Grey stuff in rad opinion

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[quote author=turbocruiser link=board=2;threadid=14475;start=msg136982#msg136982 date=1081697108]
...
the existence of any voltage indicates the presence of electrolysis. Period. What we are worrying about here is not extreme electrolysis (hopefully) but using the presence of voltage to help to determine the life left in the coolant.
...
[/quote]

Why do you think the voltage potential between the coolant and ground indicates the remaining life of the coolant?
 
Hmm. Good stuff Rich.

I'm thinking we can toss all those theories, however. 1,2 and 3 go because of Cdan and I. Always top grade coolant (strictly Toyota Red for him), always changed out regularly, and always filled by him or by me. We're both at the upper end of DIY in terms of skill and experience, and underfilling would similarly be eliminated as a possibility.

#4 goes because the sludge is accumulating in not only every 80, but pretty much every vehicle out there. It does not appear HG related at all.

So, while all of these are respectable theories, they don't stand up to the ultimate test - correlation to observed events. By that I mean we're observing sludge in virtually all 80s but not HG issues in all 80s. Similarly, we're observing sludge in vehicles that have never had old coolant in them. Sludge in Toyota red. Sludge in Prestone Green. Sludge in new DexCool. So if the theorys don't predict real world behavior there's no reason to pursue validating them.

So I feel we're still in the intel gathering stage of this and that the most obvious and productive step would be to analyze the grey sludge itself. Know its makeup and we will likely immediately know its source. Then we're done speculating. I'm not ready to bet yet, but I am slowly adopting the stance that the sludge is due to silicate dropout from the dissimilar metals in the water jacket. It involves all coolants, all levels of cooling system maintenance, and is unrelated to HG issues (though it is a contributor to HG issues - NOT caused by it).

Sludge analyisis $ contribution thread, anyone??

DougM

PS - once this posted I saw Rich's post above and also meant to address the voltage issue. I have never heard that stray voltage would change as coolant ages and think some posts above mentioned it and the ball got rolling on that as a theory. I don't think they're related at all and coolant life should not be determined by voltage.
 
Well I just got around to reading this thread, and so of course I had to run out and check the voltage thru my coolant--a whopping -350mV. The coolant was replaced about 18mo ago with Toy Red and is clean--no visible signs of sludge and the overflow tank is also clean with no debris in it.

If you're looking for possible variables in the sludge-production theory, you should add pH of the coolant to your list. It would probably play a significant role in terms of chealation of metals and precipitation reactions, as well as it's a variable in electroloysis.

Tom
 
I have read that the ph level of coolant should be in the range of 8.5 - 10.5, which is alkaline. Acids are < 7. If the coolant gets acidic then it no longer prevents corrosion.
 
Doug, additive drop out, in my mind, is one of the likely suspects. However, I am under the impression that Toyota red coolant does not contain silicates. If true, and if it is indeed an additive dropout problem, then it is due to a different additive.

Checkout www.amalgatech.com. This stuff is their business.
 
If some sludge is normal in all engines than it's important to differentiate between normal and excessive.

To say that HG failures aren't related because all engines experience sludge and not all engines have needed gaskets seems a little off.

One of the first impressions that I got was that excessive sludge and HG failure where often seen together.

As far as the contribution thing I'm not interested. My HG is new and if periodic flushes will result in normal accumilation than that's what I'll do.
 
[quote author=IdahoDoug link=board=2;threadid=14475;start=msg137021#msg137021 date=1081704446]
I have never heard that stray voltage would change as coolant ages and think some posts above mentioned it and the ball got rolling on that as a theory. I don't think they're related at all and coolant life should not be determined by voltage.
[/quote]

IIRC, the more particals in a liquid, the greater the conductivity. So if I'm not talking out my arse then an increase conductivity = increase in particals = possible indicator of when to change coolant. Any chem/physics gurus out there?
 
Checked my coolant for voltage. Engine off = .03 volts, which seemed to taper off to .01 and wiggle a bit. Engine running and normal stuff on = about half that.

DougM
 
Count me in on some $$ for sludge testing. Whoever is doing it, just PM me. i do think we are putting too much into the relationship between the sludge and HG failure (but I've been wrong before). I'll have to re-read this thread because we have covered a lot of ground here and not sure what Doug's mechanic said in the beginning ???

