1976 Cadillac Hydro-boost brake questions

D

Dana Bennett

PCS Life Member
Hi All!

I am working on getting my coach ready, here is something else I need to ask about.

My coach has the Hydro boost brakes. While inspecting my brakes and bleeding the brakes to flush and replace the old fluid I was getting noise from the ?? I'm guessing the noise was coming from the power steering pump? anyways, the noise would happen when I had the pedal about 1/2 way or farther down. And yes, as I have done since growing up I have always put automatic transmission fluid into the power steering, figuring that it IS hydralic fluid (I had always heard that this was ok), anyways, I wanted to add some Lucas Power steering sealer/conditioner to the system hoping that it may help with some leaking seals on the gearbox, so I used a turkey baster and removed all the trans fluid I could get from the power steering pump and poured in the Lucas. The noise (that I think is most likely coming from the pump) is much less but it is still there. Does anyone else have one of these Cadillacs with Hydro-boost and have you had any similar type of problems??
can anyone else give me any suggestions as to what is happening and why??
I have not driven this car in many years and can't remember but I don't think to stop the car properly that I need to push the pedal down that far during normal braking but can't remember.

Thanks!!
Dana.
 
I know what noise you are talking about. When I got my 76 M-M, it was making the same noise when I would press the break pedal, sounding like it was coming from the power steering pump. So, I checked the power steering fluid, and of course, it was about empty. I filled it up, and haven't heard the noise sence. I know this doesn't help you, but I do know what noise your talking about.

As far as using automatic transmission fluid for break fluid, I've always heard its ok to do. I personally have only used it on one car. Me and a friend of mine owned a truck a few years ago that we used for a yard dog/parts runner, that had a really bad power steering leak, and we caried around a jug of automatic transmission fluid in the bed of the truck.

Josh
 
My 1984 Buick Grand National has the hydroboost brake system. It actually says to use transmission fluid instead of power steering fluid, so I think you are okay there. Mine was noisy and I had the power steering pump rebuilt, that cured it. Not saying that is what is wrong with yours, but it may be worth a try. From what I have been told about the system on my car anyway is that they are very reliable and hardly ever give any trouble. On the '86 & '87 models, they stopped using the hydroboost and went to a system that has some sort of an accumulator bowl on top of the master cylinder. Most everyone has had problems with that system--they should have stuck with the hydroboost I think. Anyway, good luck with yours, hope this helped.
 
OK... I need to jump in here to save someone else from reading the above posts and making a mistake that could lead to disastrous consequences. You cannot, I repeat... CANNOT use automatic transmission fluid in place of brake fluid. They are not compatible, and will lead to a total failure of the braking system. In a hydro vac system, the brake fluid from the master cylinder is used to assist with the brake pedal effort. It is a complicated system that should only be serviced by a qualified person that is familiar with how the system works. While automatic transmission fluid was used in the power steering pump and associated parts, in the past, today, they now make a non foaming power steering fluid. This is what should be used in the power steering pump system. As for the type of brake fluid that should be used in the brake master cylinder, you need to know what is already in there to determine compatibility. If the old days, there was only one type of brake fluid, and it was compatible across all brands. Today, there are numerous brake fluids in use, and I don't know to what extent that they are cross compatible. Best to check the manufacturers specifications. As I have said so often in the past, a bad transmission will leave you stranded at the side of the road, but bad steering and brakes will leave in the middle of a tree or telephone pole when you least expect it. Don't gamble with your life or the lives of loved ones. If you don't know what you are doing, leave the brakes and steering to the people that do.

[ame]http://www.youtube.com/watch?v=keChCevuKk8[/ame]

If you want to learn more about a Hydraulic brake booster system, please read this....

I have posted both of these because sometimes people use the terms for the two systems as if they were the same. They are not the same, and a mistake like this can get you into problems quickly. Each has its own service techniques that are not the same as the other.
 
And by the way, just because you can use automatic transmission fluid in your power steering pump on an older car, doesn't mean you can use power steering fluid in your automatic transmission.

JOsh
 
The old transmission fluid was type A, and that was used in both transmissions and power steering pumps. Type A transmission fluid was manufactured using whale oil, but with the international laws prohibiting whaling, and the use of whale products, Type A transmission fluid was discontinued. There have been a few different types of transmission fluids that have been manufactured since, and the present type is know as Mercon III. Just because you see the name "Mercon" on the container with a different number, don't assume that it is the same product. Today, there are different formulations using the term Mercon, with a different ending number to designate it from the others. As an example, Mercon V is a whole different fluid than Mercon III. It is a universal transmission fluid for the older cars, but shouldn't be used in power steering pumps, since it doesn't have the same properties as the old Type A. For this reason, they have developed a power steering fluid that is a direct replacement for use in power steering units. Knowing the correct fluids to use in your car can save you from making a very expensive mistake. Use the wrong fluids, and you will be replacing failed parts as a result. As you get into the 1980's cars, there is even more importance in making certain that the fluid that you are adding is correct, since the manufacturers started using proprietary type fluids that have no direct cross over to other fluids. Always check your owners manual to see what it calls for, and then check to see what the modern replacement is for that fluid. As an example, if you use the wrong fluid in a differential, the bearings will fail, and that is a very expensive repair. Same for engine oil, since some modern cars call for 0-20 oil, and others require 10-40 oil. Putting a 10-40 oil into a engine that requires 0-20 will cause premature engine wear, leading to a premature engine failure. If you use the wrong fluid in the transmission, it can cause harsh shifting patterns, and lead to a premature failure. Also, I usually don't recommend using chemical substitutes for the correct oil. Some chemicals that are sold can do wonders, and other just mask the problem for a short time, but don't fix the underlying problems. The only thing that I would use in my transmission other than the oil is Sea Foam, and Lube Guard. Sea Foam will help to clean up stuck valve body pistons, and the Lube Guard will add a beneficial transmission oil additive package to the oil. Don't use them both at the same time, but you can add the Lube Guard 60 days after using the Sea Foam.
 
You must log in or register to reply here.
Back
Top