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Old 09-27-2021, 02:53 PM   #1
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Brake pedal very hard....

....and braking power is not what it should be. Sometimes I have both feet on the pedal when I have to slow quickly, and the MH just takes it's sweet time about slowing down. MH is 1999 Itasca Sunflyer 33B, with Ford Triton V-10 on Ford F53 chassis.

I have read that this model has something called HydroBoost, but I have no idea of what that does. It says the brakes are connected to the power steering pump, but I just can't picture how that would work.

Brakes were gone through and fully flushed two years ago, but due to injury and several hospitalizations, we have no been able to drive it until now. I'm trying to prep everything before we leave on Friday, so need some advice.

I checked the level in the reservoir and the front one is about 1" below the opening and the rear one about 1/2". Considering the size of the reservoir, that's not very much, but maybe that's enough to make it difficult to brake?

I'm kind of out of league on this braking system, so any help would be greatly appreciated.
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Old 09-27-2021, 03:15 PM   #2
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Brake systems are made up of hydraulic cylinders that have moving parts. When anything with mechanical parts sits for a long period of time corrosion can build up and cause excess friction and even cease up. I would suggest a thorough inspection by a qualified brake technician before your trip.
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Old 09-27-2021, 04:40 PM   #3
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The Bendix Hydroboost system has been around since the '60's and it uses hydraulics to boost your braking power. They are very simple and don't often require any maintenance but if they do, there are several large 'O' rings around a large cylinder inside the boost.

I took mine apart and cleaned it out and my '94 Bounder boost had a large plastic debris screen that was in excellent condition, as were the 'O' rings...as I expected because the entire thing is swimming in ATF whenever the engine is running. Oh, yeah, mine used ATF, not brake fluid. There wasn't any debris in the screen.

My Master Cylinder was bad, so I replaced that, but the Booster was fine. Anyway, that link will show you some things about the Hydroboost along with describing it. What they do is give large brake systems a hydraulically powered 'boost'.

I doubt your's is bad, I'm thinking that Mtn Charlie is on the right track. But...have the MC checked too as it's of an age that it may have gone bad.
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Old 09-27-2021, 08:22 PM   #4
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Quote:
Originally Posted by Jim_HiTek View Post
The Bendix Hydroboost system has been around since the '60's and it uses hydraulics to boost your braking power. They are very simple and don't often require any maintenance but if they do, there are several large 'O' rings around a large cylinder inside the boost.

I took mine apart and cleaned it out and my '94 Bounder boost had a large plastic debris screen that was in excellent condition, as were the 'O' rings...as I expected because the entire thing is swimming in ATF whenever the engine is running. Oh, yeah, mine used ATF, not brake fluid. There wasn't any debris in the screen.

My Master Cylinder was bad, so I replaced that, but the Booster was fine. Anyway, that link will show you some things about the Hydroboost along with describing it. What they do is give large brake systems a hydraulically powered 'boost'.

I doubt your's is bad, I'm thinking that Mtn Charlie is on the right track. But...have the MC checked too as it's of an age that it may have gone bad.

I went out in better light today and found a loose cable. It feels like a cable, but only has a plastic end on it with a single small hole like a vacuum line. I took some photos but cannot get them to load on here, so made them into a Word document to try to attach, and that doesn't work either. How can I post a photo on a post here? The 'attach photo' icon only wants a URL for the photo, so how do I do that?

Anyway, the white plastic connector that looks like a vacuum line matches up perfectly with a small hole in the side of the master cylinder between the two hydraulic lines. It even has a little white piece of the plastic vacuum line broken off inside.

Now it gets strange... When I pull that connector apart, it has two electrical pins and connectors inside. There's also a small hole like the one through the "vacuum" end of the connector but no hose or anything. The other end of this connector has two wrapped wires going into a wiring loom, which then disappears into the firewall.

In case anyone would have an electrical schematic of a F53 truck chassis with the Hydroboost brake system, one wire was purple with a yellow stripe, and the other one was either orange with a green stripe or green with an orange stripe (can't tell which).

I realize this might not have anything to do with the Hydroboost, but it's the only thing I can see out of place.
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Old 09-27-2021, 09:21 PM   #5
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Does it sorta look like this? Bendix Mstr Cyl...?

