Typerod

Hi all,

So I was doing an oil change on my 07 Tahoe LTZ, and saw that the coolant in the reservoir was extremely low. So I bought a gallon of the AC Delco Dex-cool 50/50, part number 12378390. This bottle does not say "extended life" on it just as the AC Delco Dex cool concentrate, part number 12346290.

Are these two parts the same Dex-cool formula, just one is pre-dilouted and the other concentrate? The back of the 50/50 bottle confuses me by saying it "may be used for top-off only".
It also says the 50/50 can be added to the Dex-cool currently in my Tahoe w/o affected the service life interval of the current fluid.

I guess my OCD is going crazy b/c the 50/50 bottle doesn't say "extended life" on it just as the concentrate bottle does.

Any help is appreciated! I don't want to possible screw up my cooling system, lol.

Typerod

I'm also looking into why I'm losing coolant as well, I don't see any signs of leaking at the water pump or at any hoses or at the radiator. My Tahoe has ~234,000 miles on it. So I'm going to start by replacing the coolant recovery tank cap. I see there is a new part number, 13502353, but this cap says its a 20 psi cap. My original cap, part number, 15075118, says its a 15 psi cap.

Should I go with the newer part number? Not sure if going with a higher psi cap will cause issues for the cooling system.

New part:
Old part:
below is a pic of my original cap

kevinkpk

I'd look elsewhere for a coolent lose. 15 lbs. is fine, and if you add an additional 5 lbs to an older system, you could force a leak. With that said, I'd suggest you pressurize the system, and check for static leaks

Typerod

Thanks kevin! The gasket on my current cap is flattened out. I've seen youtube vids that suggest its possibly the cap gone bad, the cap is inexpensive anyway.

The reason why I was asking about the new cap (20 psi) vs the current cap (15 psi), is that the new part is what gmpartsdirect.com says is the correct part for an 07 Tahoe. I'm waiting to hear back from the ebay seller to see if they can confirm that the new part number is indeed the correct one.

Typerod

So I did top off the system before we left on our 8 hour round trip last weekend. I checked the coolant level in the surge tank and it was extremely low. Got under the car this morning and I could see coolant, at least I think it was coolant, soaking underneath the car where the bottom of the winshield washer fluid tank is. My washer fluid is the orange rain-x, and the fluid I see all over the car underneath was orange-ish, so I thought it was a washer fluid tank leak as well....but after adjusting the lower rad hose clamp just to be sure it wasn't the root cause of the leak, I brought my attention over to the left side of the car where I saw all the mysterious fluid. I could see on the black plastic side of the radiator the mysterious fluid, but couldn't see a source of the fluid, fluid was orange-ish, so i checked all the washer fluid lines since they run near that area of the car, didn't find a leak in those. So I gave up, and just hosed down everything. Once that all dried up, i checked the side of the radiator again and it was nice and dry. So i drove it to the dealer to go pick up more coolant to top off the system, I get back home, coolant level has dropped a tad, and I look at the left side of the radiator and its wet again.

I followed the fluid up the side of the radiator, I take off the radiator cowl to get a better look, and I cant find the leak. Then I just happened to notice the piece of rubber flap in front of the radiator is slightly wet, has a spray pattern on it. Then I move the flap forward and then I see at least two cracks in the plastic side of the radiator.

So kevin you were correct in your suggestion! So thank you friend!

Here is a pic:

73shark

The plastic end tanks used to be replaceable by a radiator shop. Don't know if they still are or not but lot cheaper than an new radiator. Had to replace one on my IROC-Z.

in2pro

When I did mine a while back https://chevroletforum.com/forum/tah...tenance-54058/ I was able to get the Extended Life 50/50

Typerod

Thanks for the info 73shark! I didn't know that was possible....plus I needed a quick turn around time to get the car back. I'm just thankful it didn't blow out on our road trip last weekend! lol! and thankful as well to get 11 years and 235K miles out of the old radiator.

Typerod

Thanks in2pro! Yea that really confused me, why AC Delco doesn't call their 50/50 dexcool "extended life", they only called the concentrate dex-cool "extended life".

But the parts guys at the dealer are certain its the same exact coolant in both the concentrate and pre-dilouted, and the only difference is the 50/50 is obviously diluted with de-ionized water.

Now my only issue is getting all the air out of the system. When I picked up the car saturday afternoon after the repair was completed, I first checked the coolant level before I drove off the lot, and guess what it was empty! That put me on high alert once again with this dealer, b/c last time I had terrible service with them, and being they are my nearest dealer, and the high priority repair, i went ahead and had them do the R&R.

So I went back to the SA and he got the tech to top off the surge tank. btw, I was charged for only one gallon of coolant, and in my head im thinking, i feel there should have been at least a 2 gallon charge on the bill. And the bottle the tech topped off the tank with, was new and im pretty sure it was the bottle i paid for, and why didn't he use most of that bottle in the first place.

So the tech said, hmm thats funny i just topped of the tank after the repair. In my head Im like man did you even give the cooling system time to burp itself before pulling my car out of the garage? So he topped off the tank again, and said to bring it back if it the level gets lower, b/c there may be another leak. I kinda rolled my eyes a little bit b/c I doubt theres another leak.

Anyways, so I checked the level Sunday morning when the engine was cold, and the level had dropped a light bit, but it held that level all day Sunday and into Monday (yesterday), so I went back to the dealer yesterday to have them top it off again, and i asked them to over fill the surge tank slight b/c there is still air in the system, and I told them I could feel an air pocket possibly in the upper rad hose. So he overfilled it and I checked the level before I left work yesterday and it is only slightly below the "FULL COLD" line.

My question is how much longer will it take to get the air out of the system? I did put the front end of the car on ramps when i got home and let the engine run for about 20-30 mins, slightly revving the engine to about 3000 rpms for a few seconds. I wasn't able to have someone watch the tank while i was revving the engine to see if bubbles were rising up.

The heat gets warm, but when I put the heater on and set the temp to 90 degrees it gets very hot, but I hear heating system opening or closing something in the dash when I set it to 90 degrees, so I'm not sure if the computer is doing something extra to make it extremely hot or if that is normal operation. But I feel like the heat should be a bit warmer when the temp was set to 88, but when I set it to 90 you hear movement in the dash then it gets extremely hot. Granted it was about 80 degrees outside, but i still feel that it shouldve been blowing warmer air when the temp was set below 90 degrees.

Any insight is appreciated! btw, car is not overheating at all, no more visible leaks after the repair. and i feel like I shouldve called the dealer back before they started the repair and told them to replace the thermostat as well, oh well. lol

oh one more question...does the thermostat only open when the rad fans kick on? or is the t-stat always open if the engine coolant temp is higher than the set point, even though the fans are NOT on?

Thanks!

in2pro

When I drained my system I was able to get 2 whole gallons of the 50/50 and then used the 3rd gallon I had to top off and if I recall I only got about half of that 3rd in and it took a couple of days to "burp" the system.
As for the T-stat, it is constantly opening and closing to maintain the 195-210 temp range, the fans will come on if the AC is turned on, I am not entirely sure what temp sensor causes the fans to come on for engine temp only.