[redfury]

The EVO is held on with a clip, and all it really is, is an electro magnet. It has an orifice that has 3 o-rings on the part that actually screws into the pump, but the electronic part can be removed without worrying about fluid spilling. Mine was leaking, and I replaced all the 0 rings and all seems well. My Power steering is smooth and whine free finally. I made special care to properly bleed the system before firing the engine up as well.

I do have to say, the 5.7 in this van does have some advantages in regards to access to the front accessory items...nothings tucked way back or really have much interference to speak of with the AWD frame.

 

[redfury]

yes. there are some clearance issues with the a/c being stacked on top the way it is. I never removed the a/c fully, just had to lift it enough, maybe a couple inches. it's really not that bad. 4 bolts and a bunji cord. what kind of v8 did you install?

It's got the express van 5.7 which is almost exactly the 4.3 with 2 extra cylinders.

 

[97AstroLT]

The EVO is held on with a clip, and all it really is, is an electro magnet. It has an orifice that has 3 o-rings on the part that actually screws into the pump, but the electronic part can be removed without worrying about fluid spilling...

So which from which direction did the electrical harness connect to it? My wires attach to it up from the bottom. The pictures in the service manual are contradictory as I mentioned. Can the thing rotate perhaps?

 

[Gone Blue]

Wow, I have to say getting the PS pump out of the van was harder than doing the intake manifold gaskets. It took me a lot longer than I thought it should have, but it is out.

So I am confused with the sensor on the back of the pump. I guess it is for low fluild? In any case, I am stuck trying to get the mounting post off the old pump. I rounded the really short hex with out too much trouble. Can you buy this sensor or mounting post? My new Delco pump has a hex coupler on the back of the pump. I have a picture of the new pump on my phone but it wont send the pic to my email so I can upload it here????? Do I have the right new PS pump or am I supposed to swap the sensor over?

Thanks, G.B

 

[Gone Blue]

Phone finally sent picture of new Delco PS pump to my email. Here is pic of the new pump with the hex couple in place of the 90 degree line adapter and sensor on old pump. I am looking for answers to my questions in the above post.

Thanks, G.B.

 

[chevymaher]

Your supposed to swap it over.

 

[redfury]

removing the outer electrical portion allows you to get a deep socket over that for removal, or you can use a wrench.

In regards to the position, the only thing that matters is making sure you plug it in...the electrical connector position shouldn't really matter from what I noticed when doing mine.

 

[Gone Blue]

Thanks Chevymaher and Redfury. So now I am stuck getting the sending post (not sure what to call it) off the old pump and onto the new. The picture is not clear but I rounded off the corners of the hex with what I thought was the correct deep well socket. I am thinking the only way that stud is coming off is with vise grips which will destroy it. I hope you can buy a new one?? G.B.

 

[redfury]

I thought I read here that there is a replacement part from GM to replace the assist.....should almost have a thread that identifies all the replacement parts by GM part number that are harder to figure out or find.

 

[cowboydan]

vise grips are you solution imo. compress the grips several times adjusting an 8th of a turn ( or less ) simultaneously. to get the teeth to bite better, you should apply top force while loosening to prevent marring the nut further. slowly wiggle the connection back and forth and readjust before loosening, this ensures maximum bite. first tighten just a crack and then loosen, this compresses the rubber O-ring, breaks corrosion and allows air to pass through the corrosion preventing damage to the threads. tighten back up, and loosen. if you feel the grips loosen, readjust the grips and continue. if using channel lock pliers, while wearing gloves, apply top force with your thumb. in both cases, don't try and make multiple teeth marks. the secret to vise grips imo is to multiply surface contact and patience. if you're careful, you might save the nut.
if that doesn't work, a small hammer and a chisel will be left. in this case I would try drilling a small divet in the nut flange and use a small punch. do not drill through.
the reason you stripped the nut is because there was more play in the connection or your socket taper is too deep for the thin fastener. some times you have to get selective with your wrenches. often times I find that switching between sae and metric gets me the best fit. sometimes I use a hammer to tap the socket onto the nut. not all tools are created equal, so not all brands are going to spec on... all the time.

