Need Help with Pacbrake

[Les Brandt]

After spending a wack of money replacing all the rotors, calipers and brake pads on our new to us 2001 Beaver, I wondered how a coach with only 39,000 miles can need a full brake job. After finding out on our last Monaco that the Pacbrake was seized, I decided to look at the Packrake on the Beaver and sure enough seized up solid.

I really have to question if people realize that the exhaust brake needs maintenance. It is a valuable braking tool and saves your brake system not to mention, possibly your life on a steep downgrade.

Our coach has a CAT 3126B 330hp engine. I need to replace the exhaust brake. We tried to free it, soak it, bang it and nothing works to free it. I need to replace it. It's a turbo mount style.

Anyone know where I can get a used one? Lots of new ones available obviously.

[Joel Ashley]

You might want to review this old thread from the Forum in case yours might still be salvageable

http://forum.bacrallies.com/m-1253574029/s-15/highlight-PAC+Brake/#num15

Joel

[Les Brandt]

You might want to review this old thread from the Forum in case yours might still be salvageable

http://forum.bacrallies.com/m-1253574029/s-15/highlight-PAC+Brake/#num15

Joel

Thanks Joel.

I did a search yesterday and read everything on the forum. I was kinda hoping there was something current someone knew. Like a place that was giving away new Pacbrakes for "free". LOL

[Gary Wolfer]

I do not know if you mean the butterfly is froze closed or partially closed or the air ram is somehow froze but I had a butterfly that was sticking closed. I would come off a hill with the exhaust brake on then hit the bottom give it throttle and no throttle or very little as the butterfly was stuck partially closed. My remedy was I took the exhaust brake off behind the turbo and disconnected the tailpipe. Took the exhaust brake to an automotive machine shop. They drove out the pins and took the butterfly out, honed the inside of the exhaust brake and ground the carbon off the butterfly, oiled and put it back together. Cost me less than 100 dollars and works like new.

[Les Brandt]

I do not know if you mean the butterfly is froze closed or partially closed or the air ram is somehow froze but I had a butterfly that was sticking closed. I would come off a hill with the exhaust brake on then hit the bottom give it throttle and no throttle or very little as the butterfly was stuck partially closed. My remedy was I took the exhaust brake off behind the turbo and disconnected the tailpipe. Took the exhaust brake to an automotive machine shop. They drove out the pins and took the butterfly out, honed the inside of the exhaust brake and ground the carbon off the butterfly, oiled and put it back together. Cost me less than 100 dollars and works like new.

Thanks Gary.

The butterfly valve is seized open. The shop removed the brake and saturated it overnight in penetrating oil and they tried using a battery of tools on it to free it. Including air hammers. All it has done is disfigure the parts. I think she's a goner as far a freeing it. I tried using a 3 pound sledge and a chisel and the only thing that moved was me when the hammer glanced off the chisel and hit my hand by the wrist.
I think I invented a few new words yesterday when that happened! LOL

[Stan Simpson]

Good luck Les, but trust me....those words aren't new!  

Stan

[Joel Ashley]

Make sure with a new one that you use the prescribed lube regularly, and remember some malfunctions have been due to a seized solenoid rather than the valve mechanism.  As others say, though, the best prevention is probably regular use so corrosion can't get a bite anywhere.

You might shop around a bit for the replacement, as though the style of brake is commonly called "PAC Brake", ours is actually made by Jacob's, the inventor of the "Jake Brake", a different type of animal altogether;  ie- there is more than one manufacturer of what you want.

Joel

[Jerry Emert]

You guys are killing me!  Every time I look there is another thing that needs maintenance.  Geeez!

[Gerald Farris]

Jerry,
Your Thunder does not have an exhaust brake, so that is one maintenance item that you do not need to be concerned with.

Gerald

[Jerry Emert]

Jerry,
Your Thunder does not have an exhaust brake, so that is one maintenance item that you do not need to be concerned with.

