Author & Automotive Expert James D. Halderman



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Halderman newsletterFebruary 2013
Dear Karl,

Welcome to the February edition of the Halderman newsletter.

I am very excited to announce an exciting learning tool and opportunity that I've made available to each of you!


Lesson plans for Automotive Technology-4th edition are now posted on my website.

Go to

and click on classroom content then lesson plans.

Lesson plans for other titles will be posted as they are completed.



I've also enjoyed interacting with many of you through social media. Please continue to follow me on LinkedIn, Facebook and Twitter.




ASE Sample Question
Straight Talk
ASE Sample Question



A good reading for a cylinder leakage test would be ________.


a.   Within 20% among cylinders

b.   All cylinders below 20% leakage

c.   All cylinders above 20% leakage

d. All cylinders above 70% leakage and within 7% of each other




The correct answer is b. A good mechanically sound engine should measure less than 20% leakage. The lower the amount of cylinder leakage, the better the engine condition. Answer a is not correct because all cylinders should be less than 20%, not within 20% of each other. Answer c is not correct because the leakage should be less than 20% not more than 20%. Answer d is not correct because the leakage should be very low. A 70% leakage rate means that 70% of the air entering the cylinder is escaping past the piston rings or valves.

Frequently Asked Questions

How Can a Cracked Exhaust Manifold Affect Engine Performance?


Cracks in an exhaust manifold will not only allow exhaust gases to escape and cause noise, but also allow air to enter the exhaust manifold. Exhaust flows from the cylinders as individual

puffs or pressure pulses. Behind each of these pressure pulses, a low pressure (below atmospheric pressure) is created. Outside air at atmospheric pressure is then drawn into the exhaust manifold through the crack. This outside air contains 21% oxygen and is measured by the oxygen sensor (O2S). The air passing the O2S signals the engine computer that the engine is operating too lean (excess oxygen) and the computer, not knowing that the lean indicator is

false, adds additional fuel to the engine. The result is that the engine will be operating richer (more fuel than normal) and spark plugs could become fouled by fuel, causing poor engine operation.

Straight Talk

From the December 15, 2012, Wheels section in the Dayton Daily News:


The case of the luke warm Buick




Bill B writes by e-mail:

"I have a 2005 Buick Lacrosse. I bought in 2010. It had 20,000 miles. It has 34000 now. In June of 2011,  I changed the anti-freeze. I used Prestone flush and fill. I put a tee in the top hose coming out of water pump. I connected the water hose to it and flushed the system. I put a new lower radiator hose on and filled it with the Prestone extended life anti-freeze.

The heater worked well last winter, but now it just blows luke warm air.  Every once in a while it does blow hot air, not often. I put in a new thermostat a few weeks ago, but it didn't help. I think I should put DEXCOOL in it.

What do you think? I hope you can help. Thanks"


I wonder why you replaced the coolant with just 34,000 miles on a two-year old vehicle? As many know who read this column, I recommend that technicians and vehicle owners follow what the vehicle manufacturer recommends. In this case, Buick (General Motors) recommends that the coolant be replaced at 100,000 miles and that DEXCOOL be used.

Almost all coolants are ethylene glycol with about 3% additives. It is the additives (the 3%) that change the coolant. There are three types of coolant:

1.      IAT-Inorganic Additive Technology- This is the old green anti-freeze.

2.      OAT-Organic Acid Technology (DEXCOOL is one brand of OAT)

3.      HOAT- Hybrid Organic Acid Technology (can be many colors depending on the additive package) Most "long life" antifreezes are HOAT type.

The water used with the antifreeze is very important too and some vehicle manufacturers, such as Honda and Toyota, recommend the use of premixed coolant only. By the way, coolant is 50% antifreeze and 50% water. Some tap water is high in mineral and chlorine making it unsuitable for use in coolant.

I think your problem is caused by air trapped in the system. Follow the recommended procedures when refilling the coolant, such as opening a bleeder valve, to help keep air from being trapped in the system.



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Please let me know what you think of the newsletter. I would love to include any of your automotive news or any tech tips you might have. Send me your suggestions! 
You can email me here or visit my website. You can connect with me on Facebook, Twitter and LinkedIn too (links above). And I encourage you to visit this website for great car reviews and more of my Straight Talk columns.
Jim Halderman
James D. Halderman writes automotive technology textbooks for Pearson Education. He is an ASE-certified Master Technician with more than 20 years instructional experience.