Rust removal additive?

[JHZR2]

My 1991 MB 350SD that I’m bringing back due to inability by my mechanic, must have had only water or a remnant of the old G-05 in it. It was about a gallon low before I started it.

I flushed a bunch today, but it didn’t get clear. I drained from the radiator and block drain, and flushed through both.

I put some G-05 I had in there to at least get new inhibitor reacting with the surfaces. But what additive should I use to do a better cleaning? This is iron block, aluminum head, so I’m not sure I want to do citric acid flush.

Recommendations?

 

[CDX825]

Fleetguard restore plus. Supposed to be specifically for cleaning rust out of a cooling system.

 

[JHZR2]

Fleetguard restore plus. Supposed to be specifically for cleaning rust out of a cooling system.

I have restore but not restore plus. That’s a setup that needs to be run shortly then flushed a LOT.

I’ll probably use it and/or buy the plus, but I want to just passivate the surfaces and start to lift the loose corrosion products. The car doesn’t have an issue with cooling performance. Since there was oil in there I bought generators some time back but it seems that the plus is the better option given the rust that wasn’t there before…

In the interim, is RMI-25 or something else a good bet to help clean things up but not be an issue with gaskets and all?

 

[eljefino]

Citric acid is for if you have lime in your water, or the water that was native to your car where it lived before you bought it. Doesn't seem appropriate in this case.

I cleaned out my cutlass ciera 3300 (iron everything) by filling with water, driving to work for a day, draining, and repeating. It did eventually clear up.

 

[Trav]

My 1991 MB 350SD that I’m bringing back due to inability by my mechanic, must have had only water or a remnant of the old G-05 in it. It was about a gallon low before I started it.

I flushed a bunch today, but it didn’t get clear. I drained from the radiator and block drain, and flushed through both.

View attachment 232344

I put some G-05 I had in there to at least get new inhibitor reacting with the surfaces. But what additive should I use to do a better cleaning? This is iron block, aluminum head, so I’m not sure I want to do citric acid flush.

Recommendations?

I cant see how citric acid would be an issue. MB has recommended it for years in mixed metal engines.

 

[JHZR2]

Citric acid is for if you have lime in your water, or the water that was native to your car where it lived before you bought it. Doesn't seem appropriate in this case.

I cleaned out my cutlass ciera 3300 (iron everything) by filling with water, driving to work for a day, draining, and repeating. It did eventually clear up.

What was in the engine when I dropped it was proper 50/50 of distilled and G-05. Im sure they drained everything, and it was a gallon low. But I’m surprised all the same, I’d think the block would still hold a lot of G-05 silicate and inhibitor, even if they haphazardly filled it after replacing the HG. So maybe it would be 25%, but still protect. Not this.