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4ZUA787
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Discussion Starter · #1 ·
still trying to figure out whats wrong with my oil pressure, car runs fine even though it only shows about 1 bar on the gauge a tried messing with the wires on the sending unit but no luck also which wire is which on the sending unit i am thinking of hooking a temporary gauge up under the hood to see if its my gauge thats bad or my wire or my sending unit, thanks for ur help in advance.
 

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Your oil pump cover may not be any good. If it is not absolutely smooth on the inside, chances are it need replacing.
Some folks polish their covers, but I don't know the success of that endeavour.
 

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4ZUA787
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Discussion Starter · #3 ·
well could the cover jus all of a sudden go bad since this was an all of a sudden thing.
 

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4ZUA787
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Discussion Starter · #6 ·
ok so which wire iether one or the one with the screw connector or the one with the spade connector or i jus might try both, and does anyone have the thread pitch for the sending unit jus incase.
 

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pvcar said:
and does anyone have the thread pitch for the sending unit jus incase.
It's 14mm x 1.5 tapered (pipe thread). But 1/4" pipe thread ironically fits just fine, as long as the fitting is brass or aluminum (softer than the block's cast iron).
 

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The wire with the screw connector is the one you remove. This won't prove your guage is reading correctly; however, if it doesn't peg with the wire removed, the guage is suspicious.
 

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4ZUA787
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Discussion Starter · #9 ·
well ill try the wire thing in the am its to cold and dark right now, if that doesnt work ill go buy me a oil pres. gauge of somesort and test that, jus thinking out here technically if i had only about 1 bar of oil pressure and i drove the car it would have seized by now if the top end or some where thats not getting sufficent oil correct?, jus hopin its the gauge or sending unit.
 

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Actually the car will run without damage at 1 bar. The main concerns are:
1. Why is the oil pressure that low. (possible cam bearing wear)
2. If it is operating at 1 bar at highway speeds, is there enough pressure to protect the engine at idle rpm?
3. If the oil pressure lowers anymore you could be in trouble. (not much of a margin for error)
If the oil pressure is indeed that low, I would suggest checking out the oil pressure regulating valve before you tear the engine apart. This is located in the timing cover area on older 1.9's and in the oil pump cover on later 1.9's. I believe that there is a thread that covers that problem in detail.
 

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4ZUA787
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Discussion Starter · #11 ·
thanks for the info i still gotta try disconnecting the wire and seeing if it is possibly the gauge. and the oil press looks like it moves jus a small friction of an inch when u accelrate hard or at high speed the needle may move about a 1/32 of an inch but that also could jus be me imagining/seeing things.
 

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I too am experiencing a similar problem. At idle the gauge will go down to 1 bar, but at highway speeds and upon acceleration the gauge is going to 2 bars, sometimes 3. No heating of the coolant though and a brand new sending unit through OGTS. My thoughts are, 1. Need heavier oil, running 20w-50 Vavoline. 2. Gauge in console. Haven't had a chance to do a lot of checking as I just got on the road about 5:30 last night. Jarrell
 

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4ZUA787
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Discussion Starter · #13 ·
yah i run the 20/50 synthetic when i do an oil change and then when i need to i top it off with union 76 10/30 oil. but i dont htink its the oil could something have happend when i did the head gasket about a 1000 miles ago, or wouldnt i have seen something sooner if that was the case.
 

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Old Opeler
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Most Likely

The most likely thing to do the sudden oil pressure drop is gunge under the relief valve. Have a go at cleaning that first.
 

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Don't run 20w50 unless your are in a very warm climate. You need the lighter oil to lubricate the engine when its cold. 20W50 will yield higher oil pressures, but that doesn't give you better lubrication and can cause oil starvation (bearing damage), in cold weather. I generally run Mobil 1 5w-30 in my GT. I have over 2 bars at idle and over 3 at highway speeds. I agree with GTJim. The first thing you need to do is verify that the guage is reading correctly. If the pressure is indeed that low, check the pressure regulating device, (relief valve). If you unhook the wire and the guage doesn't peg, the guage is bad. Unfortunately if the guage does peg, it still could be reading incorrectly. The fact that you don't see the pressure increase with speed also points toward a bad guage or relief valve problem. Even worn bearings will generally yield higher pressures with increased RPM.
 

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Changed oil this Am and changed filters as well. I used a K&N 1002 Oil Filter as was recommended here on the board, and I now have 2 bars at idle and 3 to 3 1/2 upon acceleration. Took her for a spin, and after an hours worth of driving, still had the same results as above. Now for State inspection in the Am, and we're legal and on the road. Thanks to all. :D Jarrell
 

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4ZUA787
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Discussion Starter · #17 ·
well since i live in cali it is a warmer climate most of the time and that is what we mostly run here either that or 10w30, i will check the relife valve can anyone verify for me exactly were it is located?? thanks in advance.
 

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I'm sure someone will correct me if I'm wrong, but when you are laying upside down under the car, looking up at the oil pump, it'll be the big nut that you see. Take it loose. There is a spring and a ball. There may be some trash in, or behind it, in the oil gallery. I pulled one on an engine in a Manta and stretched it (spring) a bit. It seemed to help. Now you have to remember this was the first of the 80s, no one else I knew was fooling with Opels and probably not the correct thing to do. Jarrell
 

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Yep, on later (post '69 I believe), the bypass relief valve is behind the big horizontal nut, in the oil pump cover, facing the rear. Older CIH engines had the relief valve behind the big nut in the side of the timing chain case, up higher on the passenger side, just above the oil filter, but when Opel moved it to the pump cover, they installed a REALLY stiff spring and steel ball in the old location to render it ineffective except at EXTREME pressures. But check that as well, because if some PO installed the wrong spring in the old location, it will leak off pressure. I believe there are several causes for the relief valve to malfunction:
1) Weak relief spring (so get a new spring; stretching it is a temporary, and maybe fatal fix, if you stretch it too far, or if it breaks after stretching).
2) debris under the ball (or plunger; later models use a phenolic plunger), but if there's a bunch of junk there, it doesn't look good for the rest of the engine.
3) the plunger gets worn out. The phenolic plunger seats better than the steel ball, but is prone to getting nicks and such that allow oil to leak by. And sometimes the seat also gets damaged, so a new cover is the ticket. That gets you a nice shiny pump cover surface (better pump volume), and a new spring and plunger.

HTH
 

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4ZUA787
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Discussion Starter · #20 ·
thanks will check that, im thinking its possibly the gauge though, i did like said and pulled off the spade connector from the oil sending unit and then checked the gauge gauge did not peg like described, plugged connector back on and checked gauge again same reading, i will check the relife valve since that is easier then pulling the oil press. sending unit. thanks again.
 
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