Hello everyone,

Please forgive my lack of tenure, I just bought my first Honda in March. It's a 97 Accord 2.7 EX. I've put a lot of time and love into this car, as I tried to find a car that was worth maintaining within my meager budget. So far I've replaced break pads and rotors all around, upper and lower ball joints on the front, tie rod ends, sway bar end links, fuel filter, and spark plugs.

Yesterday evening, while running the heat I smelled coolant in the cab(which almost made me want to throw up because my last car was scrapped because of a head gasket) and started investigating. The smell was also profound in the engine compartment. There were no leaks that I could visibly detect on the hoses leading to the heater core. I did notice my heat is not very hot, which would indicate a partially blocked heater core. However, the smell is prevalent in the engine compartment as well (the smell in general is only after full warm up and coolant cycling). I live in ND BTW, and not having heat/defrost capability is not an option.

My fear is the heater core is leaking, because the repair is beyond my budget and I don't have faith I can rip apart the entire dash without help. My hope is the smell could be due to heater core blockage, and a back flush might cure this.

Does anyone with knowledge here willing to share their advice? It would be greatly appreciated!!

 

First off welcome to the new honda owner club, I myself am a new member too. What your describing to me sounds like low coolant level, so I would do what you can to rule out any leaks, borrowing a pressure tester from a parts store would prolly be a good idea, and at least point you a direction.

is it full of coolant?

if you think the heater core is clogged, I would just unhook it and run water thru it backwards, I've done this on several vehicles with good results. my old pickup had crappy heat for 3 or 4 years til I did that, now it'll cook your butt outta the cab.

you might also check and make sure the temp control valve is opening up all the way. I'm not a fan of the way they've got it set up on these 97's, Mine has rusted and won't go full hot or full cold. which kinda sucks here this week since we've gone from warm to chilly to warm the last few days.

I'm not sure where it's at on yours with the v6, but mine is down under the intake on the pass side firewall, if I want it full cold or hot I have to get a long screw driver out and push/pull it.

in the end if your smelling coolant cooking first priority for me would be to find the leak.

 

Thanks Hicksvilleshick. I'll dig around this weekend to try to find the leak, and just hope the core is okay. The coolant level seemed okay, but a little low. The rad was plump full when I checked it but the overflow had almost nothing in it. It seems like the smell is strongest by the firewall area in the engine compartment. Do you think I would smell coolant in the engine compartment if the core was leaking? I would think it would be strongest in the cab...

 

Are you sure the odor is coolant? Run the defrosters and see if the windshield gets any coolant coating. How many miles on you car?

 

If the odor is strongest on the firewall I'd be checking all those little hoses, we'll I'm assuming there isn't much difference between the i4 and v6. Wouldn't be a bad idea to get it up to operating temp and watch it idle and check for pinhole leaks in hoses. Might get the nose up in the air and get under it and look for seepage.

Even still I'd look to flush the heater core of your not getting much heat.

If the core were just leaking I doubt you would smell it. What we usually smell is the coolant cooking off something hot, which trends to indicate it is getting out of the system. I'm thinking your leak is firewall side from what you describe.

 

Definitely coolant, although I haven't noticed a coating on the inside glass; but that might be because I haven't been running the HVAC much. The car has 177k on it right now.

That's what I'll do this weekend, I'll jack it up and idle it until the smell returns. Hopefully I can find it this time. Unfortunately I don't have access to a hose at my apartment. I do have a shop nearby that will flush the system and backflush the core for like 100. Maybe do that...

 

Okay, thanks for the help everyone! I was driving around today running the heat full blast and no coolant smell at all. However, I couldn't get the temp up to where it starts to leak. I snapped a pic of the highest I could get the temp today (it was pretty chilly outside), and the coolant smell seemed to happen when it gets a little closer to the half way mark (it never goes up to half way.) The heat was working a little better today, and I think it has something to do with the fact I haven't ran the HVAC for the last 5 months because my AC doesn't work anymore.

Is it safe to assume my heater core is okay? Does this indicate the leak is confined to certain components, such as at and after the T-stat?

Again, thank you for your help with this. I really appreciate it!

 

Was the radiator still full after you ran the heater?

 

Yeah, still full. It's running cooler now than it did all summer and the fall thus far. I don't know if that has to do with me filling up the reservoir or what, but it's never overheated since I owned it and always held a consistent temp just below the halfway mark.

I'm still going to crawl under it tomorrow with a flashlight and look for residue, but it's going to be tough to find a leak if it suddenly doesn't want to leak anymore

 

Yeah makes for fun times.

I would monitor it a few days. make sure the level is staying where it should and call it good.

only thing I can think of to put off a smell outside of a leak is maybe old coolant trapped in the heater core, but I think thats reaching... I can't see it putting off a coolant smell, maybe old cabin filter smell but not coolant.

good luck and holler if you find something funkky. lol