Coolant Tank Brown, Radiator Green
12-14-2010, 04:36 PM
#1
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Year: 1995
Model: Cherokee
Engine: 4.0
Coolant Tank Brown, Radiator Green
First off- I've been using this site for research for a while but this is my first post. I do almost everything myself on my Cherokee and this site is a great resource. Here's a problem I'm having that has me baffled:
Essentially, the coolant in the expansion tank is brown but the coolant under the radiator cap is green. I haven't flushed the coolant yet because I cant figure out why the coolant would be two different colors depending on where in the system i check. I've checked this a few times over the past several weeks and it's always the same. The expansion tank coolant is brown (like the dreaded head gasket milkshake) but under the radiator cap the radiator coolant looks brand new.
The radiator, water pump and coolant are all about 2yrs and 25-30K miles old. The Cherokee is a 1995 with 168K- I've owned it since it was brand new. I change the oil religiously and there is no obvious sign of a head gasket issue. The engine overheated twice this past summer. Once stuck in traffic on one of the hottest days of year and again on the emissions dyno also on a really hot day. Manual tranny with original clutch- since there's no tranny cooler i havent bothered to check the tranny fluid.
Anyone have any ideas? Thanks!
Essentially, the coolant in the expansion tank is brown but the coolant under the radiator cap is green. I haven't flushed the coolant yet because I cant figure out why the coolant would be two different colors depending on where in the system i check. I've checked this a few times over the past several weeks and it's always the same. The expansion tank coolant is brown (like the dreaded head gasket milkshake) but under the radiator cap the radiator coolant looks brand new.
The radiator, water pump and coolant are all about 2yrs and 25-30K miles old. The Cherokee is a 1995 with 168K- I've owned it since it was brand new. I change the oil religiously and there is no obvious sign of a head gasket issue. The engine overheated twice this past summer. Once stuck in traffic on one of the hottest days of year and again on the emissions dyno also on a really hot day. Manual tranny with original clutch- since there's no tranny cooler i havent bothered to check the tranny fluid.
Anyone have any ideas? Thanks!
12-14-2010, 04:52 PM
#2
The heads warp easy once they over heat. The fact that yours pegged red twice makes me nervous. Time to check compression and cooling system pressure. If those check out to be good, no HG issues, then I would remove the expansion tank. Drain, clean and reinstall.
If the cooling system is order then the expansion tank may not see coolant from the rad for some time which would explain the color difference. Might be that simple but check the compression just to be safe.
If the cooling system is order then the expansion tank may not see coolant from the rad for some time which would explain the color difference. Might be that simple but check the compression just to be safe.
12-14-2010, 05:09 PM
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Year: 1998
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I'd remove the overflow bottle, empty it and thoroughly clean it inside and out. It could easily be stained inside from previous old rusty brown coolant. Heck, if it's 2 yrs old coolant, why not flush the whole system and start fresh?
How about the t-stat, rad cap and fan clutch? Efan come on?
How about the t-stat, rad cap and fan clutch? Efan come on?
Last edited by djb383; 12-14-2010 at 05:13 PM.
12-14-2010, 07:20 PM
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I'd remove the overflow bottle, empty it and thoroughly clean it inside and out. It could easily be stained inside from previous old rusty brown coolant. Heck, if it's 2 yrs old coolant, why not flush the whole system and start fresh?
How about the t-stat, rad cap and fan clutch? Efan come on?
How about the t-stat, rad cap and fan clutch? Efan come on?
12-14-2010, 09:08 PM
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Year: 1995
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Thanks for the comments. Let me clarify the overheating- the Jeep did not boil over. The dash light came on and I let it cool down. The jeep didn't even boil over when i replaced the radiator and water pump several years ago- that was due to a seized pump and i did everything at once. The light only came on on the hottest day last summer when i was stuck in brutal New York City traffic. Though it seemed like the dash was throwing off a lot of heat....
The thermostat seems to open when it should and the fan seems to come on when it should. Now that it's cold, the car heats up quickly and i get good heat. I haven't tested the compression (i'd need to borrow or buy the tool) but the there has been no decrease in engine power or other obvious signs of poor compression/blown head gasket. Pretty general observations i know, but there are no real symptoms...
Based on these responses, I tend to think that the cooling system is functioning normally and that the reason the reservoir tank is brown is that the cooling system isn't expanding into the cooling tank that much. It's probably just old coolant possibly pre-dating my coolant change two years ago (can't remember the color of the tank back then and maybe i just haven't noticed). The radiator is full of bright green fluid, so it's not like the fluid isn't going into the expansion tank due to a cooling system malfunction (I don't think). If the cooling system was in bad shape it'd be boiling into the expansion tank all the time right? It seems like a brown expansion tank is ok if the coolant in the radiator is still green, but not vice versa. If the radiator coolant is brown, that's when you have problems. I think I'll just clean the expansion tank really well and see if i can keep the fluid green.
