Hydroboost pump

[shepherd57]

I am looking at a 85 32.5 classic with the Isuzu diesel. It sounds like it needs to have the pump that powers the power steering and the brakes rebuilt. Anybody know if the pump can be rebuilt or if a new on can be purchased. And what would be the cost. Thanks

[Smartstream]

Originally Posted by shepherd57

I am looking at a 85 32.5 classic with the Isuzu diesel. It sounds like it needs to have the pump that powers the power steering and the brakes rebuilt. Anybody know if the pump can be rebuilt or if a new on can be purchased. And what would be the cost. Thanks

My 82-280 has this pump. JIDOHSA KIKIKK 47 5-0 3795 It is a fairly normal looking hydraulic pump mounted ahead of the injector pump and is a direct drive, no belts. It is probably in the $300 to $400 price range if you can find a common replacement. If you have to go to Isuzu you may pay more but I'm only guessing. A good hydraulic shop might be able to find you a match or you can try Hamilton Engine Sales
5540 N.E. Columbia Blvd.
Portland, Oregon 97218
(503) 280-1353

Craig is very familiar with these engines. They are industrial engines and even though they are used in trucks, the industrial and highway divisions are separate and the same part will have different numbers. It is confusing and frustrating.

[Jim Foster]

My Snap-on truck was a Chevy with a hydroboost. As I recall, it powered the brakes, but not the power steering. It had a standard belt driven GM power steering pump which powered the hydroboost.

You might check with your local Chevy dealer.

[Smartstream]

Originally Posted by Jim Foster

My Snap-on truck was a Chevy with a hydroboost. As I recall, it powered the brakes, but not the power steering. It had a standard belt driven GM power steering pump which powered the hydroboost.

The gas engine does use the belt driven GM power steering pump but the Isuzu does not. I'm pretty sure the gas engine uses the ps pump for both steering and brakes.

[Jim Foster]

Originally Posted by Smartstream

The gas engine does use the belt driven GM power steering pump but the Isuzu does not. I'm pretty sure the gas engine uses the ps pump for both steering and brakes.

My truck was gas. I think they used the hydroboost because there was not enough room forward of the brake pedal to mount the vacuum booster. The hydroboost was mounted cross ways.

In any event, I would think that rebuilt hydroboost units may still be available. I rebuilt mine with a kit that I purchased, but that was over 30 years ago. The truck was a 1973 Step Van.

[wkerfoot]

My 1977 Lincoln with a 460 4V gas engine has a hydroboost which runs the power steering and power brakes.

Bill

[Smartstream]

Originally Posted by Jim Foster

My truck was gas. I think they used the hydroboost because there was not enough room forward of the brake pedal to mount the vacuum booster. The hydroboost was mounted cross ways.

In any event, I would think that rebuilt hydroboost units may still be available. I rebuilt mine with a kit that I purchased, but that was over 30 years ago. The truck was a 1973 Step Van.

The hydroboost is readily available and reasonably priced but he inquired about the pump. It is a common hydraulic pump like found on a fire wood log splitter. Looks something like this.

The problem is I don't know if Isuzu used a standard mount or something strange and metric and the same for the shaft, spline or gear drive as I have never had to remove mine.

[Keyair]

Dan IS the man!

[Smartstream]

Originally Posted by Keyair

Dan IS the man!

No Key it's just that the Isuzu is cobbled together with the GM stuff and I have spent way too much time crawling around underneath the d*** thing trying to sort it out.

[bkahler]

Originally Posted by Smartstream

...I'm pretty sure the gas engine uses the ps pump for both steering and brakes.

Dan is 100% correct. The gas hydroboost powers brakes and steering. I know because I lost both when the belts broke.

Brad

[Smartstream]

Originally Posted by bkahler

Dan is 100% correct. The gas hydroboost powers brakes and steering. I know because I lost both when the belts broke.

Brad

Let me restate just so there is less confusion. The power steering pump provides hydraulic fluid under pressure to assist the steering, "power steering" and to assist the brakes, "power brakes." The hydroboost is the unit that converts hydraulic pressure to lineal force to assist pushing the brake pedal. Most cars use engine vacuum to assist the brakes with a "vacuum booster." GM decided to use hydraulic pressure rather than vacuum on some of their vehicles and called it "hydroboost."

[shepherd57]

Thanks for the reply's on the pump. I would also like to know what I could expect for fuel mileage with the Isuzu diesel in the 32.5 coach.I have read anywhere from 17 mpg to 10 maybe some one with this setup could give some insight for mileage. Also what problems to look out for.

Thanks John