00:00 |
After our discussions on the various other automotive plumbing systems in this section of the course, it'll come as no surprise that excess heat has an unwanted effect on the power steering system.
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00:11 |
As always, minimising these will prolong the life of the fluid and the components, as well as helping improve performance.
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00:19 |
The pump and power steering rack will have an ideal operating temperature range that's somewhat elevated and hard use from cold could shorten their life but in the real world, the negative effects of using the system cold will be mostly negligible in terms of the plumbing side of things.
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00:36 |
In most cases, when the vehicle is being used, particularly in a motorsport application, we're most interested in minimising the heat of the power steering system.
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00:46 |
Depending on the application and use, the system could generate very little heat or quite a lot, and depending on the location of the engine and other heat sources, the external heat that the system is exposed to could be significant.
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01:01 |
As power steering fluid is oil based, overheating will cause it to break down and degrade, lessening its ability to lubricate the system.
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01:10 |
If the fluid boils, air bubbles will form in the system and just like with our braking system hydraulics, this will prevent the effective transfer of pressure and therefore assistance force.
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01:22 |
Another downside of overheating the system is the risk of damaging components like the power steering pump or rack.
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01:29 |
The rubber components like seals, gaskets and hoses can quickly degrade when exposed to excessive heat, causing leaks and again the inability to transfer pressure.
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01:40 |
As we've already touched on, the source of the heat can be internal from the operation of the system or from external sources.
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01:49 |
Let's discuss internal heat management first, remembering that the pump will only pressurise the fluid when required.
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01:57 |
Cruising in a straight line or even drag racing is relatively low demand from a power steering perspective, but rally, off road racing and drifting are naturally a different story.
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02:08 |
The pump has to work a lot harder in these cases and this introduces more heat into the system as well as wear on the pump.
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02:15 |
If we're starting with a factory system not designed for these applications, aside from upgrading to a more suitable pump, we can also introduce a cooler that can help manage internal heat produced by the system and also go a long way in dealing with the heat transferred to the fluid from external sources.
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02:34 |
If the power steering fluid level is too low, there's not as much thermal capacity so the system will heat faster.
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02:42 |
Obviously, making sure our fluid levels are topped up is the best place to start, but sometimes increasing the capacity with a cooler can also help in this regard but at the expense of weight.
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02:53 |
From a plumbing perspective, there's not too much we can do to deal with this internal heat but as usual, there can be some small gains available from using convective heat transfer by having fresh air pass over the lines and importantly, when the air is heated from the process, it needs to be ducted away from the vehicle.
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03:13 |
Dealing with external heat should be pretty obvious by now if you've followed along the course so far.
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03:18 |
The best bet is always avoiding the heat sources in the first place but when our routing limitations don't allow for that, then heat shielding, insulation and ducting to lower the overall engine bay temperatures are the general methods.
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03:32 |
The final thing to mention in regards to routing is that our power steering system needs to be bled just like our coolant system.
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03:40 |
Therefore, avoiding high points that could form air traps above the reservoir fill point is critical.
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03:46 |
In saying that, the process here is helped by the ability to move the steering rack and force the air pockets out of the system.
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03:54 |
So, in summary, heat can have a negative impact on power steering just like the various other automotive plumbing systems.
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04:01 |
More demanding steering use and heat transfer from external heat sources can cause the fluid to degrade and boil, hurting its lubrication and pressure transferability as well as damaging components and plumbing.
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04:14 |
Power steering coolers are a good starting point to deal with this but depending on the root cause, routing considerations, air flow, heat shielding and insulation may be more effective options for mitigation.
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