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Discussion Starter #1
The PO didn't tell me about the oil pressure gauge problem in the replacement dash cluster. The pressure gauge will drop to "O" and the red warning light comes on above 2500 rpm. Drop below 2500 rpm and everything returns to normal. My indy checked it out and replaced the oil sender, but the problem persisted. He finally tried another dash cluster and said the problem went away. The oil gauge was the problem. I pulled the dash out and took it to a fixit place. They tested the dash cluster and fixed my odometer. They said the oil gauge was OK. I put it back in the car and I still have the same problem. I went back to my indy and he stands by his evaluation. He agreed to put a different dash cluster in my car and take me for a ride next week.
So here's the problem, what if the different dash cluster doesn't show the problem? Back to the fixit place? Has anyone had a problem like this? What could possibly cause an oil pressure to not work above 2500 rpm? The engine runs fine and no funny noises. It seems that the oil pressure is fine, but how do I really know. HELP!
 

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what if the different dash cluster doesn't show the problem? Back to the fixit place?
If the replacement cluster works, and the original cluster that was supposedly fixed doesn't work. take it back to the cluster repair shop that said there's no problem with the oil gauge.
 

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If you reeeeeeeeeeally want to know.
Is to hook a mechanical gauge on, where the oil sender is, read the REAL pressures. ;)

Regards,
aam.
 

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Discussion Starter #4
OK, Guys! Let's get technical here. What in the gauge wiring could make the gauge zero out at 2500 rpm? Also, what would make a sensor do the same thing? Anything in the wiring between the two that could cause this to happen? It's the weekend guys, but your thinking caps on and get back to me. ;>)
 

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Over the years I've had two cars with oil pressure gauges that would suddenly drop to zero while rolling down the highway.

In one case (a 1986 Volvo 240) it was a bad voltage regulator that generated a reference for the meter - the regulator was replaced and the problem went away.

In the other case it was a cold solder joint somewhere in the surface mounted components of a digital dash cluster - this was in a 1984 Pontiac 6000 STE, i.e. one of the earlier digital dashboards used in a US production car. The cluster wasn't field serviceable so after multiple return visits to the befuddled dealership they finally replaced the entire unit under warranty.

So could wiring cause this? Sure ... a short or open in the signal lead, a short or open in the ground, noise from the alternator, etc.
 

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Discussion Starter #7
My indy sticks by "it's the gauge" and is going to install another dash cluster he has and take me for a ride to prove it. If that checks out, the it's back to the dash fixit guys with the cluster for them to dig deeper into the problem. What ever voltage or resistance runs that gauge has to drop or spike at 2500 rpm to cause the gauge to think the engine has no pressure.
Thanks for the replies. I'll let you know the outcome.
 

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My indy sticks by "it's the gauge" and is going to install another dash cluster he has and take me for a ride to prove it. If that checks out, the it's back to the dash fixit guys with the cluster for them to dig deeper into the problem. What ever voltage or resistance runs that gauge has to drop or spike at 2500 rpm to cause the gauge to think the engine has no pressure.
Thanks for the replies. I'll let you know the outcome.
what was the outcome?? my gauge is acting up since i got the car
 

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Discussion Starter #9
The outcome is that the oil pressure is fine. It is a problem with the gauge itself. The dash guys have given up and I was told to get another dash cluster. My cluster was put in my indy's SL and it did the same thing. I'm going to live with it for now. More important things to fix before that. As long as it reads OK under 2500 RPM, I'll have to trust that everything is fine above that.
 

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Did you replace the oil presure sending unit?
 

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Discussion Starter #11
Yes, of course. Everything was checked or replaced. It is the gauge. I even had the dash guys check to see if the tach was shorting out the oil gauge when it hit 2500 rpm, but they couldn't find the problem. They had the dash twice for a week each time.
I sued the guy that sold me this car and won. After a year in court, he said he would make payments on the $1500.00 he owes me. First check was due by the 5th of this month. Guess what; no check.
 
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