Hi All!
For the second time in 3 mounths my heater core puked coolant in the cabin. It was not fun to replace it the last time so I am not looking forward to doing it again... but it´s not very warm this time of year in sweden so I have no choise...
Before I replace it again, however, I like to know why it broke again so soon, so I can fix the real problem thats causing the leaks...

What are your thoughts of why ithappened so soon again?
I use regular glycole antifreeze (blue), flushed out the dexcool 2 years ago.
Messured the voltage in the coolant but it was less then 0.01V so I don´t think that is the problem.
A day before it started dripping the SES light went on and I think it alarms about the O2 sensor, Bank1. It did this the last time the core went bad so now I wonder if there can be a relation? A leak in the engine?

Regards,
Freddy

 

I would do a compression test on bank 1 and a leak down test of the cooling system. It sounds like either a bad head gasket or a cracked head or internal passage in block???

Also when you do compression test check the plugs for signs of water in the cylinder.

 

Hi again,
I talked to my shop that use to do the tune up, and he said it could be a leak in the head or its gasket, and the quickest and easiest way to chek that is to do a "Block Test", that is messure the CO in the coolant to see if exhaust leaks into it. Will do it tomorrow.
If I find none I think I will just flush the system and replace the radiator cap and then install the new heater core.
If there is CO in the coolant I don´t know what to do. Think it´s a to big job for me to lift the head myself and to expensive to let the shop do it... kinda cath 22...
And I can´t run it with a leak in a top, that will for sure be expensive when a cylinder is filled with coolant and will tryto compress it...

/Freddy

 

Did the test today, no sign of CO in the coolant
So I´ll try to flush the system again and put in the new core. Then will we see how long it lasts...

//F

 

Man I feel sorry for you if you have to replace your core for a third time. I just replaced mine and it took me all day! Only good thing that comes out of it is this time you know how to do it and it will go by faster. Good luck!

 

Thanx, but looking at it from the bright side: I now do it in 3.5 hours ´coz I now know how to do it!If this keeps on I´ll be an expert soon!

It´s good to feel the heat again!
Now I will check voltage in coolant weekley so there is no electrolyzis and try to see if the coolant is good... Don´t know what else to do to asure the new core does not start leaking again.

/Freddy

 

You may want to replace your radiator cap. I understand the stock cap will cease to function around 75K and not allow expansion into the overflow tank. Result is the presure goes for the weakest part of the system, The heater core. $7 is cheap for piece of mind.

 

I had this problem also. some electricity was passing through the heater core and sparking to ground. this time put a ground wire on your heater core. see if that helps

 

I will get a new cap. But I´m not sure of the grounding, will have to think about it and check for voltage and possible sparks to...


//Freddy

 

The only problem with your theory is that when rad caps go bad they do not hold pressure they leakresulting in lower pressure in your cooling system which lowers the boiling point of your cooling system. It does not add pressure to the cooling system. New stant 10230 rad cap holds 16 psi worn out stock gm rad cap holds 4 psi if your lucky.