Cummins/Jacobs Exhaust Brake

[Schrowang]

I had a JB installed on my 04. 5 with and NV5600. That was in 2006 and it was working just fine when I traded the truck to a dealer for a 2010. BTW there were just a little over 90K miles on the JB (truck had 118K).



I tend to believe that what we see on this forum are the problems. Seems like very few of us recognize good service and give kudos where they're deserved.

 

[Prairie Dog]

I'm sure the Jake is a good performer but given it dubious failure history (no matter what the reason) why not go with one of the many other great quality systems?
And as a bonus, you get an air source.

 

[mroodzant]

point taken. I don't mean to sound disgruntled. My truck serves me well! It does exactly what I demand out of it. I am just crabby at the money Ive been shelling out the past few months.

What would be the best way for me to test for a vacuum leak? Can I without special tools or training?

 

[mroodzant]

OK, I replaced the belt with a stock one. Then I pulled the Vac pump off and drove to my local NAPA store. gave them the part numbers supplied here by all you great TDR members. The Napa pump is definitely a different pump. The diaphragm is the same though. So I pulled the diaphragm off and now I have fixed the Vac pump. I would still like to do a Vacuum Leak test. How is the best way to do that??? Also, could I put a Vacuum gauge inline umber the hood somewhere?

Matt

 

[AH64ID]

Put a vacuum tester on the end of the hose that attaches to the pump. Apply the proper vacuum (25 in hg???) and see if it holds for a few minutes.



It would be easy to plumb a gauge, just need a gauge and a "T".

 

[ELK311]

Just had my vacuum pump go bad (dealer installed brake) at 66,000 miles. Dodge dealer wanted $997 plus $204. 51 labor $1,201. 51. I've ordered one from GENO's for $359 !!!

 

[PFlory]

My first pump went out with about 32K, and I did the same as Geno's is 4 miles away and Cummins South was about 40 miles.

I changed mine out in about thirty minutes. Then it took about an hour to get the friggin belt back on.

For the record, if the pump ever fails, the stock belt can be reinstalled, bi-passing the pump pulley.

When I replaced the pump, I found that the dealer that installed the brake originally didn't put a hose clamp on the vacuum hose where connected to the pump. I added one when I replaced the pump, and the new one has over 40K, so far so good.

 

[BrianJ]

Mine went out a couple months ago (88,000 miles) and I got a new pump from Cummins for $205. Dealer also quoted me over $1k installed.

 

[amsoilman]

My 03' had 100K on it when sold to my Grandson in October last year, and the belt for the "Jacobs" exhaust brake vacuum pump had never been changed... ... ... ... ... ... ... ... . must have been lucky according to some!

 

[mroodzant]

I would guess you have a vacuum leak, which is putting too much of the load on the pump, and introducing contaminantes. According to Jacobs most recurring failures are due to vacuum leaks.

Getting back to you on the vac leak. I bought a leak test kit pulled 25 mm for 30 minutes. it held fine. I dont know why I go through vac pumps. oh well. I replaced the diaphram and now it works like new.

 

[AH64ID]

Well thats good and bad, since you still don't know why you go thru pumps.

 

[mwilson]

Getting back to you on the vac leak. I bought a leak test kit pulled 25 mm for 30 minutes. it held fine. I dont know why I go through vac pumps. oh well. I replaced the diaphram and now it works like new.

Did you do the test both with the brake both applied and at rest???

If not, you need to activate the solenoid with a jumper wire under vacuum to see if the leak occurs while the brake is applied.



Just a thought...



Mike.

 

[ELK311]

Being the cheap retired guy that I am I opted for the diaphragm only at $169 and it was delivered to my house last night. I hope to have it replaced this afternoon. I'm dreading the serpentine belt, I ordered a replacement so I think I'll install it and use the old one as a spare. wish me luck!



All-in-all $169 is much better than $1,200 !!!

 

[ELK311]

I must say that since I bought this truck new it has been in the "shop" three times and all three times were due to the Jacobs Brake... just sayin'

 

[mroodzant]

Did you do the test both with the brake both applied and at rest???

If not, you need to activate the solenoid with a jumper wire under vacuum to see if the leak occurs while the brake is applied.



Just a thought...



Mike.

I did not but I will when I get a chance. How do I do the jumper?