Engine/Transmission (1994 - 1998) Oil in vacuum lines

[T-Bone]

Well, I’ve been doing some testing and the vacuum pump pulls at least 20 inches. I think my Mity Vac gauge maxes out at that. The vacuum hose harness does not leak on the driver's side. However, whatever is on the other end of the line that runs across the top of the fire wall to the passenger side and into the firewall behind the airbox (at least that is where it appears to be going) will not hold a vacuum. I am digging through the Service Manual but am not having a lot of luck determining what is on the other end of that line. Does anybody happen to know what is on the end of this vacuum line?



Thanks,

T-Bone

 

[Joe G.]

That vacuum line goes thru the firewall to all the heater/AC stuff. There is a rubber connector just before it goes thru the fire wall. Make sure that the lines there are in good shape and the connector is sealing the joint. The heat from the exhaust manifold and down pipe can cause problems. At least that's the way it is on my '95.

 

[T-Bone]

Thanks Joe,



The vacuum system will hold a vacuum on the drivers side of that connection and that connection appears to be in good shape. When I put a vacuum on the hose that goes into the firewall, it will not hold the vacuum. I need to find what's on the other side and diagnose. Hmmm.



T-Bone

 

[Joe G.]

I was under there on mine a few weeks ago. Took the whole mess apart including hauling the dash out and putting it on my work bench. The problem was a collapsed hose in that connector. You may be able to see the connector points under the dash without taking it out. Do you have a service manual? If you do your might decide to take the dash out. It's not that hard unless you have a bunch of gauges and switches like I have. You need the service manual to do it. I don't remember all the steps. If you remove the little panel where the air routing is selected you can get at the vacuum hoses on the back of it. You should be able to see a vacuum junction block looking thru that hole. Maybe by straining to look at it from below with the knee bolster out. There is also a vacuum junction block under the glove box. It is also a PITA to get a good look at.

 

[T-Bone]

I’ll take a look in the morning and see what I can see on the actuators on the dash side of the fire wall. I do have a DC Service Manual but am not sure I am comfortable pulling the dash. My plan is to pull the dash bezel and get to the heater/AC vacuum controls to test them for vacuum. Am I on track here?



My theory at this point is that there is a vacuum line or actuator problem past the line that enters the fire wall behind the air box. Is this what feeds the vacuum junction block under the glove box? I just need to trace things out and then try and get to them without pulling the dash. I just hate to get too far into things – no shop and it’s about 25 degrees right now.



Thanks,

T-Bone

 

[JMauro]

FWIW i recently installed a Pacbrake and at the same time redid the vacuum line/s from the pump to the firewalll. they use a nice plastic line but all the ends are rubber which the oil will attack and make soft, plus there were a bunch of unneeded junctions ect. . i just replaced the whole mess with some vacuum hose from the local hardware store. i'm not sure how good the service manual is (it may have a color coded schematic and testing procedure) but if you pull the dash bezel you could probably check the operation of the vacuum motors from the back of the control panel. if you do this just be careful with the panel as plastic can be unforgiving in the cold. i'm not sure i'd want to/would pull the dash in freezing weather. worse case you might be able to get to the motor that controls the door for defrost ect. and wire it in the position you need. just take your time and read the manuel it sounds like you have/are getting the basic idea... heck just think how good you'll feel if you save a couple of thou.

 

[T-Bone]

JMauro,



Thanks for the tips and encouragement. I will be extra careful on the plastic. I may have to see what kind of poking around I can do without pulling too many things apart.



T-Bone

 

[Joe G.]

As far as I can tell the vacuum line comes from the firewall to the dashboard control. From there it goes to the junction block under the dash and the one under the glove box. Not real sure about that, but that is what it looks like. I found my problem, before I had to take all that apart.



I did use the opportunity of having the dashboard on my work bench to cable up the wiring mess that I had made under there for mods.

 

[T-Bone]

Well, the line going into the firewall on the passenger side behind the airbox is a "hard line". I was hoping it was a soft line that had gone bad (not as lucky as you, Joe!). I can't see anything on inside of the truck except one blue line on the bottom of the blower motor. According to the Service Manual, one of the actuators is on the top of the blower motor. I think I want to try and pull the glove box but it is only 30 degrees and I'm afraid of breaking plastic parts. This may have to wait.



btw. I did plug off the section of the vacuum harness with the leak and it appears that it is the heat/AC stuff. I have 4x4 back and will need to check the cruise. The dealer forgot to put the elbow back on the cruise servo so I can’t hook that up. They also forgot the main elbow on the vacuum pump but I had a spare piece that will work (at least temporarily).



