03 MC LS 3400

So lately I been having to refil my coolant in my radiator almost every 3 days and then I'd have to bleed the system to regain heat in the cabin. So last night I decided to investigate a little further and see what's leaking....

I was surprised to find out I have 4 different spots it's leaking from,
1. Lower radiator hose has a hole in it
2. Upper radiator hose has a hole in it
3. The actual radiator has a hole in it in the front left area near the bottom.
4. #4 Is a mystery to me, I think it's the water pump but I might be wrong; it's leaking towards the back of where the serpentine belt is, close to the firewall.

I know the water pump is in the front of the belt not back so I'm curious if any one have a clue to what it might be, maybe heater core hose? I traced them and they're dry, otherwise I'm completely clueless on to what it might be.

Any of you guys wanna take a guess on what it might be?
If I get any suggestions it's greatly appreciated.

To add to it 2 weeks ago I replaced my bypass hose cause that too had a hole in but it's 100% fixed now.

 

My 02's leak near the firewall ended up being my heater core. On the way to the GM Nat's last year when I was getting gas I noticed coolant kept dripping onto the ground, low coolant light coming on. And well that was it, I could see and feel coolant, think there was a little weep hole the coolant leaked from on the firewall just below the heater hoses.

And I'm assuming you already know about the notorious coolant elbow leaks just above the water pump area.

 

Yea coolant elbow is sealed and tight

I'm trying to figure out the exact location of the heater core, thought it might be the connection for the hoses getting loose maybe?!?!

 

The heater core is inside behind the dash, glove compartment area. Look directly behind the Upper Intake manifold kind of low on the firewall you will see 2 heater hoses going into your firewall. That is all you will see from the engine bay. There is a small weep hole below them where the coolant will leak out if the core goes bad so the inside of the cabin does not get wet. If you reach down below the hoses and feel about and your hand gets wet from coolant, I bet that's your problem. Usually the hose connections won't get loose as they are the constant tension clamp type, not the screw type. Feel about, perhaps the exhaust manifold / down pipe has damaged a heater hose over the years and all you have is a bad hose back there.

If it is the heater core, like on mine to keep on getting down the road, I removed both hoses from the heater core and bought a couple clamps a short piece of pipe and connected the 2 hoses together to complete the coolant circulatory system. The heater core is now completely disconnected and with all the coolant drained from it I no longer leaked coolant. Topped of the overflow bottle, run the car for awhile, leave the system closed and it will suck coolant back into the radiator to top off the system as it cools off for about 30 min.. Refill the overflow to the proper level, bleed your system with the bleeder valve and you should be good to go again.

 

Yea it's NOT the heater core leaking... Now I'm completely clueless, wish I had a lift for this.

 

Well that is a big plus your heater core is not leaking, kind of a spendy repair. So the water pump has a weep hole at the base of it too, when the pump fails it will have water leaking from it's weep hole. can you get a light and see if that area below the pump is wet or feel about. If it is wet, dry it off as well as possible to eliminate the chance that it is blow back from when the car is moving. Start the engine and let run for a few minutes, shut off the engine and recheck to see if it is wet again in that area.

Found this 3800 series II image, may help some.

 

Hab, dont want to tell you this but it could be the head gasket/gaskets at the rear of motor. Had collant leaks and turned out to be a headgasket. Had to buy reman heads from cylinder heads international. $150 each. Collant had corroded the aluminum heads and ate through the head gasket into the combustion chamber. Fine now.Hope that is not your problem.

 

When you did the elbows...
Did you use the new aluminum ones or still using the plastic ones?

If you used the plastic ones...
over time... They actually begin to leak again at the bend... when there cold..the leak seals... Once it heats up the crack opens up and under pressure the coolant seeps out...

something to consider..