 

[Gone Blue]

vise grips are you solution imo. compress the grips several times adjusting an 8th of a turn ( or less ) simultaneously. to get the teeth to bite better, you should apply top force while loosening to prevent marring the nut further. slowly wiggle the connection back and forth and readjust before loosening, this ensures maximum bite. first tighten just a crack and then loosen, this compresses the rubber O-ring, breaks corrosion and allows air to pass through the corrosion preventing damage to the threads. tighten back up, and loosen. if you feel the grips loosen, readjust the grips and continue. if using channel lock pliers, while wearing gloves, apply top force with your thumb. in both cases, don't try and make multiple teeth marks. the secret to vise grips imo is to multiply surface contact and patience. if you're careful, you might save the nut.
if that doesn't work, a small hammer and a chisel will be left. in this case I would try drilling a small divet in the nut flange and use a small punch. do not drill through.
the reason you stripped the nut is because there was more play in the connection or your socket taper is too deep for the thin fastener. some times you have to get selective with your wrenches. often times I find that switching between sae and metric gets me the best fit. sometimes I use a hammer to tap the socket onto the nut. not all tools are created equal, so not all brands are going to spec on... all the time.

Thanks Cowboydan for the tips. I finally figured out what I am dealing with, the EVO variable speed sensor. I am a little slow sometimes . If all else fails, I talked to my local Chevy dealer and they confirmed that you can't by a new EVO sensor. They have a new EVO sensor eliminator kit in stock at my discounted price of $60. I searched the net and could not find new EVO sensors for sale anywhere. Thanks again to all for your help. G.B.

 

[97AstroLT]

...I finally figured out what I am dealing with, the EVO variable speed sensor. I am a little slow sometimes . If all else fails, I talked to my local Chevy dealer and they confirmed that you can't by a new EVO sensor. They have a new EVO sensor eliminator kit in stock at my discounted price of $60. I searched the net and could not find new EVO sensors for sale anywhere. Thanks again to all for your help. G.B.

When I called the GM dealer about this also very recently, they told me it was called an actuator (which is the opposite of a sensor - an electromagnetic that moves a valve in this case). The part number of the EVO valve/solenoid/actuator was 26069030 but has not been available since 2006. It was replaced by a kit (P/N 26009895), that is also called a "fitting" that retails for $27 at GM dealers. I think you probably have either been quoted with some overnight-shipping charges or possibly they have misidentified part. This EVO actuator was only on the 1997 and 1998 Astros and Safaris. The replacement fitting makes the actuator unnecessary. I suppose it also eliminates the variable-effort feature, which is not necessary for safe control of the vehicle. I don't know if this feature was removed for the 99 & later models or if it was just implemented some other way.

Good luck. You're not the only one working on their Astro power steering ray:

 

[Gone Blue]

...I finally figured out what I am dealing with, the EVO variable speed sensor. I am a little slow sometimes . If all else fails, I talked to my local Chevy dealer and they confirmed that you can't by a new EVO sensor. They have a new EVO sensor eliminator kit in stock at my discounted price of $60. I searched the net and could not find new EVO sensors for sale anywhere. Thanks again to all for your help. G.B.

When I called the GM dealer about this also very recently, they told me it was called an actuator (which is the opposite of a sensor - an electromagnetic that moves a valve in this case). The part number of the EVO valve/solenoid/actuator was 26069030 but has not been available since 2006. It was replaced by a kit (P/N 26009895), that is also called a "fitting" that retails for $27 at GM dealers. I think you probably have either been quoted with some overnight-shipping charges or possibly they have misidentified part. This EVO actuator was only on the 1997 and 1998 Astros and Safaris. The replacement fitting makes the actuator unnecessary. I suppose it also eliminates the variable-effort feature, which is not necessary for safe control of the vehicle. I don't know if this feature was removed for the 99 & later models or if it was just implemented some other way.

Good luck. You're not the only one working on their Astro power steering ray:

Interesting, thanks for clarification and part number for EVO actuator. I will discuss your part number above for the fitting with my favorite Chevy parts guy. I have a 98 Astro. Thanks again, G.B.

 

[97AstroLT]

I meant to write "electromagnet" above, not "electromagnetic". An actuator enables the computer to have a physical effect (so sometimes it's called an "output"). I have the GM service manuals for the '97 and I read the part about the EVO. The computer causes a controlled amount of current to go through the electromagnet in such as way that as the vehicle speed is high (over about 40 mph, based on something I read) the valve somehow reduces the flow to the steering gear compared to the flow allowed at low speeds. The manual doesn't have a good enough diagram to illustrate how it moves to accomplish this. But it does say that the current is pulse-width modulated, meaning that the way the desired effect is achieved involves varying the length of time that the electromagnet energized by pulses of electricity (current). I happen to be an electrical engineer and modulation schemes were part of some of the classes (at the time I went though at least - the required classes tend to change over time).

