Coolant Reservoir Leaking

[FL335i]

Well in the past few weeks I've noticed my coolant tank is losing quite a bit.  I'll fill it, back down about 1" in a week which is very unusual. My truck since new has needed 1/4" of coolant per oil change of about 7k miles.  All of a sudden it's 1" in a week or two.  I have searched high and low for a leak and nothing came up.  Today I took the air box out to clean it up and re-mount it because it's been rubbing up against the coolant tank since the dealer did the AC condenser job.  Turns out one of the three grommets for the bottom of the air box was not pushed all the way in, so I fixed that, but realized that ever since I've owned my truck the coolant tank has been very close to the battery. The tank has two mounting bolts.  So I decided to re-position the tank away from the battery while I was on this task....   While doing so, I put my hand under the coolant tank and my hand is pretty dang wet, with what I am 99% sure is coolant. I looked very closely around the tank and could not see a sign of a leak.  So it's got to be leaking from the underside of the tank.  I wiped it down and tried to feel around a few minutes later and could not feel any wetness.  So I think it's a leak that is present only when hot and pressurized.  I put a new radiator cap on it 2 days ago, topped it off with distilled water.  I took a picture of the tank level and a picture of my odometer.  Keeping a close eye on it now.   Are the tanks known to go bad?  Mine is a late '14 with 75k.  Figured I would get 5yrs/100k out of it as a minimum. 

[Eddie 70]

I hate to hear this because I know you are meticulous about the maintenance on your truck. I've read a lot of your posts and know you are on top of the whole antifreeze thing with your truck also. I am currently at 95k on mine and so far my coolant level has changed only minimally since I got it with 42k on it. I have added distilled water to it on the past though. I'll keep an eye on this post to see if it is indeed the tank leaking. I'll also be watching and checking the bottom of my tank for leaks.

[FL335i]

Thanks Eddie.  I'm making a 200 mile round-trip run today.  We'll see how it looks.  I'm going to check the bottom of the tank this morning before leaving.   On a side note, I received my Range AFM yesterday evening.  giving it a try also today on this trip. 

[silveradosid]

it wont surprise me if it is leaking i know they have a problem with the chev sonic tanks are cracking

[FL335i]

Silveradosid-  That's what I found when scouring the net.  Everything "chevy" and "coolant tank" related pertained to the sonics.  At first I didn't even know WTH a sonic was.  I thought it was a type of coolant tank.  Turns out it's some micro car for the hipsters. I got back pretty late this evening. it was dark and we had two cranky young kids to get to bed.  I did not have time to check the tank.  Tomorrow AM i will check it out and report back.  If it's down, I'll post pics of before and after the 200 mile trip. 

 

Side note.  The Range AFM performed flawlessly on the trip.  I threw it in last night.  This morning with loading all the stuff and kids up at 7am I forgot about the thing.  Didn't realize it until we hit the highway about 20 minutes from home... oh yeah.  Unreal how nice it is to have V8 on all the time!!!!  OMG am I happy with getting rid of 4cyl mode.  Merry Christmas to me!

[FL335i]

Figured I'd throw out an update.  I did my 200 mile trip plus some around town errands.  It's been a week since the radiator cap was replaced and the coolant topped off.  Thus far, no visible leak or wetness on the tank bottom.  Coolant level is right at the fill line where i put it last Thursday.  It's looking like the radiator cap was bad.  Probably just the O-ring, but for the price might as well replace the whole thing.  If your NAPA has an o-ring kit to pick from, you might be able to match one up and buy a couple to have on hand.  Thought I would share the results so far after 250 miles +/- and 7 days.