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Topic: Exhaust Brake Stuck (Read 1251 times) previous topic - next topic

Exhaust Brake Stuck

I have been attempting to repair a few small items that have not been operating and seems that I continue to find "other" problems that I didn't think I'd run into.

Under the shift handle in our 91 GV there is a guage...I assume it's after-market, but am not sure. It says brake something...I think pressure. It has never worked and I thought ...if it's there , let's make it work. After tracking the air line to it ( spaghetti line 1/8" ) and finding it broken in many places, I thought EASY FIX :) ....Riiight!
The line was tracked back to the BD Exhaust brake. The brake that once DID operate, but I never really felt was "doing" anything while driving. Well....Now it's NOT DOING ANYTHING!

I removed all the old spaghetti line and replaced with new. Made the connections to fittings, started the coach, let pressure build up...but no pressure read on the guage under the shifter handle. I had my son pressing the button to activate the brake while I watched what happened and all I heard was the air pressure but nothing moved. I lubed everything I could find that was a moving part based around the brake and attempted to break things loose with pliers, vice grips, even a hammer by gently tapping on safe areas.

As it turns out, I wanted to see if there was a hang up inside the exhaust so I started to remove parts. This is always where the fun begins. I had to take off 2 clamps that held a short piece of flex pipe, they were of course rusted and required air tools, but did come off. Then because the flex pipe would not just slip out, I had to loosen the muffler and when I loosened the muffler, it would not allow the flex pipe to come out until I broke a rusted clamp and took off the tail pipe. Yeehaa :)

Now the complete exhaust is off,  I can see and touch the butterfly flap inside the exhaust brake body, but cannot move it. I have taken the "shock" off of the top part of the system that makes the flap open and close and with my hands can pull the plunger in and out.  I believe that it is a good part and that the only peoblem is that the flap is frozen.

I did read online that they do freeze if not operated frequently due to moisture in the system. So, that's what I've got. NOW....the question is, HOW CAN I UNSTICK IT?

I've tried a lot of different methods but had no luck. I sprayed it with BP Blaster last night but have not yet been back out there to check it.

One reason it because of the mess caused from all the exhaust carbon that came out of the tailpipe  and got all over my clean barn cement floor, my tools and clothes :(

I sure would like to know how to remedy the brake problem.

Lastly, I read that on a 3208T, when installing a BD Exhaust brake, it can only be "set-up or regulated" properly when the unit it being driven?? That didn't sound right to me..
It said that there are specific meausrements needed to calibrate it....again, when installing.
So, if mine has been "part of " the old girl for 20 years or so, I wouldn't think I would have to do any more that get the flap unstuck and mount everything back the same as it came off. Does that sound right?
I don't remember anything moving when I pulled the shock off.

Thanks in advance for any ideas

Carl Sandel
Carl Sandel
1991 36' U280
Northern Michigan

Re: Exhaust Brake Stuck

Reply #1 –
Carl,

Yes, MAXIMUM BACK PRESSURE needs to be adhered to.

Call the Caterpillar RV Hotline with your engine serial number to determine maximum allowable back-pressure: 877 777-3126.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Exhaust Brake Stuck

Reply #2 –
So it cannot be simply put back into its origanal position once the butterfly is broke free ?
Carl Sandel
1991 36' U280
Northern Michigan

Re: Exhaust Brake Stuck

Reply #3 –
Quote from: Carl Sandel –
So it cannot be simply put back into its origanal position once the butterfly is broke free ?

Only if you ASSUME it was properly set up before.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Exhaust Brake Stuck

Reply #4 –
I really do assume it was. I say that because the coach was origanally ( to the best of my understanding ) owned by the owner of Tennessee RV when it was bought new. I believe that part would have been close to original equipment.

I just came in from clamping a vice grip on it after setting all night with lube on it and still nothing. Could it be good to but some lite heat to the pivot point and tapping it with a hammer to lossen the rusted area?

