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ianacole
01-16-2012, 09:30 AM
So, I could use some guidance here. I pulled in to the gas station to fill up on Thursday, and fluid was leaking from every vent and seam on the hood of my '73 40 (Chevy powered). Quick review indicated that the power steering pump had hemoraged on the fan, spraying fluid everywhere. With the amount of build up and gunk around the PS pump I figured it had just given up and needed replacing.

Odd, though, it never got difficult to steer.

So, picked up a new pump for $45, and a new cap as well, replaced this weekend. Went driving, and the same issue. I took a close look, and near as I can tell is that the fluid came from the cap area. This to me would indicate a pressure build up in the pump, causing the springed cap to open up to release the pressure. And this is where I get confused. In order for pressure to build up in the pump, wouldn't there need to be a blockage in the system somewhere? And if there were a blockage somewhere, wouldn't it become difficult to steer? Are my next steps to replace the lines and then rebuild/replace the steering box?

Thanks for any suggestions!

Ian

Air Randy
01-16-2012, 10:10 AM
There should be a high pressure bypass valve in the steering gear. That way when you are turning the wheel hard against the stops you don't blow anything up. Its supposed to let the excess pressure bypass and return to the pump. Sounds like that valve may be stuck closed or only partially open. Thats why you are still getting pressure to the steering assist but excess pressure is building in the pump. Does your rig have the Saginaw PS conversion since it's a chevy V8 now? Those steering boxes are very inexpensive and fairly easy to replace. If you have a Toyota FJ40 power steering gear they are difficult to find. You might have to do a mini truck steering gear conversion. If you already have the mini truck gear they are easy to find.

ianacole
01-16-2012, 10:55 AM
Thanks Randy. I believe it is the Saginaw conversion, but I haven't determine via part number that that is indeed the case. Would a replacement of the whole box, or would a rebuild be better?

Uncle Ben
01-16-2012, 11:34 AM
There should be a high pressure bypass valve in the steering gear. That way when you are turning the wheel hard against the stops you don't blow anything up. Its supposed to let the excess pressure bypass and return to the pump. Sounds like that valve may be stuck closed or only partially open. Thats why you are still getting pressure to the steering assist but excess pressure is building in the pump. Does your rig have the Saginaw PS conversion since it's a chevy V8 now? Those steering boxes are very inexpensive and fairly easy to replace. If you have a Toyota FJ40 power steering gear they are difficult to find. You might have to do a mini truck steering gear conversion. If you already have the mini truck gear they are easy to find.

Hmmmm....Never seen a bypass valve in the gear before. Bypass valves are usually (for sure on a Saginaw pump) on the pump at the head of the high pressure hose. What you are describing does not sound like bypass valve failure but rather air in the fluid. Common characteristic of a sticking or malfunctioning bypass valve is steering assist in one way and not the other. (IE able to turn easily to the left but difficulty or intermittent difficulty to the right) Are you using power steering fluid or ATF? PS fluid is designed to not support air bubbles to stay trapped in suspension. ATF can and will allow foam to stay in suspension because Auto trannys have flat filters in the pan designed to strip the foam from the fluid while PS systems do not. If you have any water or other contaminants in the system it will also foam. (this includes a mix of synthetic and dino based fluids) I suggest a system flush with fresh PS fluid.

http://www.corvette-restoration.com/photos/power_steering_pump_rebuild/4.JPG

ianacole
01-16-2012, 11:57 AM
Thanks Kevin. Now that you mention it, I think the original fluid was ATF, as it was pink in color, and the PS fluid I put in was clear. I thought the PO used Royal Purple PS fluid, giving it the color, so I didn't think much of it. I didn't think about doing a full flush, but saw that mentioned in a search here for similar issues. I will run through that tonight.

Is using ATF in power steering a common practice? Are there benefits?

Uncle Ben
01-16-2012, 12:16 PM
Thanks Kevin. Now that you mention it, I think the original fluid was ATF, as it was pink in color, and the PS fluid I put in was clear. I thought the PO used Royal Purple PS fluid, giving it the color, so I didn't think much of it. I didn't think about doing a full flush, but saw that mentioned in a search here for similar issues. I will run through that tonight.

Is using ATF in power steering a common practice? Are there benefits?

Dextron ATF used to be the norm for PS. Now that Dextron is in it's third revision (Dextron III) it is no longer suggested for power steering fluid. Use specific power steering fluid! Never mix synthetics with petroleum based fluids. Royal Purple is a very good but purely synthetic lubricant. Synthetic PS fluid is highly desirable because of it's ability to withstand very high temperatures but also very expensive. Running normal PS fluid has it's advantage by being available on any shelf in any store whereas synthetics are not.

nuclearlemon
01-16-2012, 12:27 PM
Now that Dextron is in it's third revision (Dextron III) .

try 6th revision...yup, we are up to dexron vi

Air Randy
01-16-2012, 12:35 PM
Hmmmm....Never seen a bypass valve in the gear before. Bypass valves are usually (for sure on a Saginaw pump) on the pump at the head of the high pressure hose. What you are describing does not sound like bypass valve failure but rather air in the fluid. Common characteristic of a sticking or malfunctioning bypass valve is steering assist in one way and not the other. (IE able to turn easily to the left but difficulty or intermittent difficulty to the right) Are you using power steering fluid or ATF? PS fluid is designed to not support air bubbles to stay trapped in suspension. ATF can and will allow foam to stay in suspension because Auto trannys have flat filters in the pan designed to strip the foam from the fluid while PS systems do not. If you have any water or other contaminants in the system it will also foam. (this includes a mix of synthetic and dino based fluids) I suggest a system flush with fresh PS fluid.

http://www.corvette-restoration.com/photos/power_steering_pump_rebuild/4.JPG

Right, but he said he installed a new pump and the problem did not go away. So he either has a blockage in the steering gear or in one of the hoses.

