Bottom Line
Maintenance Q&A

Paul Abelson
SENIOR technical editor

Question: I got a new dedicated run, so I found a new shop to work on my truck. When I checked the dipstick after an oil change, it looked like it was overfilled. The engine holds 40 quarts. The shop charged me for 44. I understand extra oil to fill the filters, but I asked about the oil level being high. I was told that you can harm an engine if the oil gets low, so they add a couple of extra quarts to protect it. Are they right, or just selling some extra oil?

Answer: They’re not right, but I believe they’re just misinformed. They won’t get rich on the profits from a few quarts of oil. First of all, it is a good idea to pre-fill new oil filters before installing them, but the oil in the filters is included in the manufacturer’s oil capacity specifications. The oil level should always be checked after filling and running the engine for a while, after the filters have had a chance to fill with circulated oil.

As for overfilling to prevent low oil levels, don’t do it. The oil should be between the “full” and “add” marks on the dipstick. If the level is over the full mark, the crankshaft churns through the oil. This has several adverse effects. It creates drag on the engine, reducing fuel mileage. It vaporizes some of the oil, overtaxing the crankcase breather system. Worst of all, it prematurely uses up anti-foaming additives in the oil. Without these additives, air gets entrained in the oil. That lowers oil pressure and reduces the volume of oil doing the actual lubricating and cooling. Aerated oil may not have sufficient film strength to keep moving parts separated. 

Don’t let the oil level get below the “add” mark, but never fill the crankcase above “full.”

Question: My brakes vibrate when I’m in reverse. The whole front end seems to shudder. It sounds like a growling noise is coming from the brakes. What causes this? Can it be fixed, or do I need new brakes?

Answer: Approach this, as all non-routine maintenance issues, systematically. Look at the basics first. Are wheel seals leaking? Is the lining worn? Is wear uneven? Oil soaked shoes can cause intermittent grabbing. So can out-of-round drums. Worn camshaft bushings can cause misalignment that could give your symptoms. 

Brakes are critical. Just because you noticed the problem only in reverse, don’t delay getting this corrected. For insight beyond my experience, I called OOIDA member, owner-operator and ASE Certified Master Truck Technician Jeff Barker. Jeff said that when cams and bushing wear excessively, and then pressure is put on cams the opposite way from their normal wear pattern, the result could be the growling noise heard only in reverse. Jeff suggests removing the steer tires and rims, then inspecting everything. This may mean using calipers and micrometers to measure wear to the thousandths of an inch. When you feel vibration and shuddering, wear has already taken place. It compounds as misalignment in one component causes new wear in other parts. 

Years ago, we thought front brakes were not needed, and could even contribute to lock-up and loss of steering control. They were either disconnected or not installed. Today, we know that because of weight transfer, the front brakes contribute disproportionately greater effort to the truck’s braking effort. Jeff emphasized that you should never cut corners with brakes. 

If it were my truck, I’d have a brake specialist do the repairs. I’d also replace every wear part: drums, shoes, cams and cam bushings and springs. Also, check all bolt holes for roundness. You can’t mount new parts properly if bolt holes are elongated. Any and all components could be worn or damaged. Don’t take chances with brakes.

Question: I have a Freightliner Classic with a 243-inch wheelbase. The right steer tire wears on the outside and the left one wears on the inside. I had alignment and steering checked. Tie rods seem OK. There’s very little play in the steering column U-joints. Shocks are moderately worn, but not enough to cause the wear I’m getting. What causes my tires to wear out?

Answer: Nine times out of 10, the wear pattern you describe (inside/outside) is caused by drive axle misalignment. The thrust line of the drive axles is most likely slightly offset from the truck’s centerline. When you had your alignment done (most likely on the steer axle only), they may have re-centered the steering wheel, or you may have been increasing the angle at which you hold the wheel to compensate so gradually that you most likely didn’t notice.

When getting alignment checked, don’t just shop for price. You probably were sold a front wheel alignment (only) instead of the total vehicle alignment suggested by TMC in Recommended Practice RP642A. That would include the trailer if you own your own or have one trailer you pull exclusively. Any misalignment in the trailer can also drag your truck out of line.

Note to readers — more on suspension
In the May issue, I answered a question about re-bushing a Neway air suspension. I suggested the Service Specialist Association as a resource, and that the reader “upgrade” to polyurethane bushings. As I have since learned, my reply was only part of the answer. 

Roger Elkins, product manager for Neway, part of the Holland Group, wrote me suggesting that when dealing with Neway products, the first place to seek assistance should be Holland USA. He described the customer service staff and manuals available to assist customers. This, by the way, is true for most truck component suppliers. Let me now suggest that all problems not resolved at the dealer level first should be referred to the component maker’s customer service department, especially if still under warranty. 

Elkins also said that “Holland does not recommend or approve the use of polyurethane bushings for use with our AD Series suspensions for several important reasons, including …

“If the suspension is within its warranty period, use of polyurethane bushings would void the warranty. 

“… Polyurethane, being ‘harder’ than rubber, may cause fatigue issues with other suspension, frame and/or axle components. Our suspensions, as well as suspensions manufactured by other suspension manufacturers, are designed and qualified with materials of construction specified by the manufacturer. Substituting other materials of construction not qualified and tested by the manufacturer may produce undesirable results.”

Those results, he goes on to say, may include “a fatigue failure with a suspension, frame or axle component.” 

There are many suppliers of aftermarket suspension bushings. Among them are some well-known American suppliers and a large number of unknown offshore makers of generic, will-fit products. The durometer (hardness) of polyurethane can be varied, just as rubber’s can be. I trust the well-respected domestic suppliers to provide the proper durometer of polyurethane for each specific application for which they make kits. I do not trust the generic suppliers, and I understand Neway’s concerns.

Polyurethane does maintain its properties longer and resists abrasion better than natural rubber. It resists chemical and atmospheric deterioration better. But if the specification is wrong from the start, I agree that collateral damage can occur. When in doubt, check with the manufacturer and follow recommendations.

Paul Abelson can be reached at truckwriter@anet.com.

Do you have a maintenance question?
You can write to Paul Abelson, senior technical editor, in care of Land Line Magazine, PO Box 1000, 1 NW OOIDA Drive, Grain Valley, MO 64029; or you can fax information to (630) 983-7678; or e-mail your question to truckwriter@anet.com. Please mark your message Attention Maintenance Q&A. Although we won’t be able to publish an answer to all questions in Land Line, we will answer as many as possible.

Aug/Sept Digital Edition