ancashion

So, signed up for the forum a while back, only because of the FAQ above. It has been invaluable- a godsend really. I haven't had to post, as apparently I'm dangerous with the search function. Most of my issues have been resolved this way, or stumbled upon the fix by dumb luck.

This issue, however..

The truck; 1990 Dodge W250 CTD w/ banks intercooler kit, splitter and some other worthless goodies, none of which apply. I'm pretty good about my maintenence on this truck as well, if it matters. Between 238k and 250k

Day before yesterday I noticed while sitting idle at a stop light the oil pressure on the dummy gauge seemed lower than usual. Not bottomed out, but, just low. The sending unit was replaced when my vacuum pump failed and I replaced it and the power steering pump with a vain pump off a 97 and that was relatively recent so it's not that. I arrived at my destination, did my thing in the store and before I started it I checked my oil to make sure it was good. Good to go! Had a little bit of an odor to it.. I've been meaning to change out my lift pump as a precaution/prevenative maintenance anyways- I've been concerned it's been leaking diesel into the crankcase. I'm not 100% whether it is or not but I was always taught to be proactive, not reactive. It's at the top of my list until...

My issue started yesterday. I started my truck as usual. Let it idle for 15-20 minutes or so as it warmed up. The truck is parked at an incline. 20 degrees or so. I jumped in it and was trying to drive up my snowy, icy driveway. Every day that goes by I make it up it further and further. I'm in 4lo so I just creep up and when it won't go anymore I give it just enough fuel to get going again and back off. I get to a point where it won't go any further so I start slowly backing down. The brakes felt very very hard. Different then the day before, different then 5 minutes before. Almost as if there was no assist. Just before the vacuum pump went out on me I had redone all the brakes, bearings, races, all of it. From the brake booster and master cylinder to the pads. Haven't had any issues other than warping my front rotors from not adjusting my rear drums correctly, but, that's another issue all together.

Anyways, brakes feel strange/different. Hard, in the beginning. Worthless almost. If you keep applying pressure though, look out because eventually it seems the pressure builds and suddenly it stops on a dime. My parking brake also falls to a different position when it's applied. It now goes all the way to the floor when before, it only went halfway down. It still works, it's just in a different position.

So I check my brake fluid. It's good there. I look around under the truck for any leaks. Good there too. I look for seepage coming from the rear drums- nothing. I check the proportioning valve in the frame rail- dry. Ok.. not a fluid leaking issue. At least not one that I can obviously see at the moment.

With the engine running I pop off the hose that goes to the booster and feel for vacuum. It's got it. I don't know how much, but there is some. It won't leave a hicky on my finger when I cover up the hole with my thumb that's for sure but it takes some effort to remove my thumb. I put it back on and decide to do the equivalent of hit it with a hammer- I take the truck for a drive. Brakes are hammered. They're hard in the beginning, then start to go soft. As they go softer and the pedal falls, the brakes work better and better, eventually stopping the truck harshly. If you continue to apply steady and hard pressure to the brake pedal, eventually you can get it to the floor or just about.

Funny thing is, the pedal feel is constantly changing. Sometimes it works as usual. Other times, hardly at all. Odd. Pumping the brake yields no different result. It's still hard at first, eventually (3/4 to a full second later) going soft.

So I'm driving the truck and it seems like the engine is louder than usual. Something doesn't sound quite right with it. As I'm noticing this odd sound, suddenly, it disappears. She quiets right down, but feels low on power. Feels like it stumbles. I let off the skinny pedal but she doesn't die. Idles a little strange for a second is all. Continues to run. No smoke from the tail pipe. Starts well, idles well. I can't quite put my finger on whether it is down on power or not.. just, again, subtle changes here. They're noticable only to the point where you think something is wrong. The engine noise was this way, the power being down is this way.. something's just off.

I drive the truck home. I switch off the defrost and put on the heat. It's snowy here. It's cold. thing is stuck in between heat and defrost. Blessing as far as I'm concerned but it refuses switch to defrost only, vent only, heat only. It refuses to budge. Another in the long line of issues here.

I get home, and I hop on dtr. I start searching. I find the heater controls are vacuum actuated. Ok, didn't know that but right on. This could explain my brake issues as well. Vacuum. I hop under the hood again to fiddle around with some vacuum lines doing a brief check for leaks when out of the corner of my eye I see..

Oil seepage from the dipstick tube. It's at the top, where you insert the dipstick. That's a strange place to have a leak I thought. A quick google search and my heart sank.. rings. Just my luck. Blow by. . All these vacuum and brake issues at this point are a non issue. I just put brand new tires on the truck too- !

