dschuelke Report post Posted December 22, 2019 I have a 96 Winnebago adventurer with the 454. When I apply the brakes the power steering belt screams and the power steering goes away. the brake proportioning valve has fittings for power steering fluid going thru it, why it does that I don't understand. It seems to me that when I apply the brakes it somehow causes the power steering pump to stall causing the belt to slip and squeal and steering to become difficult. has anyone else had this happen and ,or, have a solution. I am thinking that I should either bypass the valve or disconnect and block off the power steering fittings to the valve. Share this post Link to post Share on other sites
wolfe10 Report post Posted December 22, 2019 Dschuelke, Welcome to the FMCA Forum. Sounds like you have hydraulic over hydraulic brakes( vs vacuum over hydraulic brakes in cars and lighter duty chassis). If so, the power steering pump provides the (extremely necessary) brake boost. Having no first hand experience with that system (Chevy P chassis I assume), hopefully someone with first hand experience can chime in. Share this post Link to post Share on other sites
huffypuff Report post Posted December 22, 2019 There is a few things you should look at. The belt and tensioner being good. Also the condition of the P/S fluid if since over 20 years old. Last the pump and relief valve may be going bad. Careful with this kind of system as fluid contamination can do lots of damage. Share this post Link to post Share on other sites
dschuelke Report post Posted December 22, 2019 it is eating the power steering belt. the proportioning valve was replaced about a year ago because it stuck and the rear brakes could not be bled. I tighten the belt but after awhile it starts doing it again. and at the worst times. a hard stop usually is all it takes to start it again. then it just gets worse until I can get somewhere where I can tighten the belt. I just don't know what to do. The chev dealer worked on the valve and replaced it but since then it just gets worse. I don't have much faith in the quality of techs these days. Share this post Link to post Share on other sites
huffypuff Report post Posted December 22, 2019 1 hour ago, Dschuelke said: it is eating the power steering belt. the proportioning valve was replaced about a year ago because it stuck and the rear brakes could not be bled. I tighten the belt but after awhile it starts doing it again. and at the worst times. a hard stop usually is all it takes to start it again. then it just gets worse until I can get somewhere where I can tighten the belt. I just don't know what to do. The chev dealer worked on the valve and replaced it but since then it just gets worse. I don't have much faith in the quality of techs these days. At this point I would flush the power steering pump with fresh dexron and replace the belt. be sure there isn't any loose bolts on the pump. Share this post Link to post Share on other sites
rls7201 Report post Posted December 22, 2019 I believe what you are calling a proportioning valve is actually your hydroboost. The hydroboost supplies energy from the power steering pump to the master cylinder for power brakes. The hydroboost and master cylinder are bolted together and could look like one device with both power steering lines and brake lines together. You could have a bad belt, bad/worn pulleys or a bad tensioner. Richard Share this post Link to post Share on other sites
dschuelke Report post Posted December 22, 2019 (edited) no, there is a separate unit bolted to the frame in front under the radiator in a miserable spot to get at. it has lines from the master cyc. and lines from the power steering pump. it looks like it was designed by mickey mouse and put in a place only he could get at. it is called the proportioning valve in the factory manual. I don't have a picture of it or I would post it. Edited December 22, 2019 by Dschuelke added info Share this post Link to post Share on other sites
dickandlois Report post Posted December 22, 2019 2 hours ago, Dschuelke said: no, there is a separate unit bolted to the frame in front under the radiator in a miserable spot to get at. it has lines from the master cyc. and lines from the power steering pump. it looks like it was designed by mickey mouse and put in a place only he could get at. it is called the proportioning valve in the factory manual. I don't have a picture of it or I would post it. This is a link to a shop service manual for the P-30 Chassis with a 454 - 7 L engine that might give you some helpful information. Section 3 page 43 is where the manual starts to explain how the power steering system works and Section 6 page 73 is where the brake system operation and plumbing system starts to explain how the vacuum and hydro boost systems work. Also should give you information on maintenance. Appendix section A Page 217 is where the belt information is found. The manual index starts at page 285. https://www.gmcmi.com/wp-content/uploads/2014/05/P30-Chassis-Manual.pdf Rich. Share this post Link to post Share on other sites
dschuelke Report post Posted December 22, 2019 thanks for the link. It does explain why the problem starts under hard braking conditions. I don't believe that I am any where near the weight but with 20+ year old springs and the bogus air bag suspension I can see that it could definitely put enough stress on the system to cause my problem. how to fix it is going to be something else again. Share this post Link to post Share on other sites
