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Engine Flushing - Cooling System Question

Feb 6, 1998
11,454
Canadian Sailcraft 36T Casco Bay, ME
I'm in the process of converting my engine away from DexCool and the sludge and such was very bad. The Westerbeke distributor even admitted to a problem with water pumps, clogged cooling passages and other items they suspect to be caused by DexCool due to the numerous disimilar metals..

I currently have my HX off and I know most engine flush products require you to run the engine to warm it up before use, except for Rydlyme. This is to open the t-stat so circulation of the acid can work but wonder if Rydlyme can also work when cool? I like Rydlyme and will continue to use it unless someone knows of a better product.

Seeing as I am on the hard & indoors with no running water I plan to do this with an external pump, & the t-stat removed by tapping into the HX supply & return lines.

The question is, for the chem engineers amongst us, other than Rydlyme (not easily availble locally), what would you use as an alternatove to circulate through the engine. Keep in mind this is not running or warm, in an attempt to clean out the sludge left by the DexCool? I trust Rydlyme but was curious of there is something new I may have missed. A magic bullet if you will....

I know there are folks here who have a good handle on all things chemical and figured you guys might know better than anyone what other productst may work on an engine at roughly room temp (boat is in the barn for a bottom job and barn is roughly 68-70f).

With an external pump, the engine off and t-stat removed what else can I circulate through the engine to clean it that will work at room temp other then Rydlyme?
 
Feb 26, 2004
22,015
Catalina 34 224 Maple Bay, BC, Canada
Lime-A-Way

of lime-away. See reply #3, here: specifically

Ron Hill, our east coast C34 technical guru, has been using it for years in his HX. I do not know whether it is applicable for the freshwater side, but see no reason why not given your plans to thoroughly flush the system.
 
Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
I was in Cabella's or Walmart and saw a portable camping shower heater that runs on a camp stove propane tank. Why not just connect one of those into the circuit?

About 100 bucks for the shower set up but it would be a nice thing to have if you ever do go camping.
 
Nov 6, 2006
9,247
Hunter 34 Mandeville Louisiana
HEY, Main.. I did a little searching and found this from the GM tech letter to the service folks on how to cure the goo.. ......This was GM's response to the lawsuit, so it has been considered.. .. hope this helps.
1 each *Prestone® Flush and Fill Kit #AF-KITP U.S. (#00050 in Canada). This kit can be obtained from your local parts supplier and can be used on all vehicles repaired under this procedure. Save it after performing the repair, as it is reusable.
1 each *Prestone® Heavy Duty Cooling System Cleaner, GM P/N 12346500 - 1 per vehicle. This cleaner is in powder form and contains a neutralizer. Do not substitute other cleaners. The diluted cleaners that are available in liquid form are not recommended for this repair.
5.7 L (6 qt) of 100% (non-diluted) DEX-COOL® coolant (GM Spec 6277M).
1 each new thermostat, GM P/N 12563335.
2 each new radiator cap, GM P/N 15075565.
1 each *Prestone® yellow funnel. This funnel can also be obtained from your local parts supplier. It fits snugly into the radiator opening for an easy fill and is reusable.
----------------------
 
Sep 25, 2008
6,355
Alden 50 Sarasota, Florida
There are a couple of commercially available products, one being lime-away and the other CLR which are relatively harmless to you and the engine and should work but I'm not sure these are the best (read - most effective). Being a derivative alcohol sludge, there are any number of solvents which will better solubilize the sludge but at some risk to the boater as well as any non-neoprene or synthetic rubber gaskets so use of solvents such as hexane, albeit not that flammable or toxic, would be more effective but at a higher risk to the unaware. If you intend on using a solvent, consider the following:

personal protection incl respirator, flammability, degradation of some components if left too long and potential damage to gelcoat if spilled.

As with most boat things, the least aggressive stuff should be tried first and only resort to hexane or it's equivalent solvent if other option fail. The efficacy of CLR, et.al., will depend on the extent of sludge buildup.
 
D

Dan Nahant

Never Pick up a stranger

I had good luck using the Prestone liquid flush in a captured loop through the engine. This takes a few hours of running and is better off after launch, the Universal 25Xp has a cooling jacket petcock in front of the final fuel filter. The radiator Shops in the Northeast have been EPAed out of business. Hot vinegar will work well on the heat exchanger.
 
Feb 6, 1998
11,454
Canadian Sailcraft 36T Casco Bay, ME
The HX is not the issue..

The HX is not the issue it was professionally boiled, pressure tested, stripped, primed and painted and is ready to go back on. The problem with the Prestone products is they say the engine must be warm. If this is not the case then I could use it but would likely use Rydlyme before Prestone anyway.