My thought is the HG issue is really a design flaw and probably an related to the iron block and the aluminum head. I assume that's a tough design task to get it right. I think we all want to believe that if we are super anal about PM that it's not going effect us but it's probably got more to do with luck and perhaps the operating temps of the engine environment. Obviously a poor cooling system will cause it to happen sooner but that's not to say that a cooling system running at 100% is a guarantee of no HG issues.

Just my hunch that's worth less than 2 bits.

Riley
 
[quote author=Riley link=board=2;threadid=14475;start=msg137347#msg137347 date=1081746560]
Count me in on some $$ for sludge testing. Whoever is doing it, just PM me. [/quote]

same here, what I have not heard is does anybody have enough to sample?
 
[quote author=Rich link=board=2;threadid=14475;start=msg137040#msg137040 date=1081707426]
I have read that the ph level of coolant should be in the range of 8.5 - 10.5, which is alkaline. Acids are < 7. If the coolant gets acidic then it no longer prevents corrosion.
[/quote]

A more acidic solution, by definition, has more free hydrogen ions, which means it could conduct electricity better. This would lend some credence to basing the need for a coolant change on stray voltage, though actually measuring pH would be more direct and reliable.
 
A point to consider is that measuring the voltage potential between the coolant and ground does not measure the conductivity of the coolant.
 
[quote author=syrinxstar link=board=2;threadid=14475;start=msg137364#msg137364 date=1081749595]
A more acidic solution, by definition, has more free hydrogen ions, which means it could conduct electricity better. This would lend some credence to basing the need for a coolant change on stray voltage, though actually measuring pH would be more direct and reliable.
[/quote]

Actually, the pH will not itself contribute that much to the conductivity of the solution. It's the ionic strength that matters. I doesn't matter much if those ions are positively or negatively charged--they both aid in the conductivity. Table salt is fairly neutral, but is a great conductor. So's road salt which is way we all cringe when we get it on our vehicles.

What the pH will do in conjunction with a high ionic strenth is to make the solution more capable of dissolving the various metals it finds along it's path.

"Chunks" of debris will not change the pH--the stuff that's dissolved might, depending on what it's made of.
 
[quote author=Rich link=board=2;threadid=14475;start=msg137367#msg137367 date=1081750788]
A point to consider is that measuring the voltage potential between the coolant and ground does not measure the conductivity of the coolant.
[/quote]

Rich, you're right, it's measuring the resistivity of the coolant which is proportional to the inverse of conductivity. :rolleyes: For a potential to exist, there must be current and there must be resistance. The coolant (among other components in the electrical path) is providing the resistance and any change in the composition of the coolant that provides for easier or restricted flow of current will be met with a change in potential.

Scamp, I agree with you that there is very likely to be something else in solution whose ionic strength would dwarf any contribution that more or less free protons would make. :whoops: I believe ethylene glycol solubilizes in water into free ions, to some degree, which would support your point.
 
OK, I will pitch in for testing, and I will also test the current in my coolant. As much as I ahave enjoyed this discussion though, I think you guys have speculated as much as you can without testing the stuff. Seems to me you have two basic possibilities: the sludge could be derived from the coolant or some chemical reaction that is nothing to do with the HG problem (except to the extent the resulting sludge might block up the rad causing overheating), or it could be symptomatic of the HG problem. I agree we should test it and see.

Long rambling observations follow. Grab a cup of coffee before starting into it.

I do notice that the only two control trucks owned and properly serviced from new (Doug and Dan) both have the sludge problem but have not had the hg problem. That may be a coincidence or a sign that well maintained/treated vehicles from birth are less likely to experience the HG problem even though they can't avoid the sludge. I also notice that Robbie does see the odd truck with a blown HG but no sludge. Again, this raises the question.

Also, Robbie seems to see an unbelieveable number of 80 hg problems even for an 80 specialist. Is it possible this is related to the fact he lives in Colorado? Could it be all those steep grades the local trucks have to negotiate?

I would like to hear what people think of possibility B, which is that the HG is basically a fuse that is an indicator that the engine has been run too hot for too long. What I think is that the damage this causes to the HG may be cumulative over time. THe hg may or may not be designed to blow as consistently as it does, but maybe the fact it goes is simply an indicator that 80s often run too hot breaking down the hg, in which case making a better hg is not the solution, but rather increasing the cooling system performance.

