928mac

Make sure the ground to the engine is good.
If you start to loose the engine ground then the currant will follow the coolant and ground through the rad if it is contacting metal.
That is why Greg said to check for voltage at the Rad.
Connecting a ground stap to it will not fix the problem and may make it worse.
Make sure the Engine and the Alt have a really good ground.
IMHO
Brad

blown 87

Well that may cause some issues for sure, but I was talking about dissimilar metals in the cooling circuit, you add a electrolyte in to the mix and you have a battery.
I test them when at normal temps with with the red lead in the coolant and the black on a good ground, anything over .2 volts needs to be looked at, and sometimes you simply can not get them that low, but if it is reading a half a volt, it is going to eat a hole in something.

Bill Ball

Hmmm... I have the original stock Behr. Never been very concerned about it. Replaced the passenger sidetank twice, the last one maybe 5 years ago. No core leaks, and this last sidetank seems good. So, I put my multimeter red probe in the coolant and black on good engine/frame ground and I saw 400 mV! Damn! This thing should have failed ages ago. So, I watch it and the reading slowly drops over a few minutes to 350, then 300, then 250, etc. Also, if I pull the red probe out it doesn't seem to change. So, I rig up a ground for the radiator. No change in behavior. Readings gradually drifted down. Seems primarily related to wetting the probe whether it's in the tank completing the circuit or not. My guess is I really have no electrical potential in the system, the readings are spurious and misleading, and the radiator is probably good for many more years like the rest of the car. I do change the coolant every couple of years and am not particularly conscious of what kind I use, although I don't buy it at the supermarket. I use Prestone long-life primarily, although don't leave it in that long.

Imo000

So one is better off to buy the the rad dissassambled from C&R or have them keep the end tanks off. Then, weld up the core and weld on the tanks? C&R should do this before welding their tanks on and charge $50 more? How can they with a straight face sell radiators that fail left and right?

blown 87

That is a lot of voltage at 400 MV, but if it goes down to 250 you are not going to have a problem.

We had one F-150 that was eating radiators and heater cores, we had one that only lasted two weeks, and these were OE parts.
Customer paid for the first one, I paid for two radiators and three heater cores before we figured it out.

dr bob

Bill--

You wrote that you see a CURRENT of 400mA (milliAMPS), and I thing Greg is talking about mV (milliVOLTS). Typo or measuring error?

Bill Ball

Sorry, let me correct that - it was the volt scale.

Also, do we REALLY want to ground the radiator? Stock radiators are not grounded directly and I rarely have read anything about core leaks with them. I've read comments by some car manufacturers that grounding radiator or heater cores accelerates galvanic corrosion.

Imo000

At the end of December, I've changed the heater core on a mid 90's Dodge Ram and it did have a factory ground strap. Didn't think much of it until the topic showed up here.

blown 87

I have some all aluminum radiators that have over ten years on them, so something must be working, these are all Griffin radiators.

laneskelton

My Devek radiator started leaking after about 1 1/2 years and my current radiator from 928 International started leaking after about 2 years. I have put some stop leak in and it doesn't seem to leak anymore...for now.

Imo000

The 828 International radiator is a C&R rad.

Iv'e sealed the one I have Tursday night by pulling vacumme throught it and covering the leak area with JB weld. Pressure tested it at 22psi and it's not leaking anymore. It will go back in the car this weekend to get some heat into it. Let's hope it works and holds for at least 2 years.

dr bob

GREAT idea with the vacuum. Never considered that option.

Imo000

The local radiator shop told me to do this. Because the leak was in an unwelddable location, they couldn't guarantee the work so they didn't want to touch it, but they gave me pointers how to do it myself.

This is what I did:
Used a heat gun to dry the rad, even had it pointed into the outlet for a bit to suck in some warm air to warm it up and reduce the chance of condensation at the repair spot. Then, dried the outside with the heat gun and used Q-Tips with rubbing acohol to clean the area as mush as possible. The leak was accross 4-5 rows. Then, dried the alcohol with the heat gun again. In the mean time, I've put the two tubes of JB-Weld in a hot cup of water to warm them up and make them easier to handle. Followed by some bamboo sticks to get the J-B into every possible spot at the leak area and only then did I turn the vacuum on. I plugged the rad in/ou/overflow outlets to pull in the epoxy for a min or so and then, let the whole thing sit overnight to set. The followign day it was put in in a Rubbermaid tub, filled with some water, and put around 22psi into it to check for leaks. No leaks so far. Next step it to put it in the car and let it heat cycle a few times. Things it looks promissing.

928 at last

As long as the repair surface was super clean, the heat cycles won't affect the JB Weld. I've had it on the front heat exchanger in the sled for years now with no issues.....YMMV

pcar928fan

So, what is the final word on this... Still seems up in the air.

My '95 GTS (hopefully makes the rest of the trip to me over the next 24-36 hours) seems to have a bit of a leaky radiator and I am guessing I will just replace it...planning on that anyway, so should I just call Rog or Mark I guess and get a Behr???

Should I get Robinson's butt over here with one of his trick GM rads and then an extra cooler for the trans and oil???