What is this sludge on my radiator cap and floating in the coolant?

[whatisgrip]

Recently flushed out the old orange coolant, replaced it with yellow, and added a radium expansion tank. Now I'm getting this sludge like foam after the coolant gets hot, either spirited driving or track day. Had this happen to me twice now, each time I've just sucked out the coolant in the expansion tank and replaced it with new fluid. Temperatures are fine but does anyone know what this is or if I need to flush the system again?

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[SheepDog]

Usually an indication of oil in the coolant. Have you done an oil change recently to see if any coolant is in the oil pan?

 

[JAJ]

Recently flushed out the old orange coolant, replaced it with yellow, and added a radium expansion tank. Now I'm getting this sludge like foam after the coolant gets hot, either spirited driving or track day. Had this happen to me twice now, each time I've just sucked out the coolant in the expansion tank and replaced it with new fluid. Temperatures are fine but does anyone know what this is or if I need to flush the system again?

I recently did the same thing - swapped out the coolant in my GT350. I filled it using my Airlift, so it gets pretty full on the first try. I did get some foaming when I was just driving around to get the engine warm so the heater would kick in but it's gone now. I did two track days last week and I just looked at the coolant reservoir to see if there was any foam and it was clear. Or, putting it more succinctly, I don't know what's causing your foaming - it's not normal. That said, I'd be tempted to just leave it and see if it goes away.

 

[K4fxd]

Most likely you had oil in your new expansion tank.

 

[whatisgrip]

Usually an indication of oil in the coolant. Have you done an oil change recently to see if any coolant is in the oil pan?

I replaced all my fluids prior to the coolant including transmission and rear differential. I did not notice any milkiness or abnormalities in the oil.

I recently did the same thing - swapped out the coolant in my GT350. I filled it using my Airlift, so it gets pretty full on the first try. I did get some foaming when I was just driving around to get the engine warm so the heater would kick in but it's gone now. I did two track days last week and I just looked at the coolant reservoir to see if there was any foam and it was clear. Or, putting it more succinctly, I don't know what's causing your foaming - it's not normal. That said, I'd be tempted to just leave it and see if it goes away.

I did the same during my fill but using the astro pneumatic system, it filled the coolant too much initially and caused coolant to come out of the pressure relief valve. Radium says it might be aerated coolant and its fine but tempted to put the old bubble back on to see if the issues go away

 

[Egparson202]

Most likely you had oil in your new expansion tank.

I was thinking the same thing… maybe some kind of residue from the manufacturing process.

 

[whatisgrip]

Pulled the radium tank off and put the oem back on for peace of mind. Didn't see anything abnormal about the fluid coming out of the radiator hose so I'll give the radium tank a good cleaning before it goes back on and see

 

[HeelToeHero]

I had a few floaters this summer switching from orange to yellow this summer but not to the extent you have there.

 

[galaxy]

I've had the Radium tank...that's not the issue. (it has other issues, but not causing gunk, LOL)

 

[WD Pro]

I've had the Radium tank...that's not the issue. (it has other issues, but not causing gunk, LOL)

Off topic a little, but would you mind sharing the other issues ? (It’s top of my list for if I ever replace mine)

Cheers,

WD

 

[WildHorse]

Off topic a little, but would you mind sharing the other issues ?

Two that I heard of is leaking, & unable to hold pressure.

 

[whatisgrip]

I had issues with it holding pressures at first but after tightening the elbow fittings where the plastic tube goes it's been fine, only issue has been this sludge. One of those not sure the juice is worth the squeeze deals. The Radium tank looks way better than oem though.

 

[galaxy]

Off topic a little, but would you mind sharing the other issues ? (It’s top of my list for if I ever replace mine)

Cheers,

WD

I had nothing but frustration with mine. Never could get it to settle down. Coolant level was all over the place; up and down, up and down. Loooong story short, the only way I could get the tank to stop overflowing when hot was if the tank was completely empty when cold. If I added coolant back in the tank cold to bring it back into the sight window, it would fill up the tank to the brim as soon as you cranked the car. Then during a drive when up to temp, it'd spit it out again. This went back and fourht back and fourth. Also, every singe time I started the car, you could hear the coolant circluating through the heater core. Like running, bubbly water. Would do that again with revs until it settled down. Next start, do it again.

I got tired of that, took it off and put the stock tank back on, and bam, all problems solved. Back to normal.

It's just an expansion tank, not really a way to put it on wrong. And the system is self venting, but mine ran like it constantly had air in the system. I don't know what the fuck was up.

 

[Mrhavasu]

Stock works great for me and I can spend money elsewhere. Hope you get
that figured out and it ends up being nothing to worry about it.

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