves are worn on top they leak and you'll never have the correct oil pressure.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[TomWesty]

[raygreenwood]

As SGkent noted.....oil hoses are dangerous. Actually the hose is not the worry. Its the connectors.

I am not suggesting to EVER run gauges as a permanent fixure in the engine compartment....neither fuel or oil.

As for big bucks for gauges that are accurate?.....not really.

You can get a huge range of class A pressure gauges....accurate to 1 psi full scale.....for under $50.

For short term use under the hood for diagnostics....without worrying about vibration (use a hose) or about having a high temp gauge ...again use a hose as an insulator.......you wont need anything else gauge wise.

Now.....if you had some crazy idea to keep a gauge attached to the engine.....then yes....you would be looking for a class A minimum gauge....liquid filled....high temperature.....and THAT gets into big bucks.

As for.....not worrying about this variation.....the "run what you got"......just toss in some thicker/thinner oil and tune with it???????????? Really?

Sorry.....not trying to piss anyone off.....but some you guys just appear to be lazy sometimes.

Sure thats all fine....+/- 5-8 psi "seems" like no big deal.....the saying that many, many engines idle when hot at 10 psi so thats no big deal....yeah thats all fine......unless you got 10 psi at idle and your gauge is off by -8 psi......in that case you are really running 2 psi.....and the receipt for the $6000-ish you just spent on the engine will make a nice post card 10-20k miles from now when you are tearing it down again.

I do not believe in the "just get it ok and drive it and not worry about".....mindset.....on a new build....an expensive build.....at the 100+ mile mark......when the REAL question at hand.....at the moment.....is.....is the gauge you are checking oil pressure with accurate?

This period of time with a new and expensive build is the PERFECT time to get anal about it. Because if you find a mistake....you might actually have something left of the engine in usable shape if it turns out something really bad is wrong. It aint like AAA is going to replace your engine when it craps.....they will only tow your smoking load of scrap back to your driveway.

Also.....I dont know what kind of sh*t gauges you guys buy.....where 5-8 psi give or take accuracy is normal......or even acceptable......but I haven't bought a gauge with less than 1psi full scale accuracy in about 20 years. I think I have ranted about this in about 50 threads now.....and even posted about 50 part #s. They are also pretty cheap. Its a tool. I dont see you guys running around buying the cheapest torque wrenches you can possibly find....why would a gauge be any different? Its an instrument.

Protect your investment. Spend a measly $35-50 on a real pressure gauge. You can use it for both fuel and oil pressure. If you buy a quality gauge, clean and store it well and it will serve you for years. Good investment.

Ralph you keep right on doing what you are doing. You were right to question what you saw on the gauge. You were right to verify whether it was the electronic gauge by putting in a mechanical gauge. You just need a good gauge and to insulate the gauge from vibration when you use it....and unless you spend big bucks on an accurate gauge that is also heat and vibration proof.....just dont leave it bolted to the engine.

If you need a part number let me know.

By the way.....if you use a brake hose....use a teflon stainless hose.....not a standard rubber brake line. Remember....brake hoses are EDPM rubber....which does not mix with petroleum oils. Its life will be short.
Ray

[RalphWiggam]