Hello everyone,

First time posting. This forum is awesome and I'm excited to be a part of the community as my new hobby of working on cars (specifically Blazers ) grows. Please forgive me as I am a complete noob to cars, and have done nothing more than change the oil and wiper blades myself. I've been building computers for over a decade and love taking things apart and putting them together, but cars are on a lever of complexity well beyond computers. It's also significantly more expensive to correct a mistake when working on one, so I definitely don't want to make one. So thank you in advance for any help.

What I'm dealing with currently, is what I believe to be a heater core in my Blazer that needs to be replaced. I've researched online and read what I could find on this forum, and I seem to be running into a few problems.

The symptoms I have currently, is just a fumy smell in the cabin. I wouldn't say it's a sweet smell (when I think sweet I think bakery with edible sweets, and it isn't that) but more of a general toxic smell. The heat works great, in fact it smells just fine coming from the vents. I live a few miles west of Chicago and the temperatures here are ranging from 15-40 degrees (fluctuating randomly from day to day) and the biggest issue right now is with the windows fogging up. The defroster doesn't seem to be malfunctioning, but there is a greasy like film on the inside of the windshield and it seems to be spreading to the other windows. It's almost impossible to clean; so far all that works is a spray bottle of RainX and some paper towels.

Assuming there was an issue with the heater core (my mechanic took a quick look at the car and believed it to be the same), I disconnected the battery, and opened a black plastic screw on the passenger side, underneath the hood. As far as I understand, that screw is the radiator drain plug, and is located more specifically about 3/4ths the way down, towards the ground, left of the radiator. When I unscrewed it, I heard a bubbling sound for a second, and just a few drops of what appeared to be the orange coolant my car uses, dripped out right there. I was unable to locate the radiator drain valve so I just closed the plug back up and connected the battery. As I was grabbing the negative wire, I noticed a hose coming from the top of my coolant reservoir that is about a foot to two feet and was not connected to anything. It was just hanging straight down through to the bottom. Unless it was very loosely connected, it came straight up when I gently pulled on it, and there were no clamps or anything other than the end of an otherwise in-good-shape black hose, about an inch in diameter. It's connected to the top of the reservoir, right next to the cap, with no clamps, just connected.

Should this be connected to something? I haven't been able to find anything on this. The closest I can tell so far is that it may be what's called the fill hose and connects to the radiator, but I haven't gone back out to look and see if there is something connected to where the fill hose connects. It is at this point I feel unsure. I really don't know what that hose is or if it should go anywhere. My other theory is that it's there to release pressure from the reservoir, if there is any at all, since it doesn't seem like there would be any coolant traveling through that hose since it is at the very top of the reservoir, about several inches higher than the "FULL" mark on the reservoir.

If anyone can offer any advice at all, I would greatly appreciate it. As of now, I have a new heater core ready to replace the one in my Blazer with, a basic set of socket and screwdriver tools, a gallon Prestone prediluted 50/50 orange coolant, the proper Haynes manual, and the drive to fix this problem myself! I trust and love my mechanic, but I just can't pay $600-800 at the moment.

Thank you again in advance.

 

Do a search on "replace heater core", there are a lot of good tips and some very helpful photos. The job is a PITA. I did my own after I got an estimate for $1000. It will likely take you several days.

 

The hose is just the overflow hose and is supposed to be exactly as you described. No problem at all. Heater core will take time and will look horrible on day two. Don't worry it will all go back together. I don't know what size all the small fasteners are but its a big help to have a screw driver handle that's 1/4 drive head on it for whatever socket it is for those.
There are some larger round headed fasteners along the seem under the steering column that run the entire way across the dash horizontal. They are torx, 15 or 20 maybe bigger. Not sure.
Good luck, just tedious.

 

Just to be sure here:
there is a hose from the top of the radiator, just below the radiator cap that connects to the bottom of the reservoir tank...on top of passenger side front wheel. Then there is a hose from near the reservoir tank cap that just goes down toward the ground...this is the overflow hose.

And yes you have a heater core leaking. DO NOT put any stop leak junk in the coolant....it might plug the heater core and the likely the radiator as well.

As stated above....it is a tedious job, nothing difficult, just lots of screws to keep track of where they come from and where they go back.
Use plastic bags for screws and lable the bags.

The oily film will just get worse and you will end-up with coolant dripping onto the floor mat or carpet and requires even more work to get out.

Temp fix is to remove the heater hoses at the heater core and put a small piece of copper tubing between the heater hoses. You of course will no longer have any heat, but avoids the dripping coolant mess.

Good luck.

 

Thank you so much for all of your help, everyone. Weather permitting, I think I may continue this job Saturday. Even driving with the windows down isn't helping get rid of the fumes. Hopefully I won't die from the fumes before it's fixed!

 

I am a very experienced mechanic of 20 years and although it is not a very hard job to replace heater core, I must warn you, it took me 8 hours to do mine using my GM service manual and the entire dash coming out Is the easiest way to get to the big black plastic module for which the core is buried deep inside

If you could not locate the drain petcock for the radiator I suggest you seek help when attempting this task of the heater core as I remember what it was like when I was starting out as a mechanic.

Don't let this deter you however from working on blazers, they require lots of tlc. I just don't want to have you get into a scenario where you don't want to finish and give up all together on your new found mechanical passion, the heater core is not the first thing I would have wanted to start out doing on a car.

If you have no one to help you and you are a resourceful gent then I say Godspeed and have patience for it will be needed.

Good luck