Submitted: Sunday, Feb 08, 2004 at 23:09
ThreadID: 10375 Views:1552 Replies:4 FollowUps:2
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Hi all

I my research travels I recently came upon a bit of info concerning stray current leakage in radiators causing premature failure due to electrolysis.

Wacked the trusty MM on the Fender and was surprised to find 0.25 V.
Same on herself's Pathy revealed 0.53 V.

Not much but still surprised to find it in any event, and I suppose it could set up electrolytic action.

Anyone else come across this in their peregrinations????

CheersFidei defensor

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Reply By: V8troopie - Monday, Feb 09, 2004 at 02:03

Monday, Feb 09, 2004 at 02:03
Rosco, how exactly did you measure that? Which MM probe onto where?
Keep in mind that digital multi meters have just pico amps flowing between the probes for voltage measurement, you may have measured some static voltage if you used a digital MM.
Try the same with an old style 50k ohm/volt pointer type meter at its most sensitive setting (0.5V full scale?). If you find the above voltages with that meter you have cause for worry. Maybe time to check and clean all the earth connections. There are quite a few of them, beside the obvious one for the starter motor. The workshop manual should show where they are. Of course, if someone has added to the wiring and connected the earth willy nilly anywhere......
AnswerID: 45938

Follow Up By: Member - Ross - Monday, Feb 09, 2004 at 08:23

Monday, Feb 09, 2004 at 08:23

Red on radiator, black to earth returned -0.25 V, vice versa returned +'ve result.

I only have a digital job. That was on the 20V setting, tried 2000 millivolt setting and got 250, as you would expect.

Same result with ignition off, on and engine running. The beast is only 6 months old so wouldn't expect dirty earth connections. May fax dealer/service requesting formal response for the record.

The issue was raised by a third party who claims it is a known problem.

CheersFidei defensor

FollowupID: 307906

Reply By: Roachie - Monday, Feb 09, 2004 at 09:11

Monday, Feb 09, 2004 at 09:11
I read all that stuff recently on this forum about stray currents etc and whilst I'd never previously heard of it, I'm not brave enough to say it's a load of bull-twang.
However, from memory, the bloke who posted the info said you had to drain the rad, flush it several times, then fill it with demineralised or distilled water (I guess rain water would do?) and THEN do the stray current test. I took that to mean that it was not worth the effort simply sticking the + probe into the coolant as presumably this has some sort of stuff in it which would give a false reading. Does anybody else remember reading all that? I thought of doing the test myself, but couldn't be bothered doing all the flushing etc. Anyway, the last time I did a test I failed dismally; and that was after studying hard for 3 weeks!!!!! The test? It was a urine test!! LOLOLOL
I wouldn't worry too much; but then again it's not my jaloppy we're talking about. The way I see it I don't have a stray current problem (because I haven't checked it) so that's one thing I don't need to worry about. Ah; ignorance is bliss!!!

AnswerID: 45953

Follow Up By: Willem - Monday, Feb 09, 2004 at 19:26

Monday, Feb 09, 2004 at 19:26
Agree....many people want to change mousetits into mountains...what for...I ask you?...Dunno..beats me. I suppose they like to complicate their lives :-)

Out on the Gibber
FollowupID: 307977

Reply By: Phil G - Monday, Feb 09, 2004 at 10:22

Monday, Feb 09, 2004 at 10:22
A simple wire from the radiator to vehicle body solves this problem. Many cars come with this as standard.
AnswerID: 45958

Reply By: Eric Experience. - Monday, Feb 09, 2004 at 22:26

Monday, Feb 09, 2004 at 22:26
This stray current problem is real, but the way it was explained in the post a few weeks back was very strange. The problem arises if there is a diference in voltage between the engine block and the radiator. THe story about flushing and sticking the probe in the water is misleading, all you have to do is measure the voltage difference between the radiator and the block. Some air con instalers bolt an electric fan directly on to the radiator core and and then earth the fan motor to the core this is the most common cause of this problem. To cure it just run a wire from the radiator to the block. If you place a multimeter probe on a battery terminal you will always get a slight voltage due to the acid which is invariable on the terminal reacting with the chrome plating on the probe. To test this place your meter on the negative terminal and the other lead on the body with nothing swithed on. Eric.
AnswerID: 46071

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