does an aluminum radiator need grounding?

Last year I installed a new Koyo aluminum radiator after my factory radiator neck cracked. I installed with new Subaru green coolant. At the same time I cleaned my engine grounds.

Last week I pulled the radiator and water pump. As I was cleaning the gasket surface I noticed pitting in the aluminum that couldn't be removed. Looking inside the radiator it had a white film like you see with aluminum corrosion. Inside my overflow tank was about 1-2 tablespoons of an unknown sludge.

A couple of questions come to mind:

1) Does an aluminum radiator have to be grounded? Could this be electrolysis?

2) Is Subaru coolant sufficient for a Koyo radiator? (ie the non-amine phsophate formula eating possible brass)

I put in an email to both RallySportDirect and Koyo and haven't heard anything back yet.

On the electrolysis question, I did find a Ford TSB that seems to link electrolysis to heater core failure.

ISSUE:

Some vehicles may exhibit (repeat) heater core leaks. This may be caused by a chemical reaction called electrolysis. Electrolysis involves an ion exchange between the heater core and engine coolant which can result in a breakdown of the heater core material. This is similar to the operation of a battery.

ACTION:

Check for electrolysis on any vehicle with a heater core failure. If electrolysis is verified, flush the coolant and follow additional steps as required. Refer to the following Service Procedure for details.

SERVICE PROCEDURE:

Electrolysis Inspection:

If there is a condition of a heater core leaking or repeal heater core leak, check for electrolysis using the following procedure:

1. To check for electrolysis use a DVOM set on DC volts. Place the positive probe of the meter in the engine coolant and the negative probe on the negative battery post.

2. Adjust engine throttle to 2000 RPM to properly get coolant flow and true electrolysis voltages.

3. If more than .4V is recorded, flush the coolant and recheck (follow guidelines in TSB 98-23-16 for Cougar). See Coolant Fill Procedure below to remove trapped air on 4.6/5.4/6.8L modular engines.

NOTE: Export markets, be sure the water is desalinated.

4. If there is still excessive voltage present in the coolant, check the engine to body/battery grounds. Also, verify proper grounding of any aftermarket electrical/electronic equipment which has been installed into the vehicle. Improperly grounded electrical devices can cause electrolysis to occur.

5. If the condition is still present after the grounds have been checked, it may be necessary to add extra grounds to the heater core and engine. A hose clamp can be used to secure a 16 AWG stranded copper wire to the heater core inlet tube. The other end should be secured to an EXISTING FASTENER on the body sheet metal. Extra grounds to the engine should be attached between EXISTING FASTENERS on the engine and body sheet metal. Verify continuity of any added grounds to the negative battery terminal.

6. If the condition is still present, add a restrictor (part F1UZ-18D406-A) on the inlet hose with the arrow facing the direction of coolant flow (toward heater core). Cut the line and install with 2 hose clamps. It is important that the restrictor be installed in the right direction of flow and as close to the engine block as possible (not near the heater core itself).

It wasn't a complete flush, just let it drain the engine from the water pump outlet. It had green Subaru coolant in it before. The last time it was the Subaru pre-mix green that doesn't need water. I haven't added the conditioner for years. The latest info I see from Subaru is they no longer recommend it?

I'll drop a multimeter into the coolant and see if there is any microvoltage, just guessing that's the issue. My grounds are clean though and show continuity to ground.

What are your thoughts on a complete flush and the Subaru blue coolant?

Oh, as far as the water goes. For the 153k miles I have on this engine if I do mix I use soft water. Right or wrong it was never a problem with the stock radiator. I never know what is right as far as water goes. Some sites, like this one https://www.hyperlube.com/blog/blog/why-you-should-never-use-distilled-water-in-your-cooling-system/ say distilled water is ionically hungry?

Distilled water is fine since it will typically still have some ions in it. Deionized water is slightly corrosive, so you probably wouldn't want to use that.That said, I wouldn't expect either to make much difference since you're using anti-freeze, which in addition to lowering the freezing point, also acts as an anti-corrosive.

So I just checked. With the key on, but the car not running, I have 0.06V running through everything, intercooler, radiator, alternator, etc. I do not have voltage on the chassis from what I can tell. That isn't much. With the motor on, it drops to about 0.027V on everything. Everything I read says electrolysis minimum voltage is around 0.4V.

Just for fun, I checked my 2017 Legacy. Key on ignition but not running, it has 0.022V through everything. With the car running it has -0.035V like the polarity is reversed, not sure what that means?

Maybe I need to rev the car and check it around 2000+rpm?

You are probably way over thinking the issue. First, the factory radiator was also aluminum. just the end tanks were plastic. The entire block and heads are aluminum. Most likely not an issue of electrolysis.

If what you see looks like malted milk, you are seeing oil and coolant mixed. In my experience with the cars that is indicative of a blown head gasket or a lifting head under boost and is very normal.

Thanks Mike, I always overthink things. I think the sludge was just contaminants from old coolant since the oil and new coolant look fine. It was clumped in the bottom, completely separate from the coolant.

