Hi, First time poster here. Been around along time, got alot of useful information here over the years but first time I have really needed help.



My problem, my car is getting hot and I am running out of options. My problem has been happening for a little over a month now. I have a 2001 Chevy Blazer , 4.3 L V6 4X4

Things I have done so far is

Replaced Fuel Pump, Water pump, Thermostat x 2, & radiator cap
I have also done a complete tune up, radiator flush and gotten bubbles out.

My vehicle is not showing any signs of a head gasket problem.

One other thing I have done in the last 2 months is we had to have the heater core bypassed because it was leaking and I had a new baby coming. I didn't think twice about bypassing it because I hardly ever need it here in South Texas.

Could bypassing the heater core be my problem? Is the heater core needed too help cool the vehicle?

Any help is greatly appreciated. Out of options, and alot of money spent so far and problem is not fixed


Thanks alot!!!

 

How hot is it running? did you replace the temp sensor?

 

Hi thanks for your reply, I have only let it get to 235 but It would get hotter if I let it.

No temp sensor replacement here. What signs would the sensor do if it needed to be replaced?

 

For one, if your temp sensor is bad your car might not actually be getting as hot as you think it is. Your temp sensor also controls when the cooling fan turns on in models with electric fans. (don't know if yours has this)

It is a very simple replacement and they generally only cost around $20.

I would also check for possible collapsing hoses. Especially the upper and lower radiator hoses. These hoses should be stiff and not easy to squeeze.
If they are soft then they can start to collapse while the engine is running when the coolant heats up and restrict the flow. The upper hose is the most common for overheating on this truck.

If all that fails then start pulling coolant hoses and look for corrosion inside the fittings. Especially if the vehicle has ever had dexcool in it. (if it does then I'd recommend removing it and using standard coolant)
If there is a lot of corrosion, usually a white buildup. Then you need to do an acid flush of the system.

The dexcool is notorious for this buildup since if you get air in the system it tends to crystallize and start clogging things up.

As for your bypass of the heater core. That should not have the effect of making the engine overheat.

 

The topic of dexcool has been discussed to death in another thread so I will not counter the opinions reflected above in this thread.

Is the cooling system actually boiling over or showing other signs that it is as hot as your temperature gauge is showing it at? If it is, then I would bet that there is still air in the system. These engines can be quite stubborn and sometimes require a vacuum be pulled on the cooling system to get all of the air out.

I do not believe that any s-series vehicles came with the electro-viscous fan clutch or an electric fan as standard.

 

my system has boiled over if I let it get to hot. My husband did another try at getting air out last night. He took it for another drive and said it was running a little cooler than it has been but he didn't drive that long i.e stop in go traffic.

He said turning off the AC once it gets close to 220 helped and the temp dropped back to 212. That is something new. Turning off the AC hasn't been helping. Maybe there is still Air in the Radiator. Hoping we are finding the problem. Would flushing the radiator with Acid help?

Where would I get it vacuumed at to get the air out?

Thanks for all the help!

 

I bet there is still air in the block. The radiator should push the air that it has in it out through the radiator cap as the system pressure rises. Air in the block can cause a restriction or blockage of flow to certain areas in the block. This is the bad thing.

You do not need to drive the truck to get the air out. The best luck I have had at bleeding the cooling system on these trucks is to do it with the front of the truck elevated as far as safely possible with the passenger side (side with the radiator cap on it) slightly higher than the driver side. This will put the radiator cap at the highest point and give the best possible potential to get the air out.

As far as pulling a vacuum on the system, I have a radiator cap that I have modified so it seals completely without releasing vacuum pressure (such as they do in stock form) as well as putting a hose barb onto it. I then have a vacuum gauge, vent valve, and check valve in the line before a hand vacuum pump. I think it is at my dad's though since that is the last place I used it.

 

I have a 2001 blazer that had a similar problem about 4 years ago, (i think the milage at the time was about 75000). The problem back then was the the lower intake manifold gaskets were in poor condition. I had a mechanic change them and it worked great for about 4 years.
That being said, recently I have had the same problem again ( about 150000 miles), and this time I changed out the intake manifold gaskets, and, again they were in pretty bad shape.
My problem now is that after doing all of that, changing the thermostat, and replacing the radiator cap and upper radiator hose, it still is overheating.

 

I am going to add this about the dexcool mixing problems...which i originally had issues with after trying to cure my engine running Hot..after pulling not only the intake and seeing the coolant passages clogged , i pulled the heads off too and the coolant passages were slam packed up with sludge also....This is just something to keep in mind.