This from the NARSA (Natl Automotive Radiator Service Assn):

NARSA OFFERS MOTORISTS TIPS TO AVOID
GETTING A CHARGE OUT OF ELECTROLYSIS
Experts Warn That Too Many Car Accessories Can Lead to Cooling System Damage

EAST GREENVILLE, Pa., March 2000 – Using multiple accessories, such as wireless phones, radar detectors and upgraded stereo systems on long trips may be hazardous to your car’s health, say experts at the National Automotive Radiator Service Association (NARSA).

Electrolysis is decomposition produced in an electrolyte by an electric current. In a vehicle, electrolysis refers to high levels of electric current in the coolant flowing through a system that results in decomposition of the soldered joints on the tubes of the heater core. While a minor electric charge (less than 0.1) occurs naturally in all cooling systems, in vehicles with missing or incorrectly placed grounds, having multiple accessories plugged in or turned on over the course of a long trip can lead to trouble.

“An increased electrolysis level can cause metal components in the cooling system to corrode,” says Don Hart, NARSA president and Texas shop owner. “It can also lead to an electrochemical reaction that could create holes in cooling system hoses.”

The best way to find out if there are high levels of electrolysis in your vehicle’s cooling system is to have the system checked by a specialist. After running the vehicle’s engine and accessories, the technician will run a static electrolysis test and examine all hoses, belts and the heater core for leaks and signs of deterioration.

Great. Time to put a zinc anode in my coolant tank.

Actually I was just reading the procedure for testing for that in one of the car service mags. I don't remember what the acceptable "limits" were, but the electrolytic (is that a word?) action of the coolant was accelerated as time went on, especially under certain circumstances.

I wonder if it's better/worse/the same with different coolants? Different coolants that are within a reasonable amount of lifespan.
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Chris Herbst, near Chicago, IL. 93 940, 91 240, 90 240, 88 740, 87 240

Apparently formulation is different, if you believe the guys at Volvo. At least in the 960, the owner's manual says to never replace the coolant. Obviously, after drving a 240 for several years and getting used to replacing water pumps/coolant like clock work at 30K, this is unsettling. So, on my 960 my interval is 60K (I think I may have mistakingly said 30K in a previous thread) which makes the high price of Volvo coolant somewhat more palatable.
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John Shatzer, '92 965 @100K; one of a few still in captivity.

Judging by your success, I wouldn't argue with THAT either! If the Volvo brand is the stuff, why not.

I'm going to check into that a little bit more, just out of curiosity.

Apparently your windshield washer fluid isn't working out for you.

Sorry, I couldn't resist.

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Chris Herbst, near Chicago, IL. 93 940, 91 240, 90 240, 88 740, 87 240

Quick, get some sacrificial anodes. After more consideration, I think this bit of work is mere pseudo tech talk. Time for George Downs to weigh in.

wb aka TRM.

Have to consider who wrote the article.

Increased electrical use in and of itself shouldn't cause any MORE electrolysis problems than would otherwise occur...the electrolysis isn't due to electrical current; it's due to the coolant behaving as an electrolyte and dissimilar metals being used in the engine/radiator, etc. Soooooo, if the coolant loses its anti corrosion and dielectric properties the radiator/hose damage accelerates, but I have a hard time believing the electrical system has much to do with it. If THAT were the case, it should also be possible to reverse the damaging current flow with an electronic gizmo....and THAT hasn't proven effective on street cars as opposed to some marine equipment.

700's are know for their ground problems so if the Mulla has a whole bunch of accessories, such as a killer stereo or a few thousand watts of extra lights up front, it could be a problem. Perhaps we all need to check our engine and chassis grounds for corrosion or looseness. Looking at the way the gounds are spread out around the car, I would think the chassis would be turning to rust by now.

It's a 960, not a 700. And I am not a Riceboy.

Sorry, I wasn't infering you were. I only commented that if there were extra currents circulating around the chassis, that electrolysis might be a concern. Since you don't have a killer stereo or extra loads, how can electrolysis be a factor in your situation? The 700's begat the 900's, with similar wiring issues.

There are enough professional reports of electrolysis problems out there in trade journals to make this a real, and growing, problem. It occurs when engine and chassis grounds are corroded so that voltage potentials build up (even to .25 volt) between the engine or radiator and ground. High current loads running through corroded grounds exacerbate the problem. The coolant can then act as a secondary ground because it is conductive. In so doing, the aluminum parts especially act as a sacrificial anode and dissolve.
To measure this, start the engine, place a voltmeter in the coolant and on ground, and measure potential. Turn on all power accessories and measure again. High readings mean you've got a problem, to be cured by de-oxidizing and protecting your ground connections.

Thanks Steve. I'll check that oun. I suspuct the 744 has some bad grounds here and there.
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Warren Bain - '86 744Ti M46 >282Kmi, '96 965 >97Kmi Wifemobile near Manassas Va