There aren't any flamable things near it and it is after all right next to the turbo so it should be used to being heated. I use the little blue hand held torch canister so wouldn't think it would cause over heating. Thought's ?
Carl Sandel
1991 36' U280
Northern Michigan

Re: Exhaust Brake Stuck

Reply #5 –
Carl,
  Just a suggestion if you use the torch and you are concerned about overheating nearby connected parts, wrap a wet rag around the neighboring parts to keep them cool.
Good luck,
Rick

Re: Exhaust Brake Stuck

Reply #6 –
I've been in the same spot you are in but it was disconnecting the exhaust outlet on the turbo.  Seemed to take forever.
Use torch to heat the joint up, apply diesel - it's thinner than oil an will penetrate better into the hot joint.  Tap, hammer and force what you can but without damaging the parts.  Repeat and apply perseverance and patience. It will seem like your going nowhere and then suddenly you'll start to see it move.
John Fitzgerald
1991 U300 (SAI) Side Aisle Island Bed 40'
Detroit 6V92 with Allison Retarder
Meridian (Boise), Idaho

Re: Exhaust Brake Stuck

Reply #7 –
Carl, I really hope you can break the flapper loose and it works properly when reassembled but Brett makes a very good point. If you reassemble it and it creates too much back pressure you can seriously damage the internals of the engine. It can also get stuck closed pretty much ruining a trip. They don't go very fast with the exhaust brake closed. A tech rep from PAC Brake once told me that a frozen flapper is very common on older coaches and should always be replaced. Of course he would say that because they want to sell more replacement brakes. The PAC Brake on my 93, U225 was working fine so he gave me a bottle of high heat oil and said to oil the brake once a month.

Mine did not have a gauge. On mine the "shock" thing is a pneumatic ram that operated the flapper. If you are hearing air back by the break, there is probably a leak. My experiences FWIW.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: Exhaust Brake Stuck

Reply #8 –
Quote from: Kent Speers –
Mine did not have a gauge. On mine the "shock" thing is a pneumatic ram that operated the flapper. If you are hearing air back by the break, there is probably a leak. My experiences FWIW.

Ooooh... a gauge. My PacBrake doesn't have a gauge either but I think that would be an interesting upgrade. I would not want to be without mine. It really takes the stress out of driving in the mountains and it's interesting to watch the brake lights of the other motor homes, trucks and fifth wheel trailers going on and off as we sped down Snoqualmie Pass into Seattle. I just hit the retarder and never had to touch the brakes except when the SOB in front of me slowed down too much.

Keep at it Carl! It is absolutely worth it. Saves your service brakes too.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Exhaust Brake Stuck

Reply #9 –
As I recall max back pressure on a 3208 is between 20 and 30 pounds. I looked it up once.
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Exhaust Brake Stuck

Reply #10 –
Carl,

Once you get the flapper moving freely, there is another aspect to the exhaust brake you have to consider. When I bought our U-280, it also came with a BD Exhaust brake, controlled by a toggle switch on the left side of the dash, just below the transmission gear handle (not push button in a '92). Sometimes it would work, many other times it wouldn't. It wasn't until I replaced the whole thing with a PAC brake PRXB that we finally figured out why it was so erratic. From the toggle switch, two wires pass down, enter the engine compartment and where the throttle is attached to the engine, those wires energize an electric switch that controlled a valve, directing air to the piston that moved the flapper in the exhaust brake. If that switch is worn out (as mine was), the piston won't move and you won't get any braking, even if the flapper is able to move freely. The swtich is not expensive and once located, is not difficult for a mechanic to replace.

Hope this helps.

P.S. There is no comparison (i.e., braking efficiency) between the PRXB and the BD, even when the BD was working.

Don

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Posting Information: Dave Head replied to the topic 'Exhaust Brake Stuck' on the 'Foretravel Tech Talk' Board.

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Don Hay
'92 Grandvilla, U-280
The Hayfever Express
Build #4055
'97 GEO Tracker
Life is like licking honey off a thorn.

