Maintenance Q&A
Fighting fluid loss

By Paul Abelson, senior technical editor

Q. I have a 2007 Freightliner Columbia with a 14 liter Series 60 DDEC 5. It has 990,127 miles on it. For about six months or so it’s been consuming a lot of oil, I mean like one and a half to two gallons every 600 miles. Do I really need an overhaul or is it something else that’s repairable?

A. This question came by fax from the fuel desk at a Petro truck stop. It was signed with the person’s first name and last initial only and didn’t include a phone number, which is unfortunate. I could not read the accompanying citation and could have used more information.

So, please, if you submit a question, provide a means of getting back to you. An e-mail address, a phone number or a direct fax (not a truck stop) number will do. Also, please provide serial numbers, at least for the truck, engine or transmission depending on your question. That helps in tracking the component’s maintenance history and any recalls.

Now, on to the question.

It is almost impossible to diagnose a problem without getting detailed information. You obviously have a major problem. Up to two gallons of oil is a lot to top off every 10,000 to 20,000 miles, let alone every 600. It reminds me of the old Detroit 8V71 engines, called “318s” for the horsepower they produced. You never changed oil, just added a quart or more every day or two.

You have a leak somewhere in your system. It could be internal, such as from broken valve guides or broken piston rings, or external from a damaged oil seal or a cracked hose to your oil cooler.

An external leak would have shown obvious signs, like oil pooling beneath the truck or streaks of oil running down the transmission. My guess is that it’s internal, allowing oil into cylinders and combustion chambers where it is burned and runs out the exhaust. Has your truck been spewing a lot of blue smoke lately? That’s a sign of burning oil.

Burning oil creates abrasives: soot and ash. They wear rings, cylinder walls, valves and if they circulate with the oil, valve guides. They will also wear cams, bearings and valve gear.

So, to answer your question about an overhaul, yes, you really need one. Since this has been going on for at least six months – more likely eight before we get to press – I recommend a remanufactured engine. You have too many variables to just redo cylinders and valves, replace obviously worn parts, and get a 90-day warranty. A re-man will perform like new and give you up to three years of warranty.

Q. I have owned seven semis, but never with a Detroit Series 60 engine. I bought a 2000 VNL 610 with 1.2 million miles. I had a complete rebuild about 400,000 miles ago. The last couple of months I started adding almost a gallon of antifreeze each month. The last oil change at Speedco showed no glycol contamination.

If there are no visible antifreeze leaks and the oil analysis comes out OK, what is the acceptable amount to add before being concerned? Also, what is the usual suspect in a Detroit Series 60? How do you feel about block/head sealers, etc.? This is a 12.7 liter, 500 horsepower.

A. Since your oil analysis (my compliments for having it done) shows no glycol in the oil, my first guess is that somehow coolant is entering the combustion chamber, being burned, and going out with the exhaust. It has none of the EPA-required emissions aftertreatment that would trap coolant and clog or alter any emissions control devices.

Just to be sure, I contacted my friend Chuck Blake, a TMC Silver Spark Plug awardee who is one of the foremost experts on Series 60 engines. Blake suggested several possibilities. The first is to check the radiator cap. Springs lose compression strength rather quickly, and cheap imported 15-psi caps may hold only a fraction of their rated pressure or none at all. A bad cap will allow excessive coolant out the overflow.

When checking, also pressure-check the cooling system.

“In any case, start with a pressure check with the cooling system warm,” Blake advised. “It could be as simple as a weeping heater core at that many miles.”

You may have a weak head gasket that is allowing coolant to pass into the cylinder head. An alternative is that the coolant is being pressurized to the point of weeping out the overflow but not enough to reverse the flow back into the cylinder during off-time, leaving no trace in the oil.

Before getting a new head gasket, you need to check cylinder liner heights, Blake recommended. You mentioned a rebuild about 400,000 miles ago. You should have had head bolts retorqued at 250,000 miles after a rebuild. Was it done?

It’s hard to say what is a reasonable loss of coolant, but Blake feels that more than a gallon in 50,000 miles is cause for concern. As for the products for plugging coolant leaks, they temporarily stop the symptoms but do nothing to correct the cause. They can also cause other problems by plugging coolant flow. LL