As a market leader in innovation and North American manufacturing, Bosch brakes utilize proprietary friction formulations and follow rigorous production standards to ensure optimal performance and reliability. Experience superior braking with Bosch braking components.

Receive a 10% instant rebate for all Bosch branded braking products (pads, rotors, shoes, fluid, and rotor & pad kits) from May 1st – May 31st, 2025. Simply add qualifying parts (marked with a ) to your cart and instantly save 10%.

QuietCast Rotors are 100% balanced with an aluminum-zinc coating to prevent rust, while OE-style casting provides heat dissipation and multiple checks to ensure quality.

ESI6 Brake Fluid is applicable for DOT 3, DOT 4, DOT 5.1 and ISO Class 7. Bosch’s next generation brake fluid offers low viscosity and high wet boiling point for extended life and reduced wear on your braking system.

Find these Bosch parts and more in the "Brake & Wheel Hub" category of the RockAuto.com catalog.

Keep your drinks hot or cold for longer with this matte Navy 20 oz. Essential RTIC Tumbler, featuring an engraved RockAuto logo! The Essential Tumbler is designed for great taste on the go, is easy to clean, and the engraved logo won't fade or peel off.

• Ceramic-Lined Interior — prevents altered or metallic taste and smell, so drinks taste better and it’s easy to clean
• Leak-Resistant Lid — features double threading and a leak-resistant tab to keep your drink from spilling and your lid on tight
• Up to 24 Hours Cold / 6 Hours Hot — with double-wall, vacuum-sealed insulation, UV heat protection, and an airtight seal

I had just completed replacement of both front control arms on my 2005 Toyota Highlander. I hopped in it to take it for a test drive. Upon turning the ignition key to start the vehicle, the brake pedal hit the floor board, and the engine shut off immediately. Panic began to set in. I was like, "What the heck? All I did was change the control arms!"

I took a breath. OK ... you had the calipers off ... pump the brakes to re-seat the brake pads. I tried to restart the engine, same result. I tried starting the car three more times in disbelief. I grabbed the code reader. What the heck no codes!!! I could not imagine what had happened. I opened the hood and looked around. That's when I saw it.

The air intake hose/boot had come off the throttle body! It probably occurred when I had jacked the engine up and down to remove the engine mounts to get access to the forward control arm bolts. I reconnected it, and the Toyota sprang back to life. Sometimes even the simplest job has a gotcha.

John in Indiana

When my socks start getting lots of holes, I check to see if I have grown goblin toenails or have been wearing worn-out shoes with exposed plastic bits inside. Similarly, it is a good idea to look upstream and downstream for problems when exhaust manifolds start cracking more frequently.

Some exhaust manifold designs (i.e. GM's 2.4L Ecotec 4-cylinder exhaust manifold shown) are just more fragile. Relatively long, loosely supported exhaust manifold runners made of iron will crack after being expanded and contracted by enough heat cycles. However, even a crack-prone manifold design will last much longer if there are not engine problems (upstream) and catalytic converter problems (downstream) that are repeatedly overheating the exhaust manifold.

2.4L Ecotec 4-Cylinder Exhaust Manifold

The exhaust systems on older cars often have a length of relatively cool exhaust pipe between the exhaust manifold and a solitary catalytic converter. Cars built this century usually have the exhaust manifold bolted (or welded) directly to the first of two or more catalytic converters. The exhaust manifold is sandwiched between the engine's hot cylinder head and a hot catalytic converter while hot exhaust gases flow through the works.

The catalytic converter will become excessively hot if unburned fuel gets into it. Some of the problems that could lead to excess gasoline entering the exhaust include the engine's ignition timing being off (timing chain/belt, tensioners...), ignition parts not working correctly (ignition coils, spark plugs...) or a leaking fuel injector.

The engine computer could inadvertently make the air/fuel ratio too rich because of an incorrect too-lean signal from the upstream oxygen sensor (before the first catalytic converter). The oxygen sensor might have been contaminated by leaking engine oil. An oxygen sensor compares the oxygen in the exhaust to the oxygen in the ambient air. The oxygen sensor voltage signal might indicate the exhaust gas had relatively more oxygen than the outside air (too-lean air/fuel ratio) if access to the outside air is blocked by oil residue. The engine computer would ramp up the flow of gasoline in an attempt to correct a too-lean air/fuel ratio that in reality is becoming increasingly too-rich.

The oxygen sensor could be working fine, but there is outside air leaking into the exhaust gas. Air might be leaking around the exhaust manifold gasket or through a small crack in the exhaust manifold. Once again, the voltage signal from the oxygen sensor will tell the computer the air/fuel ratio is too lean and the computer will increase the flow of gasoline into the engine's intake. An unfortunate downward spiral can start. A small crack in the exhaust manifold lets in air, the oxygen sensor/computer sends in more fuel, the excess fuel burns in the catalytic converter, the heat from the burning fuel distorts the exhaust manifold, the crack in the exhaust manifold gets bigger, more outside air gets into the exhaust... Burning excess gasoline, engine oil, coolant, etc. in the catalytic converter will eventually damage the catalytic converter as well.

Routine maintenance (oxygen sensors, spark plugs...) and quickly fixing problems (leaking valve cover gasket, broken timing chain tensioner...) will help prevent a cascade of more serious problems (cracked exhaust manifold, clogged catalytic converter...).

Tom Taylor,
RockAuto.com

To read more of Tom's articles, click this link and choose from story titles on the Newsletter Archives page.