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crvc
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Joined: April 28, 2004
Posts: 1308
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 Posted: Fri Aug 29, 2014 7:39 am Post subject: Measuring oil pressure... |
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Measuring oil pressure without a gauge. My plan is to take the pressure switch out then measure the volume of oil that spurts out at idle. I checked the local parts stores and none have a gauge to lend or rent.
The green light stays on at idle. I changed switches twice. Then I changed oil pumps. Nothing turns off the green light at idle. The light goes out when driving. Anyone know how much oil will come out per minute at idle?
TIA,
crvc |
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Danwvw
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Joined: July 31, 2012
Posts: 8892
Location: Oregon Coast
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| Posted: Fri Aug 29, 2014 7:53 am Post subject: |
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Not sure how much oil comes out probably all of it pretty quick! But You should not be able to hold it back with your thumb. Watch the belt! Probably what is wrong is oil pump fit is poor or there is a air leak in your oil pic-up tube. I use case sealer around my oil pump where it's cylindrical part fits inside the case. This fills the gap around the intake hole on the pump and helps oil pressure a lot.
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Northof49
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Joined: July 22, 2013
Posts: 1759
Location: Winnipeg, Manitoba, Canada
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| Posted: Fri Aug 29, 2014 8:05 am Post subject: |
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That's just way too rough of a guestimation. Hell, I'd even use a tire pressure gauge if I had to. That would be better than observing oil squirt out. Surely you can beg or borrow some sort of 0-50 psi guage and rig it up.
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crvc
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Joined: April 28, 2004
Posts: 1308
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| Posted: Fri Aug 29, 2014 8:21 am Post subject: |
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| Northof49 wrote: |
| That's just way too rough of a guestimation. Hell, I'd even use a tire pressure gauge if I had to. That would be better than observing oil squirt out. Surely you can beg or borrow some sort of 0-50 psi guage and rig it up. |
If I coulda, I woulda. I just need to see what comes out at idle.
I've got a remote starter, tubing and a screw-in connector so I can watch what comes out hopefully without a mess. If there's an air leak, as Danwvw mentioned, then no oil would come out at idle?
Thanks,
crvc |
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Cusser
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Joined: October 02, 2006
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Location: Hot Arizona
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drscope
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Joined: February 19, 2007
Posts: 15273
Location: Baltimore, Maryland USA
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| Posted: Fri Aug 29, 2014 9:16 am Post subject: |
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PLEASE wear a white shirt and video this when you do it!
This isn't going to tell you ANYTHING except that you made a BIG mistake! And maybe that oil goes places you never thought it could. And that the smell will stay in your hair, and skin for several days or weeks.
You know you have low oil pressure. So whats the point of doing this?
The question is how low is it and you aren't going to be able to figure that out by squirting oil all over everything and getting it in your eye.
If the oil pressure is low enough to turn the light on at idle, then it is too low. Worst case is that you loose a rod bearing and kill the crank and maybe a rod.
Next worse case is that it's low, but you still have a couple thousand miles to go before you kill it.
So at this point, the best thing you could do since no local places carry a gauge, is to order one. You should have it in a couple days.
If you do what you have planned, you will still be wiping up oil in a couple days, so what do you have to loose?
Order a gauge and do it right. that way you know what you are dealing with and you don't have a mess to clean up. Trust me, even an engine that is making less then 1 psi of oil pressure will spit oil out so fast you won't know what hit you!
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Todd66
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Joined: February 19, 2012
Posts: 461
Location: Utah
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| Posted: Fri Aug 29, 2014 9:45 am Post subject: |
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PLEASE do the squirt test and video it. I would love to see the results.  . Even if you found an exact way of measuring and a way to not make a mess it will tell you nothing. You would be measuring volume not pressure which are two totally seperate things. But still, do the pressure test and post the video. |
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Harleyelf
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Joined: April 23, 2009
Posts: 1572
Location: Appleton, WI
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| Posted: Fri Aug 29, 2014 10:10 am Post subject: |
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| When you replaced the sending unit for the oil pressure idiot light, did you get a 2psi sender of the standard 7psi unit most foreign cars use? You really should get at least a sending unit for a proper gauge - you can measure with an ohmmeter if you have no dash gauge. |
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Danwvw
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Joined: July 31, 2012
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Location: Oregon Coast
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| Posted: Fri Aug 29, 2014 10:52 am Post subject: |
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Something like these gauges in the 1 1/2" size would be nice. Probably pick something similar up at Home Depot or True Value But these Omega gauges are nice and you can get better scale resolution with a lower psi gauge like the PGUF-15B-30PSI/2BAR psi. Check them out. Either way you need to see why your oil light is not going out at Idle. It's simple to check the pick-up tube as it's accessible when your change the oil and service the drain screen. You may have to pull the oil pump again and plug that hole with your finger then put a hose or something over the oil pick-up tube and see if it's air tight. The thing is a Cold Air Cooled engine will have 20 or 30 lbs of oil pressure at Idle but only 5-20 lbs hot at idle depending on the condition of the engine. The single relief cases tend to give a oil light at idle when hot once they get a lot of miles on them. Thicker oil should keep the oil light off even on a high milage engine.
