Vacuum pump issue I think

[leety]

Hi All,

 

My exhaust brake has been loosing it's verve so I took the truck to Banks Engineering, well, because they are not too far from here and thought it would be fun to visit the mother ship.  It was very fun!!! They gave me a tour of the campus, except the military work section, because then they would have to kill me. They are super nice and it's very impressive operation. But I digress.

 

So they told me the diaphragm is good on the exhaust brake can, that was my theory, and the Banks system tested out from the manufacturer. They didn't even charge me for that inspection. Super nice people!

 

What they told me is my vacuum pump is not providing enough vacuum, which is what is making my ebrake work.

 

I don't have time to deal with this myself so I have a shop who will be looking at it on Monday.

 

Is there anything else we should be looking at that could cause the deficiency in vacuum?

 

If the pump needs to be replaced can anyone recommend a brand of replacement part?

 

Seems the Dorman parts don't really last and I'm not too sure about the Cardone parts. The Mopar parts are ridiculously expensive $1,200 or something like that. 

 

Any pointers are welcome!

[IBMobile]

When Banks tested the vacuum, did they do it at the brake actuator and at the pump?  If at the pump, then the diagnosis is correct but if only tested at the exhaust brake, then there might be a vacuum hose or fitting that is leaking.  Did they inspect those components during their diagnosis?   

The rubber fittings disintegrate over time  

[leety]

23 minutes ago, IBMobile said:

When Banks tested the vacuum, did they do it at the brake actuator and at the pump?  If at the pump, then the diagnosis is correct but if only tested at the exhaust brake, then there might be a vacuum hose or fitting that is leaking.  Did they inspect those components during their diagnosis?   

The rubber fittings disintegrate over time  

I believe they did test the pump and found that it is not creating enough vacuum. He said he was getting a reading of 22 inhg at the pump. In the Dodge factory manual the minimum output is supposed to be 25 inhg. I will have the shop go through all the lines to make sure there are no leaks.

23 minutes ago, IBMobile said:

When Banks tested the vacuum, did they do it at the brake actuator and at the pump?  If at the pump, then the diagnosis is correct but if only tested at the exhaust brake, then there might be a vacuum hose or fitting that is leaking.  Did they inspect those components during their diagnosis?   

The rubber fittings disintegrate over time  

If the pump is hosed do you know what the best replacement/rebuild option would be. The shop does transmission repairs, the just did my differential upgrade from 3.55 to 3.73 so they can rebuild things.

Edited July 24, 2022 by IBMobile

[IBMobile]

They could rebuild it with parts from Geno's

https://www.genosgarage.com/product/GG10FV/engine-rebuild-kits-2

 

looking around, it seems that Cardone and Dorman are the two main choses for a rebuilt part.

[leety]

2 minutes ago, IBMobile said:

They could rebuild it with parts from Geno's

https://www.genosgarage.com/product/GG10FV/engine-rebuild-kits-2

 

looking around, it seems that Cardone and Dorman are the two main choses for a rebuilt part.

Thank you!

[wil440]

Rockauto lists 4 from 3 manufacturers SKP, Cardone and Dorman, might be cheaper to just bolt a new /reman one on than rebuilding guess it depends on the hourly rate

 

I rebuilt mine as shipping to the UK, duty and vat more than offset the time it took 

[Tractorman]

5 hours ago, leety said:

I believe they did test the pump and found that it is not creating enough vacuum. He said he was getting a reading of 22 inhg at the pump. In the Dodge factory manual the minimum output is supposed to be 25 inhg. I will have the shop go through all the lines to make sure there are no leaks

 

It is too bad Banks didn't say what the minimum required vacuum is for the exhaust brake actuator cylinder.  That would have been most informative.  I think it would be a lot closer to around 15"HG.

 

A faulty vacuum pump could be be a possibility for your problem, but I am inclined to think the problem is elsewhere - such as a vacuum leak or a faulty actuator seal (even though it supposedly tested okay).  For example, the actuator seal may perform fine when cold and then start leaking when ambient temperature rises around the actuator.  Or, vice versa.

 

Also, the FSM really is not that clear as to what vacuum pressure should be at engine idle.  The FSM states, "With the engine running, vacuum output should be a minimum of 25 inches, depending on engine speed."  It is that clause, "depending on engine speed" that leaves me wondering what the real value should be at idle. 

 

If it is believed that at least 25"HG is required to make the exhaust brake fully operational, then vacuum operated exhaust brakes would not work in high altitude locations.  Example:  Leadville Colorado at just under 10,000 ft elevation - current barometric reading  is 30.53"HG.  Station pressure (the absolute pressure) is currently just under 21.00"HG.  According to Banks the exhaust brake would not perform properly.  I disagree - I believe it would perform fine.  I have personally driven my truck over many 11,000 ft mountain passes and my vacuum operated exhaust brake (although a PacBrake) operated just fine.

 

The vacuum pumps on our trucks may need a seal replacement or a coupler replacement, but the vacuum pump portion of the pump is pretty bullet proof.  

 

I have been using a vacuum operated PacBrake actuator cylinder for well over 400,000 miles on my truck (70,0000 while installed on a '99 truck and 367,000 on my current truck).  I have gone through two actuator cylinders in which the seals were slowly destroyed by heat from the exhaust system.  The early symptoms were always intermittent and / or sluggish operation.  When I tested the cylinder using a vacuum hand pump, they would sometimes pass the test and sometimes not. 

 

Also, I recommend to not use worm-drive hose clamps on the rubber lines.  They tend to distort and cut the lines they intended to seal, sometimes creating leaks.   I recommend properly sized spring tension clamps - they handle vibration and thermal expansion / contraction very well.

