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help with high oil pressure 86 300

10-06-2007, 09:45 AM
the other day after driving my z (134k orig miles on it) my oil pressure guage, which hasn't worked in years suddenly pegged. The temp was normal and the engine was running fine. I drove the couple blocks to home and when I pulled in the drive, steam was rolling out of the hood. I checked the radiator fluid and it was ok. The oil was a little low (1/2qt) and was clean, no froth. Looking under the engine, the pan has a little coolant in it. It also looked like there were a few drops of coolant around one of the spark plugs (left side 2nd plug from front) but I couldn't tell if it came from there or not.
The car has only been driven a little over 3500 miles in the last 3 years but up til now has been running great.
Can anyone please give me an idea of what might be going on. When I started up again, the it idled fine but the pressure guage pegged again right away. I am afraid to even drive it to the mechanic. Also, I don't know if this as anything to do with it, but it keeps draining the battery, even with the positive lead disconnected.
Thanks for any help, LG

11-14-2007, 05:52 PM
if the battery's draining without leads hooked up that means it's dead (check the water reserves in it, they're most likely dry)

the best thing you can do is to replace the oil pressure sending unit... that's the reason the gauge stops working 95% of the time, and they're cheap parts, and relatively easy to replace... that way you'll know for sure what's going on with your oil pressure.

what happened with your temperature when the oil pressure pegged? are you sure your water pump didn't pack it in or something of the like?

11-14-2007, 07:40 PM
Hi, thanks for answering. The battery was new (and it is sealed) and I've kept it on a trickle charger if the car was going to sit for any length of time. However the day all this happened I had been driving it all day, then the next time I tried to start it the battery was dead again. Which leads me to believe the alternator isn't working correctly even though the gauge shows it's charging. One thing I noticed is when the charger was hooked up to the positive on the battery and I had the trickle charger grounded to the body (like the directions said) is that I got corrosion on the neg battery cable where it was grounded on the body. I cleaned it off and my clock which hasn't worked in years started working, but I am wondering if it was backfeeding thru the car body and this has fried my gauge or sensors.
As far as the temp gauge. That was what was odd. As soon as I noticed the oil gauge was pegged I checked the temp and it was right in the middle like always, but as soon as I pulled in my drive (luckily only a couple of blocks away) steam started rolling out from under the hood and I could hear the boiling, so it was obviously overheating. So either it had JUST started overheating (it hadn't dropped the fluid level yet) and when I looked at the gauge it hadn't started on it's way up yet, or that sensor is toast also.
I love this car, I've owned it since it was new, so I know it has been well loved and maintained properly, and really don't want to have to write it off, unfortunately we don't have any Z car specialty places like when I was in Florida and now I'm afraid to drive it anywhere if I even knew where to take it.
I have started it up in the garage and let it run. It is idling fine but the gauge (oil) pegs right away, way before it could have built up any pressure (I think).
So do you think it could be a bad alternator? Last time it went out it overheated, but I don't remember the oil pressure doing anything.
Thanks for taking the time to help me.

11-14-2007, 07:49 PM
It could be a bad alt... you wouldn't believe the amount of screwy things that happen when the alt. starts to go bad...

it's also a good idea to check all of the sensors and replace the ones necessary... even if it isn't the issue i'd replace the oil pressure sending unit (just behind the oil filter looking at the engine) and check out the connections on the temp gauge (passenger side lower intake manifold between cyl. 1 and 3)

was there any abnormal sounds when it went? or when it idles?

12-05-2007, 09:14 PM
From the sounds of it the battery is bad... New or not if the battery losses charge even without the + terminal hooked up??? I would say the battery has what is known as a factory defect...
Go have it tested.... most parts stores can test that sort of thing easily....

01-02-2008, 03:11 AM
When my alternator in my 280z went out everything was screwy all my sensor lights were flashing my fuel gauge didnt work, but it started the radio worked the clocked worked and all other important items worked. very very odd. check it first at the battery with a volt meter when it is running it should show 14v. Also with those new batteries look for dead shorts internally they will overvolt everything and can break things happened in my parents 03' Mazda luckily nothing was damaged.

01-09-2008, 04:12 AM
it only takes 10V to start a car. And all the systems in a car run on a lot less voltage than that. Travb, This is why your car was acting wierd. Cause as the battery drained below 10v the car was tring to turn off, so it was acting funny, every spark firing was causing a very noticable pulse in the voltage level of the car. Next what are you talking about new batteries check for that stuff... batteries havent changed much in 20 years. They dont check for nothing themselves. The cars that they are put in check that themselves... The Mazda was probly a either a 6,3 or that bubble SUV thing. Those are all based on Volvo cars and they have more computers than lug nuts. Those cars check everything including the driver when they startup. This is why I keep my cars dumber than me, 95 and older.. keep life simple dont go all networked.

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