Cat brakesaver help

I've been running my 85 peterbilt with a 3406b for a while now. It's got a brakesaver and all operable guages but does nothing when I pukl down the handle to apply brake. I've never seen one in a truck before and it's all new to me any help getting it working would be appreciated. Thanks

 

There is a valve on the bottom of the oil pan that supplies oil to the brake saver.
There should be an air line going to the cap on the end of it. Make sure you air when you pull the valve.
If oil runs out of the fitting when you disconnect air line then there is a tear in the diaphragm which is quite common.

 

As Inderjit mentioned, there is a diaphragm that the air pressure pushes against, which in turn pushes a valve spool allowing oil to enter the retarder.

You should have an air gauge in the dash that tells you how much pressure is being applied to that diaphragm. I have mine adjusted to a maximum psi of 60. If the diaphragm is broken you should here air whooshing (technical term) past the diaphragm.

You can try airing up the system with shop air and pulling the valve to listen for air, or just air the system, shut the motor off, and then pull the handle and listen for air escaping.

They are a very simple system, so either the diaphragm is broken or the air supply has been disabled.

I have two 89s with B models and retarders, and one has Jakes as well. They are old, but I really like them and how they work.

If you get it working, be sure to watch your oil temperature on longer downhill grades. I turn the engine fan on when starting down, which helps to keep the oil temperature down and also helps a bit with holding the load.

 

Here are a couple of diagrams of the brakesaver control mechanism. The diaphragm is part # 12.

 

Thanks a lot. Next rainy day I'll check it out. This truck has Jake's as well but they're not working either. I can fix that with new switches, just haven't done it. Also this is the first tractor I have ever seen with two speed axles. I've had smaller 2 ton trucks with two speed rears but never a semi. Really helps when loaded and crawling to the road.

 

I have 2 speed rears on one as well, and I like them too, but heavy and expensive for typical OTR.

One of my trucks has a dash switch for the retarder.....works just like the Jake switch (off of the idle set screw). It has a solenoid that allows pressure to the retarder, and a pressure regulator. When it is used it is all or nothing unlike using the handle.

 

So I finally got time to investigate the brakesaver today. When I pull the handle, guages shows 60lb of air. I payed under the truck and listened while my dad pulled the handle. It sounded like air was blowing into the oil in the pan. Does this mean the diaphragm is bad?

 

Yes. If you are near needing to change the oil that would be the time to do it. The diaphragm isn't very expensive, but pay close attention to how everything comes apart.

 

I'm ordering a diaphragm online before I drain the oil and take it apart. Which one is it?

 

158-0507 I believe. What is your VIN#?