OM617 turbo

Previous owners did not maintain the cooling system. Hoses have thick layer of rust and scale built up on all surfaces. I am certain the block is just as bad if not worse.

Occasional high running temps, but not severe.


I have tried typical acid flushes - they're just not cutting it.

Looking into products like this (evaporust):

Evapo-Rust Cooling System Cleaner



Any one used anything like this? Any opinions?


I am not concerned about the radiator, or if it clogs.

__________________

Have you tried the citrous flush method specified in the FSM? One thing that I believe is included in the FSM is that you need to degrease the system before you add the flush. That seems like a good idea for any procedure you use, in my opinion.

I can't speak for the Evapo-Rust cooling system flush, but I have used their other rust soak products and had good results.

Personally, I'd consider switching to waterless coolant after the flush, just to prolong the life of the system.

I bought 5 lb of citric acid on ebay (food product) and use ~1 lb per flush. First, flush all coolant out and open the block drain (passenger side, behind turbo), putting it back loosely to remove again.

Evapo-Rust's main product is a liquid you soak rusted parts in. Their coolant flush may be different. It seems the Prestone flushes are pretty wimpy today. I think their older flushes used citric acid and worked better.

I changed both my 300D's to Evans Waterless, after a good flush. But, currently my 1985 is back to straight water + anti-rust, with an upcoming re-flush. Temps started creeping up last Fall, but see same creep w/ water, so isn't due to Evans. Hope not a crack in the head.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I have the same issue. Unfortunately, you will never be able to remove all of it. I put in a Gano coolant filter and a new radiator, so hopefully I am keeping it out of the radiator. But, as you said, there is still a ton of it in the block. I believe each time you do one of these types of flushes, you are scraping a layer of it off. Unfortunately, there are a ton of layers remaining in the block. Another consideration is that you may be prematurely damaging the heater core and the only replacement heater cores at this point are non-OEM, Chinese crap not to mention the job being an extreme PITA. So, I don't think there is a "proper" solution. I've also replaced both radiator hoses, which is a good idea considering the age, but the new ones have scaled up like the old ones within six months. Previously, I was going to replace all of the coolant lines, but at this point, I'm not even going to bother with it as long as my engine temperature stays around where I want it.

I've been able to control mine pretty well with outside temps in the 90s and driving with A/C on high with stop and go traffic,but the engine got a bit hot today while driving in 110 deg weather and I had to turn off the A/C a few times in slower traffic.

Dkr.

I don't know about the product you mentioned, but have had excellent results with RMI-25 Radiator Treatment. Add 8 oz to coolant, and it removed the rust in about 2 weeks, just like they claim.

My car's story: no service records of prior owner having had the coolant changed for 16 years. It had a very rusty cooling system. Had done the flush per FSM, numerous times, every 12-18 months, over 8 years. De-oiling step, using the specified MB de-oiling chemical, which is sodium metasilicate, 5% concentration. Red Devil TSP90 Heavy Duty Cleaner, is also sodium metasilicate. You can get the Red Devil TSP90 in paint stores or paint departments for a much lower price than what you would pay for the 500 g tubs of sodium metasilicate at a dealer. Drained, flush with water, drain, then follow with citric acid 10% flush per FSM.

For some of the citric acid flushes, I would drive the car around for a few days. Citric acid can be bought at stores which sell soap making supplies. For a 13 quart capacity cooling system, I would use 2 lbs 13 oz citric acid for each flush to make the concentration 10%. Some years, I did two 10% citric acid flushes back to back. Each time, a few days after doing the flush and putting in new coolant (Zerex G-05) mixed with de-ionized water, the new coolant mixture would be back to the same rusty root beer/Coca-Cola color.

Within 2 weeks of adding RMI-25, the coolant mixture was back to it's original/new orange color; rust color was gone. It leaves a ring of residue around inside the overflow tank, which can be rinsed out. I learned about RMI-25 on this forum, but don't know what others here have experienced with it. According to their literature, it has other additives, such as water pump lubricant, and an anti-cavitation additive.

I've been using it for about a year and a half. No financial interest, just a happy customer, at least so far.