T-Bone

 

[T-Bone]

I followed the Service Manual testing procedures for vacuum controls. Here is what happened:



Remove cup holder. Remove ash tray. Pull the dash trim. Pull the heater/air conditioning controls. Remove vacuum assembly from the back of the controls. Test each line. The only lines that did not hold a vacuum are the black line and the yellow line. Not sure about the black (vacuum reservoir). The yellow line runs the panel-defrost actuator door. This actuator is located right above the go fast pedal. I was able to remove it (small problem, I broke a plastic tab on the connector - too cold or too rough?) and test it. The actuator will not hold a vacuum. So, I’ll need to replace it. I also am assuming that I need to replace the check valve on the vacuum pump and clean out the lines best I can. I plan on using electrical cleaner and some compressed air. We’ll see how that goes…



I will pull the actuator apart when I get a new one to check the internals. I’m curious if there is oil in there or not. If there is oil, I’m probably just a short time away from other components failing.



Thanks for all the help and encouragement.



Here is a pic of testing the vacuum ports on the controls and the test of the panel-defrost actuator.

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T-bone

 

[T-Bone]

Well, it was above 50 degrees at the house so I tore into things this afternoon. I disassemble the faulty actuator and found oil. I guess the oil broke down the rubber boot and caused a leak. So, I cleaned all the lines I could with electrical cleaner and installed the replacement actuator. I also removed the check valve from the side of the vacuum pump. I guess I was expecting something else, but there is just a ball and spring. Kinda makes sense for a “check valve”. There was oil on the check ball.



My question is – Should there be oil on the check valve ball? Kinda seems like this is a sign of an internal leak in the pump. If so, do the vacuum pump rebuild kits contain the required seals or do they address external leaks? I do not have any external oil leaks on the vacuum pump.



Thanks for all the help on this one. I'm learning, albeit very slowly.

T-Bone

 

[Andy Redmond]

T-Bone:



The oil degrades the rubber and makes it sticky then faulty (or vacuum that can't overcome the oil and goo). The oil got into the vacuum lines because of the ck. valve failure, albeit perhaps intermittant failure.



When the truck is turned off, no more vacuum is produced (its pulling a vacuum towards the vacuum pump from all vac. components). If the ck. ball/valve doesn't hold we have things going both ways rather than one way as it should. As the acuator for example loses "prime" without the ck. valve working properly it "wicks" engine oil into the vacuum lines. I think its a gradual process over time and many cycles before it eventually migrates into the dash vac. components. Gravity also takes affect as the ones lower in the blower box are most affected typically.



You discovered the dirty side of the vacuum with oil, the oil is necessary as a lubricant for the vacuum pump. Everything is fine, unless the ck. valves failes even at times and contaminates the vac. sys. with oil.



You can cut the large rubber line leaving the ck. valve at the vaccuum pump and add an additional inline one way ck. valve that will fit your tubing. I would source the valve before cutting the tubing. I also sometimes add a second ck. valve to the line just before it enters the cab near the a/c dryer (accumalator).



I think I gave the the Mopar and Cummins part no for a new oem ck. valve. I would disassy the one you have and replace the "guts" with the internal parts from the new one from the Cummins part no (most reasonable) or simply replace the unit with the Mopar part no for complete parts change with minimal hassle.



I think the plastic retainer under the sping that guides the ck. valve ball in the metal/brass bore gets cocked or crooked causing insufficent seal and incomplete closing when the engine is shut down. Likely over the course of months or years the oil built up until enough was in the system to cause failures of certain components.



I see no need to remove or disassy the vac. pump, it operates as designed from your description, save the issue with the ck. valve.



Pat yourself on the back and think of the money you save by diving in even though your hands are still cut and bruised and cold?



50 deg. ? It was colder in Dallas today!



Good luck

Andy

 

[T-Bone]

Thanks Andy. What you said makes perfect sense now that I think about it and have seen the parts torn down. I ordered a check valve from Cummins. The Cummins part was $18. Dodge quoted $160. However, the part I got from Cummins will not replace the factory part directly due to different threads. I think I remember you saying there are a few different types. I’m hoping I can use your idea to put the new check valve in-line or Frankenstein one together. I will post pics of the parts if I get a chance. If I cannot put the Cummins part in-line, I may try and source the correct replacement part. I’m hoping there are not more oil contaminated parts waiting to fail.



A few cuts and bruises is right on. It’s kinda tight in there! Thanks again for all the time and help. The TDR and its members are the greatest!



T-Bone

 

[Andy Redmond]

I would disassy the cummins part carefully on your workbench, then disassy what is on your truck.