The thermostat seems to open when it should and the fan seems to come on when it should. Now that it's cold, the car heats up quickly and i get good heat. I haven't tested the compression (i'd need to borrow or buy the tool) but the there has been no decrease in engine power or other obvious signs of poor compression/blown head gasket. Pretty general observations i know, but there are no real symptoms...
Based on these responses, I tend to think that the cooling system is functioning normally and that the reason the reservoir tank is brown is that the cooling system isn't expanding into the cooling tank that much. It's probably just old coolant possibly pre-dating my coolant change two years ago (can't remember the color of the tank back then and maybe i just haven't noticed). The radiator is full of bright green fluid, so it's not like the fluid isn't going into the expansion tank due to a cooling system malfunction (I don't think). If the cooling system was in bad shape it'd be boiling into the expansion tank all the time right? It seems like a brown expansion tank is ok if the coolant in the radiator is still green, but not vice versa. If the radiator coolant is brown, that's when you have problems. I think I'll just clean the expansion tank really well and see if i can keep the fluid green.
12-15-2010, 05:43 AM
#6
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Year: 1999
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The level in the coolant reservoir should go up and down between the min/max lines when cold/hot.
How old is your radiator cap? If you didn't replace it when you replaced the radiator, do it now. They are only about $5.00 and are an important part of the cooling system.
16 pound, don't get one with a release lever!
How old is your radiator cap? If you didn't replace it when you replaced the radiator, do it now. They are only about $5.00 and are an important part of the cooling system.
16 pound, don't get one with a release lever!
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12-15-2010, 11:32 AM
#10
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I believe all of those parts were replaced along with the new radiator. I know I did all new hoses... i'll need to check my records when i get home.
12-15-2010, 09:27 PM
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1) It's normal for crud to accumulate in "dead" overflow tanks (like yours - the RENIX pressure bottles are actively involved in circulation...) over a couple of years. As mentioned, just remove the tank and scrub it out. The cap usually does not provide a good seal - it's just a dust cap, and not a very good one.
2) From what I've been able to find out, the typical service life of an XJ fan clutch is five years before it starts to deteriorate beyond utility. Write the date on the replacement with a Sharpie pen when you put it in.
3) While you have the mechanical fan & shroud out, remove the electric fan and blow out the radiator from the backside using a garden hose and a small-orifice nozzle. Not a bad idea to replace the e-fan and fan shroud hardware with 1/4"-20 clip nuts and thumbscrews, so you don't have to find that small damned wrench again (it's what I've done on all of my rigs...)
4) When was the last time the system was actually flushed? If it's been more than two years, use a "seven-hour" flush. If it's been more than five, use the two-part acid/neutraliser powder that Prestone makes - follow the instructions on the back, but add in one flush after the neutraliser using plain cold water. Do this before you scrub out the overflow, or do it while you've got it out and are cleaning the thing.
5) Make sure you clean out the overflow hose as well - or just replace it outright. Most automotive "rubber" hose should work, I believe they're usually 3/8" ID.
2) From what I've been able to find out, the typical service life of an XJ fan clutch is five years before it starts to deteriorate beyond utility. Write the date on the replacement with a Sharpie pen when you put it in.
3) While you have the mechanical fan & shroud out, remove the electric fan and blow out the radiator from the backside using a garden hose and a small-orifice nozzle. Not a bad idea to replace the e-fan and fan shroud hardware with 1/4"-20 clip nuts and thumbscrews, so you don't have to find that small damned wrench again (it's what I've done on all of my rigs...)
4) When was the last time the system was actually flushed? If it's been more than two years, use a "seven-hour" flush. If it's been more than five, use the two-part acid/neutraliser powder that Prestone makes - follow the instructions on the back, but add in one flush after the neutraliser using plain cold water. Do this before you scrub out the overflow, or do it while you've got it out and are cleaning the thing.
5) Make sure you clean out the overflow hose as well - or just replace it outright. Most automotive "rubber" hose should work, I believe they're usually 3/8" ID.
12-15-2010, 10:13 PM
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12-17-2010, 09:56 AM
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Found my records:
8/10/07 replaced thermostat/antifreeze/clamps/gasket
6/27/08 replaced water pump & radiator, antifreeze, upper hose, clamps replaced.
I'm curious to see if the line to the overflow tank is clogged, which might explain the different coolant colors. Not sure where the coolant would be expanding into if that was the problem... we'll see.
8/10/07 replaced thermostat/antifreeze/clamps/gasket
6/27/08 replaced water pump & radiator, antifreeze, upper hose, clamps replaced.
I'm curious to see if the line to the overflow tank is clogged, which might explain the different coolant colors. Not sure where the coolant would be expanding into if that was the problem... we'll see.