Fascinating milage change with broken PS Pump

Harpo

Original poster
Member
Dec 4, 2011
419
Sweden
I cant believe this, i changed my PS Pump summer 2010 and now its gone again!!!!????.

It went out with a short sqeek a few seconds after i started the truck, and after that its muscle power steering for me and believe me its not funny at all.

I dont really know yet what happened but somehow it stopped pumping, the pump spins freely and are totally quiet now, have to look in to that later.

Anyway, i have been driving along for a couple of days without PS and started to notice a dramatic improvement in mileage

I could easily tell by looking at the DIC when traveling known roads and highways that the mileage is much better so yesterday i reset my average mpg and started from scratch as i use to do every time i fill up.

After two days of driving i noticed a difference of 2,5 - 3 L/100km in difference:eek::eek::eek::eek:( sorry i have to do this in metric)
That is a HUGE difference my friends, all of a sudden this numbers some members here and on TV been talking about seamed more real to me than before.

"highway driving i am at 23-24mpg" - Yeah sure:crazy: has been my thought on that before......but now:undecided:.


OK, right now i am driving around with a PS pump thats not making any resistance at all, but how much can the PS take if we talk mpg L/100km?.

Thing is that i changed my old PS pump because it was screaming but it was working and this happened almost the same time as my T-stat was starting to act up.

First i changed my PS pump and a couple of months later my T-stat, at that time i thought my mpg was bad at 15-17 mpg city/highway driving combined.

After i changed the T-stat i didn't see any improvement i mpg at all and that makes me wonder today if i got a faulty PS pump and have been driving around with this for a year and a half and now it failed on me.

OK, now i tried to make the difference clear in mpg after some research. Old mpg before PS failure was 14,7/MPG. After is 20/MPG and that is with a EXT with 2 adults and 4 kids as always, i hardly ever drive alone.

And its going like a bat out of hell. Wheel-spin driving straight with 6 in the truck on dry tarmac:eek: I like this, its like a free PCM tune:yes:
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
I surely can't explain it. If the old pump was stealing 20 HP, that's effectively 15,000 Watts disappearing somewhere, being transformed into heat. Whatever it was would take very little time to explode or melt, not months. And the serpentine belt would be incapable of sending 20 HP to the pump pulley anyway.

They fail by shearing the internal shaft, so the pulley won't stop suddenly and kill the belt, thus making it impossible to even drive to a place of safety. Think of the thin shaft from the pulley to the pump as a mechanical fuse.
 

Harpo

Original poster
Member
Dec 4, 2011
419
Sweden
I cant understand it either.

It is such a enormous difference in both mpg:s and power.

Thing is that this pump has never been as quiet as the old one, it started foaming the fluid at first but it was due to a air leak between the pump and the reservoir.
Got that fixed by some extra O-rings.

But now it is dead quiet and now i know how noisy it was.


Do you mean that it is risk of the pulley to fall off?? i pulled at it the other day and it seemed just as firm as before.


I talked on the phone with the company that i bought it from to get them to send me a new one, but he told me to check if i any debris caught in the backpressure valve located right under the output.

Could that even be possible??
 

Sparky

Member
Dec 4, 2011
12,927
Roadie, where is the 20 HP loss coming from? :confused:
 

Sparky

Member
Dec 4, 2011
12,927
Oh ok.
 

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