It doesn't seem likely that it is a wrong type of fluid issue. I assume it was working OK for an extended period of time with that same fluid in it, then all of a sudden he started spewing fluid all over?

If it is air in the fluid then something must be causing the pump to cavitate and foam it up.

corsair23
01-16-2012, 12:59 PM
I can't help with the issue but on the fluid, after a lot of searching this is what I put into my '97 LX450:

http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=4zf33&op=search&Ntt=4zf33&N=0&sst=subset

Before the change out the pump was a whiny SOB and after, quiet as a mouse :) - I don't know what weight oil is suggested for your system so this may not be applicable. But if it is, the local Grainger store should have it. I just ordered it online and it arrived the very next day :thumb: - shipping cost was about what it would have cost me in gas to drive over and get it.

Uncle Ben
01-16-2012, 01:02 PM
try 6th revision...yup, we are up to dexron vi

Yup....I meant after the third revision. I'm old ....give me a break! :rolleyes: ;)

Uncle Ben
01-16-2012, 01:03 PM
Right, but he said he installed a new pump and the problem did not go away. So he either has a blockage in the steering gear or in one of the hoses.

It doesn't seem likely that it is a wrong type of fluid issue. I assume it was working OK for an extended period of time with that same fluid in it, then all of a sudden he started spewing fluid all over?

If it is air in the fluid then something must be causing the pump to cavitate and foam it up.

He also stated his steering was working. No workie if no fluid movement!

RockRunner
01-16-2012, 05:55 PM
I was thinking air, I had that problem in my Dodge and 4Runner. At speed the steering on both trucks was fine but on the Dodge during slow maneuvers the steering was heavy and choppy. The 4Runner was OK at slow speeds since it is a 5 speed and I would just add a little throttle.

I flushed the Dodge and have not had a problem since and my problem came out of no where too. I also checked all the hoses and tightened all the clamps so no air could enter. The 4Runner got new lines since I went hydro assist and that took for ever to bleed all the air out.

Check all your hoses/clamps even if it is the pump won't hurt.

PS do you have an in-line cooler?

ianacole
01-16-2012, 07:26 PM
Thanks all! The steering behaves just fine at both speed and rest. I do not have a cooler in line. No noticeable leaks, and I went through and made sure all the lines were tight when I replaced the pump. This started last Thursday, with no changes prior to that. I've been driving this in this configuration for almost a year now.

TIMZTOY
01-17-2012, 12:09 AM
i would guess gear box.

Get a second person to help.
*Have the truck running and full of fluid (at proper level).
*With the cap off the reservoir, turn the wheel all the way to the locks. don't keep it at lock, but bump it on and off, it doesn't matter which lock, but test both. see if the fluid level over flows.
*If it does over flow, it is a issue with the gear.
The fluid will raise and drop a bit when bumping, but should not over flow.
you should also see the fluid flowing inside the reservoir with the car running turning or not turning.
Also your system is very easy to bleed the air out of.

if it does over flow then take the pressure hose off both the gear and pump and blow the hose out with air. just to make sure its not a clog. good to check the return line also. (both bairlly ever get coged, but i've seen stupid'r)

ianacole
01-17-2012, 12:13 AM
Thanks! I'll give that a try and see what happens.

nattybumppo
01-17-2012, 02:06 PM
Dextron ATF used to be the norm for PS. Now that Dextron is in it's third revision (Dextron III) it is no longer suggested for power steering fluid. Use specific power steering fluid

OK, now I'm confused. I thought we were supposed to use ATF in old Toyotas, as it says on the pump top, and that PS fluid might actually degrade the system and make it fail. Help, clarity needed!

Air Randy
01-17-2012, 06:20 PM
Thanks all! The steering behaves just fine at both speed and rest. I do not have a cooler in line. No noticeable leaks, and I went through and made sure all the lines were tight when I replaced the pump. This started last Thursday, with no changes prior to that. I've been driving this in this configuration for almost a year now.

I agree with Tim. I would drain the system thoroughly and replace with the right fluid. Go through the steps Tim outlined for checking the hoses for clogs and getting the air out of the system. If it still pukes out of the pump then it's probably a steering gear issue.

TIMZTOY
01-17-2012, 06:42 PM
OK, now I'm confused. I thought we were supposed to use ATF in old Toyotas, as it says on the pump top, and that PS fluid might actually degrade the system and make it fail. Help, clarity needed!

your susposed to use powersteering fluid.. it has always been that way.. BUT ATF is a sutable replacement.. just dont mix if possible, i personally use ATF unless its a honda.

SteveH
01-18-2012, 10:07 AM
Many so-called 'Power Steering Fluids' that I see at chain stores seem to contain 'seal conditioners' and other junk in them, so I have avoided them in general. My '95 FZJ has been plagued by power steering noise and problems for years, in spite of a Toyota reman pump. I am intrigued by the ISO-32 oil idea, and my try using AW-32 hydraulic tractor fluid (which I'm pretty sure is the same thing). I have read on other forums that Dex III is not a suitable replacement for Dex II in all cases. Most hydraulic fluids are ~10 weight oil, and the differences between them are in additives. My last Dex III swap in my FZJ seemed to make it worse than before, so I'm going to try some different fluids.