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Old 11-22-12, 10:30 AM   #1
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12a No oil pressure and weird vibrations

I just bought a 82 gs and it had a weird vibration that was rpm dependent and assumed it was just a u-joint. The gauges weren't working at the time though so I bought it and got it home. I replaced the u-joints and that fixed most of the vibrations.
The problem is that at idle my gauge is showing the oil pressure as 0-15psi. At 3,000rpm it is usually around 30psi and then if I redline it sometimes it will go up to 45psi-60psi and other times it'll just linger around 30psi-45psi....
The vibrations happen at around 2,000-3,000rpm and 5,000-6000rpm. Anything below, in between, or above is fine. It runs really smooth so I'm not willing to say the bearings are worn out and it doesn't smoke so I have a hard time believing that the oil control rings are sticking/worn.

Any idea of what could be causing the vibrations and/or the low oil pressure?

My ideas are alignment (but it isn't shaking the wheel, it is more of a butt/seat/drivetrain vibration).
Worn out internal parts (but it runs so smooth all the way to redline and doesn't smoke)

Those are my only ideas.... actually.
Thanks.
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Old 11-22-12, 10:38 AM   #2
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change the drive shaft
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Old 11-22-12, 10:41 AM   #3
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Driveshaft checked to be good at one of the shops we've got here.
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Old 11-22-12, 12:48 PM   #4
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Does it vibrate while stopped in neutral but clutch engaged & being revved, or only while driving?

If it only vibrates when moving down the road, is the vibration speed-dependent, or RPM dependent? Does it vibrate when coasting in neutral & you rev it?

If it vibrates with the gearshift in neutral but clutch engaged, but not with the clutch pressed, you could have bad input shaft bearings in the transmission.

The oil pressue is kinda low, though not horrible; if you know the gauge to be accurate, try changing the oil to proper 20-50 & see if it helps.
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Old 11-22-12, 01:00 PM   #5
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I made the mistake of changing the oil to 10w-30 for this winter already.

I looked in my oil and saw a few flakes and chunks of stuff but it looked more like dirt than metal. I think from where the car sat a while that the oil just broke down.

I thought it was rpm dependent but I went to write down what rpm it does vibrates at and it happens the worst between 45-55 in 4th and 5th. I noticed it really doesn't vibrate any in the lower gears.


(From what I've searched it seems to point towards the engine mounts or transmission mounts being bad, but I've checked them a few times and they were fine.)
Are there any tests other than just prying up btwn the mount and tranny. And revving the engine in neutral and watching the engine?
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Last edited by slitherz90gxl; 11-22-12 at 01:03 PM.
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Old 11-22-12, 01:21 PM   #6
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Some things that always happen:

Stock gauges are always off by a bit. Use them to get an indication of oil pressure, but not actual accurate oil pressure. Research what it takes to get an aftermarket gauge and sender installed. Racing Beat has a decent pressure and temp adaptor. Either version 1 or 2 will work.

The oil pump in 82 and older engines were small 12mm. These provide less volume and can lead to worn thrust bearings and thrust plate. When you are able to do a rebuild, change to the 17mm oil pump and new thrust assembly pieces if yours are wearing and dropping metal pieces into your oil.

Front bearing is probably worn into the copper caused by over tightening the alt belt and lack of adequate oil volume over a lifetime.

Switching to 10w30 for winter is a smart move. You oil pressure sounds ok so far. Little low, but ok.

The tranny mount always separates rubber from steel when they get old. New ones are like 30 or 40 for stock and 70 for competition. I like competition personally. You can find it at Racing Beat. The stock one from Mazdatrix.

Motor mounts tend to sag and lead to missed shifts and annoying drivetrain slop. Again I like competition. But you can do hockey pucks easily in a 1st gen, and the results are great. But it increases vibrations. Solve your vibes first, then go for the harder mounts. Then again the soft stock mounts may be causing the vibrations.

