"Burnt" smell coming from under the hood

W

Wuster

Member
:
Whitewater Pearl Mazda5 Touring
So back in June I posted a thread about how I had smoke coming out of the back of the Mazda5 when I was climbing through the mountains of SW PA in 3rd gear.

Well, I took the car back to the dealership and they couldn't find anything wrong, blah, blah, blah...

Well now it has been super hot in the DC area and I'm noticing a "burnt" smell coming from under the hood after any 30+ minute drive. But if I let the car sit for an hour or so, it goes away.

Anyone else smelling a "burnt" smell under the hood? I'm wondering if it is the transmission fluid...

BTW - Is there a transmission cooler for the Mazda5?
 
Can you describe the smell? Oil smells different from coolant which smells different than brakes which smell different from transmission etc. It is an experience thing more than anything, next time you detect the smell stop at the nearest mechanic, any one should do, and ask them what they think.
 
I'm not sure if this would apply to your 5 specifically but when they were first released, Mazda instigated a massive recall. We had to pull all of our 5's off the sales lot until inspected and/or repaired by our service department. We even had to call all customers who had purchased before the recall to return their cars to our dealership for repairs to be made (the cars were returned to the customers after repair, we didn't have to buy the cars back permanently). I'm not 100% clear on the specifics of the recall but I remember it having something to do with something overheating (I think it was the exhaust) and melting certain components (mainly in the undercarriage and body). If I were you, I would triple check to see if your 5 was part of that recall/inspection and make sure that the proper actions were taken.
 
Yeah, mine is one of the early ones that was recalled. It's got an extra sticker on the firewall with the recall repair date.

I don't think it's the coolant. Coolant has a slight sweet smell to it. I'll have sniff around under the hood after my next long drive.
 
Make sure it's not an electrical burnt smell either. But they're right. There are different kind of smells depending on the culprit. The kind of sweet smell from the coolant, burnt oil smell, gas smell, burnt tire smell, electrical short smell, etc. If you turn the car on and after it sits idle does it smell or only after driving it for a while? Did you actually lift the hood and sniff around? Can you smell it from inside the vehicle or only from the engine compartment?
 
The smell only happens after a 30 min + drive. I've smell it from the outside of the car and it's the strongest under the hood.

Of course this weekend, I didn't smell it after driving the car. I've checked all the fluid levels and they all look good.

It doesn't smell like coolant, oil, or tires. It almost smells like the clutch, but I have an automatic. I'm leaning towards the transmission fluid, but it's nice and clear with a hint of redness.

Good thing the car came with a 4yr/50k mile warranty....
 
Maybe it's the brakes just getting broken in. I drive cars with less than 50 miles on them every day and if you get on them hard enough, they sure can smell. It's almost like a burnt clutch smell but not quite the same. The smell doesn't linger very long after you stop the car and shut it off but if you come to a stop and open your door right away you can get a pretty good whiff.

Just my $0.02
 
Wuster said:
The smell only happens after a 30 min + drive. I've smell it from the outside of the car and it's the strongest under the hood.

Of course this weekend, I didn't smell it after driving the car. I've checked all the fluid levels and they all look good.

It doesn't smell like coolant, oil, or tires. It almost smells like the clutch, but I have an automatic. I'm leaning towards the transmission fluid, but it's nice and clear with a hint of redness.

Good thing the car came with a 4yr/50k mile warranty....
Click to expand...
Did the dealer do a compression test on the car? If not or if you're unsure, ask them to do one. It doesnt take that long and make sure that they tell you what your ratios were. I believe that the ratio's should be between 180-190 so make sure none of them are below that. When you see the smoke, it's probably under load only.. ie acceleration, going uphill, etc. So have them do that and then think it over again. I'm sure you've already checked for fluid leaks in the engine bay. So there may not be anything residual burning off anywhere if you dont see any small wet spots.
 
No, no compression testing on the car. It's only got about 5k miles on it and my seat of the pants dyano has not detected any lost in acceleration performance.

I'm just going to keep driving it and keep an eye on the fluids. It's one of those "can't reproduce" problem according to the dealer.

Here is a question, is it possible to get the transmission so hot that it boils the transmission fluid? And if so, what happends to the fluid? (e.g., if the transmission is a closed system and the fluid starts to boil, in theory there needs to be some sort of vent to reduce the pressure created by the boiling fluid or the system will burst at the weakest point.)
 
No, I havent heard of that kind of thing happening in any of the Protege's. Not sure that it's even possible. If there was some sort of "boiling" over, there should've been a leak somewhere, if it WERE possible. If there was a problem with the tranny at all, you'd probably have some sort of problem with the car's drivablility. It'd be more noticable and you'd notice a problem when the car automatically changes gears. The color & amount of transmission fluid is also a good indicator of problems, but you said it was clear. I dont think you said anything about a "burnt" smell to it.

I guess just wait to see what happens for the next week or two. Could just be one of those freakish things that have no explanation. If not, take it back to the shop and tell them to give you a loaner for a few days while they look it over. Rome wasn't built in one day and you can't always find the problem with a Protege in one either. lol
 
Well, I've narrowed it down to the transmission fluid. Took a long drive this past weekend and sniffed just about every fluid reservior aftwards and the transmission fluid has a burnt smell to it.

But the weird part is that the smell goes away after about an hour of sitting. I came back out to the garage later in the day and check the transmission fluid again, and no smell.

Any ideas why?
 
it could be coming from your transmission overflow hose. If I remember the location properly it is near the firewall and is a small hose that just dead ends in the air in a vertical position.
When your trany gets to hot, (mountains and long drives) it will 'boil over' and spill out the overflow and spill onto your hot engine creating your smell. How to fix it is not my area but it could be as simple as too much fluid in the reservoir or all the way to new tranny time.
Exact thing happened to me in my Suzuki Sidekick and I eventually got a new tranny. So you might want to find a good transmission shop to look at it. Good Luck.
 
first of all find out what trany fluid they use. cause sythetic will be a lil darker and WILL have a burnt smell that normal for sythetic tranny fluid. just a lil info
 
Amarek said:
it could be coming from your transmission overflow hose. If I remember the location properly it is near the firewall and is a small hose that just dead ends in the air in a vertical position.
When your trany gets to hot, (mountains and long drives) it will 'boil over' and spill out the overflow and spill onto your hot engine creating your smell. How to fix it is not my area but it could be as simple as too much fluid in the reservoir or all the way to new tranny time.
Exact thing happened to me in my Suzuki Sidekick and I eventually got a new tranny. So you might want to find a good transmission shop to look at it. Good Luck.
Click to expand...

Interesting... i was wondering if the Mazda5 transmission was a closed system or had a vent on it.

I'll look for it.

Thanks!
 
Please log in or register to reply here.

Similar threads

T
Worried about piston rings...
2
Replies
25
Views
6K
theblooms
theblooms
O
Mazda5 Transmission issues
Replies
4
Views
3K
OrganicRobo
O
S
TCM failed, replacement still throwing codes (2010 Mazda5)
Replies
1
Views
657
edmaz
E

Latest posts

Back