Use the "guts/innards" from the Cummins part to "rebuild" your oem design. I doubt the Cummins part will thread into the vacuum pump. I had a difficult time sourcing metric reducer bushings, so I gave up.



I have several trucks running around with this "fix" with no oil in the vac. sys.



For starters, if you add a ck. valve maybe look at a Napa or other parts catalog to source the proper diameter "inline" design. I wouldn't use the Cummins version as an "aux. " ck. valve, surely we can find something that looks a bit nicer than that "hunk o iron. " Although a 90 deg. rather than a straight in/out style (which would look like an oem add on) the 94-96 model ram diesels have a brake booster ck. valve that is usually the right size of the vac. line that exits the vac. pump.



You might also try a Ford dealer, they must use a plethora of ck. valves, the dealer sometimes will let me pilfer thru the parts pins to find something that will meet my requirement.



Make sure your "electrical cleaner" is safe for rubber. I prefer "electronic" and electrical "contact" cleaner, for safe use on sensitive rubber and plastic parts and for its quick evaporation properties. CRC makes some in a red can avail at Napa or any chain auto store for less than $5 per can.

 

[T-Bone]

Andy, when I pulled the oem check valve, I’m not sure it went back together with the spring in the correct position (against the ball). If I can replace the innards of the oem check valve with the innards of the Cummins part that would be great! I will definitely check that. My concern is being able to reinstall the check valve with everything lined up. This would be easy if I could rotate the pump on a bench. Just not so easy when trying to feed the check valve assembly into the side of the pump.



My alternative approach was to use a piece of rubber hose between the oem valve and the Cummins valve attached with hose clamps. The oem check valve has a barbed type fitting that appears to be hose friendly. The Cummins check valve has a threaded end that would need a coupler to attach the hose. Does this make sense? I will take pictures this afternoon.



T-Bone

 

[Andy Redmond]

T-Bone:



Remove the 6 fasteners on the intake manifold. (four, one and the dipstick support bolt, all 10mm heads and 18 ft. lb torque spec. ). Go under the truck and loosen the charge air cooler clamp (innercooler end 7/16 deep or 11mm deep socket. . 44 inch lbs = torque spec. . ) and remove as an assy, for better access. Probably a good idea to cover the intake opening and the innercooler opening to prevent the entry of FOD.



You can also remove the battery and battery box if you need more clearance, although I think the first will make plenty of room.



Although the parts my look different somewhat they should interchange.

 

[T-Bone]

Thanks for the tip. Getting the intake pipe out of the way would be great! I have another thing that will be moved at the same time - I have a PrimeLoc. I'm planning to start in about 30 minutes. Wish me luck! If I wasn't such a wimp, I think this would actually be fairly easy.

T-Bone

 

[T-Bone]

I wrapped this up today. I was able to take the Cummins check valve apart and use the nipple/ball seat, ball, and spring. I did not use the piece on the right side of the Cummins valve. I did use the plastic spring seat from the OEM part. The top valve is the OEM valve. The Cummins valve on the bottom.



In order to get everything installed back in the vacuum pump, I put a thin coat of grease on the spring seat to hold it in place on the side of the pump and the spring to it. Kinda hard to explain, but when you put the spring seat and spring in the pump prior to threading in the housing, it falls down to the bottom of the hole and does not make contact with the check ball.



The system now holds enough vacuum without the engine running that the air no longer defaults to the defrost position (i. e. the panel-defrost actuator is being held in the correct position.



Thanks, Andy and the rest of you folks, for all your help. Could not have done it without you. This saved me $1950.



T-Bone

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[dvieira]

any idea of what kind of secondary check valve that i could use, i have already replace the vacuum pump check valve twice. . and clean out the lines, and today [monday] will replace the actuator valve under dash my foot pedal for the third time, and we are having a heat wave [kalifornia], today i will also buy/order 3 more actuator valves, in case they stop making them in the future, buy does anybody have any idea of what kind of secondary filter/ck valve i could buy to place downstream of the main ck valve... . thanks. .

 

[Andy Redmond]

Assure that the ck. valve at the vacuum pump seats well. Then you could get some tees and soft rubber tubing for connectors run the vacuum supply through a created low spot, at the bottom of the low spot, insert your plumbed filter (maybe a filter like an automotive spray gun/auto body application (round orange disk filters that attach just before the air line enters the HVLP paint gun). Or you could install a drain valve and drain the low spot occasionally.



I would back flush from the acuator back thru the lines with QD contact cleaner by CRC available at any auto parts store for less than $5 p. can.



Good luck

Andy