For my 98 740 Turbo I want an oil pressure gauge. From what I understand is that only V6 cars in the 700 line up ever got a stock oil pressure gauge. And they were pretty minimal (no numbers). I want a gauge that looks stock enough. So I found some gauges on ebay from Volvo Trucks. They all go to 90 psi, where cars were mostly 5 bar (72ish psi). I'm wondering how compatible these senders are and where I could pick a truck sender. Mostly I just want anyone's thoughts and experience on this.

 

Joe just get a gage from a V6 car and the matching sending unit and it will work. I would get a tee fitting and put the sending unit where the low pressure switch is. Just as a point of reference here we have 316K miles on our 89 740 and I don't want to know what the oil pressure is. When it blows , it blows. By the way my fun car has a 160 psi gage in it and it normally runs at 80-85 psi at 3K rpm. Most cars use a 0-100 psi gage.

 

Have you given thought to where you will mount it? N/A cars have two blanks in the upper corners of the cluster but turbos already have a volt and boost gauge there. I ask because my solution was a triple gauge A pillar pod for extra gauges. I put a stock oil temp gauge where the boost gauge would go...


The A pillar got oil pressure, cylinder head temp and ambient temp

 

I decided to put it between the key hole and sunroof button in the dash. I have a spare chunk o' dash for that section. I know the the steering wheel kinda gets in the way, but it's the same with the turbo and battery gauges. I'll have to make a custom hole and such, but that's not the hard part. Getting a gauge that matches and will be accurate is the tough part. Another consideration was to see if Dave Barton could make a custom face for an aftermarket gauge. I'd still need a matching needle.

As for other gauges, check out that attachment. This is out of a car with the B204GT engine. They have a combined instrument where the tach goes and a few other changes to fit at least one more gauge in there.

The second pic is another I found. I don't like the placement, but it shows a stock looking oil pressure gauge.

 

Okay, so I'm back on the project.

I was planning on getting a 0 to 80 psi gauge. Should I get on that's higher?

Also the place that I'm going to get it from has a lot of adapter stuff, so I was wondering if anyone knows the thread type in the block for the sender.

The last question is just checking, but the idiot light comes on at 7 psi, correct?

 

Bumpity-bump.

 

that space just left of the heating/ventilation controls would be sweet, but I don't know if there's room for it behind there.

re the range, seems like most cars I've had with factory gauges, they are nearly pegged when running at full pressure. they often drop to 1/2 or less at idle. so if 72 is the spec pressure, an 80 or 90psi gauge would be fine, I'd think.

 

Okay. So 80psi is what I'll get.

I may have to cut a bit of material behind the trim, but I think it's not important structurally.

Anyone know the thread size?

 

For all interested parties, I pulled the oil pressure switch and this is what I found out:

I needed a 24mm deep socket. I used a u-joint on my 1/2" drive with extensions to clear the oil feed line to my turbo to loosen the sender.

The sender has a simple 14mm diameter thread shaft with a 1.5mm pitch.

 

Well, here's the follow up on what I did:



The gauge is in the space between the climate control and the Sunroof switch. It was a very tight fit and left very little room for error. Cutting the plastic trim right was tough. I had a few spares from junks yard to practice on. The second one turned out perfect. I got it right in the middle of the top and bottom edge and as far to the left as possible to keep it away from the climate control. I had to cut the main clipping device for the trim out, but I'm going to fasten it a new way later.



You can see the tight fit against the climate control. Most of the member got cut out, so I made a plate out of some stainless to span the gap and be out of the way. It also the anchor for the screws that hold in the climate control in and the radio box:



Here's everything after all the cutting:




Power for the Gauge is connected to the back of fuse 13. Nothing in my car's configuration was connected to that circuit and it met the power scheme requirements. I also grounded to a grounding rail in the back side of the fusebox. I had to make a spare connection:

 

Here's the sender. I got everything from egauges.com, the sender, the gauge and the adapters for the oil sensor hole. I wanted to maintain the original functionality of the idiot light, so I got a sender with a sensor sender and low pressure switch. Unfortunately, these were only available in NPT size threads. However, they sold me the correct adapters, and you can see that it fits. You stick the brass adapter on with no plumbing tape and crank it down. Then the adapter seals to the block with an o-ring. I just tightened it with me hand. The thread on the block is M14X1.5. I only ran one new wire to the sender and kept the original idiot light wire and just adapted that.



Here's where I went through the firewall. There's a big grommet under the strut tower buttress. It has some small nipples that are not being used and a ridge marking where to cut them off. I little snip and the wire was in the car.



Five wires total to run, here's how they turned out:



This is everything before the trim is snapped on. You'll notice a plate around the gauge. I wanted the gauge to be recessed behind the trim, to that it what it tightens into, as well has the hole in the dash. I also angles the gauge to better match the angle of the trim.



So one more look at the final product:



Actually, I'm going to go back and make a clip to make it hold down better and a custom gauge face to match the rest. I have a few spare gauges too, so I might see if one of those needles will swap onto this one. But that's for later.

One thing that I have noticed is that the new gauge is a bit brighter than the gauge cluster. I might throw in a resistor to tome it down a bit. But I've been really happy with it. On a hot day at idle it will get down to 25 PSI, but I never see it go lower.

 

Looks good. Very complete walk-through as well.