roller1150

So, I have 93 Prelude SI with the H23. It has 199,9XX miles on it right now. It is cold and I have decided to start using the heater, but the odor is unbearable...My A/C works perfect though with no odor and is ice cold!

PROBLEM:

When I switch the heater control to heat, I can smell a foul exhaust/coolant odor. I don't even have to have a fan on. Happens when the car is cold (right upon start up) or warm. It is so bad it is giving me headaches...

CURRENT SOLUTION TO GET RID OF SMELL:

Switch the temp controls to the cool mode, which pulls the heater door to shut via the cable, thus eliminating the foul odor.

KNOWN SOLUTIONS FROM EXPERIENCES:

?

Thanks for your assistance in advance. I have searched this issue and it looks as if a heater core replacement is necessary, but before I start tearing down the dash - is it possible a heater hose or something simple can be replaced?

aaron7

Not sure of the exhaust part but if you have coolant smell with the heat your heater core needs to be replaced. Usually you'll get some slimy buildup on the passenger side of the windshield.

The dash has to come out to do the job... it's costly. I need to do mine too but for now I wear a coat when I'm driving!

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jsmooney

How long has it been since a coolant flush? Just an idea....

Is there small leak in the valve or hose on the firewall that lets in the exhaust smell?

Good luck

jkoni426

bump for having the same problem...

Did you ever get it fixed? What was the solution?

I really hope I don't need to replace the heater core...

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minilogoguy18

Seems to me that your smelling whats under the hood, the fan draws air from that cowl at the bottom of the windshield, hows that rubber seal look around it? Still check the water valve on the firewall and the hoses going to it.

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roller1150

Thanks everyone for your questions and answers. I have simply been keeping my temp setting on cold and dealing with cold temps in my car. It totally sucks, but luckily I have another cool vehicle I can drive on a daily basis!

aaron7 - no slimy buildup on the passenger side of the windshield.
jsmooney - coolant flush was done less than a year ago and it is perfectly green as it should be. Definitely smells of exhaust and I notice at night I can visually see some smoke coming from the engine bay area when my headlights are on. There must be a leak in the heating system that is letting in the smoke from the exhaust. I know my car leaks oil, but it does not smell like oil (I wish it did - as I know this smell can't be good for me).

Also, it smells bad when the car is bone cold. I will check:

1 - cowl at the bottom of the windshield rubber seal
2 - water valve on the firewall and the hoses going to it

Can I see the water valve on the firewall from the outside of the car?

Thanks everyone for your input. Hopefully I can tackle this issue by this weekend and hopefully it is something simple!

pbarb

It's never happened in my lude, but my Chevy had a broken heater core. It was behind the dashboard on the passenger side. Coolant would leak down the firewall and absorb into the carpet and floor sponge. It was a mess. Check the carpet in the passenger side for moisture. Better yet, pull it back and check underneath. Last I checked it is a big job to replace a heater core.