[catch2otwo]

Here is what happened. I decided to use the oil pressure feature on my attitude and found it interesting that when it said 60psi, my trucks oil pressure gauge said over 60, somewhere between the 60 hash mark and the next one.

Anyway, on my way from mass to ct yesterday running around 75 @ 2500 rpm, i noticed the oil pressure constantly dropping. Went to around 40ish, then 30s. We stopped, and there was oil dropping off all under the truck. My drivers side rear wheels were covered and so was the back of the bed.

I checked around the motor and didnt notice any leaks, so it leads me to believe its coming from the "blowby" tube. I was told that it was the blow by tube and that some blow by is normal. But i lost around 2 gallons of oil. oil pressure would go to zero when truck was at a stop.

From CT back to Rochester ny, we ran no more then 2000rpm around 55mph the whole way. Oil pressure was around 55-57psi and idle is around 25. Stopped every 100 miles or so and checked oil level and it was fine. Not much oil on the bottom of the truck either.

So whats the deal? Truck is stock except for an edge programmer usually kept on mileage level.

I tried to check for codes, but when i went to turn the key to the crank position three times and then on the third time left it on "on" i didnt see any messages. actually nothing happened

 

[DIESELMAN3500]

that code/key trick will only work on trucks 2001 and newer sometimes late 2000, not our 98.5 unfortunately. but the CCV shouldnt vent a whole 2 gallons, if the truck was literally dripping oil i highly doubt its the CCV (crank case vent) but then again some guys have had the vent juke puke oil when going up steep driveways or down but ive never heard of it happening on straight highway runs. i would check the power steering pump/vacuum pump under the VP44 make sure the seal didnt let go thats the only place that i can see a large volume of oil coming out of. it could e hidden by the CCV grit and grease making u think its that, but the vacuum pump and powersteering pump run off the same gear and the vacuum pump oil seal is a common failure. dash oil pressure guage is just a dummy guage tho the edge is way more accuarate.
let us know what u find.

 

[catch2otwo]

thanks dieselman, I didnt know the ps used the same engine oil. I will check it to make sure. However, I have to get to work this week and dont really have a choice but to drive. Are my oil pressures ok? mid 50s running down the road and about 25ish idling? I dont want to hurt anything, but if those are ok, im going to drive it until i get some time off.

 

[DIESELMAN3500]

no, im sorry if i confused you a little bit, but the vacumm pump has a seal in it bc it is semi lubricated i do believe and there is also an output shaft to drive the power steering pump, both of which are driven off of the front gears in the front timing case. but this seal usually goes and pukes oil. the vacuum pump comes directly off the front cover then a seal and then the power steerin pump behind it youll see once you take a look. the seal between the power steering pump and the vacuum pump is what goes and that seal keeps in the engine oil. power steering pump is a seperate unit just held on with the feet with nuts. but this is the first place i would look. maybe degrease everything and then watch the bottom at idle see if you see any leaks.
oil pressures seem ok, 25-28 at idle, and 50-60 at cruising, just dont go chancing anything, running that engine outa oil will be catastrophic to everything including the turbo but that would be the least of your worries lol.
ive never seen a seal fail completely, but if u lost 2 gallons in that short of time id be cautious, it only takes a few seconds and things will go south at a compounding rate
keep us informed of ur findings

 

[catch2otwo]

I see what your saying. Ill check it when i get out, but oil pressure was steady today. I will be checking the level before i leave too. I looked under the truck when i got to work and nothing seemed out of the ordinary. Maybe it was an rpm issue, too high for too long, but i dont see why would wouldnt be able to operate within its operating range for as long as you wanted. i will check the seals and report back.

 

[dozer12216]

Is the heater working correctlly?? If the vacuum pump cannot hold a vacuum it will pump air into crankcase and cause blowby and oil loss. Generally hose at cowl comes loose.

 

[catch2otwo]

Is the heater working correctlly?? If the vacuum pump cannot hold a vacuum it will pump air into crankcase and cause blowby and oil loss. Generally hose at cowl comes loose.

My air is a little messed up. It only works on the highest level but its a resistor problem. And my settings control doesnt really work, aka it only blows to defrost. But the heat/cool works.

 

[dozer12216]

Let me explain again. The vacum pump generates a low pressure by pulling against a closed heater control vacuum system, in order to opeate heater doors, ect. Since it is stuck in defrost, the heater doors are not working correctlly. Probably because of no vacuum. If the vacuum pump has no restriction, it becomes a air pump into crankcase. Since it is positive displacement pump, the faster the engine turns the more air would be forced into crankcase and the more blowby you will have. So check the plastic tube from vac pump and plug or stop it up. Now see if problem is resolved with engine blowby and loss of oil.

 

[catch2otwo]

Let me explain again. The vacum pump generates a low pressure by pulling against a closed heater control vacuum system, in order to opeate heater doors, ect. Since it is stuck in defrost, the heater doors are not working correctlly. Probably because of no vacuum. If the vacuum pump has no restriction, it becomes a air pump into crankcase. Since it is positive displacement pump, the faster the engine turns the more air would be forced into crankcase and the more blowby you will have. So check the plastic tube from vac pump and plug or stop it up. Now see if problem is resolved with engine blowby and loss of oil.

thanks for the explanation. now for more stupid questions. where is the vac pump? :confused013:

btw, all the seals on the front of the motor were good.

 

[BigBlue]

Put a drop of oil on a piece of computer paper and let it sit for 24 hours. Come back and look at it. If it has a light ring around it then you have fuel in your oil and it's time to start testing injectors and replacing o-rings. That's the most usual answer when your truck starts dropping oil pressure and you suddenly have huge amounts of oil under your truck. I know. I've been there and done that.

 

[dozer12216]

The vacuum pump is thingy on left side of engine and is silver (aluminum) colored. It has the power steering pump attached. I attaches to back of front cover. Sort of inside the left battery and below. The left side is drivers side. It is also below the VP44 Injection pump.
Eventually you may find a black plastic tube from the aluminum vacauum thingy, and it goes toward the rear of engine compartment.Maybe you would be well advised to take to dealer.

 

[catch2otwo]

Put a drop of oil on a piece of computer paper and let it sit for 24 hours. Come back and look at it. If it has a light ring around it then you have fuel in your oil and it's time to start testing injectors and replacing o-rings. That's the most usual answer when your truck starts dropping oil pressure and you suddenly have huge amounts of oil under your truck. I know. I've been there and done that.

k i will do that. but will the drop in oil pressure be consistent. its acting now as it did before it all happened.

The vacuum pump is thingy on left side of engine and is silver (aluminum) colored. It has the power steering pump attached. I attaches to back of front cover. Sort of inside the left battery and below. The left side is drivers side. It is also below the VP44 Injection pump.
Eventually you may find a black plastic tube from the aluminum vacauum thingy, and it goes toward the rear of engine compartment.Maybe you would be well advised to take to dealer.

k i will check that. i'll prevent going to the dealer for now. im mechanically inclined, but this is my first diesel, just dont really know my way around it yet. thanks for the help

 

[blow'n smoke]

if your defrost is where your ac comes out then youve prob got a vacume leak and that can be from the line that runs across the firewall right at the top of the motor and down to the vacume pump(connected to the powersteering pump) start checking there!!

 

[catch2otwo]

sure enough found an unhooked vacuum line. must have knocked it loose when i changed my fuel filter. Plugged it back in and got my heater settings back. been checking the bottom of the truck the last week too, and there seems to be no more oil coming from the blowby tube. oil pressure is constant at around 58ish cruisin and 23-26 idle. thanks for the help, glad it wasnt something more serious