You make a good point about the factory radiator being aluminum.

This is long, bear with me. After a run at the drag strip last year, the car went lean, I have another post on that. It went 12% lean everywhere, idle, cruise, WOT, on boost, off boost, very consistent. I went through checking fuel pressure, voltage, MAF voltage, pressurizing the intake with smoke for leaks, I had the injectors cleaned and flow tested, I took the intake manifold off and replaced every gasket and vacuum hose, cleaned the bottom engine grounds.

Finallly, I gave up, with 153k miles on the car, original motor, abusing it daily, I just decided to drop injector size 12% to bring it all to zero everywhere. I know that's the wrong way to go about it, but I was done and I'm not sure how much life was left in the car. I threw it on the dyno and it made the same power and AFR curve with the correction as it did before the issue occurred, Learning View zeroed out. I was satisfied.

Then this "issue" popped up. Before you posted it wasn't necessary, I thought what could it hurt to ground the radiator, so I did. I went for a ride and all of a sudden I'm hitting 10.8 at WOT vs my 11.6 target. I went home and pulled a Learning View, the ECU is pulling 12% fuel out everywhere, basically back to my original injector size.

I'm having a hard time believing running 12% lean across the board was a ground issue and a crappy ground at the radiator fixed it. The car has at least 8 factory grounds that I know of and I've cleaned most of them and checked continuity.

Two on TGV

One on passenger side frame rail

Two on bottom of motor

One on pitch stop

One on trans

One on driver side strut tower

Am I missing any?

I guess if nothing else putting that ground there gave me insight to that original issue I had awhile back and can help me get to the bottom of it.

May be its time to take the car for a ride to Dave at CRYO Performance ?

May be at least reach out to him for advice.

There are multiple grounds. However, if you lose just one, it can change everything. Some are shared. I am not a fan of "grounding kits". But, a big 3 upgrade has fixed more than a few oddball electrical issues. When in doubt, run some new oversized grounds. You would be AMAZED how many cars came into my shop with issues caused by faulty grounds. Had a few towed in by other shops and had to make the call to the owner of the car and shop to explain.

Glad you stumbled across a fix.

Hey Max, Dave is a good friend, I helped him install his dyno. He's heard more about my car's oddball issues than anyone else.

Thanks Mike, normally I'm not a fan of them either if everything is working right. There is definitely some sort of oddball issue going on that is caused by grounding, or insufficient grounding. I'm going to recheck and clean all of the factory grounds and see if one broke or something. Dumb question because I've never considered it, the Big 3 kit is that the Paranoid Fabrications kit or a general term people use? The PF kit says sold out on their site.

Overthinking again... All of the factory grounds are on painted surfaces. I see when people clean them they often wirewheel down to bare metal? Isn't that a recipe for rust? And why didn't the factory grounds have to be on bare metal? Are they grounding through the bolt threads vs the head surface?

Yes, the grounding would be happening through the bolt threads any any of the paint that is broken by the knurling on the flange of the bolts/washers (if any). I would personally wirewheel down to bare metal since you'll get a much better connection that way. Rust shouldn't be too much of an issue for anything besides the couple of grounds that are directly exposed to the ground. In those areas you could put some dielectric grease to cover the joint after bolting the strap to the chassis to prevent any moisture from getting in there.

The "big 3" is just a general term: battery negative to chassis, block to chassis, and battery positive to alternator.

This is long, bear with me. After a run at the drag strip last year, the car went lean, I have another post on that. It went 12% lean everywhere, idle, cruise, WOT, on boost, off boost, very consistent. I went through checking fuel pressure, voltage, MAF voltage, pressurizing the intake with smoke for leaks, I had the injectors cleaned and flow tested, I took the intake manifold off and replaced every gasket and vacuum hose, cleaned the bottom engine grounds.

This sounds really similar to what I, and a few others, recently experienced with the MAF connectors loosing contact overtime. Here is how I re-did the MAF connectors that resolved that issue.

Did you bump into the MAF plug/wire or touch them when regrounding the radiator? For me everytime I looked at the MAF connector/wires it would start going bad or back to normal. Even the slightest tug on the wires would cause the connection to change.

Logically it makes no sense for radiator grounding to affect your MAF like that. UNLESS your engine grounds are completely toast and it's grounding through the water in the coolant....

No, my MAF connector was fine. I tested that to no end with a multimeter and logging in Romraider, that was one of my first guesses. It wasn't affecting my MAF, the MAF was reading as it should, voltage-wise and airflow wise. My guess is bad grounding was either affecting the injectors or the ECU, but I have no idea. Basically the ECU was telling the injectors to send x amount of fuel and that signal was getting reduced by the time it got to the injectors, dead consistent on idle, cruise and WOT.

Don't know on the grounding, my car has 153k. No rust anywhere as it's Colorado. I cleaned the lower engine grounds, but never checked continuity to ground. Sometime in the next few weeks I'll check all 8 factory grounds that I know of. I did check the passenger frame rail ground and continuity wasn't great. I just ordered new factory grounds for all the ones that can be replaced.