Now it so happens that I just spent 5 days driving through beautiful mountainous British Columbia in my truck crossing several mountain ranges and watching my temp guage like a hawk. It did not move (touching wood) and I used no coolant (touching wood again), but while I was staring at that gauge I did have occasion to think about a few things.

1. A loaded cruiser weighs over 5500lbs. That motor works exceedingly hard to propel it at highway speeds on any kind of a grade. Those are big paint can pistons by modern standards and they must generate an unbelievable amount of heat for that cooling system to disperse.

My question is, seriously, given the weight of the vehicle and the speeds it can manage, is there a cooling system on any passenger vehicle on the road today that has to work harder? As a maybe unfair example, during my highway musing, I could not think of a clear example of a gas powered vehicle on the road where the individual pistons work harder. I think maybe a late model series II trooper or a 4runner with the 4 cylinder might be propelling about the same number of pounds per cylinder, but there is no way they could push the same weight at the speeds on grades that an 80 can manage.

Anyway, I don't know how the capacity and flow rate of the 80 cooling vehicles compares to other vehicles, but I would be very curious to see how they compare.

Now the other observation I have is how easy it is to abuse an 80 when running it up a grade. During my recent sojourn I ran my truck up sustained steep grades for 20km or more with the revs never dropping below 2600 rpm and speed usually holding steady at 60mph and never dropping below 50 mph (My rule was not to run it at over 3000 rpm for a sustained period based on my unscientific experience with i/o boat motors). I think/hope I was taking it fairly easy on those hill climbs. The point is that a new owner might have kept the throttle right down on the long grade to keep up with that stupid Denali that just blew by him. He also is likely to have let his wife, son, or brother in law drive it over the years and they might be even less fastidious. He also might not flush the radiator very often. If they do that they could be overheating it without seeing any indication on the temp gauge and breaking down the HG over time.

2. I can also say that my 80 has the hottest engine bay of any vehicle I have ever owned. It is like opening a furnace door when you pop that hood after a good highway run. I think the engine bay is so crowded it just does not disperse heat. I also wonder if it is intentionally more closed off than other vehicles, maybe to prevent dust infiltration? I do not know if engine bay temp can affect engine temperature or not, but it sure bothers me.

3. Last comments relate to the design limits and decisions on these trucks. It seems to me that Toyota is pushing the envelope a little with the weight to power ratio on these trucks to get them to perform as well as they do on north american highways, and so maybe it is putting stresses that push the envelope on aluminum head technology in a mass production car. I also assume the 80 was designed to be run in relatively stripped down form for 3rd world applications (how much do all the extra seat padding and soundproofing and power accessories weigh) and then adapted for the 1st world environment. I also wonder, did Toyota engineers design the 1fz to have an iron head and then adapt it for an aluminum head? Did they maybe design the 80 cooling system and maybe even the engine compartment venting expecting the vehicle to be operated at lower speeds rather than racing down north american highways at 75 mph all day long?

Anyway, musings off.
 
[quote author=syrinxstar link=board=2;threadid=14475;start=msg138036#msg138036 date=1081829659]
Rich, you're right, it's measuring the resistivity of the coolant which is proportional to the inverse of conductivity...
[/quote]

No, it is not measuring the resistance of the coolant. It is measuring the voltage potential between the coolant and ground, and that is all. :slap:

Knowing the voltage in the absence of knowing the current flowing through the same circuit tells nothing of the resistance of anything in the circuit (or it's reciprocal, conductivity). :slap: :slap:

In order to measure the conductivity of the coolant in any sort of meaningful way one would need to create a known voltage potential across a known volume of coolant and then measure the current. Or alternatively one could generate a known current through the same volume of coolant and measure the voltage drop. In either approach the coolant would need to be enclosed in a non conductive container. There would be no radiators, hoses, engine head, engine block, ground cables, or auto batteries involved.

Many may not care, but the fundamentals of electricity are getting thoroughly mangled in this thread. :slap: :slap: :slap:
 
well, one could conceivably stick an ohmeter in there, say the exact center of the cap at a known depth, measure the resistance and then try again a year later and see if it has changed...?
E
 
Semlin,

Nice ramble. Were it morning, I'd have taken your advice on a cup o' joe.

