Good evening, I am the proud new owner of a 1994 Volvo 850 wagon, non-turbo 5cyl. 2.4litre, automatic. This car from all evidence given to me has been very well maintained since new. I have been working on cars all my adult life and love everything about cars from theory of operation to hands on knuckle bleeding late nights in the driveway, on rickety jacks and flashlights. My question, very slight sweet smell in vehicle when heat on. I pulled lower dash trim and pulled back carpet, absolutely no external leak from heater box and floor all around box dry, no evidence of past leaks. The heater pipes are black in color and look to be made from steel, perfect condition, literally look brand new. I have read a lot of forums and found that there seems to be a lot of trouble with the fitment of pipes when replacing heater core. If these pipes are good and not corroded as the steel pipes do can they be reused with new O-rings? I also noticed that the small hose going to top of coolant reservoir tank on passengers side inner fender well was tight but able to spin by hand. I have the new heater core in hand with new weather strip package and new O-rings. I need to remove heater from pipes and box to physically see if there are any internal leaks in box, my thought is just replace core while in the box, does anyone agree? I would greatly appreciate anyone's opinion. thanks in advance..

 

It's a leaking heater core. I've seen several where the leaking coolant gunks up on the fins instead of showing by leaking into the cabin.

 

Hey guys, well the removal for inspection went well. The heater core was leaking ever so slightly. I have pictures but being new to forum and unfamiliar with how to download pictures, eventually they will be posted. The heater core was much easier then expected, didn't lose a drop of coolant in car. Proper prep work makes a world of difference. Total time about 1.5 hours. Zero smell of coolant in car when heat turned on now! Yeah

 

Nicely done! I used a big black trash bag when I replaced mine last fall, not a drop of antifreeze in the cabin either.

 

Yes, Big Black Trash Bag, it worked like a charm. the heater core was not leaking enough to leave residue in any area of the heater box, and because we planned before just diving in coolant loss was minimal. I used two needle nose vise-grips with cardboard to keep heater hoses under hood from getting damaged while crimping them enough to allow replacement with no loss except for the coolant in the heater core itself. with a little preplanning and finesse this was a great afternoon project with my son, who drives a really sweet S40.

 

Nice. I need to do the heater core in my 850 as well. To post pics, click on the "go advanced" on the message create,then find the file attachment which lets to upload from your PC.

 

i am trying to attach pictures, thanks for the help. Notice how minor leak actually is and I was still able to smell a very sweet smell when fan on.

 

That's almost exactly how mine looked when I replaced it. Oddly enough, the smell wasn't the main reason I knew it was failing, it was the strange condensation I was getting on my windows that was slimey and a hassle to wipe off.