Making the Hydraulic Systems in your Vehicles Last

A great way to save money is to not spend it. One great way not to spend money is by doing everything possible to extend the service life of your vehicle and its systems.

This idea of extending life is especially important for the hydraulic system.

Vehicles with manual transmissions have two hydraulic systems. Most people have heard of the hydraulic system for brakes.

But if your car has a manual transmission, it has another one–for the clutch. Both use the same hydraulic fluid, brake fluid. It is contained in a fluid reservoir (the master cylinder) and routed through the hydraulic lines whenever you push down on the brake (or clutch) pedal. This hydraulic pressure reduces the effort necessary to apply the brakes and operate the clutch.

This system (this fluid) is probably among the most taken-for-granted automotive fluids, which probably explains why it’s often not changed, especially for the clutch circuit. Many owners are not even aware that it’s there and needs changing until the day the clutch pedal no longer operates the clutch. Now, they are very aware—and need to pay for a new clutch master/slave cylinder, as opposed to paying much less for fresh fluid.

Brake fluid is regularly neglected, too.

If it is left unchanged for too long, the potential for master cylinder problems, brake line problems, ABS pump problems and brake caliper problems (all of them a great deal more expensive than a $10 bottle of fresh brake fluid) goes up.

The fluid in both systems is replaced by bleeding the system. This involves opening a bleed valve with one at each wheel for the brake system and usually just one for the clutch system.  You then use the brake/clutch pedal to force out the old fluid while topping off the reservoir (master cylinder) with fresh fluid, being careful to not let any air into the system. Air in the system leads to a squishy-feeling pedal.

It is not a difficult as a do-it-yourself job and it’s not expensive to have someone else do it for you. But it can get very expensive if you forget to do it or have it done.

Left unchanged for too long (no more than 40,000 miles or three years, whichever comes first) the fluid is apt to turn from almost clear to brown, and (eventually) black. The color change is a visible measure of its degradation and contamination.

The longer you don’t change it, the more likely it is that expensive parts such as the master cylinder, ABS pump, slave cylinder (for vehicles with manuals) brake caliper pistons and so on, will cost you a lot more money than the cost of a $10 bottle of fresh fluid, or paying someone else to instill it.

Keep an eye on that fluid–that is something anyone can do. The only skill needed is the ability to open the hood and look. The brake master cylinder is usually on the driver’s side, close to the firewall. It is usually see-through (or has an “eye” you can eyeball) to have a look at what’s inside. The clutch fluid master cylinder typically looks similar, just smaller.

There is also a lid that anyone who can open a jar can open. Have a look. If the fluid is darker than maple syrup it probably needs to be changed. The sooner the better if you’d rather not open your wallet, wider.

Another hydraulic fluid that’s often taken for granted is automatic transmission fluid, and the reason is often a function of the marketing deception that the fluid is good for a “lifetime.”

By which is meant the lifetime of the warranty.

If you’d like your automatic transmission to last a lifetime (meaning, as long as the car does) it is sound policy to replace the fluid (and the filter) once every 50,000 miles or so. Or have it replaced, if you’d rather not replace it yourself. It will save you a great deal more than what you’d spend on a new/replacement transmission.

Anyone can check the fluid themselves–condition and level, and there’s no cost involved. On the other hand, failing to check (once every couple of months) can lead to massive costs, if a slight leak (as from a leaky gasket) goes undetected and the fluid level drops. Letting it get too low can quickly destroy an automatic transmission. Chemically degraded/contaminated fluid will do the same, just not as suddenly.

Until all-of-a-sudden.

The fluid can be checked by raising the hood, and finding the dipstick (your owner’s manual will tell you where to look) and looking at it. Make sure the level is where it ought to be (again, see the owner’s manual if the dipstick isn’t clearly marked) and that the fluid isn’t browning. It ought to be red (usually) but never brown. If it is, it’s time to change it. And even if the fluid isn’t browning, if it’s been in there for more than 50,000 miles, changing it is still a good idea because the filter inside the transmission probably needs to be changed by then.

Unless you’d rather it not filter.

Another thing you can do to extend the life of a manual transmission (in addition to also changing its fluid) is to gently let the clutch out with transmission in neutral and let the engine idle for about 10 seconds before you drive off first thing in the morning. This will engage the transmission without loading it and circulate the fluid (lube) within the transmission.

If you want to maximize clutch life, try to keep the vehicle moving even if it’s just a crawl. Most clutch wear occurs when getting going from a complete stop. If you’re rolling just a little when you let the clutch out, it will wear less and so last longer. Avoid abrupt shifts, and too much slip. Properly treated, the clutch your vehicle came with can and should last 150,000 miles or even longer.

Much depends on how you drive, and how much you’d like to not have to spend.

Eric Peters lives in Virginia and enjoys driving cars and motorcycles. In the past, Eric worked as a car journalist for many prominent mainstream media outlets. Currently, he focuses his time writing auto history books, reviewing cars, and blogging about cars+ for his website

Editor’s Note: The opinions expressed in this article are those of the author.

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