Valve Train Archives - UnderhoodService
Valve Lifter Technology

Hydraulic lifters are precision-fit assemblies.

Understanding Engine Timing – Chains, Gears and Belts

Perfect timing is critical in the performance world, and now, it’s required by your regular customers too.

Measuring Compression And Cylinder Leak-Down Is A Vital Skill

Today’s engine systems can recognize conditions that are destructive and take countermeasures to prevent damage.

Honda Timing Belt Tips

There are some things to keep in mind as you tackle these jobs.

Induction Cleaning Service For Direct-Injection Vehicles

You may have seen it before: misfire codes, stumbling and suspicious fuel trim numbers. On a scan tool, the engine may show a loss in volumetric efficiency. The driver may complain about a loss of power, poor fuel economy, hard starts and a rough idle. But this is not a 12-year-old engine; it is only

Diagnosing Variable Valve Timing

Fully variable valve timing can be achieved only by using computer-operated solenoids to precisely control the intake and exhaust valve opening and closing events. Although the various combinations of valve timing events are theoretically infinite on an electronically controlled system, their applications are limited due to issues of cost and, in some cases, reliability.

Tech Tip: Kia Constant Variable Valve Timing Oil Control Valve Inspection

This bulletin provides information related to the oil control valve (OCV) used in constant variable valve timing (CVVT) systems. If, at any time, the OCV is suspected as a cause of rough idling, poor acceleration, camshaft timing misalignment-related trouble codes, misfire-related trouble codes, etc., on a Kia vehicle equipped with a CVVT system, be sure to perform the OCV inspection procedure in this bulletin before replacement.

TIMMING BELTS: Bridging The Service Gap-CRP

By David Hirschhornt, CRP Automotive   Remember the good ol’ days when your customers came in for regularly scheduled maintenance? Oil change at 3,000 miles, tire rotation at 5,000, tune up at 10,000, and so on. While these helped you keep their vehicles in good shape, a hidden, but truly valuable benefit was the “advanced

Nissan VVT Diagnostics – Boosting Engine Performance, Fuel Economy And Emissions

Due to the ability of Nissan’s variable valve timing system to provide increased engine performance, Bob Dowie offers his diagnostic, electronic and mechanical expertise for how import vehicle specialists can most effectively perform engine service.

Phaser-Style Variable Valve Timing System Controls And Operation

Phasers commonly can be found on just the exhaust cam or on both the intake and exhaust cams.

Memory Lane: Nuts, Bolts And Screws – Finishing A Chevy Restoration Project

Gary Goms discusses the mechanical challenges of restoring a truck that he began maintaining when he went to work in a gas station – back in 1957!

The Ins and Outs of Variable Valve Timing (VVT) Systems and Their Role in Vehicle Emissions

By the early 1990s, almost all import automotive manufacturers had a successful variable valve timing (VVT) system in production. These systems offered higher performance from smaller displacement engines at higher rpm. Do you know that VVT is playing a direct role in vehicle emissions and the way gases are burned in the combustion chamber?