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Blown head gasket or Cracked head?

SpenceXJ

NAXJA Forum User
Location
Reno, NV
I have been having brown/dark colored coolant in my reservoir for ahwile now and thought it was dirty and should just get it flushed. Well I talked to guy that said it could be oil and to check if it looked the sam in my rad cap. Well it does... He said that I probably have a blown head gasket or maybe even a cracked head. Now the jeep runs fine, it gets to around 210 pretty quick and stays there fairly well but its been hot here lately (100*) and if stopped it can raise above 210 and kick the fan on. I was on a dirt road last week and it rose to around 220 and I stopped at the campsite to find the crappy coolant boiling out of the reservoir. Any ideas? I just don't like how weird this is...

Thanks in advance
 
Had the same thing happen not long ago,it was off and on and I thought it was just the bottle. As it turns out it was a very slight gasket problem that took awhile to go out. I never had water in the oil or anything in the water until it went,but that is what was causing it to overheat.
 
Had the same thing happen not long ago,it was off and on and I thought it was just the bottle. As it turns out it was a very slight gasket problem that took awhile to go out. I never had water in the oil or anything in the water until it went,but that is what was causing it to overheat.

Cool cool man, same symptoms then?

I hope it just the gasket.
 
I have noticed the same thing in my 99. Every time I take the radiator cap off, it's covered with nasty brown gunk and I had to take my reservoir off and wash it out. My temp has not increased noticeably though. Let me know if its the gasket.
 
I have noticed the same thing in my 99. Every time I take the radiator cap off, it's covered with nasty brown gunk and I had to take my reservoir off and wash it out. My temp has not increased noticeably though. Let me know if its the gasket.

I will let you know for sure, mine is not just on the cap though, its the fluid. It's all dark brown and gross looking.
 
Before jumping to conclusions and spending a bunch of money, run a good radiator flush and refill with antifreeze. It is normal for coolant to turn dark over time. You should change antifreeze at least every two years if not more often.
 
220 is not overheating for an XJ. Usually a cracked head or blown gasket will use antifreeze. Drain out all of the old and do a couple of flushes with water until it gets clear. If you can get it to work good on water, drain it again and do the 50/50 antifreeze.
 
X2 on the flush and refill first. There are radiator additives out there that make the coolant oily, and brown colored almost immediately. The combination of copper and and iron dissolved in the coolant (especially if it is more water than antifreeze), will turn it a dark color.
 
I'm glad I posted up here and didn't tear my engine apart. I'll get a flush and see what happens. Also to add to the symptoms my motor get to 210 really really fast, within a few minutes, and climbs around 5* when just sitting for a few minutes also.
 
It is pretty hot there in NV so that doesn't help much, but yeah I would certainly say do a good flush before you tear into the engine, unless you just really want to do some work.... I had a similar looking gunk in my cap when I first bought my 98' and I did a quick flush, and haven't seen it again, another thing you can do is do an oil change, and see if there is water in the oil, that would be another tell tell sign you have a gasket issue, but I am thinking you don't!!
 
If flushing doesn't resolve, there are some tests that can be done to determine if you have something going on internally. I'd proceed in this order. TEST your way to a solution if you need to.....

*Check coolant for the presence of hydrocarbons (block test)
*Cooling system pressure test
*Compression test
*Cylinder leakdown test
 
Definitely do the flush! If it's water in the oil, simply removing your fill cap on top of your valve cover after you've run your engine will tell you 'cuz it'll be all gooped up. Mine was the same way as yours - runs at about 210, go up about 5 more whenever I was sitting still for about 10 minutes and then drop to 210 again once I was moving. I did a flush and put in a stant 190 thermostat and I haven't had any issues since.
 
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