 

So, after saying all of this, I would make absolutely sure there are no vacuum leaks on your truck and I would get a second opinion on the performance of the vacuum operated cylinder.

 

- John

 

 

 

[Tractorman]

@leety, I checked the on-line Banks vacuum operated exhaust brake owner's manual for 98.5-02 trucks.  Unfortunately, there is no information for testing the vacuum source in the troubleshooting section.  However, there is information for the 04.5-07 trucks where a vacuum pump is provided by Banks.  Here is part of what is stated,

 

"Connect this hose to a vacuum gauge while keeping the other end connected to the Vacuum Pump.  Make sure the truck is in park and start the engine. Measure the vacuum at 1900 RPM. The Pump should generate a minimum of 10 psi (20.4”Hg) of vacuum."

 

I think your vacuum pump is fine.

 

- John

[leety]

1 hour ago, Tractorman said:

 

It is too bad Banks didn't say what the minimum required vacuum is for the exhaust brake actuator cylinder.  That would have been most informative.  I think it would be a lot closer to around 15"HG.

 

A faulty vacuum pump could be be a possibility for your problem, but I am inclined to think the problem is elsewhere - such as a vacuum leak or a faulty actuator seal (even though it supposedly tested okay).  For example, the actuator seal may perform fine when cold and then start leaking when ambient temperature rises around the actuator.  Or, vice versa.

 

Also, the FSM really is not that clear as to what vacuum pressure should be at engine idle.  The FSM states, "With the engine running, vacuum output should be a minimum of 25 inches, depending on engine speed."  It is that clause, "depending on engine speed" that leaves me wondering what the real value should be at idle. 

 

If it is believed that at least 25"HG is required to make the exhaust brake fully operational, then vacuum operated exhaust brakes would not work in high altitude locations.  Example:  Leadville Colorado at just under 10,000 ft elevation - current barometric reading  is 30.53"HG.  Station pressure (the absolute pressure) is currently just under 21.00"HG.  According to Banks the exhaust brake would not perform properly.  I disagree - I believe it would perform fine.  I have personally driven my truck over many 11,000 ft mountain passes and my vacuum operated exhaust brake (although a PacBrake) operated just fine.

 

The vacuum pumps on our trucks may need a seal replacement or a coupler replacement, but the vacuum pump portion of the pump is pretty bullet proof.  

 

I have been using a vacuum operated PacBrake actuator cylinder for well over 400,000 miles on my truck (70,0000 while installed on a '99 truck and 367,000 on my current truck).  I have gone through two actuator cylinders in which the seals were slowly destroyed by heat from the exhaust system.  The early symptoms were always intermittent and / or sluggish operation.  When I tested the cylinder using a vacuum hand pump, they would sometimes pass the test and sometimes not. 

 

Also, I recommend to not use worm-drive hose clamps on the rubber lines.  They tend to distort and cut the lines they intended to seal, sometimes creating leaks.   I recommend properly sized spring tension clamps - they handle vibration and thermal expansion / contraction very well.

 

So, after saying all of this, I would make absolutely sure there are no vacuum leaks on your truck and I would get a second opinion on the performance of the vacuum operated cylinder.

 

- John

 

 

 

Thanks for all of that great info.  Yes that's why I'm taking it to a place I believe will do a comprehensive evaluation.

[Mopar1973Man]

Me personally I would replace all vacuum lines making sure there is no cracked plastics or fittings. Even if you used a different hose and hooked from the vacuum pump and directly to the exhaust brake it should move. If not iveseen exhaust brakes that have seized from lack of use.

[Max Tune]

I have this in my shed for when I have any problems. I'll replace everything from the pump to the firewall. If you put the part number into the Googler, there are many options. I just figured it's easier to replace it all rather than search for a failure point.....

[leety]

Just now, Max Tune said:

I have this in my shed for when I have any problems. I'll replace everything from the pump to the firewall. If you put the part number into the Googler, there are many options. I just figured it's easier to replace it all rather than search for a failure point.....

I like your style!

[leety]

19 hours ago, Mopar1973Man said:

Me personally I would replace all vacuum lines making sure there is no cracked plastics or fittings. Even if you used a different hose and hooked from the vacuum pump and directly to the exhaust brake it should move. If not iveseen exhaust brakes that have seized from lack of use.

What component seizes? I there a way to unsieze it?

[wil440]

8 minutes ago, leety said:

What component seizes? I there a way to unsieze it?

The pivot where it passes through the cast exhaust tube seizes, the shaft that the actuator rod connects to

 

I have 2 here one is absolutly solid, one is brand new but no canistor

[leety]

1 minute ago, wil440 said:

The pivot where it passes through the cast exhaust tube seizes, the shaft that the actuator rod connects to

 

I have 2 here one is absolutly solid, one is brand new but no canistor

Thanks good to know!

[wil440]

2 minutes ago, leety said:

Thanks good to know!

get a pair of mole grips or a wrench that fits the actuator lever and see if it moves, there is a spring in the canister so will take a little force to move , or if there is a little play in the actuator clevis pin you just might be able to see if it's free by wriggling it

[Mopar1973Man]

57 minutes ago, leety said:

What component seizes? I there a way to unsieze it?

The butterfly valve. Typically the brake is junk.

Edited July 26, 2022 by Mopar1973Man

[leety]

2 minutes ago, Mopar1973Man said:

The butterfly valve. Typically the brake is junk.

Got it thanks!

[Mopar1973Man]

This is why the old term holds true...

 

"Use It Or Lose It"

 

Mine was installed back at 20k miles and currently I'm at 449k miles and it's still working. I use it daily.

[leety]

Break back in service.  Vacuums leak found and corrected.  There appears to be 28 psi at the vacuum pump which exceeds the minimum of 25.

 

Thanks everyone for all of your comments and suggestions.