I’ve been fighting a bit of a cooling system issue for the past year or so. It is keeping me from going on any extended wheeling trips for fear of some sort of catastrophic failure.
My Jeep: 75,000 miles. 3.5” lift, 37” tires, 4.88 gears, Metal Cloak Fenders, Smittybilt SRC Classic front Bumper with Warn winch. I’m including this because it may be pertinent to front end air flow and cooling system efficiency.
My problem:
What have I changed / checked:
Questions:
Any suggestions on how to proceed? I am leaning pretty heavily toward doing a bit of a cooling system overhaul. I was thinking about an aluminum radiator (like the Mishimoto), replace the thermostat and housing, water pump, and ?
Any suggestions on a good radiator brand?
My Jeep: 75,000 miles. 3.5” lift, 37” tires, 4.88 gears, Metal Cloak Fenders, Smittybilt SRC Classic front Bumper with Warn winch. I’m including this because it may be pertinent to front end air flow and cooling system efficiency.
My problem:
- 2 Fold - I noticed about a year ago heading up to Big Bear to do some light trails that when climbing mountain highway roads (and pushing a bit hard) that the coolant temperature reading on my TrailDash 2 was getting up to 240, and maybe 245, at times. Air temp outside was in the 80’s. On the Jeep coolant gauge in the dash it was getting maybe half way from normal (right in the middle) to about half way to full scale. This was definitely concerning. On the trails the coolant temp behaved pretty well. Then on the way home outside air temps were up in the 90’s and it was still running pretty hot (maybe getting into the 230’s on the TD2). I also noticed, when I got home, that coolant had overflowed the overflow tank.
- Since then I have noticed that coolant seems to slowly (over weeks) pushes out into the overflow tank and does not return to the radiator. Every few weeks when the engine is cool I’ll put coolant from the overflow tank back into the radiator. I haven’t specifically measured but this has easily been 10 to 15 oz of coolant (in the overflow tank it is more than the difference from the “Min” line to the “Max” line. You can tell it needs it when I start it in the morning and there is a definite sound of water running/ flowing coming from the engine compartment.
- Typical freeway driving, depending on the outside air temp, can get the coolant temperature up to maybe 230, but usually runs cooler.
- In just the last 2 weeks or so I have gotten two P0128 error codes which not surprisingly has to do with the cooling system. Both times it was on a short trip at lunch time. I believe that it in a perceived error that the coolant isn’t heating up as fast as expected. I really didn’t notice any difference in how the temperature was behaving soon after starting it cold. It is supposed to be an indicator of a thermostat problem.
What have I changed / checked:
- New radiator cap (Jeep actually recommends a 17 versus the original 18 PSI cap).
- Replaced overflow tank and hose.
- I purchased a coolant filling funnel that is supposed to allow proper air purging of the cooling system and done that several times. The issue of coolant migrating out into the overflow did not improve.
- I bought a Combustion Leak tester that checks for combustion gas in the cooling system (like with a head gasket or cracked block or head leak). Per the instructions I sanity checked the tester by blowing into my cupped hand while using the tester to draw in my exhale and it correctly registered combustion gas (I think it is looking for CO2). Another test drawing fresh air into it did not show any combustion gas. I used this tester on the freshly opened radiator without any sign of combustion gas. This seems to rule out a blown head gasket or cracked head (little bit of a sigh of relief).
- No sign of coolant in the oil, or vice versa. I even checked the little bit of ‘sediment’ in the bottom of the old overflow tank. It didn’t seem like oil, it was very water soluble.
Questions:
- Has anyone had this issue? What needed to be done to fix it?
- I know that this engine is supposed to operate at a higher temperature. I could probably accept the temperatures that I see if the coolant flow back and forth from the overflow was as expected and didn’t continue to fill up the overflow.
Any suggestions on how to proceed? I am leaning pretty heavily toward doing a bit of a cooling system overhaul. I was thinking about an aluminum radiator (like the Mishimoto), replace the thermostat and housing, water pump, and ?
Any suggestions on a good radiator brand?