Maybe your pressure plate lost a bolt? These cars have had several clutch jobs by now and someone probably screwed something up at some point. It's best to go over the car at your convenience and correct things over time. Otherwise it's overhwelming.
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Old 11-22-12, 01:47 PM   #7
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check thrust play on the front hub and pop the plug out of the transmission and see if you can verify that all the clutch pressure plate bolts are installed and tight.
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Old 11-22-12, 04:38 PM   #8
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Had my brother drive it today and I rode shotgun. I'm pretty sure the vibration is coming from the tranny mounts. Going to check for the third time tomorrow.

Quote:
check thrust play on the front hub and pop the plug out of the transmission and see if you can verify that all the clutch pressure plate bolts are installed and tight.
\
Alright I'll do that, and I was also considering the clutch pressure plate bolts missing one or something....
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Old 11-24-12, 09:11 AM   #9
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Well it has been really cold here so I've not done much in the way of checking anything. Buying a heater for the garage soon though. I did find out that the engine has been rebuilt as long as the information in this thread is correct: Determine 12a engine year / series

Because it has the dimples by the spark plug holes, or the 84-85 12a style rotor housings.... That means there is a chance that maybe the pickup tube was bent during the rebuild, but I still want to hook up a new gauge before I drop the pan.
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Old 11-24-12, 07:27 PM   #10
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Just a thought, if its not RPM dependant, what about the tires? Wheel alignment and balance?
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Old 11-24-12, 09:43 PM   #11
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It is.. It is one of those things that sort of make you scratch your head because everyday it seems to manifest itself differently. I think it needs an alignment but I'm pretty sure that what has happened was that they did a later model engine swap but put the old flywheel/counterweight on.
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Old 11-25-12, 12:13 AM   #12
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unless there are loose steering/suspension parts, the alignment does not cause vibrations
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Old 11-25-12, 04:33 PM   #13
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So I guess the previous times I wasn't prying hard enough, but the transmission lifts quite a bit off of the mount. I'm replacing it tomorrow and hopefully that fixes the vibration. However, I still haven't figured out the low oil pressure issue..
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Old 11-27-12, 04:43 PM   #14
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Update: Transmission mount was bad, I removed the rubber by itself before I got the steel off the transmission. The vibration is now taken care of as far as I know. (I still have the exhaust off so you never know...) Now I just need to figure out the oil pressure issue.

Since I already have this thread going, is it possible that a 84-85 oil pressure sender would cause issues with a 82 gauge cluster? Because the engine is out of a 84-85.
Cold it shows 60psi at idle and up to 120 at 3k rpm.
Warm it shows 0-15psi at idle(900rpm) and then it goes up to 30-45 from 1500rpm-redline.
I know that is really low so I'm not driving it except to troubleshoot issues.
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Old 11-27-12, 07:34 PM   #15
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Did you switch to 20w-50 yet?
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Old 11-27-12, 07:46 PM   #16
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Quote:
Originally Posted by DivinDriver View Post
Did you switch to 20w-50 yet?
I just changed to 10w-30 and I really can't afford to spend money anything I don't need. I doubt it'd increase the warm oil pressure at idle from 0-5psi to 25-30psi. I've made a list of possibilities and most of them involve having to remove the front cover at least... After I find money to check the pressure with a mechanical gauge.
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Old 11-27-12, 09:55 PM   #17
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I had low oil pressure and was very worried until I swapped in a different oil pressure sender from another engine. Try that first, maybe put up a want to buy, they're tiny and would be cheap to ship. Good luck!
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Old 11-28-12, 10:35 AM   #18
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Changing oil viscosity is probably the second cheapest thing you could try that has any influence on gauge pressure indication & it has the plus of possibly actually raising your oil pressure if you have internal leak/bypass issues.

The cheapest thing you can do is verifying all your electrical connections & grounds are clean and tight & system voltage at idle is proper, which is essentially free.

