Help: Coolants again :^}

**disco2hse** · 24th February 2009, 06:59 AM

OK. Sorry to drag this one out and I know there's a whole bunch already said on the matter but frankly when it comes down to the dirty detail most does my head in something awful, but then organic chemistry always did

Last year while trying to find the cause of a phantom overheating problem on George - 109 Stage 1 V8 (which turned out to be a dry joint in the temperature gauge

) I had the engine flushed out and the radiator cleaned out, then refilled with antifreeze, etc. Now, I assumed all was good except since then the low water alarm kept spiking (going off momentarily) until the engine had warmed up but I thought that maybe that was a sign the batteries were on their way out.

Having read a couple of the previous threads and the point that using the wrong antifreeze could cause the coolant alarm symptom I have been experiencing I thought I had better check with the guys and see what it is they used. It turns out they have one dirty great drum of antifreeze that gets used on everything

They use Autohaus EURO550, which from what I can see is one those new organic acid type products.

Question. What do I do now? Should I proceed, without delay, to the nearest radiator specialist who actually knows what they are doing and have the engine flushed and replaced with a glycol product? Or can I leave it there and hope for the best assuming they used enough water to get the remnants of the original glycol out?

Talking to my favoured mechanic, he suggested as an interim solution to earth the radiator to the chassis and remove stray electrolytic action.

Alan

**rick130** · 24th February 2009, 07:41 AM

Was the system flushed properly ?
Ideally, when using an OAT inhibitor coolant an acid flush should be used, then flushed thoroughly with clean water.

How will coolant cause the low water alarm to go off ?
Earthing the radiator is fine, but no coolant on earth will protect against stray current.

FWIW, OAT coolants are 95% ethylene glycol, they just use an organic acid as part of the inhibitor package.

I'm not familiar with Autohaus Euro550, is it a HOAT ? (hybrid organic acid)

**disco2hse** · 24th February 2009, 08:00 AM

Originally Posted by rick130

Was the system flushed properly ?
Ideally, when using an OAT inhibitor coolant an acid flush should be used, then flushed thoroughly with clean water.

I can only assume the engine was flushed thoroughly, but I was not there to observe.

Originally Posted by rick130

How will coolant cause the low water alarm to go off ?
Earthing the radiator is fine, but no coolant on earth will protect against stray current.

Well, from the previous thread it was suggested that there is a build up of electrolyte on the sensor and it is this that increases the resistance to the sensor, hence it sounds off. It appears this may be happening in my case. I still need to take the top plug off the radiator to see if there is any of that black gunk mentioned.

Originally Posted by rick130

FWIW, OAT coolants are 95% ethylene glycol, they just use an organic acid as part of the inhibitor package.

Dang, that's where I start getting confused.

Originally Posted by rick130

I'm not familiar with Autohaus Euro550, is it a HOAT ? (hybrid organic acid)

Ummm, I think so. There was very little info on the drum except that it said it was some kind of organo-oxylate-type-thingy, so probably. I haven't been able to get any info on it yet.

Alan

Shaker · 24th February 2009, 08:33 AM

What is the correct way to flush the cooling system in a TD5?

**rick130** · 24th February 2009, 09:01 AM

Originally Posted by disco2hse

<snip>

Well, from the previous thread it was suggested that there is a build up of electrolyte on the sensor and it is this that increases the resistance to the sensor, hence it sounds off. It appears this may be happening in my case. I still need to take the top plug off the radiator to see if there is any of that black gunk mentioned.

<snip>
Alan

Any chance of a link to the other thread ?
Looks like I've missed it (or part of it)

Stray current is caused by bad earthing, it has nothing to do with the coolant type.
It's easily checked with a digital multimeter. Turn it to DC volts, place the positive probe in the coolant with the engine running and the earth probe on the battery earth (if possible)
Can't remember what it should be under, but it's fairly small.

<edit> pinhed this from my Tectaloy catalogue.

As this form of corrosion is virtually invisible
until it’s too late, Tectaloy went to work and
evaluated several different methods of testing
cooling systems for current flow. The end
result was a simple yet very effective method
of testing using a standard analogue multimeter.

Step 1: Remove radiator cap from the vehicle
when safe to do so.

Step 2: Turn your multi-meter to mV range.

Step 3: Insert the positive lead of your multimeter
into the coolant. (Be sure not to touch
the metal of the radiator).

Step 4; Connect the negative lead of your
multi-meter to the earth pole of the battery
if possible.

Step 5: Check your meter for a reading
above 50mV, any reading above 50mV should
be considered potentially corrosive.

Step 6: Turn on the vehicle’s accessories
one at a time and check your meter, if any
accessories cause a high reading then this
item probably has a faulty earth path.
Accessories include head lights, indicators,
car heater, electric fans, windscreen wipers,
brake lights, radio, mobile phone chargers,
etc.

**disco2hse** · 24th February 2009, 11:16 AM

Originally Posted by rick130

Any chance of a link to the other thread ?
Looks like I've missed it (or part of it)

Of course when you want, you can't find it

Originally Posted by rick130

Stray current is caused by bad earthing, it has nothing to do with the coolant type.

It's easily checked with a digital multimeter. Turn it to DC volts, place the positive probe in the coolant with the engine running and the earth probe on the battery earth (if possible)
Can't remember what it should be under, but it's fairly small.

<edit> pinched this from my Tectaloy catalogue.

Thanks, I'll give that a shot.

In the meantime I have spoken to the folks here that import Autohaus products (Fargo International). They said that it is a hybrid di-basic(?) acid. It is long life at 5 years or 250000 k's before the next change.

They also said this stuff is, apparently, perfect for the Stage 1 V8. So maybe I was just panicking for no reason

I'll when I pop the radiator bung and see if there are any deposits.

Alan

**rick130** · 24th February 2009, 02:28 PM

I've never heard of problems with HOAT's like you may get with OAT's and are often the recommended coolants with vehicles like VW and BMW.

I'm not au fait with a lot of the chemistries, apparently there are quite significant differences between OAT's too. It comes down to exactly what acid they use for the inhibitor. eg. the Japanese OAT's apparently use a different acid to most US ones.
Ford and Chrysler in the US use HOAT's, GM the infamous Dexcool which is an OAT and identical to the Land Rover one (made by Texaco)
I posted some good links in a recent thread on Dexcool from the US and how it softens, or at least used to soften/react with some plastics and didn't tolerate low water levels and lots of air mixing with it in primarily cast iron engines.
I haven't heard of any issues with it in the all aluminium V8's and new Holden/GM V6. (yet)

It's also claimed by Zerex, developer of the G-05 HOAT that a lot of manufactures use that a little of the old style coolants wont react with it, just reduce it's long life properties.

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