Taking the plunge. My journey as an O/O.

Okay folks, I have not said anything about this here yet, because it didn't quite make sense. Now an issue with my truck finally makes sense, and I'm going to address it here.

About a week and a half ago, my truck shut down for low coolant. Left me stuck on the side of the road. I refilled with a gallon of coolant and a gallon of water. Truck was still throwing low coolant errors though the coolant reservoir was full. Stuck on the side of the road for 6+ hours. Used the kitty litter bucket. All that jazz.

I finally managed to get service to the truck, and it turns out that my coolant level sensor had failed. The tech said it's not uncommon for that to happen very rapidly after they are exposed to air in the reservoir, rather than being immersed in coolant.

So, I crossed my fingers and started checking coolant levels every few hours of operation.

I made delivery, picked up a load, made that new delivery, then went on home time to get the leak fixed in a shop, do some training on our lovely new ELD software, and renew my DOT cert. The whole time, I was losing about a gallon per day of coolant. No visible leaks anywhere. No codes. No engine performance or fuel economy issues.

So, the Freightliner dealer in Knoxville said they found and fixed a couple minor leaks caused by loose connections in the heat exchange system connections for cab/sleeper heat. They also replaced the reservoir overflow cap.

Since I had used about 4 different types of coolant in the last few days of operation, I had them do a flush and fill to make sure I had proper coolant chemistry, and to get the bottled water out of the system (not distilled.)

I rolled 200 miles to get from hometime back into one of our freight lanes, and checked my coolant the next morning. Down a gallon.

There had been no engine codes, fuel mileage was good, and still no visible leaks. I wanted at least one load under my belt to make the truck payment this week, so I took a short load, and a longer load, total of about 1000 miles, with my final destination Dallas.

Dropped the load in Dallas. Truck was still losing about a gallon a day of coolant, with no other symptoms I could find. Took the truck to Dallas Freightliner South and put it in for follow up service.

They pressure tested the system, and found no leaks, except they said the reservoir cap was bad. (*AGAIN - that same cap had been replaced less than a week prior.*) I explained this to the tech on the phone, and he was confident that he had diagnosed properly. So, I retrieved the truck, topped off the coolant, rolled across the street to the TA, and parked overnight, advising my dispatcher that I needed to test the repair before taking another load, since I was pretty certain that it wasn't fixed.

So, this morning, I wake up and check the coolant level after it had been opti-idling off and on for about 18 hours. It was down over a gallon.

Took it back across the street to the Freightliner dealer again, and explained the problem was not resolved. They put it back in the shop on a priority basis, and a couple hours later they found a problem.

My diesel fuel was red. I #### well had not been putting off-road diesel in it, nor was I using any colored fuel additives. My coolant is red. So, apparently, the engine coolant is being drawn into the fuel mix and then at least part of the unburnt fuel/coolant mix is being returned to the fuel tanks.

This appears to be a problem the technicians understand, they advise that there is a problem with the injector system.

All the symptoms and evidence now make sense.

So, now, I get to see if the aftermarket warrantee I bought when I bought the truck is worth a crap. There is a $300 dollar deductible, but the total cost for this repair is not going to be pretty.

Downtime and hotel costs won't be pretty either. I'm booked in this hotel now for 4 days. I'll be pleasantly surprised if the truck is done by then.

 

TruNorth

 

I have been told that simply getting to the injector cups is a six hour job.

 

Good point. I may ask them to run a forced regen to clean it out after we verify the issue is resolved.

What has me confused though...

How is coolant being injected into the fuel system near the engine?

Coolant in a diesel engine is all relatively low pressure, even when very hot. Fuel in a diesel engine is all very high pressure around the injectors., after it leaves the fuel pump.

For coolant to be forced into fuel lines means that somewhere in the system, there is coolant and fuel near each other, where coolant is a higher pressure than the diesel.

There are no injectors before the fuel pump, and all the injectors are fed very high pressure fuel.

Where is the high pressure coolant and low pressure fuel connection? Is there a water jacket cooling unused fuel after it depressurizes, before it returns to the fuel tank?