JoeR Posted March 31, 2017 Share Posted March 31, 2017 A friend at a local fleet shop has a 6.4L that has been losing coolant for a couple of weeks. With no obvious external leaks they pulled the cab to begin forensics. When they pulled the Charge Air Cooler it had over a gallon of coolant in it. I understand this is as likely as saying coolant was found in the rear tires....but I promise that it is the case. So other than discovering a wormhole in Central North Carolina, anyone have an explanation for me? There's no obvious path for the coolant to get there. Sabotage is unlikely. Real answers, as well as smart-ass comments are welcome. Joe Quote Link to comment Share on other sites More sharing options...
lmorris Posted March 31, 2017 Share Posted March 31, 2017 Have you drained the oil pan yet? I ask because if the oil level is overfull it will fill the CAC. If you have coolant in the oil it could be carried with the oil and get separated in the CAC. Quote Link to comment Share on other sites More sharing options...
KDS Posted March 31, 2017 Share Posted March 31, 2017 Early style EGR valve leaking back down the CAC cold tube? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted March 31, 2017 Share Posted March 31, 2017 Without ignoring your CAC issue, the first thing that comes to mind is why did they pull the cab? Second thing is did they do normal EGR cooler diag like pulling the outlet temp sensor and checking it for goop or being too clean? The third and very common issue is the front cover, I tell guys to pull the WP and likely they'll see the cover is pitted or rotted. Fourth is that if the rad/wp were leaking and spraying near the air cleaner inlet (is this possible?) or a loose band clamp it would also cause your issue. Most 6.4s with slow coolant loss are going to be an EGR cooler or front cover. Like L said, drain the oil, check for coolant, maybe get an oil analysis done (Napa/Wix/CQ 4077 or 24077, $14) and see how much coolant is in the oil. I hate guys that pull cabs to "do diag", it drives me out of my mind, they just f* ** themselves if you ask me, and shows incompetence. They need to diag the truck while it still runs and drives. Edit- They should have done a cooling system pressure test while it ran, too, to see if it built up abnormal pressure while driving. I tee a 30lb gauge into the degas bottle line and drive it. 1 Quote Link to comment Share on other sites More sharing options...
JoeR Posted April 1, 2017 Author Share Posted April 1, 2017 Have you drained the oil pan yet? I ask because if the oil level is overfull it will fill the CAC. If you have coolant in the oil it could be carried with the oil and get separated in the CAC. They didn't pull the drain plug, but the oil was not overfilled. They'll check that on Monday though. Early style EGR valve leaking back down the CAC cold tube? Never knew that was even possible. Great suggestion. Thanks! Without ignoring your CAC issue, the first thing that comes to mind is why did they pull the cab? Second thing is did they do normal EGR cooler diag like pulling the outlet temp sensor and checking it for goop or being too clean? The third and very common issue is the front cover, I tell guys to pull the WP and likely they'll see the cover is pitted or rotted. Fourth is that if the rad/wp were leaking and spraying near the air cleaner inlet (is this possible?) or a loose band clamp it would also cause your issue. Most 6.4s with slow coolant loss are going to be an EGR cooler or front cover. Like L said, drain the oil, check for coolant, maybe get an oil analysis done (Napa/Wix/CQ 4077 or 24077, $14) and see how much coolant is in the oil. I hate guys that pull cabs to "do diag", it drives me out of my mind, they just f* ** themselves if you ask me, and shows incompetence. They need to diag the truck while it still runs and drives. They pulled the cab because they couldn't find a leak and figured it was time to start taking stuff apart to diagnose it. They've got a bunch of 6.0s and 6.7s in their fleet, but not many 6.4s, so it's understandable if they're making rookie mistakes. I've done stuff equally dumb on stuff I was inexperienced on too. It is good to know that you can get to all that stuff without pulling the cab. You wouldn't think so at first glance though. It's so tight in there. They drained the cooling system and pressure tested it with a high pressure smoke machine. At 15lbs of pressure it indicates no leaks. Thanks everyone for the help. This is exactly what I was looking for. Joe Quote Link to comment Share on other sites More sharing options...
KDS Posted April 1, 2017 Share Posted April 1, 2017 Well, If they're doing dumb rookie stuff, I hope they didn't mistake the Secondary radiator for the CAC. That would explain a lot the coolant they found. lol 1 Quote Link to comment Share on other sites More sharing options...
jimmy57 Posted April 1, 2017 Share Posted April 1, 2017 That 6.4 drank coolant as an attempt at yet another way for a 6.4 to commit catastrophic suicide. The problem is 6.4s don't have kidneys and livers to be fatally damaged as with humans, dogs, cats, etc. Quote Link to comment Share on other sites More sharing options...
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