A new known-good sender or calibrated mechanical gauge will not come near so cheaply as 5 quarts of oil. Unless you can find someone who will loan you one.
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Old 12-07-12, 04:57 PM   #19
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Okay, I tried two different oil pressure sending units and the gauge acted a little different but more or less the same deal.
Idle 0psi, 2k rpm 30psi and up to near 110 at redline.
Whenever I redline it the oil pressure sits at 30psi at idle for a few seconds and then slowly goes down to around 15psi but will hit zero if it sits for a few minutes.
So I'm wondering if maybe the problem is actually the gauge or is it the front cover o-ring?
I'm not really sure what would cause the idle oil pressure to "leak down" after you redline it and it sustains 30psi for a couple of seconds.
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Old 12-07-12, 05:55 PM   #20
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MANUAL GAUGE ,manual gauge, MANUAL GAUGE. everything else is a lie
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Old 12-12-12, 05:05 PM   #21
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Well I just figured I'd update this, I developed a water pump leak and when I went to take the fan off I noticed that the water pump pulley has a lot of play in it. I've decided just to park it for awhile and replace... almost everything. I'm going to go ahead and put a high volume oil pump on it and replace the oil pressure regulator. I'd rather it sit over the winter than lose my engine in the spring and miss out on driving in the warm weather.
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Old 12-13-12, 12:13 AM   #22
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My RX7 is having oil pressure issues too. then something that Jeff20B said stuck out to me like a sore thumb==

Quote:
Front bearing is probably worn into the copper caused by over tightening the alt belt and lack of adequate oil volume over a lifetime.
which reminded me. i tighten the hell out of my alt belt because it wasnt contacting my clutch fan pulley. i mean i put a pry bar and lifted it i tighten it so hard. i never knew it could hurt. -_- needless to say my clutch fan work for quite a while then stopped and i just said fudge it. but now it makes sense why i dont have oil pressure either. Mine is 20 psi at idle (normally 40 psi), full tilt is at 60 psi (normally 110-120 psi) * i have a few oil pressure mods being as im going to turbo my car*. NOW how do i got about replaces said worn out part from my overzealous engineering?
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Old 12-13-12, 12:09 PM   #23
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Quote:
Originally Posted by Kn0CKzillA View Post
My RX7 is having oil pressure issues too. then something that Jeff20B said stuck out to me like a sore thumb==



which reminded me. i tighten the hell out of my alt belt because it wasnt contacting my clutch fan pulley. i mean i put a pry bar and lifted it i tighten it so hard. i never knew it could hurt. -_- needless to say my clutch fan work for quite a while then stopped and i just said fudge it. but now it makes sense why i dont have oil pressure either. Mine is 20 psi at idle (normally 40 psi), full tilt is at 60 psi (normally 110-120 psi) * i have a few oil pressure mods being as im going to turbo my car*. NOW how do i got about replaces said worn out part from my overzealous engineering?
Well it depends. If it is the front rotor bearing he is talking about you'd have to pull the engine to replace it. Though he might've just been talking about the Thrust bearings/torrington bearing. Front Pulley / Thrust Bearings
Not for sure if those being worn out cause oil pressure problems or not.
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Old 12-13-12, 03:54 PM   #24
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Hum. well i hope dont have to pull the engine i would much rather not have to haha. hopefully he gets back on here soon so i can grab up that info and decide which route i want to take :/
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Old 12-14-12, 05:11 PM   #25
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I have the same problem on my 83 rx7. and i also had the same thoughts as most of u. but i did change the oil two days ago to some fresh 20w-50 with no help. and its not the gauge cuz i do have a mechanical gauge inside the car and reads the same thing. So, what i'm seeing is normal pressure when cold idles around 35psi and drives between 65-110 psi. when hot it will idle 0-15 psi and it wont go much higher than 30-40 psi no matter what i do. I went to mazda trix this morning for some Q&A and got a lot of the same. front cover o-ring, oil passage, pick up leak, worn oil pump, and weak oil press regulator springs. not sure which is most common or which to attack first. or if i should just go after everything.
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Old 12-14-12, 05:11 PM
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