When to replace radiator w/ grey sludge

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Just spent several hours reading through a bunch of "grey sludge" posts. I don't know if anyone ever figured out what the stuff really is, but if they have, can anyone enlighten me? I've read all the theories, but I wasn't sure if anyone actually had it tested. My system has had both green and red and I recently flushed and went back to red after the PO had green in there.

Anyway, the top of my radiator looks like its full of the grey sludge. Really thick to the left of the fill cap. I don't have overheating problems, but I'm in the middle of a major cooling PM and have the radiator out right now. I had a local, sort of fly by night, radiator shop flush it for me, but it looks the same inside. At least they did a good job on the outside.

From what little I can see, it looks pretty bad, even like some tubes are pretty well clogged up, but the radiator still cools the engine. I'm not sure how, with the way it looks to me.

At what point would you guys just replace this radiator with a new one. I figured on going with a 3 core '94 from C-dan if/when I ever needed too, but wasn't sure if this justifies the replacement or not. The only other option I can see is maybe having a competent shop rod it out maybe.

BTW, '95 FZJ80 w/ about 96K miles, original radiator, original headgasket. I'm currently replacing all the hoses, water pump, thermostat, heater hoses, clutch fan, etc.
 
.....the radiator still cools the engine.


Well, its doing what it should be. It just depends how picky you are. If it was me, Id replace it just because the radiator was already out. Time is very precious to me though.
 
Well, we all know the stock gauge is worthless, but it's never gone above the "normal" position since I've bought the rig early last year. Over the winter, my scangauge indicates usually around 185 when fully warmed up and stayed there. Recently in traffic on a 75 degree day, it was going past 190, but not by much. I haven't had a chance to run the scangauge in the really hot weather yet.
 
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your numbers are good but that only means that the system can cool OK under the conditions you were running it at, of course. Where you'll get in trouble is under severe heating and then things are likely to escalate quickly with potential warpage etc which you don't want.
So I would not go around driving with a rad like that.
Play with the thing a bit, rig something, use a power washer. If that doesn't work, have it rodded out (not that I know how that's actually done) if significantly cheaper than a new rad. If little difference in price and/or $$ not critical get a new rad and do major flushing before you put it in.

Is the gunk loose or solid?
 
Just spent several hours reading through a bunch of "grey sludge" posts. I don't know if anyone ever figured out what the stuff really is, but if they have, can anyone enlighten me? I've read all the theories, but I wasn't sure if anyone actually had it tested. My system has had both green and red and I recently flushed and went back to red after the PO had green in there.

Anyway, the top of my radiator looks like its full of the grey sludge. Really thick to the left of the fill cap. I don't have overheating problems, but I'm in the middle of a major cooling PM and have the radiator out right now. I had a local, sort of fly by night, radiator shop flush it for me, but it looks the same inside. At least they did a good job on the outside.

From what little I can see, it looks pretty bad, even like some tubes are pretty well clogged up, but the radiator still cools the engine. I'm not sure how, with the way it looks to me.

At what point would you guys just replace this radiator with a new one. I figured on going with a 3 core '94 from C-dan if/when I ever needed too, but wasn't sure if this justifies the replacement or not. The only other option I can see is maybe having a competent shop rod it out maybe.

BTW, '95 FZJ80 w/ about 96K miles, original radiator, original headgasket. I'm currently replacing all the hoses, water pump, thermostat, heater hoses, clutch fan, etc.

When i changed the radiator out with 175k miles on it I thought I had no sludge.
There was none on top but when I took the bottom cap off it was about .75 inches of it all across the bottom. Seems like it would be almost impossible to get it all out without taking bthe caps off.
 
How do you pull the tank off, just bent back all the little tabs? I figured once I order new radiator, might be interesting to see what the old really looks like inside.
Yea bend them all back there is a rubber O Ring/gasket (it was in great shape)in between.
 

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