What should the pressure be?

[JoshC]

Well i finally got the Nubria put together and started. My oil pressure light is still coming on, so i bought a gauge. I pulled the sensor out (1wire) and put the gauge in it's place. I was a bit suprised that the light didn't come on since it was unplugged. Cold the engine ran about 52 lbs of oil pressure at idle. Would run up to about 60 half throttle. Once it got to operating temp it settled in at about 7PSI and would see about 23PSI at half throttle. This is setting in my driveway and the outside temp is about 75. Those numbers sound good to you all?

[Spider]

Well i finally got the Nubria put together and started. My oil pressure light is still coming on, so i bought a gauge. I pulled the sensor out (1wire) and put the gauge in it's place. I was a bit suprised that the light didn't come on since it was unplugged. Cold the engine ran about 52 lbs of oil pressure at idle. Would run up to about 60 half throttle. Once it got to operating temp it settled in at about 7PSI and would see about 23PSI at half throttle. This is setting in my driveway and the outside temp is about 75. Those numbers sound good to you all?

Hey Josh,
I don't have a Nubria FSM. And thats where your answer is.
Are you using an electronic oil pressure gauge ? If yes, than you won't get an exact reading off of it.
Only a mechanical gauge will do that.
Those numbers are pretty low.. especially 23psi @ half throttle.. at idle 10 psi is better than 7.. many oil pressures sensors will trigger an oil light at lower than 10psi Again, you need the FSM for that, should be in there. I wish I could help you more. But wrote this because that 23psi seems too low to me.

[Daniel]

I pulled the sensor out (1wire) and put the gauge in it's place. I was a bit suprised that the light didn't come on since it was unplugged.

That's normal since you removed the ground path.

Once it got to operating temp it settled in at about 7PSI

From service manuals available here the minimum oil pressure at idle and operating temp should be 30kPa = 4.35PSI. There is no mention for other engine speeds.

Here is a pic of the 90336039 oil pressure switch.



You can see that the triggering level (lamp ON) can be 0.3 to 0.6 Bar (4.35 to 8.7 PSI) depending of manufacture tolerance. If your oil lamp comes OFF at fast idle then you have maybe a "high rated" pressure switch.

OR is you oil lamp always ON??

[JoshC]

The lamp didn't come on until it got warmed up and then at idle, around 800 RPM it would come one, rev it up to a 1000 and it would go off. Then when it got really warm it would stay on. The gauge is mechanical. And i said half throttle on my post, but i really was guessing there because i was moving the throttle from under the hood and couldn't see the tach.

[Daniel]

Have a look for a well closed bypass valve #13 (if any, my 1.6 didn't have it I believe) and a free moving relief valve #3&4.



To be sure your oil switch is ok you can make a test fixture to pressurise togheter your gauge and the switch. Use some kind of "Y" or "T" connexion. Check switch with a ohmmeter and watch for opening/closing pressures.

[JoshC]

Looks like you'll have to get behind the timing belt to check 3 and 4. 13 looks like it is under the oil filter. I can test the switch to check myself i guess. I mounted the gauge today. Started it up and it was just fine. Let it sit for a while and then went for a little drive. The gauge kind of froze at about 40 and then slowly bled off, i'm sure i have a loose connectiong after routing the tubing. It was the first time i've had it on the open road and she ran great!

[JoshC]

I think i do have a pressure problem. I drove the car for a while this evening. It starts off fine, with good pressure but after it really gets on the road and warmed up the pressure gets weaker and weaker. I thought i had a bag gauge, but i did a little check and while the car was idiling i loosened the connection on the back of the gauge and the oil just barely dribbled out. I reved it up with the hose in the towel and it just picked up the dribbling by a small margin.

So i guess a pump can be fine when the motor is cold, which is what it does every time, but then when it gets warm, really warm, it quits working. Is this normal?

[Spider]

I think i do have a pressure problem. I drove the car for a while this evening. It starts off fine, with good pressure but after it really gets on the road and warmed up the pressure gets weaker and weaker. I thought i had a bag gauge, but i did a little check and while the car was idiling i loosened the connection on the back of the gauge and the oil just barely dribbled out. I reved it up with the hose in the towel and it just picked up the dribbling by a small margin.

So i guess a pump can be fine when the motor is cold, which is what it does every time, but then when it gets warm, really warm, it quits working. Is this normal?

" ......It starts off fine, with good pressure but after it really gets on the road and warmed up the pressure gets weaker and weaker. "

How weak ?.. What does the pressure drop to ?

The 'test' you did with the oil line loose..is not all that accurate. Your mechanical gauge is most likely good.
The oil when it's cold will show a higher pressure until your engine heats up to normal operating temperature than pressure will show a lower reading.. that's normal.

If I were you this is what I would also be doing:

Which is basically trying to eliminate all these possibilities.

