News
Comment

Heavier oil grade may ease van's engine knock

I suspect an oil gallery is partly clogged, causing poor lubrication. There is no overheating or appreciable oil burning. The noise usually goes away after a short period.

  • salon of expensive car new luxury

Q How exact a science is engine lubrication?

I’ve owned a 1993 Nissan Axxess for more than two years. This small van is still a delight to drive, even though it has done more than 320,000 km.

The only problem: an engine knock that sounds like noisy tappets after a highway run or a restart when the motor is hot.

I suspect an oil gallery is partly clogged, causing poor lubrication. There is no overheating or appreciable oil burning. The noise usually goes away after a short period.

 


Ian Wilkins, Hastings

 

 


A Technician David Gerson replies:

Lubrication is critical and is precisely engineered to meet engine requirements. Engine longevity and fuel economy are key factors here.

Many manufacturers suggest the use of thinner 5W30- or 5W20-grade oils to meet fuel-consumption standards. See your owner’s manual and check the oil filler cap for guidelines.

In many cases, an owner’s manual may say thicker 10W30 or 15W40 oil is preferable at higher temperatures, as gaining better fuel economy can adversely affect longevity.

Low oil pressure may be the cause of your engine knock. A simple oil pressure test could confirm this.

Try using a heavier grade at the next oil change. It may just do the job.

I’d use no less than 10W30 for winter and 15W40 for summer.

Q The cruise control has stopped working on my 2000 Chev Z24 Cavalier.

I changed the headlight switch and the contact switch, but the system still doesn’t work.

Can you offer a plan of attack to rectify this problem?

 


Paul Dean, Woodville

 

 


A Technician Tony Prochilo replies:

Your Cavalier has a “stepper motor” type cruise control system.

This simply means that an electric motor is used to maintain and set a cruising speed.

First, have a few basic items verified for proper operation, such as fuses and the brake lamp switch.

Are any diagnostic trouble codes stored in the PCM (powertrain control module)?

If all checks out, a diagnostic test tool should then be installed at the cruise control module’s electrical harness and each input to the module tested in a specified sequence.

Keep in mind that the cruise control system on your Chev is designed not to operate under these conditions:

vehicle speed is less than 40 km/h;

when reverse, neutral or 1st gear is selected;

if the car battery has been overcharged or undercharged;

with low or excessively high engine r.p.m.

Nuts and Bolts

ASTRO ADVICE Daren Murdoch of Mississauga writes:

Reader John M. Cook’s 2000 “Chev Astro had starting problems in damp” (Service Centre, Aug. 12).

My 1996 Astro shut down twice in similar conditions.

I investigated and noticed the ignition coil arcing to its mounting bracket. Replacing the coil solved the problem.

Mr. Cook said he was looking at “performance” ignition cable set.

My advice is: don’t replace the ignition components with aftermarket performance stuff. GM and ACDelco make the best ignition wires for this van.


Email mechanical questions to

wheels@thestar.ca.

State make, model, year, engine, km and your full name and address.

Letters may be edited.

    Avatar
    Wheels.ca
    Show Comments