Diesel Service Tips

Posted by Mighty Auto Parts on Aug 28, 2018 3:08:17 PM

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That Can Save a Lube Service Tech Much Frustration

Diesel applications often present the most challenges for lube service technicians. Unfortunately, most do not get the opportunity to service many diesels, and therefore do not establish a pattern of normal characteristics of the engine.

Check engineHow many times have you serviced a vehicle and the customer returned complaining that the engine was making a noise or doing something that is wasn't doing prior to your service? Most likely it was making that noise all along, and he has just now focused his attention on it. You must deal with it to keep your customer happy. Often, there is factory information available to support your explanation. Let’s consider some of those incidents and especially where the vehicle manufacturer has responded.


Ford's Diesel Engine Noises Following an Oil Change

Ford advises that some 2008-2010 Super Duty 250-550 vehicles with the 6.4L engine may encounter a ticking or tapping noise that is most evident when the coolant temperature is above 185°F. The noise is most prevalent from idle to 1,500 RPM. Some vehicle owners complain the noise becomes more evident after 3,000-5,000 miles have been accumulated, of following an engine oil change. The noise is most noticeable at the rear of the driver’s side wheel well. This is to be considered a normal characteristic for this engine.


The noise is caused by the relationship between the engine block, crankshaft journals, bearing inserts, and oil viscosity. This relationship allows a pulsation that resonates through the engine block, producing the metallic ticking/tapping noise. Improvements in engine design and noise reduction make this issue seem new, when it has been prevalent all along, just masked by other noises. Do not attempt to make repairs for this symptom, as it is a normal characteristic of all diesel engines.


Similar complaints have been registered on the 6.7L engine following an engine oil change. Applications include 2011 Super Duty 250-550 vehicles. The complaints are described as a mechanical typewriter noise, especially when driving near a building or wall that improves the acoustics, making the noise prevalent inside the cab. Ford claims that improvements to the 6.7L engine to better reduce noise make the typewriter noise more noticeable than on previous engines.


Stacked tolerances may vary from one engine to another, and can contribute to perceived differences in the intensity of the noise. A noise comparison to a like vehicle should not be performed, as they will likely sound different, resulting in a conclusion that the vehicle has a problem. The typewriter noise emanates from the bell housing or oil pan area, and should be considered a normal characteristic for this engine. The noise will likely diminish significantly within the oil change maintenance interval.


GM Duramax Diesel With Intermittent Low Oil Pressure Warning Message

Imagine performing a lube service on a GM Duramax diesel and having the customer return, complaining of an intermittent Low Oil Pressure Warning Message display. Be aware that a lube service, replacement of the oil pressure sensor, oil pressure gauge, oil pump, or an engine re-build is not going to satisfy this low oil pressure warning complaint.


Vehicles affected include 2008-2010 Chevrolet Express and 2008-2010 GMC Savana with the Duramax, built prior to September 11, 2009. The customer may comment that the low oil pressure warning message may display when the vehicle comes to a stop after driving at highway speeds, especially during high ambient temperatures. The message may not appear until the vehicle comes to a stop and then is accelerated. The cure is a new ECM calibration from GM.


Improper Air Filtration

Make certain you follow the proper air filter installation procedures, and do not allow a vehicle to leave your shop with a damaged air filter housing or a broken hold-down clamp. Perform a thorough inspection of the air-box and housing for evidence of unfiltered air entering the engine through poor sealing or dusting. Dusting is where debris has been pulled through the air filter. It is not uncommon for a restricted air filter to lose its seal or to be pulled from its mounted position, allowing unfiltered air to enter the engine. These conditions can promote engine knocking, hard or no start, oil consumption, loss of power, excessive blow-by, etc.


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Mighty - Larry HammerBy: Larry Hammer, Mighty Technical Services

Originally appeared in Mighty Auto Parts On The Line

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