__________________
Marshall Welch
Seattle, WA
1982 300D-T

that is excellent info.

thank you.


For reference, you can squeeze the hoses on this engine (any of them!) and feel the resistance added by the layer of rust as is crunches and flakes off.

Will the RMI go deep into this stuff?

__________________

I suppose what you're describing could be scale (minerals). I don't know what it would do with that. I replaced all of the hoses in my car in 2007, so my car didn't have anything like what you're describing when I added it.

__________________
Marshall Welch
Seattle, WA
1982 300D-T

The issue is dex-cool. You can research it on this forum and elsewhere. It cruds up in the system when mixed with other coolants. I have done extensive research on it and never found anyone to claim to have fully solved the problem.

It is completely unlike a normal old car that has just not had regular coolant changes and needs a good flush out with the normal ensuing rust.

Dkr.

I use vinegar in my 617.951.I dump a gallon in a cold engine with thermostat removed,I add a squirt of dawn dish washing liquid,and run engine with heater on for 15 minutes.Then drain,and let engine cool down and flush till no smell with garden hose feeding upper hose to radiator,with hose disconnected from thermostat housing.Learned this trick years ago,as vinegar is a mild acid.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran

I am a big fan of vinegar for rust. I strip blocks for rebuilding with it.


In this case, as mentioned in the first post, its jst not getting anywhere. I've done 3 vinegar soaks. 3rd one barely took off anything.

Thank you dkr... I am looking into the dex cool issue. you may be onto something there.

__________________

A few thoughts:
1) Have you tested the coolant for un-burned hydro-carbons? (simple test to check for head gasket & head/block leaks) If combustion gasses are getting into the coolant it will turn to a rusty gunky mess. You will never get it clean till the leak is fixed.
2) Have you tried flushing the block w/water till clear before the acid wash? I like to isolate the heater core from the process (pull the heater hoses off the core) and flush till clear plus thirty minutes.
3) If vinegar/acetic/citric acid flushes don't seem to be gaining you might try something more aggressive like CLR into a warm block. The acid reaction needs a little heat to get going (it is an endothermic reaction). It also takes a little time.

there is a trade off when using an acid flush, the acid attacks the aluminum. Also, Safety First - wear PPE (eye protection, apron, sleeves, gloves etc) and have plenty of fresh water handy to flush spills, and baking soda to neutralize spills & splashes.

Funny you should mention. Engine had an undisclosed overheating issue when I got it. It has a new head and gasket now. That still doesnt solve the problem of the buildup.

After each vinegar run, i flushed until clear. the first flush before all acid rinses was a strong detergent... I think it was "blahblahblah purple". the type you're not supposed to put on aluminum. ha....ohh


I have been reading a lot about CLR. It sounds possible, or a big waste of time. Mostly because I have NFC what this build up is made of.

I can bypass the heater core and I can scrap the radiator- I have a nicer one up at bat.



I appreciate your post. very helpful brainstorming, thank you.

__________________

So here are some interesting chemicals for this issue other than the typical acetic and citric acid flushes.

diammonium citrate

phosphoric acid



Industrial Water Scale Remover For Aluminum - Descale 518

Heavy Duty Cooling System Cleaner


Dynamic will not sell to you as an individual - only to a company. However, their MSDS is very useful and can help you make your own.

The other chemicals mentioned in this thread will take longer, I think but they may be worth a shot if your system is still working 'well enough' and you just want to set it and forget it.

I want something aggressive that wont murder a bunch of small children and the entire coral reef.

Likely, I will try to source the main ingredient in 'Descale-518' after I try one flush with CLR.

__________________

with extreme heavy scale and rust you need to first deoil the system and then derust it with citric acid or oxalic acid. You need to run the engine for an hour or so to peel off the rust from the engine. (thermostat removed and bypass blocked with something like a cork) so the liquid runs at full capacity through the engine and radiator.

With this much rust it would be a wise investment to get a coolant filter with no charge additive in it from NAPA complete with fitting kit and install it. The filter will keep on catching whatever stray rust particles will be floating.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

It isn't rust. It is solidified coolant.

You can test it when you do a flush. The particles are not magnetic.

Dkr.