'05 Trailblazer overheating

[JCC]

I know there are other forums for this, but I thought I would start here. I have an '05 Trailblazer with a V6. I recently had to change the temperature sensor and decided to change out some other things while everything was taken apart. I replaced the thermostat, upper radiator hose, lower radiator hose and ended up having to change the radiator due to putting too much force on the hoses when changing them. I obviously lost most of the fluid when changing out the radiator. I have added more fluid to the system and bled it out where it will not take more fluid. There seems to be a leak and I am not sure where. My suspicion is the water pump. I considered going ahead with replacing the water pump while everything was taken apart, but did not think it was necessary. I was not trying to replace every part I laid eyes on. Anyway, anyone have any ideas? I am thinking the water pump is blown and that is why the leak.

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[Dawico]

I have seen water pumps wear the fins off and not leak so it could be the culprit.

 

[JCC]

I am thinking my replacing the other stuff put pressure on other parts of the system.

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[Fishkiller]

Not much of mechanic. I usually check the tire pressure. If that is good it goes to the shop.

 

[Bozz10mm]

Does it have the electric cooling fan? Is it working? That or the water pump. See if you can find a leak on the water pump. If so, that's the problem.

 

[Wiliamr]

Did you replace radiator cap?
You say there "seems to be a leak" Why do you think that? do you see coolant on ground?

 

[ZX9RCAM]

Overflow tank holding fluid?

 

[JCC]

Does it have the electric cooling fan? Is it working? That or the water pump. See if you can find a leak on the water pump. If so, that's the problem.

Fan is working.

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[JCC]

Did you replace radiator cap?
You say there "seems to be a leak" Why do you think that? do you see coolant on ground?

I did not replace the radiator cap, but it does not seem to be leaking there. Fluid is slinging everywhere from the fan. Seems most likely the water pump and then getting on the other pulleys/belt/fan. I may replace the cap also.

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[Brains]

I did not replace the radiator cap, but it does not seem to be leaking there. Fluid is slinging everywhere from the fan. Seems most likely the water pump and then getting on the other pulleys/belt/fan. I may replace the cap also.

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Well that's pretty telling right there That's a large leak, and its source should be visible.

FWIW, you can verify the pump is moving water by draining some off and looking down inside the radiator with a light with the motor running. Do it with the motor cold obviously.

 

[JCC]

Thank. I do not have any experience with water pumps, but I know where it is and how a leak there would sling fluid everywhere.

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[pronstar]

Water pumps are cheap enough that they generally get replaced whenever “you’re in there” since it’s usually a PITA to even get to it.

Sucks that you’ll have to dive back in to get it.


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[ttuttle]

In my 55 years of building Chevy engines I've found these mystery overheat problems can ususally be cured by purging air out of the block. These engine have a habit of developing air pockets, and by repeated running, pulling the radiator cap, and refilling with 50/50 mix you can work the air out.
FYI, replacing the water pump is good idea too.

 

[Wolf63]

My son has the same truck. We had this problem a while back. There was a hair line fracture in the plastic radiator. Only way to find nmlm it was run the motor for a while and shut it off. Watch for the seepage. Good luck.

 

[ZX9RCAM]

My son has the same truck. We had this problem a while back. There was a hair line fracture in the plastic radiator. Only way to find nmlm it was run the motor for a while and shut it off. Watch for the seepage. Good luck.

Welcome to the Forum!

 

[chubbs]

i don’t know what all you have done in the few days since creating this post, but i’d like to point out a couple of tips & observations as i’ve had experience with a finicky coolant system a couple years ago.

1st of all, what’s stands out to me is that you suddenly have this coolant ‘leak’ that wasn’t a problem before you began the repairs & replacements. it’s suspect that a serviceable component fails in the specific time frame of just a day or 2 where you were working on the vehicle. i’m of the school of thought that you should go back over your work - where you were actually removing & reinstalling parts since that is the most logical explanation.

the best way to find leaks in the coolant system is to pressurize it. you can either buy 1 outright or borrow it from a big box auto parts retailer. i’ve gotten all sorts of specialty tools on loan from Oreillys Auto. (you have to pay a deposit but the total is reimbursed in-full upon return of the tools) they will have a coolant pressure tester that is nothing but a radiator cap attached to a pump & valve that displays pressure. HF also sells these things, come to think of it. just make sure you get a kit that accommodates your make/model.

secondly, most DIY may go ahead & replace WP w thermostat, etc but it’s usually a project that is saved up for or parts acquired over time then work performed when you have everything needed including tools, workshop manual, extra vehicle, maybe a helper.