I just spent about 20 minutes on the phone with the tech folks from Rydlyme and have decided I will be using that product for this project, despite needing to mail order multiple gallons of "hazmat" shipping..

They actually advise doing it the way I planed to by removing the t-stat and using an external circulation pump. Evidently I am not the only one with a marine engine sludged up by Death-Cool...;);)

Thanks for all the tips. It looks like Rydlyme works really well at room temps so I'm good to go..
 
Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
I'm guessing that the primary active ingredient in Rydlime is acetic acid. :) It is in some other commercial descaling compounds...
 

RichH

.
Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
The very best is any inhibited commercial boiler descaling compound: RydLyme or Marsolve are the most common 'marine' descalers (also will dissolve zebra mussel shells). DO NOT use hydrochloric or muriatic as these will also dissolve any exposed 'base metal'.
Marsolve may have been in stages of 'bankruptcy' so you may have difficulty in obtaining it.
Most of these inhibited boiler descalers can be dumped overboard, etc. as they are 'biodegradable' and do not need complicated neutralization steps before dumping it. If you cant find a convenient source, just go to your local boiler repair shop ... but make sure what they offer is inhibited and easily biodegradable.
 
Feb 6, 1998
11,454
Canadian Sailcraft 36T Casco Bay, ME
The very best is any inhibited commercial boiler descaling compound: RydLyme or Marsolve are the most common 'marine' descalers (also will dissolve zebra mussel shells). DO NOT use hydrochloric or muriatic as these will also dissolve any exposed 'base metal'.
Marsolve may have been in stages of 'bankruptcy' so you may have difficulty in obtaining it.
Most of these inhibited boiler descalers can be dumped overboard, etc. as they are 'biodegradable' and do not need complicated neutralization steps before dumping it. If you cant find a convenient source, just go to your local boiler repair shop ... but make sure what they offer is inhibited and easily biodegradable.

Thanks Rich! I have Rydlyme in my shop and have used it before but we lost our local distributor so was looking for other options. Funny that is exactly what the tech support folks at Rydlyme said..
 
Feb 6, 1998
11,454
Canadian Sailcraft 36T Casco Bay, ME
The Dex-Cool

Just curious, was the Dex-Cool original or was it changed from the green stuff?
Dex-Cool was original & installed by Westerbeke at the factory. It had been changed religiously too with only genuine Dex-Cool. I used to think the class action law suits were bunk but I'm now more of a believer that they had merit..:doh:
 
Jun 21, 2007
2,093
Hunter Cherubini 36_80-82 Sausalito / San Francisco Bay
MaineSail:

I participated in a dex-cool black coolant thread a few months ago. I don't really know if the thick black crud that was my coolant when I bought the boat was because of dex-cool, but let me convey my situation and the eventual successful outcome. If similar to yours, maybe you can first try what I did (but probably you will find a more efficient variation of the theme) without the flushing chemicals.

- First thing I did, before I knew how stubborn the black problem would be, was to drain once my system and replace with a prestone green anti-freeze mix. Draining wasn't easy because sediment had blocked openings at the drain cocks. I actually had to blow on drain tubes several times to keep them free. But eventually the block and exhaust manifolds were drained.
- After replacing the coolant, and using the engine, when the engine had been sitting for a day or so, whenever I removed the h/x cap, it was coated with a fine black residue, as was the surface of the liquid. But if I brushed aside the black on the surface, the liquid was a clean crystal green. After starting the engine, the sediment from all inside the engine would be put back into solution. Shortly after starting I could remove the h/x cap and see the coolant again running black.
- After several outings I decided to drain again. Interestingly in the bucket, after a few hours, the black would precipitate to the bottom. The upper portion of the drained coolant would be crystal clear green. By this time, the coolant was less black.
- Eventually, I decided one afternoon to keep draining and refilling with plain water until completely clear. Being in a marina, I could not rig for flushing overboard. So for the first few drains (without the engine running), I collected the coolant in jugs for proper disposal. Then when the coolant began to look quite clean, I would fill the system again, start the engine and open the engine block drain cock into a bucket. As soon as the drain flow began to sputter, I would stop the engine, fill the system with water again and repeat the drain process. By this time, the drained water was clean enough for disposing in a more direct manner overboard. Finally I let the engine run for a while and then drained one more time, before filling with water/antifreeze mixture.
- Its now been many months and the coolant is green with no black any more. I had the end cover of my h/x off a few weeks ago. The inside was clean. No black sludge anywhere.