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5.7L needs coolant constant, but no leak.

24K views 21 replies 12 participants last post by  brandon51107  
One thing I do like to add is that I added green 50/50 coolant in it, and it all seems to be gone while there is still orange coolant left in the reservoir. Does the 5.7L need specific coolant? Could that be it?
Yes, it does.
Never mix coolant types.
Flush it and fill only with spec'd coolant.

Back to your original problem, roughly how much coolant do you lose?
Is it about the same for a given week, or does it vary with miles driven?

Suspects would be slow leaks where the coolant is getting on something hot that evaporates it such that you don't see a visible leak.

The coolant recovery bottle has been known to get small cracks, where it will leak.

Or, the fluid may be gathering where it isn't visible, say at the !@#$!@#$ plastic tanks on the radiator or the !!#@$&#$%^ plastic fitments for hoses.

Suggest picking up a bottle or two of dye and the matching UV light. Wash the engine, radiator, underside completely, then add the dye and drive a bit. Check in a darkened garage or with a blanket over the hood to make it a bit easier to see even small amounts of dye.

If all else fails, pressure test it--with dye.

If still nothing, compression test all cylinders for a gasket leak.
 
I can take it for a 30-60 minute ride and loose the delta of full vs add on the reservoir. Now, I looked yesterday and interesting enough, the green 50/50 coolant disappeared but the orange coolant was still in the reservoir, as it looks like the green coolant dried up on hot temps.

I am going to try to do a coolant flush this evening and see if it makes a difference. Funny how they say "mix with any color coolant" on the bottle....
That bottle may say that, but your system should be using HOAT type coolant.
If you have the owner's manual, check it.
If not, you can probably get an answer at Jeep SUVs & Crossovers | Official Jeep Site | Jeep, or from a local mechanic with a FSM for that thing.


HOAT [orange] coolants carry this warning:

CAUTION: Mopar Antifreeze/Coolant, 5 Year/100,000 Mile Formula (MS-9769) may not be mixed with any other type of antifreeze. Doing so will reduce the corrosion protection and may result in premature water pump seal failure. If non-HOAT coolant is introduced into the cooling system in an emergency, it should be replaced with the specified coolant as soon as possible.
 
I guess a radiator cap is always a thing to buy, but I like to figure out what these two lines are for that run behind the passenger front wheel. There I see a drop of coolant hanging, which might be the answer.
Do they head from the radiator back to the transmission area?

Note that you may see coolant on them, but that doesn't mean those lines are leaking--just that wherever coolant is leaking allows it to get on those lines--presuming it is coolant you see.

You can spend a lot of money guessing, or you can buy the dye kit and pressure kit and test your system. While looking, see if your parts house can test your radiator cap for holding pressure--or just drop a couple bucks and buy one as most of the comments have noted.

And make sure next time you buy coolant, it is the same as what you have.
If the parts clerk insists there is a universal coolant, try another store.

Actually the stuff is reasonably cheap at most dealers if your local parts places suck.