Sludge Buildup in Radiator

[sleeoffroad]

[quote author=landtoy80 link=board=2;threadid=6701;start=msg54968#msg54968 date=1067022724]
Did it have the Green coolant in it? [/quote]

Nope, what was once Toyota red.

 

[scottm]

I just flushed and changed mine, green from the dealership that serviced it from new (now 125k). No sludge or sediment, it looked fairly fresh. I'm not sure the block was ever drained before, I had to use an impact wrench in to get it out (tight sqeeze).

The year-old Prestone red in my wife's truck looks like mud, I'll tend to that soon. Hers has a dubious maintenance history, but looks like a replaced OEM radiator with sludge (at 115k). I'm hoping with annual coolant changes, it will gradually stop looking like mud so quickly.

This coolant system is supposed to hold 4 gallons. After several flushings and long rinsings through the radiator out through the block, I blasted all the water out I could with compressed air. I still could only get two gallons of coolant and maybe a quart of distilled water in. Where's all that hose water getting trapped and how do I get it out?

 

[Beowulf]

>> I still could only get two gallons of coolant and maybe a quart of distilled water in. <<
>> Where's all that hose water getting trapped and how do I get it out? <<

Or, is the radiator clogged so bad that you can't get all of the coolant in?

-B-

 

[scottm]

[quote author=Beowulf link=board=2;threadid=6701;start=msg55333#msg55333 date=1067195920]Or, is the radiator clogged so bad that you can't get all of the coolant in?[/quote]

Heh, two gallons of sludge? I hope not, it looked pretty clean and nothing settled in the bottom of the bucket of old coolant. I've had the same situation with other cars, even when pulling hoses and blasting with air.

 

[Rich]

[quote author=Scott M. link=board=2;threadid=6701;start=msg55298#msg55298 date=1067187545]
This coolant system is supposed to hold 4 gallons. After several flushings and long rinsings through the radiator out through the block, I blasted all the water out I could with compressed air. I still could only get two gallons of coolant and maybe a quart of distilled water in. Where's all that hose water getting trapped and how do I get it out?
[/quote]

Another possibility is that an air block is preventing you from filling the cooling system. After running for a while, what is the specific gravity of the coolant mixture? Is it around 50/50, or is it mostly coolant (8 quarts coolant, 1 quart water, as you installed)?

 

[scottm]

[quote author=Rich link=board=2;threadid=6701;start=msg55353#msg55353 date=1067198668]what is the specific gravity of the coolant mixture?[/quote]

I'm keeping an eye on that, plan to carry a gallon of distilled water. I helped my neighbor put a radiator in his econoline, it took weeks to get all the air out.

 

[IdahoDoug]

I've noticed this on mine as well. I've never been able to get the full amount in despite draining the block, pulling hoses, draining the rad etc. I'm quite familiar with the rig after 10 years and 5 flushes. I always premix the coolant after the first time it happened, so I will get the proper ratio in.

On an embarassing side note, I changed all my hoses this spring, including the PHH. Over the summer, the overflow tank went down about an inch which I attributed to getting all the air out. Last night, I got out of the truck at a Halloween party and smelled coolant. This morning I looked around and found 2 hoses seeping a bit and tightened them and noted the overflow tank is now at the Low mark. Then I noted wet coolant down by the PHH!! Eeek!

Laying on my back, I can see that the spring clamp on the end away from the block is only 3/4 on the hose and lots of evidence of steady leaking. From the angle I was working during the install, it must have looked fully on, and I'd intentionally put it very close to the end of the hose for maximum flexing. I'll get to it when I put the winter rims/tires on in a couple weeks.....

The other thing I wanted to comment on is this. I'm using DexCool by Havoline - the orange non silica stuff with extended life just as a reference. And it was flushed in an off-the-scale thoroughness before I switched it from the green Prestone this spring with the belts. Yet, there is a trace of grey sludge in the overflow tank! What is this stuff - it's only been 7 months?? Send in a sample, eh!

