86 930 Turbo oil pressure gauge pegged

[SG930]

Taking a cruise yesterday and noticed while shifting that the oil pressure gauge stayed maxed out at 5 bar. Later after cooling down, with ignition on the gauge is also pegged out. It's pegged out after removing wire at the sending unit. It does go to zero when I ground the wire at the sending unit. It goes to zero when I remove wire at the gauge itself. Seems like a gauge issue and not a sender issue? Gauge is also foggy too. Only water it sees is the occasional wash. Any help appreciated! Thanks.

[GrangerFox]

Originally Posted by SG930

Taking a cruise yesterday and noticed while shifting that the oil pressure gauge stayed maxed out at 5 bar. Later after cooling down, with ignition on the gauge is also pegged out. It's pegged out after removing wire at the sending unit. It does go to zero when I ground the wire at the sending unit. It goes to zero when I remove wire at the gauge itself. Seems like a gauge issue and not a sender issue? Gauge is also foggy too. Only water it sees is the occasional wash. Any help appreciated! Thanks.

Sounds like you’ve already done a solid round of diagnostics. Based on what you described:
• Gauge stays pegged at 5 bar even with ignition on and engine cold
• Still pegged with wire removed at the sender
• Goes to zero when the sender wire is grounded
• Also goes to zero when the wire is pulled from the back of the gauge

That does point more toward a faulty gauge than a sender issue, especially since grounding the sender wire brings it to zero (as it should). The fact that the gauge is foggy also suggests moisture intrusion or internal corrosion, which could be affecting its function.

If it were the sender, you’d typically see erratic readings or pegging that changes with engine temp or vibration. But pegged output even with the sender disconnected leans hard toward a short or internal fault in the gauge itself.

You might try:
• Pulling the gauge and checking for any corrosion or moisture inside the housing
• Cleaning or reflowing solder joints if you’re comfortable opening it up
• Replacing with a known good unit or testing with a spare if you have one

Let us know what you find — you’re definitely on the right track.

[gorskined]

sounds like the sending unit is bad if it goes to zero when you ground at the sending unit. i would recommend swapping out the sending unit. if i remember correctly if the sending unit fails open it maxes out the gauge and if fails closed ( shorted) the gauge goes to zero.

[SG930]

I reviewed this fellows chat and leads me to think the gauge is faulty. https://www.impactbumpers.com/forum/index.php?/topic/37201-oil-pressure-gauge/

I'll try reading the ohms in the red/green wire at the gauge to see if it is in the 9 to 169 range. I did not see any erratic changes just went pegged. I'll check it tonight. Thanks!

[SG930]

It was the sending unit. I was lucky and a 24 mm crows foot was able to take it out out. Still had to loosen AC bracket and belt for better access. Thanks for all the help!

[flightlead404]

Originally Posted by GrangerFox

Sounds like you’ve already done a solid round of diagnostics. Based on what you described:
• Gauge stays pegged at 5 bar even with ignition on and engine cold
• Still pegged with wire removed at the sender
• Goes to zero when the sender wire is grounded
• Also goes to zero when the wire is pulled from the back of the gauge

That does point more toward a faulty gauge than a sender issue, especially since grounding the sender wire brings it to zero (as it should). The fact that the gauge is foggy also suggests moisture intrusion or internal corrosion, which could be affecting its function.

If it were the sender, you’d typically see erratic readings or pegging that changes with engine temp or vibration. But pegged output even with the sender disconnected leans hard toward a short or internal fault in the gauge itself.

You might try:
• Pulling the gauge and checking for any corrosion or moisture inside the housing
• Cleaning or reflowing solder joints if you’re comfortable opening it up
• Replacing with a known good unit or testing with a spare if you have one

Let us know what you find — you’re definitely on the right track.

AI Bot

[mark houghton]

Originally Posted by flightlead404

AI Bot

Huh. AI, is it real or is it Memorex? (gotta be old to remember that slogan).

AI is just another glorified search engine that takes available information from anywhere and anyone, and strings it all together (kind of like forum members do). Pretty cool in that regard, but it's far from what I would call intelligent.
The info gathered may be accurate, and may not...therein lies the downfall.The old saying "garbage in...garbage out".

[kev01]

Had this on mine when I bought it. Thought I had great oil pressure...actually had very low oil pressure when tested with an external gauge and had to overhaul motor. It was the sender unit.