Looking at the picture of your AC Delco pump, it's not real clear to me how it is to be used for the '97-'98 models. I wonder if they have a tech support line that would put you in touch with someone that could answer that question. It seems that hex nut would have to come off for you to put the bracket and EVO actuator on their pump. At least that nut would have to come off or be covered by the bracket if it is supposed to end up looking the same as the
'97 OEM pump.

 

[redfury]

The output has a hydraulic valving that is moved by the EVO unit restricting the output of the pump. Interesting to read that it was only on 2 model years though. I don't understand why they put it in in the first place, or why they took it out. Seems like somebody at GM decided they wanted to try something and it didn't work as intended.

 

[97AstroLT]

The output has a hydraulic valving that is moved by the EVO unit restricting the output of the pump. Interesting to read that it was only on 2 model years though. I don't understand why they put it in in the first place, or why they took it out. Seems like somebody at GM decided they wanted to try something and it didn't work as intended.

I think you're right - they dropped it for some reason. Reading the service manual section on this a bit more, this EVO was pretty complex: a separate computer module behind the instrument panel to the right of the radio, a sensor to detect steering wheel position (and about that it says the sensor detects "evasive maneuvers" so it may just detect quick changes to position, not raw position), then of course, the EVO actuator on the pump. This is a logical target for cost-cutting and reliability enhancement. And after noticing the part about it being supposed to detect and reduce power assist to "evasive maneuvers" when at high speed, it's possible this is only a safety feature that never benefits a driver who knows not to overcorrect when responding to a hazard.

Another surprise was that the service manual says that EVO equipped vehicles have a special pressure line with a 1-way valve in it. The purpose of that is to prevent a "kick-back" effect from the EVO when the vehicle hits bumps in the road (pot-holes and railroad track are examples). I know neither of my pressure lines have a 1-way valve in them!

I'm posting more details about my recent steering issue on another thread (http://www.astrosafari.com/viewtopic.php?f=46&t=27202&p=280786#p280786), but the EVO system is now my prime suspect.

 

[gordo999]

seperate the a/c pump and support a/c. remove 4 13mm bolts from the top of a/c pump. there is a short, black bracket which is held in by one of the a/c bolts and a 10mm bolt holding the oil add tube. remove bracket but not the oil add tube, just remove the 10mm bolt. wrap a bungi cord around the a/c pully, then stretch bungi up to hood pin. the hood support will hold. you only want to support the a/c pump about 1"

I realize this is an old thread but I am curious about the method used.

Is there a typo here? Should a/c references be p/s references as in power steering? I don't get why it is necessary to remove the a/c 'pump' which is non-existent. There is an a/c compressor and a p/s pump but not an a/c pump.

I am not being picky, I just want to confirm that removing the a/c compressor is not necessary. I can pretty well derive the meaning from the description but would appreciate confirmation.

Also, the description could fit the a/c compressor (2001 Safari) removal since there are 4 bolts on top and an oil add tune nearby that I think has to be removed for a/c compressor removal. There is also a short bracket attached to one a/c compressor mounting bolt.

It does not make sense at this point since the p/s pump is well below the a/c compressor.

 

[chevymaher]

Cowboydan is no longer a resident and the phone is disconnected.

 

[gordo999]

Cowboydan is no longer a resident and the phone is disconnected.

ok, thanks. I'll figure it out when the time comes, which should be soon.

 

[97AstroLT]

I assumed Cowboydan meant the A/C compressor since a compressor is a type of pump. My van is on a drive at the moment but I think A/C compressor mounts on the same large metal bracket as the P/S pump. The P/S pump attaches to the lower part of it and there are 4 holes for bolts on top of the bracket where I assume the compressor goes (I do have a spare bracket I could look at quickly - which I'll probably never use now, but I pulled it at a salvage yard in case my bracket was broken when I worked on my steering system last year). I'm pretty sure it's one of those 4 upper bolt holes where the tube for adding engine oil attached, which would is also consistent with Cowboydan's comment about the oil add tube. The bolt that held my add oil tube had stripped out and I had been using a small bungee cord up to the steering fluid reservoir to hold it in place for a while and I wanted to fix that when working on my steering system. Instead of replacing the bracket I ended up cleaning up the threads in oil tube bolt hole with a tap and getting a longer bolt in order to also reach deeper threads, and that made it solid again. Replacing that while metal bracket would been a big job. Pulling it at the salvage yard wasn't bad because so much had already been removed.