Mako 928

When the car is cold and I turn the key W/ out starting the engine the oil gage pegs past 5 bar ( MY 85') After the car is warm it stays at 5 bar even at idle. After I drive the car for aprox. 20 minutes it will then give normal readings, 5 bar under load 3 bar at idle.
Recent work includes.
1. Last spring I replaced the oil pressure sender and tested wires/connections including the oil level sender. I again inspected/tested this recently.
2. Last month I removed the pod to replace the ignition switch/ODO gear. I removed the electrical strip/board and all connections and cleaned. All grounds in the car are clean/tight.
It would seem that it is a short of some sort or bad connection in the pod, but it seems strange that the oil gage will work normaly after driving for 20 min. and continue to work, I can shut off the car turn the key to Acc. and the gage will register on 1 bar as it should. When the car is cold/not driven for a while the gage will peg past 5 bar when the key is turned to Acc.
Also when I removed the U shaped connections held in place W/ a nut on the backs of the gages I did not put them back to the same gage they came from. How important is this.?
I am going to remove the pod and inspect connections but would like any advise on what else to look for.
All of the other gages work fine and the oil gage worked fine before removing the pod.
Oh yeah the VERY last thing I did was check the timming belt tension and used the Porken 32 valve to set the cams.(which is a FANTASTIC tool) but I can't see this as being related to the oil gage reading but I always look at the last thing I did.

Mike Frye

Your gauge is working properly.

When you first start and the oil is cold you should get 5 bar.
Even after you run it for a few minutes and the water temp gauge comes up, the oil is cold, so it's still going to be 5 bar.
After you drive it for a while and the oil gets a chance to warm up, which takes much longer than the water, it will move down to 3 bar, and then go back up to 5 bar with higher revs (over 3k or so).

Oil gauge readings

How did it work before removing the pod?

Mako 928

Mike
The gauge unfortunately is not working as it should. When you turn the key to Acc. when engine is cold/off the oil gauge should read 1 bar, not shoot past 5 bar as it is doing now and stay there well beyond when the engine has warmed and not read below that at idle.
Then aprox. 20 min. or more after driving it will read 5 bar at idle well beyond after the engine has stayed at 650 RPM and warmed up and then flick down to 3 bar and operate as normal.
After this I can turn the car off while still warm and the oil gauge will read 1 bar W/ the key at Acc. as it should not 5 bar.
Another way to put it is......
Cold engine: turn key gauge shoots to 5 bar and stays there. start engine gage stays at 5 bar even after warm/idle drive around for a while and gage shoots down to 3 bar and then works normaly.
Warm engine: turn key gauge goes to 1 bar W/ low oil light on. Start car gauge goes to 5 bar and settles down to 3 bar at idle.
Another way yet again to put it is...
Gauge acts like there is a short, oil pressure sender wires crossed (they are not) and always stays at 5 bar, but in my case at some point well beyond after the car has warmed up the gauge comes back to life.
Thanks for the link I remember reading the post good info there.

Mike Frye

Greg,

Sorry, without the 'flicking' and 'shooting' in the description it sounded normal to me.

Does sound like something is loose back there, and if the pod is what you did last, I agee that's the most likely culprit.

Sorry no help on this one.

Mako 928

Mike
Thanks for givin it a shot. Again good thread you started on normal oil pressure readings,this does help in isolating what I am experiencing.

Mako 928

UPDATE:
I have inspected/removed the pod and do not see any loose connections or seem to be able to find any shorts. The oil gauge still pegs past 5 bar when the key is first turned to Acc. before turning the key to start the engine and stays there when the engine is started and warmed and exhibits the same behavior as before. Why will the gauge work properly after driving it well past when it warms up?
Is there anything to look for in the oil gauge itself for this behavior.? I am pretty much at my wits end on this and no longer enjoy driving the car like this.

Mrmerlin

it might be possible that you have a wire at the sender with bad insulation and it is a temporary ground, i would check the harness under the car........... Ahh dont forget to ask yourself the important question, what was the last thing you fixed

Mako 928

Update part 2.
I removed the pod again a few months ago and did not find any loose connections or shorts. Everything looked good and I put it all back together. Since then the oil gauge has been working normaly. Moving things around may have caused the problem or now may have fixed it. I do not like not knowing for certain what the cause/cure was but just wanted to update this thread.

Mako 928

Update # 3
Well the oil gauge (and all other gauges) have been working normaly for the past 5 months now except that now the oil gauge is acting up again.
When I turn the key to acc. the oil gauge goes to 1 bar and the oil warning light is on as it should be. When I start the car (cold) the gauge climbs to 5 bar in increments as it should but then it pegs past 5 bar and stays there.
When the car is hot and I start it the needle pegs right to 5 bar with out climbing in increment.
After driving the car and turning it off I will pull the key out of the ignition and the needle will stay at 5 bar for aprox. 5 seconds and then drop to 0 on the gauge.
Again the oil sender is 1.5 years old and does not seem to be the issue.
I have pulled the pod 3 times now and all connections look good.
So my question is could the oil gauge itself be the problem and how can it be tested?

Landseer

Porken tool? Proximity of 14 pin connector? Oil gauge wires run through it. Disassemble and check both male to female for corrosion and backs for bad solder joints. Intermittent behavior is possible.

Mako 928

Chris
Not sure of which Porken tool your referring to. I have inspected the 14 pin connector and did a inspection/continuity check on the front harness when the engine was out a year ago and again inspected the connector a few months ago. Also I do have a cover for the 14 pin connector and it is kept dry.
Also I like your wife's minivan comment

Landseer

I had an eratic voltmeter and a pegged / sometimes variable oil pressure gauge. I traced the problem to weakened, corroded broken solder joints leading into the back of the 14 pin connector. You've described a lot of circuit checks relative to the oil pressure gauge, but not the 14 pin.

It might or might not help to see this, esp. about post 18 or so with pictures.
https://rennlist.com/forums/928-foru...er-solved.html


If you were deep enough into the car to have the passenger cover off, depending on how you did it, you could've disturbed those wires. Maybe not, but if its giving you a lot of frustration you might want to take it apart and see.


My wife used to drive a Chevy conversion van set up for towing that would launch. Not many soccer mom's in minivans could beat her off the line. Comparitively, she's hell with the 928. She asked tonight if anyone commented about her comment.

Rob Edwards

At my house on Sunday, Luan (REDSHARK1990) was chasing a flaky oil pressure reading and opened up the 14 pin connector to find a bunch of corrosion and very shaky looking connections at some of the pins. I was a little busy to see how he got it all back together, and I don't know if he cured it, but it's definitely worth opening up the connector and ruling it out (and at least shooting some contact cleaner or stabilant on the pins....)

Mako 928

Thanks guys for the input.
I guess I will go back and re-check the 14 pin connector. No harm in looking and besides it is easier than pulling the pod (again)

dr bob

There's also some local history here with damage to the front-of-engine harness where it passes the dipstick tube. If the wire bundle is in fron of the tube, it will rub and may eventially cause some of the symptoms you describe. If your harness is in fact in front of the tube, you'll want to inspect it carefully for rub-through, and repair any damaged conductors you find. Get some of that silicone tape for the first wraps after the repairs, and consider adding some split loom for added protection and to clean up the look.

It's easier to move the dipstick tube than it is to remove and replace the harness, plus you'll need to unbolt the tube anyway. Make sure the seal at the bottom is in right of course, and it might not be a bad idea to do the dipstick part with the front of th car up a ittle to keep the oli level below the bottom of the tube. To make sure there's no chance of a rub through, it's not a bad idea to tie-wrap the harness snug to the tube.