Engine running too hot? You can check the actual temp w/a candy thermometer, set it in the resavour when the engine is cold and watch were temp goes as the temp heats up.. compare it w/the dash gauge. be careful, don't burn yourself.

oil too thin (wrong grade/viscosity) ? what weight oil are you using in it?
loose or worn crankshaft bearings ? They would knock.
restricted oil galleys/oil filter? Change oil and filter again, add some "Marvel Mystery Oil" w/it.
weak/ worn/or restricted oil-pump? your working on that now, right?
hope you find the problem and it doesn't cost much to repair.

[JoshC]

Very good post, i'll try to answer everything.

I figure my gauge is good now that it is the second time i've seen pressure drop. When i say drop i mean it goes to 0. I don't see how my little test couldn't be accurate because even if my gauge was bad and 0 actually meant i had about 7 or 8 pounds, then 7 or 8 pounds out of that small vacuum hose would be alot, then reving it up to about 20 pounds would have shot oil all over the place. It did neither.

The engine does seem to run hot just by feel under the hood, but the temp gauge inside acts normal. It warms up normal and not excessivly fast, the fans kick on and off. I have a new water pump on it with the correct amount of new antifreeze. I had thought about doing that little test you mentioned, but isn't the resavor pressurized????

I am using 10W30 oil with a fram filter. I also added some seafoam to it. I'd say it has a total of 1 hour run time on the motor, idling and driving. I have seen the pressure drop to 0 twice, both times when driving.

I don't hear the crank bearings knock, but last night i did notice the valves (at least i thought so) getting noisier. Maybe it was the crank bearings, but it sounds like valves or lifters to me.

I don't know what else to check on the pump. If i get good pressure when it's cold and quits working when it's hot it does seem to me that the oil is too thin for the pump to move. One thing that gets me is that last night after i did my little test when the motor was idling, i went under the hood and removed the oil fill cap and it had pressure on it, i could hear it, and it was throwing oil around on the cams. So i can't really make my mind up with what the problem is.

[Spider]

Very good post, i'll try to answer everything.

I figure my gauge is good now that it is the second time i've seen pressure drop. When i say drop i mean it goes to 0. I don't see how my little test couldn't be accurate because even if my gauge was bad and 0 actually meant i had about 7 or 8 pounds, then 7 or 8 pounds out of that small vacuum hose would be alot, then reving it up to about 20 pounds would have shot oil all over the place. It did neither.

The engine does seem to run hot just by feel under the hood, but the temp gauge inside acts normal. It warms up normal and not excessivly fast, the fans kick on and off. I have a new water pump on it with the correct amount of new antifreeze. I had thought about doing that little test you mentioned, but isn't the resavor pressurized????

I am using 10W30 oil with a fram filter. I also added some seafoam to it. I'd say it has a total of 1 hour run time on the motor, idling and driving. I have seen the pressure drop to 0 twice, both times when driving.

I don't hear the crank bearings knock, but last night i did notice the valves (at least i thought so) getting noisier. Maybe it was the crank bearings, but it sounds like valves or lifters to me.

I don't know what else to check on the pump. If i get good pressure when it's cold and quits working when it's hot it does seem to me that the oil is too thin for the pump to move. One thing that gets me is that last night after i did my little test when the motor was idling, i went under the hood and removed the oil fill cap and it had pressure on it, i could hear it, and it was throwing oil around on the cams. So i can't really make my mind up with what the problem is.

Sorry i didn't get back to you sooner, Josh

You could try some heaver oil.. Like Rotilla "T" 15-40 not the synthetic but regular old dinosour oil. It's a very good oil and designed for diesel and automobiles. Castrol 20-50 is also good if you live in a hot climate and have high mileage on your engine..
I live in the desert and have never used 10-30 in any of my vehicles because it just seems too thin for this climate.
It is good for a new engine though.

Sounds like your engine is not overheating.. And yes the system is pressurized.. But you can do the test I outlined if you remove the cap WHEN THE ENGINE IS COLD..
Than with the candy thermometer sticking in the opening, start the engine and as it warms up, watch the temp rise until the engine gets up to normal operating temp.. I don't have the actual specs handy but some place under 200..like 180-195 (F) should be about normal...If it goes over 200 and keeps on going up? Shut it down as you may have an overheating problem.

If you remove the oil fill cap (w/engine running) you do need to see oil splashing out the opening and all around & on you and the cam's.
That's a good sign.

Zero pressure on your gauge is not a good sign..

Your loose oil pressure gauge feed line leak-test is just guessing. That only tells you that some oil is going to the gauge.

Seafoam is good stuff and remember it is making your oil thinner than it was before you put it in.
I would change it again. Try 15-40 and a new filter.

Having researched the current Fram oil-filters. I feel it is true that they are not what they use to be. Outsourced and made very cheaply nowdays. Even the glue inside is inferior and the check valves are made of plastic.

Fram used to be one of the the best oil-filter manufactures around. But not anymore.

I use Bosh filters in my woo. Purelator filters are also very good.

P.S. & FYI .........

"....out of that small vacuum hose would be alot,....."

Your using the hose that came w/the gauge, right?
Its not a vacuum hose it's either copper (or most likely) a hard nylon line. Never use a rubber vacuum hose for pressurized stuff.

[JoshC]

Alright, here is what I've got.