Gerald

Yay, what is the Jake brake?  Does it need maint?

[Gerald Farris]

Jerry,
The term "Jake Brake" is used for the compression brake on a diesel engine that was developed by the Jacobs Company. The only maintenance that is involved with a "Jake Brake" is the periodic adjustment that is done as part of the valve adjustment. The majority of Beaver coaches will only need the one valve adjustment that is preformed early in its life, usually in the 20,000 to 40,000 mile range.

Gerald

[Edward Buker]

Jerry,

You won the lottery on engine braking systems when you bought a coach with a Jake Brake. They are a trouble free internal system that basically converts your engine into either a 3 cylinder compressor on low and a 6 cylinder compressor on high. The amount of braking that you get is related to the RPM range the motor is in and generally the range of 1700 to 2100 RPM is desired for braking horsepower. Some understanding of using the right gear for the grade situation is in order. Some grades may require the use of 3rd or 4th gear and slower speed while others may work well in 5th gear. That part will be a learning experience. How it works which was the question, I grabbed this from an earlier post...

Just to add a little more info to Gerald's post about Jake Brakes given it is a bit hard to understand (at least for me) as to how opening an extra exhaust valve momentarily at the top of a compression stroke slows a vehicle down.

 The compression stroke is consuming energy and therefor is providing braking HP. The problem is that if you do not release the compressed air at the top of the piston stroke, it then expands on the downstroke and gives back the compression energy, basically nullifying the energy being absorbed on the upstroke.

 So it is all about changing the pressure of the downstroke that provides the benefit here....it is a great system and does not rely on increasing any compressive forces on the head and pistons and therefor does not negatively affect the long term durability of the engine. We call it a compression brake but it really does not increase compression at all. Just in case anyone else had been scratching their head on that one....

There is one issue with this system that has generated a lot of debate that you should be aware of. Many of the coaches with the C12 and Allison 4000 transmission were programmed by Beaver to go to 4th gear when the Jake is selected. Many of us have had a hard downshift situation and engine RPMs above 2300RPM. The max RPM recommended by Cat is 2100RPM so there is a bit of a personal dilemma here of knowing which gear your coach is programmed to use with the Jake on, what speed would equate to 2100RPM, and personally managing the Jake engagement point. The engine will tolerate a higher RPM then the 2100RPM but it is not recommended and frankly there is no reason to go there. Many of us have had a simple Allison reprogramming done from 4th to 5th gear for Jake use which has allowed a higher highway speed safe engagement point RPM wise. Yours may have already had that change. You can manually select 4th gear if the RPM vs braking vs speed warrants it. Some tend to drive slower and have remained with the 4th gear selection.

This note is not intended to open any debate just to make you aware that there is learning to do here on the Jake subject. Knowing how your Jake system on your personal coach is programmed and how it works is an important aspect of safe driving for these coaches.

Later Ed

[Jerry Emert]

yálls knowledge of these complicated beasts never ceases to amaze me and my thanks to you all!  How do you tell what gear the tranny is in?  Mine always says "6"on it.  

[Edward Buker]

On the Silverleaf, if you have one, on the drive page upper right numbers will tell you the gear you are in. You can watch the shifts being done by the Allison. You can use the tranny up down arrow to select a gear and the tranny readout pad will follow also. Other systems beside Silverleafs were used but I am not sure of the models and years and if they also had the capability to indicat the gear you are in.

Later Ed

[Keith Moffett Co-Admin]

Jerry
I had upgraded the old coach from 'Intellidrive' to a entry level 'Silverleaf'.  I cant imaging that your Thunder didnt come with at least that.  If you dont have one or if you do but like me are just learning how to use it, go to www.silverleafelectronics .  They are in Albany Or. and can set you up or just help you get up to speed.  
I am a fairly cautious driver and still was able to improve mileage significantly.  It also gives you real time transmission sifting, temp. and engine updates.

Just FYI
Keith