B250 Oil Pressure Help Please!

[dodge200]

When we start our b250 van the oil pressure gauge needle takes a long time to rise. When it does rise it gets to around the half way marker (there are no numbers on gauge). It doesn't matter if the van is warm or cold it still takes a time for it to raise. Is this normal? We are using 10-40 oil, is this oil to heavy or do you think we might have the wrong oil filter fitted? Does anyone know what is wrong with it?

[VanMoreSon]

Did it just start doing it all of a sudden? Or has it been gradual? What year and how many miles on it? 10w-40 shouldn't be the problem.

[hemidogg]

dose the van make any kinda engin noises are it would be if starving for oil. if not good change ur oil pressure sender cud be taking a dump on you. u cud try getting a oil presser tester on there and see how it rases on that

[alloro]

When you turn the key off, does the needle also go down slow? If so, it could just be a slow gauge.

[97B2500CCV]

On some vans you may need to shut down the engine then turn the key back to on but not start the motor to see how fast the gage returns to bottom or low mark.

My 97 will freeze the oil and water temp gages upon shut down and then reset upon the next start up.

[landyacht318]

I put in a mechanical oil pressure gauge, but 'tee' d the line so that the stock gauge would still work.

There is little correlation between the 2.

The mechanical gauge will rise to 66 psi within 5 seconds of startup.
The stock gauge will take 20 to 30 seconds to reach it's highest point, which is slightly over half.

When the oil gets up to full temp after a long highway drive the mechanical gauge will read 20 psi at idle. The stock gauge will take about 45 seconds to drop to the 1/3 mark.

So without any corresponding engine noises or tapping, don't stress it.

[lilredex]

One of the first things I do on a "new" truck is add a mechanical oil pressure gauge, voltmeter and a vacuum gauge so you can see what is really going on under the hood. Good idea to "T" into the existing gauge as the new ones have a low pressure warning light that can be useful. Don't put much faith in the stock electrical oil pressure gauge, as the sender gets old and tired real fast. Just take an old one apart and you'll see why it no longer works accurately.

[97B2500CCV]

Don't put much faith in the stock electrical oil pressure gauge, as the sender gets old and tired real fast. Just take an old one apart and you'll see why it no longer works accurately.

Doesn't the same thing that wears on a electronic gage also wear out the mechanical gage as well? How often do you change the mechanical gauge?

[lilredex]

Those electric oil pressure gauges work the same as a gas gauge. The gauge is powered and the sender (rheostat) goes to ground. If you ground the sender wire (from both gauges) it reads "Full" or "high" in the case of the oil gauge. So by varying the position on the rheostat you get readings between Hi and Low. Take an oil pressure sender apart and you'll see a small rheostat driven by a bourdon tube (I think, been a while since I looked at one)

A Mechanical gauge, theoretically will last a lifetime. The difference is you now have that same bourdon tube driving the needle on the gauge directly.

Car makers likely went "electrical" to keep that oil pressure line out of the passenger area. The (the mechanical gauge) can be messy if the line happens to leak. But in the years I have had old cars and trucks, have never been sprayed with oil...............yet.

[landyacht318]

It's also kind of neat to be able to see the color of the oil in the mechanical gauge's clear line.

[lilredex]

It's also kind of neat to be able to see the color of the oil in the mechanical gauge's clear line.

Well yes and no to that one. First the oil should not actually reach the gauge, it should be air in that line that operates the gauge. If oil does reach the gauge it will put the gauge into slow motion reading changes in pressure. Oil in the bourdon tube will act as a damper. But yes, you will see the oil in the line where it exits the engine.

Also I tend to stay away from those plastic lines (use the hard ones, usually copper) that's why I haven't been sprayed yet!!

When running a mechanical gauge I always keep a few fittings in my truck that will allow me to block off that engine port in the event of a problem while you are out somewhere.

[landyacht318]

I have not looked at the back of the gauge to see if the oil is reaching that far up. But when the engine is off I see a lot of bubbles in the line. When I turn it on it turns to solid oil as far as I've looked, about 2 feet from the gauge. It responds to changes in RPM quickly.

I have not had any leaks in 3 years, but I will now look for an easy way to cap the line if it does.

[97B2500CCV]

Good point about having some fittings to cap the line in an emergency.

For those whom still use the original gauge along with the mechanical where did you put the mechanical gauge at?

[landyacht318]

I cut a 2 inch hole through plastic and metal to the right of the 4 wide ventilation outlet, over the doghouse. Not exactly an Ideal location, but it's always out of the way as opposed to the other locations available.

[alloro]

It's also kind of neat to be able to see the color of the oil in the mechanical gauge's clear line.

Ever see one of those clear lines get broken under the dash. It wasn't pretty!

[landyacht318]

I did take some extra steps to prevent chafing, or unintentional breakage, but I'm sure a break would be ugly.

[charlie1935]

You could use the armored flex hose (woven stainless steel covered) for this.

[lilredex]

Here are a couple of shots of my underdash setups. Lil Red and a B150, also doesn't hurt to add a "Pigtail" as shown in the last pic. The black panel was purchased, the SS version was made from a pre-bent piece I saw in the garbage, just had to add the holes (hole saw in the lathe, nice and slow). As you can see the gauges are nothing special, stuff that was accumulated from garage sales, clearance counters, Princess Auto, Etc, Etc.

[citichap]

I only use 5W30 oil in my van here in NYC all year round. anything thicker such as 10W40 then the connecting rods would start to chatter. possibly because oil is not getting into the small nooks and crannies.

1997 b1500 3.9

[landyacht318]

I read an article a while back that says a thicker oil temperature at high temps is not really an advantage. Sure the pressure is higher, but pressure means more restriction and less flow. A thinner oil will read less PSI on the gauge, but more oil is actually getting to the lifters and rockers and valveguides, keeping them lubed, keeping them cooler. Robbing less horsepower as it is pumped and circulated.

I think the article said not to worry about oil pressure unless it goes below 10 psi for every 1000 rpm.
It also stressed that cold starting is when the most wear takes place, and you want as thin of an oil as possible when cold, on start up, to get to the top of the engine as fast as possible. It also said the viscosity of an 30 weight oil at full temperature is only very slightly thinner than a 40 weight oil at the same temperature.

So it seems to me that if at full temperature a 10w 30 oil will flow the same as a 5 w 30 oil, then 5w 30 is the better choice, and 0w 30 even better, and if your engine is loose, a 0w 40, or a 0w50 will be best.

I think any 0 w oil has got to be synthetic and more expensive.
It might not be needed or worth it.

I used to use valvoline dino 10w30. For 10$ more ( T.Y. wally world)I use Mobil 1 5 w 30 and an oversized Purolator 30001 filter.
No more lifter tapping or valvetrain clacking on startup. I actually burn less oil than dino 10-30, and have extended drain intervals.
My oil pressure has dropped about 4 psi across the rpm range when hot, but it's high enough.

So I guess I've become a believer of that article even though it flies in the face of conventional oil wisdom.

[B-300]

If your fuel gauge is also slow to respond this is because the gauges use an archacic voltage regulator for the gauges that responds slowly. It's voltage also varies with temperature.