In a nutshell, I disagree that Toyota is pushing the envelope, that the 80 is a design that cannot handle hard work, or that the engine bay is crowded (this engine has more space around it than any vehicle I've ever owned). This vehicle was designed with a difficult light duty commercial life in an offroad environment in mind. In no way is highway cruising challenging to a vehicle like this. It's a solidly engineered vehicle and the sludge is likely to be exposed as a normal part of gasoline engine cooling systems. Tracking the sludge source is one thing, but I don't think you need to be watching your guage like a hawk or constantly concerned about an overheat. We're a bunch of anally retentive vehicle owners with too much time on our hands. As I've said before, I routinely tow 6000lbs over passes here in the PNW in 90 degree heat with my foot at 90% throttle settings and the air conditioning on. I have only seen my guage move a needle width. In my opinion the cooling system has plenty of capacity.

Also, thanks for the link Rich. I sent them an email regarding our sludge and will report back.

DougM
 
[quote author=IdahoDoug link=board=2;threadid=14475;start=msg138103#msg138103 date=1081835184]
...I routinely tow 6000lbs over passes here in the PNW in 90 degree heat with my foot at 90% throttle settings and the air conditioning on. I have only seen my guage move a needle width...
[/quote]

But the gauge lies! Oops, wrong thread :)

In reality, the engine compartment does get really hot when the engine is run under heavy load in hot weather. Aluminum heads on iron blocks have always been a challenge for headgaskets, and the challenge got a bit steeper once they stopped using asbestos in the headgaskets.

It will be interesting to hear what Amalgatech will have to say. If I had a decent sample of sludge I would engage them myself. I'm betting they have seen it all before. What specifics did you pass on to them?

Rich
 
Rich,

I gave them our vehicle's system sketch (block/head/rad matl's), the range of known maintenance. Wait, I'll copy and paste it below:

"I am a member of a fairly large club of 80 series Landcruiser owners. We have all found significant amounts of a grey paste-like substance in our cooling systems over the years. This includes vehicles owned since new and properly maintained with the Toyota Red coolant and distilled water, vehicles using the green coolant types, and vehicles using the DexCool type. In several cases, this sludge has blocked radiators enough they had to be removed and professionally cleaned due to overheating issues.

As one of the more experienced owners, I have seen grey/black flakes about 2mm in diameter and half as thick as a piece of paper during my coolant changes every other year since new. The theory is that these flakes end up being abraded by turbulence and end up as the source of the uniformely grey sludge. A fine drift also ends up in the overflow bottle.

The Toyota 4.5L straight 6 engine we all have is an iron block/aluminum head design and half of us have the older 4 row copper radiators and the other half have a thinner aluminum radiator. The switch happened halfway through the model run from 1993 to 1997 and there seems to be slightly more accumulation in the aluminum radiator models.

The current theory is that the material is from "silicate dropout" as posed by several mechanics. We're told the additives adhere to the aluminum engine parts until they're a layer, which then breaks free in the form of flakes and ends up sludge. We've found no pattern of stray electrical charges, either.

Do you have any input on what this is to settle some bets?? Thanks in advance, and also for the information on your website I read to see if there was any information pertaining to this.

Regards,

Doug Miller"

I took a look at their testing prices and it was kinda steep. I'm basing this on Blackstone Lab's $20 price to analyze my oil with some sophisticated lab gear and have no similar experiences with coolant, so it may be typical. Just seemed kinda scary to see test prices ranging from $40 to hundreds of dollars for many. In the end, they may be candidates to analyze our sludge though. I'm thinking they will literally have the experience to confidently make the call that it's normal coolant additive dropout. There was one thing on their site (I read everything relevant) that mentions PH as way more important than I'd known. It states that coolant additives are designed to operate in a narrow PH range and this varies by type (DexCool, Green, etc). When the PH changes to the limit of this range, the additives solidify or accumulate. That's one of the reasons dissimilar types of coolant (DexCool vs Green for instance) should not be mixed. The PH of one may cause the additives of the other to drop out or solidify. This was all new to me, so it's a quick and dirty explanation.

DougM
 

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