Anti-freeze smell in cabin

Ananda

Ananda

True Classic
when I turn the heater on in my 86 non AC X1/9 it smells bad. Based on things I have read here I believe it is anti-freeze. Now I can’t find the threads that I read before.
Can someone either point me in the direction of old threads talking about this or give me a clue about how to find the problem and hopefully fix it?
As always, I am extremely grateful for the help and info of this forum.
 
Smells bad.

Does it smell sweet? If it smells sweet then it is likely a coolant leak at one of the connections, the heater core or even the rigid pipes in the tunnel leaking.

The heater core requires pulling the HVAC system out to replace which would be easier if you also removed the instrument panel.

Smells bad could alternatively be mouse or some other infestation sitting on top of the hot heater core giving you the fine odor of mouse droppings/urine cooked at 190 degrees. Or if you have AC it could be a stopped up drain holding water and growing mold or some combination of all of these. On my ‘85 it still smells like olive tree leaves from when it was parked for years under one and there are still leaves on top of the heater core.

Either way there is some work ahead of you.
 
Also, check the heater control valve - this is a typical point where leaks develop (at least in my experience). Easy to check - I had a passenger let me know that mine was leaking. He kept complaining of hot coolant dripping on his foot! haha..
 
I know on my 85 that the heater control valve gets very stiff once hot. I forced it off once and it started to leak. Luckily once cold again it quit and has not leaked since even though moved many times while not hot. I never move it once hot! Probably living on borrowed time.
 
Pretty sure it is anti-freeze smell, bad probably isn’t the best description but it does make me a bit ill. It happens pretty much as soon as the heater is switched on regardless of whether it is heated up or not. What Would be a good first step?
 
Anandastar said:
Pretty sure it is anti-freeze smell, bad probably isn’t the best description but it does make me a bit ill. It happens pretty much as soon as the heater is switched on regardless of whether it is heated up or not. What Would be a good first step?
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As noted above :) - look at the heater control valve. Easy to check. Located in the center of the car, on the passenger side - just to the left of the fuse panel. Keep us posted!

upload_2018-1-16_14-42-54.png
 
Anandastar said:
Pretty sure it is anti-freeze smell, bad probably isn’t the best description but it does make me a bit ill. It happens pretty much as soon as the heater is switched on regardless of whether it is heated up or not. What Would be a good first step?
Click to expand...

When you write "switched on" do you mean engaging the heater blower motor at position 1 or 2, or do you mean sliding the hot-cold lever from full-cold at the right toward full-hot on the left?

Go to a local chain auto parts store with tool loans, pick up the big cooling system pressure test kit. Pressurize the system to approx. 10 lbs (don't go crazy, the system is only designed to operate to about 11 psi and then the rad cap relief pops), and go spelunking in the passenger footwell with a good flashlight and an inspection mirror. From the footwell you'll be able to eyeball
the prime suspect, ​
the heater control valve, while working the hot-cold lever from side to side. Hopefully you'll find the leak in the valve or the hose connections. If not, then the alternatives (heater core connections or heater core itself leaking) are much more painful repairs.
 
Good question, I believe it is moving the heater control slider from the right “off” position to the left “on” position that initiates the smell. Will double check that. I think the blower just makes it more or less intense depending on it's position.
Probably not related but the blower tends to screech but can usually be quieted with some fiddling.
 
screeching heater fans are fairly typical for Fiat heaters. Also look for water stains on the carpet under the heater box and the valve.
 
Now I’m not so sure now. After a run on the freeway I got home and experimented a bit with the heater and blower controls and couldn’t really tell much difference either way and the smell wasn’t as strong. Could it be that it changes depending on whether the car is warmed up or not?
 
Anandastar said:
Now I’m not so sure now. After a run on the freeway I got home and experimented a bit with the heater and blower controls and couldn’t really tell much difference either way and the smell wasn’t as strong. Could it be that it changes depending on whether the car is warmed up or not?
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Hot antifreeze like any hot liquid will have more smell due to vapor.

A cold engine will not have a lot of system pressure until the coolant heats up and expands....maybe your leak needs a higher internal pressure to "spring."

The heater circuit is integral to the engine's water jacket, so even if the coolant is not hot enough to open the thermostat and circulate to the rad, if the heater control valve is open, you have coolant circulation from the right rear corner of the cyl head, up to the heater core, then back to the coolant pipe along the back of the engine that feeds into the water pump.
 
I haven’t seen any signs of leaking liquid anywhere under there that I could see from the foot well.
I haven’t rented the coolant pressure test yet but wouldn’t I see some evidence if it’s been leaking for a while? This leads me to believe that the leak is inside the heater core itself, Does this make sense? Especially because The smell blows in the vents
 
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More likely leaking from the inlet/outlet ports than the core itself, tho a broken core is not out of the questions. To that end, thought I'd post a couple of phots for reference. This is from a 1976 non-AC car. Good luck -Darin
IMG_20160726_210254.jpg IMG_20160726_210356.jpg
 
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