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Topic: Hydro boost problems

Posted By: Grandpa Rick on 08/12/04 09:19am

I have a 93 Itasca Suncruiser on a Chevy P30 chassis and have had some prior problems with the hydro boost unit. It just failed again on some mountain roads and had to get towed 100 miles off the mountain. Because of the failure, the brakes got quite warm and fried the calipers, rotors, master cylinder, plus the new hydro boost unit. Over 6G in repairs. Have any of you ever experienced problems with the hydro boost unit? The previous work was done by a reputable RV dealer in Las Vegas. The dealer said he had to replace both hydro boost units at about $800 a pop. This mechanic seems very knowledgeable and says there is only one unit and the previous one was installed incorrectly, causing the brakes to be dragging most of the time, which caused them to glaze over which then caused them to heat up much quicker in the mountains. I don't want this to occur again as my heart won't take another moment of the brake pedal going to the floor and the coach picking up speed. Good emergency brake and good trailer brakes on the tow dolly saved us. Good point to make sure that your dolly has brakes or the toad has a braking system installed.
We are on the road again in a day or two much poorer but safe.

Posted By: jenks60 on 08/12/04 12:57pm

I really do not understand how the hydroboost has anything to do with your brakes getting hot while driving in the moutains! The hydroboost is only to power the brakes. There is only ONE hydroboost on your rig! I think you are being taken! Chances are the brake fluid got hot and boiled, thus no brakes! Rusty calipers will stick, keeping the pads rubbing the rotors, brake hoses will swell up on the inside, and not let the pressure release from the caliper piston, then that brake stays on and heats up everything. If the hydroboost quits working, then you will not have power brakes, but you still should have some brakes.
It is always a good idea to change brake fluid every so often.
Sorry to hear about your problems.
I re-read your post, maybe if the hydroboost was installed improperly it may make the brakes drag. If the reputable dealer charged you for two hydroboost units, then you should not refer to them as "reputable"!

jenks, fulltiming with the DW.
92 Southwind P3(32) 33 ft.
99 Saturn SL2
Rallys attended-TX 2, LA 2, MS 1, AL 2
MA. 1 drop in for visit.

Posted By: grzwmpf on 08/16/04 08:18pm

I'm new to this, so please bear with me. I am having a problem that may be related to your topic and I can use some help. I just bought an HR Imperial 35 on a P30 chassis. On the way home the brakes went soft and did not want to slow the coach unless I got really aggressive. When I got home I checked the master cylinder, and found it wet. I can't find the fluid reservoir, so don't know the status, but I suspect a master cylinder failure. Any help would be greatly appreciated.


Posted By: aircraft_electrician on 08/17/04 04:07am

Yes if the hydroboost was not properly installed it could cause the brakes to stay partially applied all the time. The pushrod between the hydroboost and the brake pedal is adjustable. If this rod is adjusted too long, it won't let the master cylinder release the brakes all the way. Also i believe on some models there is a gasket between the booster and the master cylinder, if this gasket is left out the booster output shaft may keep the master cylinder depressed slightly(the thickness of the gasket), not allowing the brakes to release fully.

Tom Parsons
1974 Revcon 250DT
455 Olds(front wheel drive)
"Engineered Elegance"

Posted By: toolman1 on 08/17/04 06:17am

Hello GrandPa Rick. Agree w/Jenks60. Been w/ Chevrolet 30+ years. Only one hydroboost on you're rig. And yes, the pushrod between the pedal and HB unit is adjustable. If the brakes had been dragging, you should have been able to feel it. Should have felt similar to E-brake being applied, or some lack of power, and by the time you had gone just a few blocks, the brakes would be so hot, they should have been smoking, and should have stunk something fierce. I discount the caliper sticking theory, and the brake hoses also. Sure sounds like improper installation to me. Hopefully everyone's safe. Even though there is probably a warranty on the unit, I don't believe even I would go back to the facility that performed the installation. Small claims court, here ya come! See Ya.

See ya out there!!
Hooliville member #128

Gary & Lynne.
'04 Dolphin 5320 WH-22 370W Solar
22' Mighty Mover Trailer, 60W. Solar.
Sand Sprite 4. 2.3L EFI sand buggy
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2011 Black Lab "Lucy" for both of us ">

Posted By: Grandpa Rick on 08/12/04 02:35pm

Thanks jenks60,
By failure of the hydroboost, I should have said that because of improper installation, the booster was stuck partially in the on position. Also, I believed the RV dealer in Vegas was reputable until the mechanic that is fixing our rig now explained how the system works and why the improper installation caused it to be stuck partially in the on position most of the time. I am still doing some research with this and will let you know how everything turns out.

Posted By: jenks60 on 08/19/04 09:05am

Well Grandpa Rick, they should be working right after spending that much to get them repaired!! This is another reason I like to do my own work, but sometimes have to TRUST someone else!
Good luck!

Posted By: Grandpa Rick on 08/17/04 10:16pm

The hydro boost unit is mounted directly in front of the master cylinder. The master cylinder on my unit has a reservoir typical of most master cylinders, on top of the unit. The only way to check the level is to take off the motor cover. The hydro boost unit is pressurized by the fluid of the power steering pump and the reservoir for that is located in front of the coach accessible by the hood. The soft brakes sound like air in the brake lines and maybe they need to be bled.
Hope that helps and good luck.
Grandpa Rick

Posted By: Grandpa Rick on 08/17/04 10:29pm

Thanks for the information from everyone. The update is that when the RV dealer in Vegas installed the hydro boost unit, the mechanic used the old push rod. The instructions that come with the unit tell you not to use the old one and order a new one that is constructed slightly different. The mechanic didn't do that and in order to keep the old push rod so it wouldn't keep falling out, crimped the bushing that is to keep the push rod in the hydro boost. (The new push rod has a rubber pressure-fit washer that slides over the push rod and then is pressed into the new bushing)
The push rod then hung up on the crimped bushing once in awhile and forced the bushing farther into the hydro boost unit where it stuck and prevented the cylinder in the hydro boost unit from returning to a neutral position. Consequently they hydro boost unit kept calling for fluid which was being supplied by the power steering pump. When that happened, there was an awful growling noise coming from the pump. When I picked it up the first time, I just drove it around the block and parked it in their lot again as there was still some noise, the service manager listened to it and said it must be the other boost unit then, and said that it needed to be replaced also.
We are working on getting everything together and seeing what can be done about the cost of this whole mess. I paid the RV dealer in Vegas $1500 for the repairs, and this time cost me about $4000, because all the bearings, seals, calipers, rotors, master cylinder and the hydro boost unit was replaced. Have about 750 miles on it already and everything works as it should. If anyone is interested, I know of a great mechanic in Cody, Wyoming.
Grandpa Rick

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