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post #1 of 3 Old 07-17-2019, 11:56 PM Thread Starter Rookie
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Sludge under oil cooler questions

Hi all, I'm in the midst of replacing the oil cooler (with an OEM cooler) and the EGR cooler (BPD) on my '04 F-250. I just got down to removing the oil cooler and in the cavity it sits in there was sludge... thick and kind of in clumps in the oil. The oil sitting around the bottom of the oil filter housing is also thick and sludgy. Am I right in thinking this is most likely coolant leaking from the oil cooler in addition to the EGR cooler I knew was blown? Are there additional steps I should take besides cleaning this junk out from where I can see it? Any advice very welcome.

I should note I flushed the cooling system out pretty thoroughly, I think, before starting work. Drained and filled and ran it for a while three times, then continuously draining with a hose in the degas bottle for 30 minutes or so, then filled and ran and drained once more with distilled water. Basically following a video from No sign of sludge in the coolant as far as I could tell although the water at the end came out looking pretty rusty.

I also drained the oil from the pan since the truck was due for an oil change anyway. That oil is sitting in a drain pan and shows no signs of sludge.

Background: I had taken the truck to a shop for a diagnostic because it was losing coolant, blowing white smoke, also intermittently chugging and losing power when towing my trailer up a hill. The tech pulled the EGR valve and showed me that it was cleaned out by steam, meaning ruptured EGR cooler. Their suggestion was BPD EGR cooler, new oil cooler while in there, also service the turbo while it's out and some other assorted things. The labor was more than I could afford and I have lots of time on my hands at the moment so after watching some videos I decided to tackle it myself. So I knew the EGR cooler was bad but had no indication of a bad oil cooler til now.

Like I said, any thoughts very welcome.

Last edited by straight_up; 07-17-2019 at 11:57 PM. Reason: typo
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post #2 of 3 Old 07-18-2019, 11:08 PM
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Coolant in the oil won't make sludge. It's probably from lack of maintenance from previous owner.

If you're in an area that doesn't do smog, an EGR delete would be best
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post #3 of 3 Old 07-19-2019, 05:30 AM
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Sludge can be a bit ambiguous in this case. Depends on what color sludge your talking about. If it’s a tan/brown then it’s related to moisture/coolant. If it’s a black sludge, then it’s from infrequent oil changes and heat. If it’s the latter look under the oil cap and inside the fill tube-maybe pull a valve cover for grins. Early Chrysler 2.7s were bad about making sludge, and we’d flush them with diesel to clean them out. However on a PSD I wouldn’t recommend using straight diesel in the crankcase. This would be the only time I’d recommend a conventional oil. Use a high detergent oil like castrol or valvoline and change it every couple hundred miles. A picture would be helpful to identify this sludge.
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