Hello, i bought an after market oil pressure gauge. Is it hard to install on a 1990 Volvo 740 GL?

Thanks,
Scott

 

Anybody know if it's hard to install it?

 

Mechanical or electric? One has a small pipe/hose that connects to the gauge while the other has a sender that screws into the block in front of the oil filter where currently the oil idiot light sender is. Odds are you'll need an adapter to fit the sender to the block. Let us know what sort of gauge you purchased. Where you mount may be another issue. Unlike the 240, the 740 has no built in "blanks" for standard 52mm gauges. If you look at your instrument cluster you'll notice two blanks at the two top corners above the gas and temp gauges. The top left is generally a volt gauge in the GLE and the top right was variously a boost gauge or oil temperature.
Or, you could opt for a single pillar mount gauge pod...
http://www.gaugepods.com/740.jpg
or a triple if you need more info...

 

swiftjustice44, i think it's mechanical. I thought it would be nice to have one installed so i can watch the old girls oil pressure. I have no clue how to install one. Do you know of any places that will install one & about how much it would cost?

Thanks,
Scott

 

Well, there are two schools of thought on mechanical versus electric gauges. The mechanical doesn't rely on electronics and gives you a physical reading but there is a tiny plastic pipe carrying oil to the back of your gauge. I had one burst once and it made a Hell of a mess. Electronic is neater, but depends on the sender mounted on the block to correctly interpret oil pressure and submit accurate readings to the gauge. In my opinion the electric are a bit easier to install as you can route the wiring a bit neater than the pipe which can't be bent as sharply when routing. Really, either is fine. I would think any reputable shop could do it and charge 1 hour labor...whatever that might be in your neck of the woods. Here in Dallas that would equate to $80-100. The real issue, as I mentioned before, is where to install the gauge. The other issue is that the odds of the adapter that came w/ the kit screwing into your block is slim to none. Most likely, an adapter with external male threads matching the block and internal female threads matching the kits adapter will need to be sourced. Again, many shops will have them on hand. The first one I did was in my own driveway...I unscrewed the existing oil sender that goes to the oil light and took the sender with me along with the new sender. I ended up finding a coupler and an air compressor repair shop.

 

swiftjustice44, Did you mean an auto repair shop could install it?

Thanks

 

Yes. Not a Pep Boys or a tune up shop. Those guys are pretty well maxed out removing oil filters. Any independent full service shop can knock it out. They may not actually mount the gauge as that is "trim" stuff, but if they can remove engines, dismantle them, rebuild them and such...they can undoubtedly do a gauge. We do them at our shop occasionally...depends how busy we are. When things are slow, there isn't much we won't do on cars.

 

Just curious, but why would you want an oil pressure gauge? The warning light is pretty adequate for a 740 as it tells you pretty much what you need to know. I mean, why go through all this for something that has, I don't know, what value?

 

Well, let's see 1. The factory oil sender "idiot light" has a threshold of 7 psi. At 8 psi, it doesn't light. 2. Oil gauges, over time, can give the driver a sense of the internal wear of the main bearings by watching the gradual reduction of o.p. over the years 3. Far more common than the oil pump failure in B230's is the rubber seals failing at either end of the transfer pipe as seen in the diagram below...as these seals fail, oil pressure drops significantly, yet not below the 7 psi threshold of the idiot light except possibly at idle. 3. Likewise, a clogged pick up screen on the oil pump as a result of prior owner's neglect, will not be picked up by the idiot light.
Is an o.p. gauge a must? Nope...is it a good thing? My opinion is yes but that's what it is...just an opinion.

 

Oh, so the oil pressure gauge tells you the oil pressure of the engine... I wonder why car manufacturers don't put them in as standard equipment. I wonder in fact if any new car comes with this kind of a gauge. I know old Mercedeses in the '80's used to have them but since then?

 

Actually, until the last few decades, many cars had o.p. gauges. What engineers realized was that most drivers are oblivious of gauges,period. Hence, idiot lights, now including low fuel lights for people who can't seem to interpret what the little needle pointing to "E" means. Ford Explorers currently have o.p. gauges, but they're idiot gauges. It points to mid-line unless the o.p. drops to a level of 8 psi. Then the gauge points to "L" and a light comes on saying low oil. For today's average driver I don't guess gauges mean much but there is a reason why 240's built since 1981 had built in provision for 5 auxiliary gauges. Take turbo cars for example. Running at factory boost levels, nothing extra is really needed. Start running 15-25 psi of boost and all of a sudden, unless you want melted pistons, the need for engine monitoring becomes vastly more important. A wide band O2 sensor to monitor air/fuel ratios, exhaust gas pyrometer to measure exhaust gas temps at the rear of the turbo, oil pressure, oil temperature all become significantly more valuable. Lousy night shot...

 

Here's a picture showing the two built in locations for gauges with the 740...
upper left was almost always the volt gauge...

The upper right was a boost gauge in turbo cars, often an oil temperature in Bertone's and six cylinder 760's. This is the oil temp gauge...

Boost gauge...it should be noted this is not an o.e. face. Volvo used a simple color band.
This gauge has been modified w/ an overlay from davebarton.com

 

swift, your absolutly right, theres a hand full of things that an op gauge can tell you that the light cant...

 

I was considering buying on of those turbo gauge faces. It looks like the color is a bit off.

Now on the subject: My first (and only) experience in installing an oil pressure gauge was on my friend's 87 VW Golf. We got it out just to see what we might need and instead had it in in about an hour. The new fitting just fit right in. It's an AN tapered thread. That's on a VW, but would figure that it's the same on a Volvo. But it's still possible that Volvo just used a metric thread. Swift's experience definitely trumps mine.

Two gauges I wish I had are oil pressure and exhaust gas temp. I wish they had an RPM gauge for a turbo.

 

My son had a oil-pressure related gasket problem, then mice attacked the wiring harness. For a reason the Volvo mechanic has been unable to ascertain, even with a new sensor the low oil pressure light comes on but the pressure is OK. My son would like to sell the car, but be able to assure the buyer that the oil pressure is OK and that it can continue to be monitored reliably.

How can an after-market dial gauge (ideally, or light) be added (cosmetics immaterial)? Use existing sensor? Different sensor? Plumb an additional sensor? If the sensor is replaced, will disconnecting the existing wire cause the car's computer to become unhappy or confused and interfere with normal car operation?

Advice welcome

 

To put an aftermarket oil gauge you will need to plumb the new sensor that comes with the gauge. Removing the old oil pressure sender will not affect functioning of the engine computer. It is used just for the idiot light on the dash. The tricky part of installing and aftermarket gauge is finding the right threaded adapter that fits in the existing sending unit hole.