So here I am again, I just finished a head rebuild on my 2006 S40 Which turned out great. After Driving it for a couple miles I noticed my carpets were full of coolant.
I don't have money or time to replace heater core right now. My question is can I bypass the heater core? If so do I just connect the upper heater hose in the engine bay to the lower one? Any help is appreciated. Thanks.

 

You will find that the hoses have a coupling to attach to the heater core. To do this right, you are going to have to remove both hoses and attach a bulk bypass hose. There is no issue with bypassing the heater core since the coolant flows through it back to the engine.

 

Awesome! Thanks for the quick response!

 

Then again, in the time to fashion a heater core bypass, you could probably repair the heater core issue. My suggestion is to take the time to open up the side of the console to take a look - its quite possible that during your head repair you dislodged or tore the hose from the engine to/from the heater core and simply need to replace the o-rings or hose - some have even used clamps to retain the hose more securely - I doubt if the core would suddenly pop open coincidentally to your recent work.

 

Check the o-rings. Probably not the heater core itself.

 

I did the bypass for the meanwhile, I have not had a chance to dig into the side console. I actually bought the vehicle and it had a small leak on the lower heater hose, which I took too pep-boys to replace ( huge mistake ). A week after it was replaced I blew my head gasket for failure to check the coolant levels. I figured the heater core was the problem all along, or pep-boys newbie wrenchers broke the inlet trying to remove the lower heater hose. Either way, I will be checking it this weekend. Hopefully its an easy fix. Thank you all for the response

 

Four Seasons and Everco make manual shut off valves which allow you to easily turn off water flow and on when you fix the heater core. Most parts stores have them and pretty cheap. MySwedishParts.com