I switched my truck from green to red coolant, my stock radiator was plugged up, I replaced the radiator with an aluminum radiator, I flushed the system prior to the radiator replacement with water and simple green, removed block drain plugs and flushed it till it was clear water, I noticed the old radiator was full of sandy greenish sludge and the radiator hoses have the same sandy sludge in it, my question is will this cause problems in the future, obviously you cant inspect the inner block coolant passages and I refilled with detroit extended life coolant, I used the detroit coolant because I work at a freightliner dealership and I get it for dirt cheap, has anyone else had issues with this? Its definately not oil in the coolant, just a film all over everything from not changing coolant or putting to much sca additives in it from the previous owners, I also did water pump, and thermostat, heater core, heater lines and radiator hoses, I'm pretty sure there is a film still in the block, I'm not a scientist I'm just trying to keep this truck running as long as possible, will this film mess up the anti cavitation quality of the extended life coolant

 

Post some pics and it'll help us diagnose

 

I didnt take any pics, I still have the radiator at work and I'll take a pic tomorrow, you can stick a screwdriver in the lower radiator hose port and scrape out some gray greenish sludge, it feels like sand if you rub it between your fingers

 

Its normal to have some actual sand in there, leftover from when the block was cast. Flushing doesn't get it all out. Also possible that the previous owner used a block sealant product that left some residue.

 

Here is a pic of the stuff I'm talking about

Lower radiator hose port

 

almost looks like someone filled it up with leak stopper.

 

That's kinda what I'm thinking too, ive never used a leak stopper so I have no clue what it looks like in the system, I guess I'll just put a coolant filter on it and see how it goes

 

That appears to be silicate fallout from traditional green coolant that is way too old. Almost completely inert chemically, but it can clog up the overflow hose if there's enough of it. A good flush or 3 will get it out. On another note, is your old radiator by any chance the "w/o A/C" version? If so please send me a PM about selling it.

 

I originally thought that's what it was but everyone I talk too kept telling me it was a stop leak sealer, I took the radiator in to have it inspected and cleaned out and they also confirmed that it is a mixture of silicate dropout and corrosion, it is an A/C radiator and I was going to keep it, sorry, thank you for the reply.

 

very interesting. never saw the silicate before. but then again i am strict about changing coolant every other year.

 

Dont feel bad, the only time I have ever seen it was on a training video 20 years ago when I worked at a local truck stop, I've never actually seen it in person and I've worked on thousands of trucks, but as soon as I saw it with my truck it kinda clicked but i wasnt sure, it only happens when your green coolant is old, back in the day they called it green goo, that was also on the video, and i also remember now that if you put too much sca in the coolant it can also fall out and collect all through the engine, that's kinda why i started this thread, i wasnt sure and I've never really experienced it, so I'm gonna flush it again, coolant filter and cross my fingers it goes away

 

I'm new to the forum and I appreciate all the help, And as a side note I have worked on freightliner trucks for a while now, I have read about all the different coolants to put into an IDI engine, from my experience over the years a detroit DD15 engine is a standard cast iron block, cast iron head, aluminum water pump and a bunch of rubber o-rings and I've honestly never seen the detroit extended life coolant eat through any rubber o-rings, aluminum or the cast iron, the o-rings that I have seen fail are in high heat areas like in the injector cups and they become rock hard and brittle and they crack, infact most of these engines have really clean internals coolant wise, it's cheaper then cat and fleet guard coolant, I'm just throwing this out there as another option to add to the list, BUT the IDI has brass/copper radiators and oil coolers so I have no input on that, maybe someone else can share there experience with how they work together

 

Some good info here, thanks for adding all that. My $0.02, informed by a combination of experience and reading the SDS sheets for dozens of different coolant brands over the years-

Theoretically our engines, as well as most highway diesels from before 1995 or so and any off-highway diesels up to about 2000, do best with the old-school high silicate green coolant they were designed to use. Worked great with any "drinkable" (Ford's words) water, didn't have to be distilled or pH neutral or anything. These coolants did an EXCELLENT job of protecting cast iron, and it is not uncommon to see factory-clean coolant jackets with coolant that is more than twice its rated service life of 3 years.

Unfortunately, that formulation is very hard to come by these days, and most green coolant is only "green coolant" as far as the dye is concerned. If you care to do a ton of reading about the dozens of different coolant formulations out there you will quickly realize that color is no longer the reliable indicator of chemistry type that it used to be.

Most of the heavy-duty (usually red) stuff is designed to do a decent job of protecting ALL metals, since HD truck engines are still made of iron for the most part and often have a significant wetted area of brass. Most of them are pretty cheap too. My view is that if one has access to red coolant at a good price, it's probably the best way to get an SCA precharge with an SCA that you know is compatible, AND be sure you don't have any EHA in the mix.

 

Good man, I do the same. Everyone seems to think that coolant and brake fluid last forever, I have a feeling both of us can testify otherwise from the things we've seen.

 

you pretty much answered every coolant question I've ever had, thanks for that! That's the scientific part that I know nothing about, good info!