Re: Exhaust Brake Stuck

Reply #11 –
Good info everyone. I really appreciate hearing all the different perspectives. My neighbor who as mentioned before is and has been the head mechanic for our county road commission trucks. He told me tonight that exhaust brakes suck, lol. He said if you repair it, it will be stuck again in 6 months if you don't use it. I know he has a great deal of education and hands on, but I think too that he looks at it from the perspective of working on trucks that really have no need for an exhaust brake....in my honest opinion. The guys who drive them, drive them like they stole them and he gets what's left over to repair. I actually took the brake unit off and put it in his front seat....along with a fitting I broke, a hose that is completely plugged ( WHICH GOES TO THE SHOCK FOR THE BD BRAKE! ), a muffler clamp and another clamp that ALL broke while trying to get the stupid brake off to Begin with. Honestly, I just want to have working what is already on the unit. I've had a long dry couple years with my wife having back surgery last year, a few months after her I had a 5 part elbow surgery and just months after ( Dec,31, 11 ) I had shoulder surgery and am STILL recovering. So, I've got a lot of work to do playing catch-up with bills and responsibilities. I just thought....Hmmm, here's something that is not working and if I have it....it needs to work. That's what lead to the repair to begin with. Actually it was the spaghetti air line GOING to the brake that was broke...going to the gauge that never worked, lol. So, I WILL get that working regardless. I know an upgrade would be a great thing but it won't be happening for some time.
My neighbor did mention that more than not, you really can't salvage the flapper. He said he would try but in most cases he just replaces the body. So we'll see what he has to say.

I wish I would have known about diesel being a good lube for stuck bolts because I would have used that instead. I know now :)

I mentioned the open close thing about what Cat says and he didn't think much about it...which sorta scared me too. He just said when your driving...you want it to be 100% open and when you want it to work it needs to be closed. I will wait to see how he gets it working then decide what I want to do to reassemble it. If everything is in the same place and bolts right back on without missing a mark, I will just bolt it back up.

Don....MY whitch ALSO was hit and miss. I told my 12 year old son...now when I say, press the button. After I said OK!! ( nothing ) I said OK!!!. He says, I've BEEN pushing it for about the last 5 minutes, lol. It really hadn't been that long but I did experience it doing the same as you mention. I will replace the switch. I know right where it is.

I've learned a lot about working on this thing that I NEVER knew before. I'm quite glad to be learning and able to do a lot of what needs to be done myself. And mostly....I'm really glad I have all of you. You are a huge blessing :)
Carl Sandel
1991 36' U280
Northern Michigan

Re: Exhaust Brake Stuck

Reply #12 –
Exhaust brakes are quite reliable, IF used and/or lubed.  As with most pieces of machinery if neglected, they will fail.

I agree with Don, if you can't get this one working, go with the PacBrake PRXB-- light years ahead of the BD.  I installed one of the PRXB prototypes 8 years ago and it has worked flawlessly ever since-- including today.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Exhaust Brake Stuck

Reply #13 –
Quote from: Dave Head –
As I recall max back pressure on a 3208 is between 20 and 30 pounds. I looked it up once.

I have driven 3208's with the 30 pound back pressure exhaust brake.  Works a little.  The v8 engine does not have the same effect as an inline 6 and the low pressure does not help.

Does work just not a lot. 

Bob
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Exhaust Brake Stuck

Reply #14 –
Quote from: Carl Sandel –
My neighbor who as mentioned before is and has been the head mechanic for our county road commission trucks. He told me tonight that exhaust brakes suck, lol. He said if you repair it, it will be stuck again in 6 months if you don't use it. I know he has a great deal of education and hands on, but I think too that he looks at it from the perspective of working on trucks that really have no need for an exhaust brake....in my honest opinion.
Carl,
I don't know about the BD exhaust brakes, but for the PAC brake brand, they make a special lubricant for them to keep them operating properly.  You lube it as part of the preventative maintenance every couple months.  The PAC brakes even have lube points.  When properly working, provided they are maintained, they are worth their weight in gold.  But if you don't lube them, their going to quit working!

But that PAC lube isn't going to help with the bolts and clamps and such.  There you need liquid wrench or a good penetrating oil and maybe even heat, and some will still break.
1994 U225
build #4514

Re: Exhaust Brake Stuck

Reply #15 –
Lubing a PacBrake:  Maintenance

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Exhaust Brake Stuck

Reply #16 –
My neighbor came home today after taking my exhaust brake to the county garage. He said he had the whole thing glowing red / orange from the torch...then put a 24" pipe wrench on it and reafed as hard as he could. Mind you, this guy is a BEAST! I'm talking HUGE STEEL GUNS on this man. He said it never budged. I'm putting it back on for now and not going to mess with it. He said I could throw $300 at it and I would be mad that I spent a dollar on it. I don't do much hill driving and NO mountain driving at all. From the comments from others who have had the 3208....I'm just not going to bother. Maybe someday I will invest in a PAC....but when I do I think I will find one that comes with a 99 U-320 M-11, hahaha :)
Carl Sandel
1991 36' U280
Northern Michigan