What is this in my coolant filter?
 

With 440k miles, my 2001 Excursion is still running strong (new injectors and some mods, otherwise original innards). Synthetic 5k oil changes and keeping up with the maintenance has proven an effective strategy to keep the 7.3L running.

I was changing my bypass coolant filter (water pump to coolant reservoir) and decided to cut it open and see what had collected. It was pretty much 100% blocked with a smooth, peanut butter-like substance. Not particularly oily and water soluble. Here's a pic.


https://cimg8.ibsrv.net/gimg/www.for...f3a4cbaa32.jpg

I am doing a full flush and refill with CAT ELC today and another new filter (it's been a couple of weeks since I changed out the sludgy one).

I am losing a minor amount of oil at the turbo o-ring and am losing a little bit of coolant, but my engine oil is fine--no signs of water. And the coolant in the reservoir doesn't show any signs of oil.

Any ideas what the residue is? I expected some casting sand but not sludge.

--Scott

I would do the flush, with a new filter, BUT I would not add the ELC yet Scott. I'd run it for a few days on distilled water and then recheck the coolant filter for this sludge. ELC is too expensive to waste, if the system isn't completely cleaned out. I can't think of anything other than oil in the coolant or two antifreezes that were so incompatible they formed this sludge. Good Lord, that is some nasty stuff! I'm betting on oil in the coolant...

Hmmm. I am sure I have mixed coolant brands over the years. This will be the first ELC fill.

It's been at least 200k since the last flush (my bad). I didn't detect any oil when I mushed it with my fingers.

I like the mixed coolant hypothesis and the idea of running it on plain distilled water for a few days. I was planning on some Prestone system cleaner and multiple flushes.

Good advice, thanks.

Anyone seen incompatible coolants gel up like this?

The sludge was easily washed off the filter and my hands with a hose so I am hoping I don't have any blockages...

Several years ago when I was working in a lube shop, more than once I saw where people had added old school green coolant to systems that were filled with dex-cool or G05. It formed a NASTY sludge and one suburban even ended up overheating the engine and warping the heads. when he had the engine torn down, it was a buddy of mine that did the work. he said every single coolant passage was blocked to some extent, and several were completely plugged. But on a positive note, the owner of the suburban said that it had been running progressively hotter and right before he brought it in he even described hearing and feeling things that I can only guess would have been detonation. so the truck tried to tell him it was sick, he just didn't have the presence of mind to listen. the sludge was a little different from what you have in your picture though. it was almost a gel. a lot more thick and it was actually kind of squishy.

It looks like you're a good candidate to continue using a coolant filter after you make the ELC switch-over.

That's the worst one I've seen. Aren't you glad you added that filter?

It might be interesting to send off a sample of the old coolant to Polaris Labs to see what's wrong with your system.

Are your hoses getting soft?

Pop

curious question, are you smelling any fuel when you open the degas bottle? I've seen several threads about fuel in the coolant on the forums here and I wonder if that might be another viable suspect.

I had the exact same stuff in my filter at about 425ishK, it was my oil cooler. Re ringed my oil cooler and I am now at 460k+ without issue.

Think what the OP's would look like without that filter?

Or......... maybe it STILL does........... :-((

Pop

Steve, can you elaborate on what your symptoms were and what exactly you did to resolve the issue? I have never delved in to the oil cooler...

--Scott

No fuel smell (or oil for that matter) in the reservoir.

I did have the injectors changed out about six months ago...mine were really weak, I had a noticeable, gradual loss of power over the past couple of years and hard starting...but that's another story. The coolant and filter were not changed when the injectors were done.

--Scott

The only reason I spotted mine was my coolant filter wasn't flowing. Everything else in the coolant system and the oil system was nice and clean.

I searched and found the thread, it was back in 2011 and I was closer to 340k not 440 as I stated earlier. The thread was titled "look what I found in my coolant filter!" There where originally pics in the thread but I am not seeing them on my iphone,

Would someone mind digging that old thread up and throwing up a link to it, that also is tough to do on An iphone from the IB app.

The photos are still there, Steve.

Pop

Instead of running distilled for a few days, I'd suggest doing a few flushes of the cooling system. Here was my experience on this project: https://www.ford-trucks.com/forums/1...procedure.html

I've heard bad things happen when Dex-Cool is used in vehicles not made to use Dex-Cool (like Ford vehicles) or mixed with another coolant, but mixing traditional green with Ford gold (the same as Zerex G-05) won't cause a goop like that to form.

Stewart