What you wrote here makes it sound like this is an intermittent issue and that the noise and lower power don't happen all of the time, is that correct? If the power steering feels fine and runs quiet sometimes that is a relevant clue to the extent of the issues and what may be going on, etc.
I'd say this is mostly correct. The issue really picked up around January this year during the coldest part of the winter in Green Bay. Always started and ran fine, but winter just seems hard on some components. Because I attributed this to likely being due to the cold, I didn't think much of it. It's my daily driver although my commute is only a few miles to work each day. On days when I did drive further, I'd notice improvement as the vehicle "warmed." However, once temps warmed and the issue was still consistent, I decided to bring it in.
A few possible causes to your symptoms:
- Old and contaminated fluid can have moisture in it, etc. and can fail to perform well in cold temps. This could be related to the issues you are seeing now or how some of them came about during the cold winter, maybe. If the fluid gets too thick due to it freezing with contaminants then it's not going to flow well, the pump will starve for fluid and cavitation (which wears the vanes/surfaces in the pump) etc. will cause groaning and low power and can do relevant damage to the pump pretty quickly.
- Leaks can allow air to get into the system which can then cause the fluid to froth up and absorb compression which causes a reduction in power and other issues in the pump as it tries to compress the air (also can cause cavitation and groaning at the pump).
- Clogging of the filter/screen in the fluid reservoir can restrict flow, starve the pump and cause groaning (cavitation) and lower power.
If it were mine I'd of course start with a close inspection of the system but my expectations are that my next steps would be to do the following, on my own, at home:
- Drain fluid from the reservoir and clean the filter/screen to make sure that fluid can flow properly.
- Do a full fluid replacement until the fluid in the system runs clean (search mud for how-tos).
- Clean the area around the pump, steering box, hoses, etc. to make inspecting for leaks easier.
- Note how dirty the fluid that came out was and what was in it (hopefully not much metal/shiny stuff).
- Run the truck to see how the fluid change impacted steering operation and if there are relevant leaks, etc..
- Find any leaks and diagnose if any hoses, lines or components need replacement.
- If performance is acceptable, without leaks, I'd run it for a few weeks and then re-inspect and possibly flush the fluid again until it stays clean after operating for a while.
From there you may not need to replace any components, lines or hoses or you may have leaks or a damaged pump that need to be replaced, etc.. Hopefully the steering box is ok and not compromised from metal in the system and I'd personally give it every chance to prove that it's ok before jumping into replacing it.
All great suggestions - thank you. Tomorrow it'll be in the shop and I'll pass along this advice. To your point below, I really don't think the place I brought it to previously did a very thorough review to understand the issue. It seemed to more of a guess based on what they noticed vs a diagnosis based on actual evidence. And then threw a large quote at me and told me that since it was such an old vehicle, maybe it wouldn't be worth repairing anyway. Which I was pissed about. Hoping for the best - will provide an update on the thread!
There could be other issues with the system not reflected in the above plans / steps. Loose components and major damage to the system could be present, as the dealership seems to indicate with their recommendations, so be careful not to run it and cause more damage if you are hearing increasingly loud and concerning noises, etc. Based on my experience working as a dealership mechanic years ago though (not Toyota) the techs may have been being a combination of lazy, careful and greedy with their recommendations. Rather than take the time to diagnose the issue and only recommend you replace what actually needs to be replaced they may have decided to have you replace everything that may be involved. Without being there I don't know if their recommendations were based on something they observed but it's common practice for some shops to simply take the 'replace it all' approach with minimal/no reason and minimal/no real diagnostic time. That is the safest and highest profit path for them to take so it makes sense why they would do this.
Try to minimize the groaning as it is likely cavitation and wearing the pump but getting clean fluid to the pump should improve, and likely fix, that. If the system operates without noise and adequate power some times then I'd take the above steps that I listed and be optimistic that some/all of the major components are actually ok and that you just have air, contamination and/or blockage in the system causing the pump to cavitate and that once the system has clean fluid in it that it will work fine with no other changes beyond possibly fixing a few leaks.
