Hello there!

I've got a 2001 Blazer 4.3 4x4 with 126k and last week on the highway I noticed the temperature gauge suddenly maxed out and a white plume of smoke started trailing behind me. Thinking it may have been the thermostat getting stuck I turned the heat on full blast, but I was surprised by cold air. I pulled over on the side of the highway and got a tow back to my house.

I've done a little research and poked about the car since then. Replaced the thermostat, which did nothing, besides cause the leak to worsen. I realized that I had bought the car with green coolant in it, and am unaware of a flush done on the vehicle, I began to assume that dexcool sludge may have clogged up the heater core lines. However, the leak was coming from the front of the engine, and there was little to no sludge in the radiator. After sitting for a couple days there is a puddle beneath it. I can see coolant dripping from the water pump gasket. There is also moisture around all of the hoses coming off of the pump itself. This leads me to believe the water pump needs replacing? Or would just the gasket do? I also noticed the lower intake manifold gaskets are pretty well shot, and figure if I'm going to be delving into this, I might as well replace those too.

Problems:
-Overheating
-No Heat
-Constant Leaking from water pump gasket (as far as I can tell, moisture around all coolant lines coming from pump)
-Lower intake manifold gaskets are showing signs of leaking

I'm prepared to replace the water pump/gasket and the intake manifold gaskets, as well as do a comprehensive flush of the coolant system, and a separate flush of the heater core (hook garden hose to return line and run low pressure water through it to reverse flush it). As well as burping it with the passenger side jacked up and all that jazz.

Do you guys think this is a good plan of action given the problems that I have? Are there any other things I should do while I've got it all taken apart? I don't have any record of maintenance at all, now would probably be a good time to do a tune up as well, you think? I'm just wanting to make as few trips to the parts store as possible, hahaha.

 

I think you've got your bases covered...that's exactly where I'd start. While you have everything apart, always a good opportunity to inspect the distributor cap and rotor; maybe replace pugs and wires. The distributor is prone to cracking where the cap screws thread into the housing (it's all plastic). Not a lot you can do, except be prepared with zip ties, duct tape and hose clamps until you decide to replace the whole thing.

There are some good how-to's in the DIY section for most of this.

 

I have a 1999 Blazer 4.3. I can tell you from experience. The dexcool really screwed up everything. I bought it and someone started using the green stuff. I have replaced the heater core, all hoses, thermostat, radiator, oil lines, valve cover gaskets, intake manifold gaskets, water pump, clutch fan, serpintine belt and new coolant. She runs great with no leaking issues. I changed one thing then still had a problem. I did everything myself. Parts were about $500.00 from local autozone. I honestly would do everything and you will not have anymore headaches. Good luck Bernie11

 

Looks like you actually searched the forum and read a lot of messages about similar problems. There are a couple of things you can do to further analyze the issue. Since you reported smoke out the tail pipe it can either be a head gasket or the intake gasket leaking into the injection port. A compression test would indicate whether the head gasket is leaking...compression good head gasket good and LIM gasket bad. A pressure test of the cooling system could help pinpoint where the LIM is leaking. Sometimes using a stethoscope you can hear a leak even if you can't see it. I'm sure you've seen where the LIM is a very common issue on the 4.3l motors and replacing it is a good idea. It's real easy to change the water pump while doing the LIM and the parts are cheap. I've actually had better luck with rebuilt OEM water pumps than new cheapies....mainly with the mounting surface and gaskets.

 

Sounds like you got it figured out. The fun part is tearing it apart!

 

Alright, been busy the past couple of days with work and moving into a new apartment. I've gotten everything ripped out down to the water pump, going to drain the system then tear out the pump. While taking it apart to this point, I've noticed the LIM gaskets are still good, there's no leaks coming from around either of the manifolds. I've decided against replacing those now (funds are tight from the move, ideally I won't need to replace them.)

I got the new water pump and picked up a prestone backflush kit as per recommended in a couple posts I've seen on here. I assume this should take care of my problems. And if I find that the heater core is the problem, I'm just going to bypass it until inspection time comes in November to give me a little bit of a buffer.

Thank you for all of your responses! I will update when all is said and done.

 

check the felpro gaskets.... people are sayin its a top knotch gaskettt.... and for 95 bucks you can get the intakes, valve cover gaskets, exhaust manifold gaskets and throttle body gaskets... add another 10 and get new bolts

 

this link may be a help to your intake problem https://www.youtube.com/watch?v=WVTFRgw57M0