I can't remember if when I checked my oil the other day if there was any seepage. I wished I could. I wished I had thought to check for it in the first place. I yanked off oil filler cap and yep- white smoke coming out in a quick puff puff puff as you would expect to see a gasoline v8 run with a single fouled plug. It's cold here though, so, it could be heat. I put my hand over it and I don't feel much pressure. Nor does my hand come away oily. Gases are definitely coming out though.

At this point I'm thinking.. maybe the truck is done for. Maybe I pushed it too hard. Maybe it's just her time. But I can't shake the thought that it all seemed to have happened at ONE time. Brakes, blowby, HVAC, Parking brake... I try not to believe in coincidences. Particularly with mechanical objects.

So, I spent last night with 12 tabs open on my browser searching for issues. I can't find whether a vacuum pump definitively goes bad and starts pressurizing the crankcase or not. I can't even find a vacuum diagram for this truck. There's not much in the way of vacuum lines really but it would be nice to have some confirmation that what I'm seeing is correct. I don't really know what to think.

So far I've searched quickly for vacuum line breaks but haven't found any. I know I'm getting vacuum from the pump. How much is a mystery and until I make it two hours to the parts store for a gauge I won't know for sure. The vacuum in the line is there. It's not instant. It builds when you close your thumb over it but it takes a half a second or so. I did start the truck, let it run for a minute or so, stop the engine and pulled off a vacuum line hoping to hear a hiss but I didn't hear anything. I'm going to try this test again today now that it's daylight.

The oil seepage from the dipstick tube isn't constant. It's not a steady flow. It could be my turbo has had it and is pressurizing the system when I'm on boost. It could be too much pressure in the crankcase but I'm not about to tear the side of the engine apart to clean the ventilator- I'll drill holes in the valve covers and insert filters before I do that.

These could all be a related issue or they could all be separate. I'm open to suggestions at this point on where to look. If anyone has had any of these symptoms please advise. I'm going to start the trouble shooting by looking for vacuum leaks. Isolate and interrogate. I'll plug off the hvac. I have no cruise control so it's not that. There's an odd device on the drivers side fender under the hood hinge that gets vacuum but if I can find out what it is. Again, no vacuum diagram to look at so if you have one or know where one is at I'll offer you a coke and a smile. Google and every cummins board I search yields me zero results.

If no vacuum leak I guess I need to look at the amount of vacuum the pump is achieving. Again, I have found plenty of references to the vacuum pump becoming a compressor but nothing definitive. It all seems like hearsay. I don't have tons of blowby so I don't know if this would be the issue either.

The rear brakes will need to be adjusted properly before I start the master cylinder interrogation and I'll do that just as soon as I've determined there's no vacuum leak and the vacuum system is functioning properly.

Totally open to ideas and suggestions at this point. I got some things to check but I'm pretty well stumped.

Thanks for any help in advance.

Cheers

tl;dr Truck was fine one day and suddenly I have issues with my brakes and hvac controls. At the same time, the engine makes a noise I can't explain and suddenly disappears, but seems down on power. There's oil seepage from the dipstick tube but not constantly. All these issues can be related, or unrelated and I'm looking for guidance. I'm starting with vacuum related diagnostics but am open to suggestions on where to look. My search for a vacuum diagram has yielded no results so if you could offer one, please do.

(edited to apologize for the wall of text/novel. I can be long winded sometimes.)

maybe368

First off, welcome to the board and wow, that is a long post. What I have to say about my experience, with the same truck as you, is is that rebuilt boosters are notoriously unreliable. I had every malady possible with the brakes and they weren't completely good until I converted to rear disks. There was a recent thread about bleeding the rears with a fluid filled reservoir. Check you vacuum at the booster, Should be between 16 and 25 inches of water, IIRC, good luck ...Mark

jogl

x2, check, fix, vacuum first, go from there.

JP.

P.S.: I think that Maybe meant inches of Mercury.

JP.

BC847

Vacuum-pump is showing its age. Most notably at idle. It gets worse as the outdoor air temperature drops in my experience.

dB Zac

time to isolate some things from the others. Disconnect your brake booster and plug the check valve fitting (since this is also where your HVAC gets its vacuum it will have to stay on the hose). Once that is done, check your HVAC box for normal operation. Change modes a bunch of times, waiting to verify they are as they should be before changing again. This should be an easy task for the vac pump. If the HVAC operates as it should with out the booster connected (but the nipple on the check valve capped off), reconnect the booster, give it a few to level out and then try the AC and heat functions again, making sure not to apply the brakes at all. If the HVAC box acts at all different, I think the booster is your issue. If not, apply the brake and hold it and go threw the HVAC settings agian. If any functions fail, again its your booster, if not, pump the brakes and see if the HVAC box has any issues. If it does, it could be the pump or booster, get a vac gauge.

