Can coolant need flushing but still look good?

[OldJeep]

I've been having a little trouble with overheating at idle in my Jeep, I'm thinking about flushing the cooling system. I've only had this jeep about 5 months, don't know how old the coolant is. It still is a nice bright green - no brown at all. Does it need to be changed if it still looks perfect?


Also - what about those flush chemicals? What's the best brand to use? Are there any that could actually cause harm to the cooling system?

 

[JohnBrowning]

Bad coolant would not cause over heating at idle! Yes it can still look good and be bad.

 

[Chris142]

Check your fan clutch.

 

[Kestas]

The antifreeze and boilover properties of the coolant may still be good, but the coolant is replaced because of additive depletion, which is 3yrs/30K for the green stuff. If you wait until the coolant changes color, then you've waited too long! If you don't know ow old the coolant has been there, you may want to go ahead and change it. It'll make a good starting point for future maintenance.

I would recommend using flushing agents only if you know there is deposit buildup in the system.

Does the Jeep have an electric cooling fan or viscous fan clutch?

 

[rgl]

OldJeep, if you don't want to flush but want to see what color it really is, I would suggest this: Get a small container and open the radiator drain and drain off maybe a quart or so. Then take a flat bottomed pan like a paint roller tray or such and pour a shallow amount in. My guess is you will see that it is a marked olive color rather than clear green. If you just look in the radiator or in the overflow tank it tends to look brighter than it really is. You can pour in a little fresh coolant in the pan to see the difference. I agree that waiting till it turns brown is not a good idea at all.

 

[Ray H]

I agree with the comments that appearances can be deceiving. Having said that, I inadvertently misread Honda's recommendations (36 mos./45,000 miles) on my Accord and left the factory coolant in for five years.(!) Sweet ignorance somehow persuaded the corrosion demons to look the other way. By the time I got around to flushing and changing, low and behold, the old fluid drained green and clear, with no sign of sediment, gunk, or corrosion, until the flush effluent ran water clear. With startups and full warming at idle between flushes, it took about 8 flush cycles as I recall. I then refilled with 50/50 Havoline Dex-Cool and tap water. Drove the car another three years before totaling it in a wreck. The Dex-Cool seemed to work fine for me during those three years - stayed quite clear, and the core, as much as I could see with the radiator cap removed, always showed deposit-free metal. There were never any indications of leakage, nor were there ever any signs of ever overheating in inland southern California's 100+ F. summer temperatures. (and I live by the AC!) Would I vary my routine on my replacement Sonata? Yeah - I'll drain and flush the green factory-fill coolant* at two years, and substitute distilled water this time. I happen to be among those who believe Dec-Cool's received a bum rap. As before, I'll keep a weekly watch on the overflow bottle and the radiator's innards, too.

*Hyundai noncommittaly specifies "high quality ethylene-glycol coolant in a 50/50 mix with water". Yep, that really narrows it down...

[ June 29, 2004, 03:32 PM: Message edited by: Ray H ]