'84 240Ti Part III

That means that the green wire going to the oil pressure sender is off. The oil pressure sender is just behind the alternator, just below the exhaust manifold. You may need to remove the alternator to work on it. Start with a cold engine!

Ok, I'll give it a go.

I took it back to the shop; they checked the sender and said the gauge was bad.

I tried two others, both hid the needle to the far right.

If the alternator has to come off...does the belt tighten just to "firm" as gauged by hand, or does it need some special setting?

Thank you.

Allan Ballard

They should be as loose as possible (to save bearings) without slipping. So check how they are now, if they're reasonably firm (and not slipping), just put them back the same way. If they're hard as a rock, put them back a little looser. If the belts slip, tighten them a little.

P.S. I just fixed this problem on my brother's 83 240 Turbo. The terminal on the end of the green wire had cracked and wouldn't stay on, so I had to remove the alternator to get enough room to attach a new terminal. With a light, you can actually see the sender between the alternator and the heat shield below the exhaust manifold if you position your head just right.

You don't have to remove the alternator. Take the plastic pan off underneath the engine and you can get to it from there. The insullation falls of there and the wire touches the alternator. Usually a simple fix.

I'll take a closer look. The car lost the plastic pan long ago, so I pulled the passenger front wheel onto a flat piece of granite I use.

Underneath all I could see was a blue wire ascending to whereabouts unknown.

Maybe it's a replacement from the green, or else maybe there are two wires, and the green one is missing.

The shop guy checked the sending unit, said it's ok.

They think the gauge is dead.

However tonight I swapped out two such oil pressure gauges and both do the same thing.

The needle at once goes to the extreme far right, and stays there. Once the engine is off, it goes back to the far left.

Maybe there is a wire short>You don't have to remove the alternator. Take the plastic pan off underneath

Under the crankshaft pulley is the end of the engine wiring harness. Follow that toward the alternator. Inside the harness will be a large red wire (alt power), a small red wire (amp light), a black wire (oil light) and a green wire (oil press gauge). Keep in mind that the large red wire is essentially connected directly to the battery, unfused.

I took the car back to the shop that repaired the harness, along with two other Oil Pressure gauges behaving the same as the original one.

They said they had replaced the wire to the sender; maybe that's why it is blue not green, and had tested the sender to be good.

They believe the problem must be between the firewall and the gauge.

I supplied them with all the wiring from a good gauge to the harness.

Might know by tomorrow.

Allan

TURNED OUT TO BE THE SENDING UNIT, OR SO THEY SAID.