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crvc
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Joined: April 28, 2004
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| Posted: Fri Aug 29, 2014 2:18 pm Post subject: |
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I don't understand what the relief valve has to do with it. Wilson's book, page 36, shows a case cut in half. It shows two directions for oil to flow. If there's a bubble of air resting on the relief valve what do I do to get rid of it? What will pulling the spring and valve out tell me? Why doesn't a hot engine let the air dissolve into the oil?
TIA,
crvc |
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crvc
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| Posted: Sat Aug 30, 2014 3:00 pm Post subject: |
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I unscrewed the plug nearest the crankshaft pulley. The spring slid out. I can see the valve is still stuck at the top of the shaft. I sprayed the shaft with wd40, no movement. I slid two screwdrivers in to act as a wedge but no movement. I have a second valve and tried whittling a dowel to fit tightly into the recess, no movement. I have a good magnet that fits into the channel but it didn't move the valve.
How about I screw the plug back in without the spring. Run the engine for a while then see whether that moved the valve? Anything safe to add to the oil to lubricate the valve?
Any suggestions?
TIA,
crvc |
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glutamodo 
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Joined: July 13, 2004
Posts: 26325
Location: Douglas, WY
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| Posted: Sat Aug 30, 2014 3:23 pm Post subject: |
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Do you have a set of Metric taps? that's the trick to getting the relief valve plunger out. 12mm tap
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crvc
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Posts: 1308
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| Posted: Sat Aug 30, 2014 4:17 pm Post subject: |
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Umm, never mind. I solved the problem that was causing the green light to stay on at idle. You'll never guess.
crvc |
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Danwvw
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Joined: July 31, 2012
Posts: 8892
Location: Oregon Coast
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| Posted: Sat Aug 30, 2014 5:00 pm Post subject: |
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Oh, I will guess! Since your say we will never guess that means it's something else right! How about a loose wire!
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Eric&Barb
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| Posted: Sat Aug 30, 2014 5:02 pm Post subject: |
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| crvc wrote: |
Umm, never mind. I solved the problem that was causing the green light to stay on at idle. You'll never guess.
crvc |
Idiot light wires crossed?
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Danwvw
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blue77bay
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| Posted: Sat Aug 30, 2014 5:37 pm Post subject: |
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Waiting!!! 
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crvc
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Joined: April 28, 2004
Posts: 1308
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| Posted: Sat Aug 30, 2014 7:47 pm Post subject: |
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| blue77bay wrote: |
| Waiting!!! |
Years ago my dad gave me two short blocks, a t-2 and a t-3. He said one had low oil pressure but he wasn't sure which. I split the case on the t-3 and found a deep gouge in the #4 main bearing. I had the case line bored with all new crankshaft bearings. No problems with oil pressure after that.
But the t-3 had constant vapor lock. Dad mentioned it had a racing cam. So I switched to the t-2 block. It took a while to notice the green light never came on because the switch was bad. When I replaced it suddenly the green light was on at idle. When I replaced it again no change. When I replaced the oil pump, no change.
Someone suggested checking the relief valves. I unscrewed the plug closest to the crankshaft pulley and the spring shot out. But no valve. It took several days to realize it wasn't stuck in there. There just wasn't a valve. A spring but no valve. Maybe this was the block with the low oil pressure all along. Maybe he never put the valve in. Or maybe I forgot to put the valve in when I split the case. But why would I remember to put the spring in with no valve?
Regardless, I put the valve in from the t-3 and suddenly no green light at idle.
You'd think nine years of college and graduating cum laude I wouldn't forget things like that valve. So I'll blame my dad. 
crvc |
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Danwvw
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| Posted: Sun Aug 31, 2014 1:33 pm Post subject: |
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Probably some oil change jockey unscrewed it by mistake and lost it! I vaguely remember un-screwing one by accident back in my early VW days!
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crvc
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| Posted: Sun Aug 31, 2014 3:54 pm Post subject: |
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No, I always change my own oil. Thinking back a few years, I was taking jugs, heads etc off one block to build a second motor. I probably used a flashlight to look into the bore and assumed I saw a piston, then added the spring and plug and didn't think anymore about it.
I took a long drive today. At first I was checking to see WHETHER the green light would come on. Then later I was checking BECAUSE the green light wasn't coming on.
crvc |
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