There can be one or several different electrical connectors. Differential Pressure Switch, Fluid Level Indicator Switch, Flow Switch. But in my old '94 RV, if I recall correctly, if there had been one installed (it wasn't), it would have just turned on an idiot light on the dash if the system was low on brake fluid. Pretty sure. Just going by memory from ~10 years ago. Here's my ad free blog article about it. There's a nice picture of the MC and Booster there...Brakes.

Point is that it's unlikely that wired device, even if it's in terrible shape, would make it difficult to 'brake'. So maybe pull the MC, get the number off of it that embossed into the metal of the MC and google it. My new MC cost me over $500 way back when, but it fixed my problem of no brakes.

Your problem is different, but given the age, and the recent work done on the brake system, plus the lack of use, would cause me to think about removing the MC and using a MC test kit, test it in my sink with a long lever. Just to be sure that's not were the problem lies.

Meanwhile, don't discount Mtn Charlie's suggestion.
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Old 09-28-2021, 07:28 AM   #6
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Quote:
Originally Posted by MotoMac View Post
How can I post a photo on a post here? The 'attach photo' icon only wants a URL for the photo, so how do I do that?
Don’t use the Photo icon in the Quick Editor. Here’s how to Attach a photo to a post:

How to add photos to a post

Click reply and scroll down to bottom of text box.
  • Click "go advanced" add text to message window and then scroll down.
  • Click "Manage attachments" (OR you can also click the Paper Clip icon on the format bar). A separate window will pop up.
  • Click "browse" Then select the photo file to be uploaded. Important: you can only select files from your computer, tablet or phone. (Photo files end in jpg, jpeg, gif or png extensions) Be sure that the photo is appropriately sized. 1000 x 1000 pixels (or smaller) and no more than 50K. Forums software will automatically reduce the size, but smaller size photos will upload much faster. You may select several photos to upload at the same time by repeating the last step.
  • Click "Upload" After pics have loaded close the pop-up window
  • Click "submit reply" to mount the text of your message - photos will automatically appear at the bottom of your post.
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Old 09-28-2021, 01:15 PM   #7
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My setup doesn't say anything about going 'Advanced'.

There is a 'Manage Attachments' button and I'm trying to add a picture now...

Ahh, yes, it does work.

Thanks for the info!
Attached Thumbnails
Click image for larger version

Name:	Brake Job 1-06 001.jpg
Views:	19
Size:	148.3 KB
ID:	180951  
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Old 09-28-2021, 01:28 PM   #8
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Quote:
Originally Posted by Jim_HiTek View Post
My setup doesn't say anything about going 'Advanced'.
Here, in the Quick Editor below the last post in the thread:
Attached Thumbnails
Click image for larger version

Name:	B7DF8307-5B04-4BDE-A305-9B24C66C2127.jpg
Views:	9
Size:	163.9 KB
ID:	180952  
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Old 10-03-2021, 04:40 PM   #9
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All hydro-boost means is that it uses hydraulic pressure from the power steering pump to provide brake pedal assist when the motor is running and also has a small electric hydraulic pump to continue providing some assist if the engine stalls. You should be able to hear the electric pump run when you press on the brake pedal when the engine is not running. This systems provides a higher and more consistent level of boost than a vacuum based system.

An F53 is considered under Severe Service when used for a Motor Home so the brake fluid needs to be flushed out and replaced every 2 years plus the caliper pins, guides and mounts need to be lubricated with brake grease at the same time and perhaps annually if driven in the winter.

Back in 99 they were using fairly reliable Kelsey Hayes brakes on the F53 and they should provide excellent stopping power if properly maintained and the pads are not scorched. If they were not broken in correctly then you could also have hardened/glazed surfaces on the pads which may need to be roughened up to get them working correctly again however since the heat from improper break-in can weaken the resin used to bond the pads to the backing plates your better off replacing them since loosing the friction pad off the metal backing plate will result in rotor and caliper damage which costs a lot more to deal with than replacing a set of pads early.
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Old 10-05-2021, 09:05 PM   #10
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A bit of an update

Quote:
Originally Posted by Jim_HiTek View Post
Does it sorta look like this? Bendix Mstr Cyl...?