Now, as for blow by, sounds like you have a open and shut case but you don't want it to be true. If you really want to confirm it without tear down, you will need to pull the injectors and do compression test, It takes and adapter. the over all # isn't the important thing, you want all of the cyl to be about the same #, if one is way off, you have a problem.

patdaly

First thing is get the Vacuum correct. Then I would look at your suspected puffing issue, I think it will have resolved itself. Diesels by their very nature of compression ignition will puff more than a gasser.

When she starts using oil is when I would get worried.

ancashion

I had hoped more information would be helpful

I don't hear any hissing from the booster either in the cab or in the engine compartment. Feeling around it while the engine is running yields no results either. Not to say its not bad of course.. Rear discs must be nice!

Thanks for your help.

ancashion

Thank you for the welcome.

The vacuum pump is less than a year old. At this point, without the proper equipment I can't say definitively but I think the chances are relatively low.

Thanks for your help.

Isolation was today's war path. I first checked the check valve on the booster- good. I then capped both the hvac control line and the mystery line- no difference in braking ability. I'm still getting an assist from the booster. One thing I think I have figured out though is the combination of the parking brake landing in a different spot and the sudden surge of braking power from the rear wheels moments after the pedal begins to fall leads me to believe the issue lies with the rear brakes suddenly being out of adjustment. You step on the brakes, the truck begins to slow. The pedal continues to fall and at a point, the truck begins to slow at an increasing rate. I'm guessing at that point the rear brakes are beginning to engage. Stay on it and the truck will stand on its nose. Interesting that nothing had changed over the course of two days, but obviously something did. Why, is the question.

I'll reserve my opinion on the blow by for now. I understand the engine makes a mess of itself when it's the rings that are shot and that certainly isn't the case. I lose no oil, and have no smoke coming from the pipe. I also understand that these older 6bts make a considable amount of blow by as "normal." as for the smoke/steam emminating from the breather tube and oil filler tube, this is the coldest environment I've lived in so far and I just moved here. It could simply be temperature related and I am hyper critical at the moment. I could also have rose colored glasses on. Certainly, I hope it's not the case of failed rings but my diagnosis will take me where it will.

Tomorrow I will go to town for a vacuum tester. Also I will acquire the items necessary to change my oil. I will cut apart the filter and inspect for metal shavings. I also, years ago, installed a magnet on the oil drain bolt and will inspect that as well.

Thanks for your help.

ancashion

One thing at a time. You're right. She uses no oil and blows no smoke. My fingers are crossed on this one!

Thanks for your reply

ancashion

Update...

Rear drums have been adjusted. Much of the slack has been taken out of the pedal. It no longer has a "second" brake engagement as it feels like front and rears are engaging at the same time. Parking brake pedal no longer goes to the floor so my hypothesis seems correct. That being said...

Brake pedal feel still feels off. It feels like if you put your foot on the brakes there's an initial light brake, then the system figures out you want brakes and it stands on its nose. They are not instant. Nor are they consistent.

To reiterate, the pedal has an initial feel of no brake assist. After a moment, the pedal falls slightly and the brakes begin to engage. As if pressure in the booster takes a moment to begin the assist rather than it being instant.

A vacuum test is on soon as I get the required tools. Keep the suggestions and theories coming! Somewhere, there's a solution. This can't be the first time this has happened to anyone!

ancashion

Ok. This yielded some results. Except, not as you said. Everything hooked up, engine running, heater on is the start. Change hvac to vent, nothing happens. Ok. Step on the brake, hvac changes to your selected setting. Change hvac to defrost, with foot off the brake and nothing happens. Let's minutes pass and step on the brake and the defrost comes on.

It's happening like you say, but in opposite.

Thoughts?

dB Zac

It's possible that your check valve is bad. Since the booster houses a large amount of vacuum it acts as a vac can. When you hit the brakes you pump some of that vacuum back. Out. Even if the check valve is bad, I feel that your vac pump is also bad. Get a gauge and check it since they aren't cheap.

Sent from my Transformer Prime TF201 using Tapatalk

ancashion

Booster must be leaking before the pedal is depressed. Depressing the pedal must seal the leak and it takes that "moment" for the vacuum pump to supply vacuum. Thus why the hvac controls work when the pedal is depressed and also why the brakes take a moment to "turn on."

For clarification, the hvac controls don't work if you just blip the brake pedal. You must hold the pedal. If you give it a second before you hit the vent or defrost, it happens quickly. If you hit the vent or defrost and then apply the brake it takes a second or two before it switches over

Thoughts?

ancashion

Thanks for following up.

I did check the check valve on the booster. It functioned correctly.

I'll check the check valve on the vacuum pump tomorrow.

patdaly

As strange is it sounds, I think you have hit it. To verify, remove the booster from the system ( plug off big vacuum line to booster ) and see if the heater switches normally.

If it does, I would replace the booster.

If it doesn't, time to call the priest for the exorcism.