Rep Power: 0

Hi all,
2003 civic coupe auto. Hope this isnt too long.

I am getting a waft of hot coolant smell when I drive the car. Not perpetually, not strong, not the sweet coolant smell, just once in a while. It started when the weather got hot here a couple months ago. Its the last thing to get fixed on this car, and it drives me nuts because the car is perfect otherwise. I havent been able to find the issue yet. Its still happening even after I replaced the radiator.

• Head gasket/timing belt/water pump done last year
• Radiator replaced with Denso -Burped air out and all
• Radiator cap replaced with new OEM
• Car doesnt overheat-even with A/C on. never overheated since head gasket
• Not losing coolant/coolant is still clean green/no mixing with oil
• Reservoir not gaining coolant
• No leaks, pressure test was solid.
• Did the UV fluid and light test while the car was idling, no drips at all.
• Mostly smell it when stopped in traffic, and when I start the car (WTH??).
• Isnt worse with A/C on, Heat works fine.
• No smoke from tailpipe, engine runs great.
• Trans fluid was flushed with new non-honda ATF.
• Im not driving it hard, Im putt putting, 160k miles. Its my commuter car.
• No leaks inside the car by the condenser or its pipes
• I often smell it by the left rear of the motor.
• The Blocks drain plug isnt leaking
• Fans work as designed

My only wonder is when I replaced the radiator I didnt use genuine honda coolant. I used Prestone.
My mechanic told me it doesnt make a difference.
Because of reading this forum I dont believe that anymore, so I wonder.

Has anyone experienced this before?

 
Rep Power: 126

I was running prestone in my integra without any problems. I wouldn’t worry about that.

My only guess is there’s a leak somewhere and it’s pooling.

 
Rep Power: 0

Where could it leak where it doesnt show? When I replaced the radiator, in between the radiator and a/c radiator was dry.
Had the car jacked up to check behind the block where the water pipe goes into the back of the block, no leak there either.

Only other thing I saw was A/C condensed water dripping straight from the pipe on the exhaust. Im getting a replacement hose for that. But I havent had the A/C on for the past couple of days, and I havent seen anything dripping on that pipe. Still getting the smell.

 
Rep Power: 224

Maybe try cleaning everything really well? It will help you find a leak if there is one. Plus get rid of any residue that may still be around from the previous engine work.

I also use Prestone without issues.

 
Rep Power: 0

Engine is clean enough to lick off of. Made sure of that first because thats the first thing I thought of, maybe something is burning off from heat.
At least the parts I could reach without pulling the motor. Around the belts and pulleys is a little tight, but I dont see any caked up residue anywhere anymore.
Even under the intake manifold, I couldnt find any residue there to clean off.

Is the temp gauge supposed to be at 8pm, or in between 8 and 9pm? Mine is in between. Maybe the engine is running slightly hotter than normal and shouldnt.

 
Rep Power: 126

Your coolant temp is fine. What cleaner were you using?

 
Rep Power: 0

I was using brake clean then purple power to clean the motor off.
The smell is the same as before I cleaned it, so my cleaning did nothing. Im definitely missing something.

 
Rep Power: 367

check around under the intake, between engine and firewall? need to see from under

 
Rep Power: 0

So last night I tried something thinking it wouldnt work. I noticed new pink drops, thinking they could be from the top hose by the manifold.
I noticed the top hose was mounted far down the pipe. So I loosened the clamp and pushed the hose all the way up and reclamped it.
Today driving to and from work I only smelled a hint of anti freeze a couple times. But the weather is not as hot as it usually is.

But now there is antifreeze creeping out of the hose. Just a tad. This hasnt been this obvious before.

What do you guys think, new regular clamps, new oem clamps, or new hoses?
The clamps have beaten a groove into both hoses.
Maybe the clamps arent as strong as they used to be, or maybe the hose is too beat up inside to seal? These hoses arent swelling, they feel fine.

 
Rep Power: 222

Either new normal hose clamps, or new hose + clamps

 
Rep Power: 0

So it turned out to be the hoses were breaking down on the inside. Once I took the upper hose off the manifold pipe, some of it was melted to the pipe, which makes sense. Also the anti freeze was seeping out the threads.
Once I replaced the two hoses, no more smell. Makes sense why my new reservoir is lined with black stuff.
The system actually pulls coolant from the reservoir now after I worked the air out.

Replace your hoses people!

 
Rep Power: 367

glad you found the source!
fixing cars is always a check here, there, sometimes it is something you never even thought of, truly.

 
Rep Power: 0

Kinda bums me out that I didnt think of the hoses sooner. I made this much more complicated than it needed to be. Which happens with every repair Ive done to this car.

 
Rep Power: 367

it's normal for fixing cars, really...
imagine the guys with wires chewed by rodents? (yes, it's common in winter with warm cars parked...). They also find nests in the weirdest places under the hood... baked Mickey Mouse

 
Rep Power: 0

Hey I have the exact same problem with my 2003 Honda Civic. Can you please post a picture of the hoses i need to replace so i can show it to an auto shop?

 
Rep Power: 224

They replaced both radiator hoses from the looks of it.

 
Rep Power: 0

Its the two big hoses right in the front of the engine as soon as you open the hood. Just tell the mechanic the radiator hoses.

 
Rep Power: 222

Or get a mechanic that can tell a leaking hose from a non leaking hose