There can be one or several different electrical connectors. Differential Pressure Switch, Fluid Level Indicator Switch, Flow Switch. But in my old '94 RV, if I recall correctly, if there had been one installed (it wasn't), it would have just turned on an idiot light on the dash if the system was low on brake fluid. Pretty sure. Just going by memory from ~10 years ago. Here's my ad free blog article about it. There's a nice picture of the MC and Booster there...Brakes.

Point is that it's unlikely that wired device, even if it's in terrible shape, would make it difficult to 'brake'. So maybe pull the MC, get the number off of it that embossed into the metal of the MC and google it. My new MC cost me over $500 way back when, but it fixed my problem of no brakes.

Your problem is different, but given the age, and the recent work done on the brake system, plus the lack of use, would cause me to think about removing the MC and using a MC test kit, test it in my sink with a long lever. Just to be sure that's not were the problem lies.

Meanwhile, don't discount Mtn Charlie's suggestion.
Sorry, I'm a bit behind on providing updates. Turns out the plastic switch was, in fact, the pressure differential switch. I couldn't find one through any Ford source but did find out it's also used in Freightline, Kenworth, and international. Order one from the local Freightliner parts place.

The old switch was broken off flush with the port in the master cylinder. The plastic bit was apparently glued in because the EZ-out I used to back it out just stripped it out. The little steel pressure differential pin was seen all the way inside the hole and cocked at an angle. A mechanic friend said it appeared that the pin was jammed between the MC bore and the spool valve.

That's when I decided to just replace the whole MC. There seems to be a zillion remanufactured ones on eBay and a few other places, but I'd prefer to trust my life with a new one. Again, the Freightliner folks came through again and order me a new one yesterday. It will be here next week.

I finally got an appoint for 30 October from the shop everyone recommended.

Thanks for the info and especially the links for more explanation of the Hydroboost system.

Cheers,

Mac
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Old 10-05-2021, 09:11 PM   #11
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Posting Photos

Quote:
Originally Posted by creativepart View Post
Donít use the Photo icon in the Quick Editor. Hereís how to Attach a photo to a post:

How to add photos to a post

Click reply and scroll down to bottom of text box.
  • Click "go advanced" add text to message window and then scroll down.
  • Click "Manage attachments" (OR you can also click the Paper Clip icon on the format bar). A separate window will pop up.
  • Click "browse" Then select the photo file to be uploaded. Important: you can only select files from your computer, tablet or phone. (Photo files end in jpg, jpeg, gif or png extensions) Be sure that the photo is appropriately sized. 1000 x 1000 pixels (or smaller) and no more than 50K. Forums software will automatically reduce the size, but smaller size photos will upload much faster. You may select several photos to upload at the same time by repeating the last step.
  • Click "Upload" After pics have loaded close the pop-up window
  • Click "submit reply" to mount the text of your message - photos will automatically appear at the bottom of your post.

Thanks for the info. I've copied it into my Winnie folder and printed a copy too!
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Old 10-05-2021, 09:13 PM   #12
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Brakes

Quote:
Originally Posted by NeilV View Post
All hydro-boost means is that it uses hydraulic pressure from the power steering pump to provide brake pedal assist when the motor is running and also has a small electric hydraulic pump to continue providing some assist if the engine stalls. You should be able to hear the electric pump run when you press on the brake pedal when the engine is not running. This systems provides a higher and more consistent level of boost than a vacuum based system.

An F53 is considered under Severe Service when used for a Motor Home so the brake fluid needs to be flushed out and replaced every 2 years plus the caliper pins, guides and mounts need to be lubricated with brake grease at the same time and perhaps annually if driven in the winter.

Back in 99 they were using fairly reliable Kelsey Hayes brakes on the F53 and they should provide excellent stopping power if properly maintained and the pads are not scorched. If they were not broken in correctly then you could also have hardened/glazed surfaces on the pads which may need to be roughened up to get them working correctly again however since the heat from improper break-in can weaken the resin used to bond the pads to the backing plates your better off replacing them since loosing the friction pad off the metal backing plate will result in rotor and caliper damage which costs a lot more to deal with than replacing a set of pads early.

I had the brakes redone when I bought it. They had been changed about 6 years earlier according to the maintenance log, but they seemed to make a lot of noise and pulsed a bit. They did, however, stop just fine so the problem I'm having now came along later.
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