3rd: the entire coolant system must be flushed completely. that red DexCool coolant has a long service life but beyond 10-years & 100k miles, once you open the system up & start adding coolant & water, it supposedly begins to break down & begin sludging - ESPECIALLY if you’d didn’t add that same GM red DexCool trademark stuff that was in there to begin with. you cannot mix any other coolant with red GM dexcool FYI. that’s a BIG no-no.

4: you really need a GM service manual for your truck. I got 1 on craigslist or ebay for $10 but any auto parts store will have 1 for your truck. this is an automobile and a manual is essential for DIY repairs & diagnosing issues like coolant leaks. large expenses and time consuming DIY. it just makes sense to use a manual and do everything correctly the 1st time in a methodical fashion, less you find yourself with more problems than you started with.

5. if you haven’t replaced the WP already, get a pressure tester and find out what exactly is spewing coolant. you could have cracked another plastic boss or failed to seat 1 of the radiator hoses down low - that would result in coolant getting sprayed everywhere by the fan. just 1 possibility.

if you DO have the extra cash for a WP, it wouldn’t hurt to replace it but don’t go & buy the cheapest 1 in the stock. buy quality parts like AC Delco. trust me on this. buy a new gasket if 1 is not incl with replacement part. you have to prep the block perfectly when you remove the original pump. clean & prep is always 95% of the success of your work no matter what it is. if you don’t get all of the old gasket off or leave an uneven surface, it will just leak & you have to do the whole thing over again. careful what you use to clean the mating surface. you cannot gouge/scratch or distort the engine block AT ALL or else it will leak and you prob won’t be able to repair that hiccup DIY. a manual will explain what to use and how to go about it so that you don’t fudge it all up.

6: back to coolant flush and purging air - use the GM dexcool 50/50 or dexcool concentrate with ONLY distilled water. do NOT use tap water in your coolant system. that’s another big no-no. tap water is full of minerals that do not belong inside of an engine with metal & aluminum parts. the minerals deposit in the cavities & build-up until water flow is restricted. i’ve seen orig factory water pumps that have come apart and the inside & propeller looked like it was just pulled from the ocean bottom. completely corroded and incomplete where the components just broke down over time. a result of mixing coolants and using water from the outside faucets to ‘top it off’ here & there.

lastly, purging air is no joke. usually it’s not enough to let the engine run with the cap off. i had 1 truck that i would park with front tires up on the curb, cap off, rev engine lightly in a particular sequence, drive it around the block a few times, park it back up on the curb, let the engine get up to temp, so on & so forth. that’s what it takes for the old land rovers & i may just do every vehicle like that from now on. overheating, air pockets in the coolant system is no joke and personally i wouldn’t take any chances. just do it thoroughly correct the 1st time. if you are driving to work the next day & the engine temp is swinging up & down then there is air trapped in the coolant, still. that’s a big problem that will either leave you stranded or worse. i just think you should do some research, get a service manual, and pressure test the radiator & go from there. i used to browse ‘tahoeyukonforum’ all the time. trailblazer i believe has its own fan site with forums & tutorials as well. please login there, do some browsing & searching before you turn any more wrenches on that thing. you will end up overheating the engine if you jack around & don’t pay close attention

 

[TxStetson]

trailblazer i believe has its own fan site with forums & tutorials as well.

I believe the Trailblazer is just about out of fans.
We had an 04 trailblazer EXT. That was the only bad GM vehicle I ever owned, and they bought it back for more than my payoff 3 years later. I believe that was done just to shut me up and hope I would go away.

 

[oldag]

My '01 Blazers were fantastic. Sadly, both were in wrecks (family members driving but not at fault).

 

[JCC]

It has hung in there, but not without its problems. It was my wife's parents' vehicle before her and was passed along to me. Transmission rebuild was the worst that has happened. Pretty sure it has the original alternator and pretty sure this was the original radiator. Suspension is shot, but it moves noisily.

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[chubbs]

I believe the Trailblazer is just about out of fans.
We had an 04 trailblazer EXT. That was the only bad GM vehicle I ever owned, and they bought it back for more than my payoff 3 years later. I believe that was done just to shut me up and hope I would go away.

that’s right. i’m thinking of the Trailblazer SS. i think that’s the only worth a damn but i don’t know much about TBs. TBSS.com

i’ve only owned & driven v8s myself - i’m an avid DIYer - and smaller engines are a different animal. v8 is set up basically the same no matter the manufacturer but v6 i don’t know. i can open the hood on any full size pickup & suv & know what is where but give me a car or midsize and i have to really slow down and look over schematics. i’ve never seen 2 that are the same. i’m speaking strictly on older gens, the newer vehicles i don’t and haven’t owned so i don’t know