Doug

 

[scottm]

[quote author=IdahoDoug link=board=2;threadid=6701;start=msg55373#msg55373 date=1067203757]I always premix the coolant after the first time it happened, so I will get the proper ratio in.[/quote]

That's the opposite of my thinking. I assume there's still water left after I flush and run it a few times with water. Two gallons of Prestone should give me 50/50. I'll test it after I drive it a bit, see what the specific gravity is.

 

[cruiserdan]

How about two heater cores and the lines to the rear heater?

 

[Beowulf]

Scott,

>> Heh, two gallons of sludge? <<

Not 2 gallons of sludge, but a relatively small blockage can keep coolant from reaching a significant portion of the radiator.

-B-

 

[Gumby]

[quote author=Scott M. link=board=2;threadid=6701;start=msg55380#msg55380 date=1067205786]
That's the opposite of my thinking. I assume there's still water left after I flush and run it a few times with water. Two gallons of Prestone should give me 50/50. I'll test it after I drive it a bit, see what the specific gravity is.
[/quote]

Yours is the correct thinking. 1/2 the total capacity of coolant after flushing with water. Worst case you will be slightly too much coolant, the correct side to err on.

 

[IdahoDoug]

I'm going to disagree, though I will test the gravity and get back to this thread. Regarding the flush. I have a steep driveway and habitually drain the 80 with the front downhill, heat on, lower hose off, block drain plug out, radiator drain open, upper hose off. Last time I drained, I also started the engine for just long enough for it to catch and shutdown, which yielded perhaps a pint.

Unless there's a serious blockage somewhere holding a lot of fluid, then I cannot explain it except to assume Toyota mislabeled the capacity. I've owned this truck since new and the coolant has been changed ahead of schedule over those 10 years by me personally each time. Ditto the thermostat, which has a bypass valve and I've never seen any of the 3 I've installed come out with the bypass clogged. If anyone has been able to get the full listed capacity into their truck, I'd like to hear about it.

I can explain it no other way, but I've never checked the gravity and will do it this week. As a final comment, this truck has frequently pulled a 6000lb trailer over mountain passes at high temps with nary an issue.

Doug

 

[scottm]

I tested the SG, and my fluid is a little weak. I think it's because I ended up putting a lot of the coolant into the overflow tank, hoping it will exchange with the radiator eventually. I assume it will, because it gets so dirty so fast on my wife's 80 and sludge collects there. I'll test again before it gets really cold, it tests good for only +5F now.

 

[landtoy80]

Grey sludge. Is it like warm pudding texture???
The old Mack concrete truck I drove has air tanks for brakes and water tank.
When the compressor gets old (they are engine block mounted and lubed with the engine oil) they start to suck oil. The air tanks have a drain to drain the water out. When I drained my air tanks I would get some water and about a cup or so of grey creamy sludge.
If the sludge in the rad is the same, then it is motor oil. I don't know how it could get in there without water leaking though.

 

[Photoman]

landtoy80,
I sure know about draining the air tanks etc. that you talk about; but in the case of the radiator sludge if it was oil should it not be floating on top as opposed to being on the bottom?
Bill

 

[IdahoDoug]

Also disagree that the sludge is motor oil. Oil in rad fluid floats at the highest point - the cap neck. And temps in the water jacket never come close to temps in the oil galleries to cause the oil to break down into something like this grey stuff.

Doug

 

[IdahoDoug]

Checked the coolant today with a cool tool at a buddy's shop. It's called a reflectometer or refractometer (can't recall) and you put a drop of your coolant on it and smear it around, then close a lense over it and look through a calibrated eyepiece. Mine's at 48% and -30 protection, so I guess I got the right ratio and indeed did not get the rated system capacity in. Strange.

Doug

 

[e9999]

while we're talking about coolant, the last mechanic who did a full service on my -sorry- Honda, told me he always puts in pure coolant rather than the traditional 50/50.
Is this safe?
thanks
Eric

 

[IdahoDoug]

Check the Honda manual, but I'd be stunned to learn they recommend this. Pure coolant doesn't transfer heat (aka cool) as well as a 50/50 mix will. In my opinion, that's pure folly.

 

[scottm]

Didn't someone (Slee?) say he thought the sludge could be from not diluting coolant enough?