Replace heater core trick

volvomadness · Post by **volvomadness** » 25 Mar 2014, 20:55

Have replaced a good number of heater cores v70, s70, 850's

One trick I learned to avoid all that nasty coolant in the car without clamping off lines is to vacuum out the reservoir completely. I use a wet vac, tape a smaller extension to the hose, stick it in the reservoir and suck out all the coolant. Only a tiny amount of coolant remains when I remove the heater core.

Post by **erikv11** » 25 Mar 2014, 21:04

Great tip. Compressed air works great too (keep the psi down!), you can blow it into a bag then you don't have to clean out the shop vac.

Post by **rspi** » 25 Mar 2014, 22:08

Deleted

volvomadness · Post by **volvomadness** » 25 Mar 2014, 22:33

every good shop should have a wet-vac. Its was just a tip!

instarx · Post by **instarx** » 26 Mar 2014, 03:53

My shop vac is a turkey baster.

Post by **kahl** » 26 Mar 2014, 04:21

Would you have to get the coolant level below the inlet pipes on the firewall?

Post by **abscate** » 26 Mar 2014, 23:17

I had blown so much coolant into the carpets another gallon didn't matter...

Post by **cn90** » 27 Mar 2014, 09:12

If one decides to replace the coolant as part of the heater core job, then there is an easy way to deal with this:

1. Drain the coolant (d/c the lower rad hose ---> radiator).
Unless your radiator is new, you don't want to open the petcock, which can break!

2. Loosely re-attach the lower rad hose.

3. Add water to the reservoir.

4. Run the engine for 2-3 min just to circulate the fluid through the system.

Repeat this cycle a few times with water refill between cycles.
After a few cycles, the system should be 95% water and 5% coolant.

So when you replace the heater core, try to catch any spilled fluid so the carpet is not wet. Even with a spill, some water will soon evaporate anyway.

Once you are done, remember the system is mostly water, so calculate appropriate amount of pure coolant to add. Do not use premixed 50-50 type in this situation.

Post by **rspi** » 27 Mar 2014, 09:18

My experience is, when you drain the radiator you get about 1 gallon of coolant out. So if you have washed the system out with water, you can drain the rad, measure it, and add back full strength coolant, about a gallon. When washing the system out with water, you should do it with a few gallons of distilled water, not tap water.