First off, yes it is the nylon hose, I'm just used to calling vacuum hose for work.

I changed the oil to 15w40 and a purolator filter. After the pressure built up on the first start, the sound difference was amazing. You could hear the valves rattling at all! I was pleased with that. I guess the Seafoam had it to thin, good call buddy!!!

I removed the cap for my antifreeze before i started it and insert my tempurate gauge i use for work. I never saw it above 175 idling in the driveway. Pressure looked decent on the gauge so i decided to go for a drive.

I noticed then when i got out on the main drag doing about 45 that when i would give it gas to kick down a gear, the pressure would drop from about 25 to about 15, then when it shifted back into OD it would climb back up fairly quickly to about 25. I didn't make it far before the pressure once again fell off to 0. I turned around and headed home. By the time i got home you just hear the valves clicking a little bit. I noticed that same sound from the other day when i had 0 on the gauge. I'm not worried that i hurt anything because i didn't drive it long with 0 pressure.

I really don't understand why i would have good pressure when i start it up and STILL get to 0 when i get out on the road. I could see never building enough pressure, but not just bleeding off. When i got back home i did remove my antifreeze cap and tested it again and it was 178.

So we know i'm 1-not overheating 2-running new 15-40 oil and filter 3-i have plenty of oil in there 4-have good pressure on a cold start and 5-loose it well after i get to operating temp.

I called a local shop and I'm 99% sure i'm going to have them put a new pump on this week. But man, i just can make heads or tails of why it's acting like this. I'm to the point when i need to get this on the road, i bought it so my wife would have something easy on gas to drive and it's a sweet little car. Not doing me a lick of good in my driveway. Some please chime in this weekend so i know whether i should order the pump. Thanks.

[Spider]

Ok than Josh,

It's not loose crank bearings if it were, you would hear heavy "thud' (knocking) from the bottom-end which would speed up accordingly as you brought up RPM's. These a strong engines, especially the bottom-end.

So, it must be the oil pump. What else could it be?
You have eliminated everything else and it doesn't seem to be any of that stuff.

I wish someone that has had this problem would reply in here.


My engine has about 100k miles on it and the oil pump is doing fine.

But...
I understand an oil-pump can go bad.
Could be something sticking, like a back-flow or relief valve or worn-parts, when it gets hot.. I mean just normal road-speed hot as your engine isn't overheating.

I don't think it's a very hard job to replace it but you do have to get some stuff out of the way to get it out.

I wish I could tell you exactly what the problem is.

But I will say...
I also suspect the oil pump now.

And...
Every time you run your engine at zero oil pressure you run the risk of burning a bearing.
Even at idle.

So...
If I were you? I would be buying a new oil pump about now.
Even if it turns out to not be the oil pump ?

At least you will know that for a fact....
And..you will have a spare one.

Stay positive,
keep us posted.. good luck too...

[Spider]

Posted twice..deleted this one.

[JoshC]

Yeah the one thing i have noticed about this forum is that this type of thread happens alot, 2 people reply and then it is just a 2 person conversation. In this case i'm fine with that because you have been a tremendous help!

Now i wish i would have just replaced the pump when i had it all apart. I just put a new timing belt on and replaced a valve when i pulled the head. But serisouly i didn't think i had a pump problem. Oh well. I found a pump on ebay for 147, that's the cheapest place i've found, you know of anywhere else?

[Spider]

............... I found a pump on ebay for 147, that's the cheapest place i've found, you know of anywhere else?

These people are good, I've bought from them.. They just sold a Lanos oil pump for $57.00 (usd)
How much more could a pump for your engine be? Try a search at their store:

http://stores.ebay.com/Daewoo-Parts-4-Less

You should register with Daewoo of America :

http://www.daewoous.com/Default.aspx

Online shopping and sometimes they even have good sales going. Well worth a look at. They also have factory part numbers and detailed part drawings. So you can get a good look at whats going on inside your oil pump.

You could even order specific oil pump parts from them. Rebuild it yourself on the cheap? Of course that's for retired guys like me that have more time than money.


Let us know how your progress.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

P.S. CHECK THIS OUT:

copy/paste of a GsiTurbo post from this forum...................................

GsiTurbo
Super Moderator
Joined: 13 Mar 2003
Posts: 1731

Location: Edmonton, Alberta, Canada

Post

This engine family is somewhat known for sticky brass oil pressure relief valve, which could be a problem especially after a few months in storage.

If the motor flush does not help.... Dive under the car with 22mm spanner (??) and undo the bolt on the right-hand side. Its spring-loaded so be careful when it pops out. Ensure the piston underneath it can be moved freely by hand. If you cannot move it, or if its sticky, that is your problem. New oil pump can be obtained inexpensively off eBay (keyword Nubira oil pump). If you are in Europe, I'd recommend Z20LET oil pump from Opel Astra (they feature nylon relief valve and higher output). Also, if the piston moves fine, the oil pickup in the oil pan may be clogged with sludge (sign of poor motor maintenance), or its o-ring seal may be shot. Hope this helps.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~