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-   -   Burning / grinding metal smell when driving (https://maxima.org/forums/4th-generation-maxima-1995-1999/703363-burning-grinding-metal-smell-when-driving.html)

Shrout1 01-08-2019 02:21 PM

Burning / grinding metal smell when driving
 
So I noticed that it smells like someone grinding metal when I drove home last night. It persisted today. Spent a fair amount of time hosing off the car last night to test the trunk for leaks, but never really got the front end wet. Did test the sunroof drains quite thoroughly.
  • The metal smell only happens when moving (clutch? It's a 5 speed)
  • The car is behaving normally
    • Brakes normally
    • Shifts normally
      • I don't feel any clutch drag
      • The clutch doesn't slip when revved in 5th gear
  • When stopped there is no detectable smell anywhere
  • The smell seems to be coming from the front, outside of the car.
    • With the windows rolled up I can't smell it.
    • I can smell it when driving forward with the windows open.
  • The car's fluid levels look fine (oil / antifreeze / brake fluid / clutch hydraulic fluid / power steering fluid)
  • Front rotors don't look excessively worn
    • Some minor grooves and small pits on both sides
    • Rotors have approx 16k miles on them
  • Replaced rear calipers approx 16k miles ago
    • Rear calipers were seized and rusted in place
    • Haven't replaced fronts, but braking still seems consistent
So this might be something gross that got washed onto something hot, but I only smell it when the car is moving. Even popping the hood directly after driving does not yield the smell.

I'd hate to drive to failure if it's the clutch... Looking for thoughts!

KP11520 01-08-2019 03:15 PM

I'd go with BRAKES first and foremost. Recently, my left front caliper seized. Imagine that after 19.5 years it decided to quit. Bastid!

These eat front pads faster than rear. if your front calipers are original, it's TIME! And watch the rears, they can seize at any time because they just suck and are already rebuilt!

HTH

Shrout1 01-08-2019 04:50 PM


Originally Posted by KP11520 (Post 9192338)
I'd go with BRAKES first and foremost. Recently, my left front caliper seized. Imagine that after 19.5 years it decided to quit. Bastid!

These eat front pads faster than rear. if your front calipers are original, it's TIME! And watch the rears, they can seize at any time because they just suck and are already rebuilt!

HTH

Tru dat! I got Centrics for the rears, so I'm hoping they'll go for a while (fingers crossed!)

Wish I still had my garage... The rear brakes were a project that I don't really want to put on someone else. I'll probably just have to get it done at the shop here, if that's the issue. It likely is, seeing as there isn't any smell once I stop driving. Something grinding in the engine compartment would certainly leave a stink under the hood.

KP11520 01-08-2019 05:14 PM

PowerStop makes a front Rotor and Pad kit that really increases stopping power. Buy extra pads and never let them score the rotors when they get low. Drilled and slotted rotors can't be cut.

Just Bed them properly for optimum results.
One of the two rating guys probably overheated and didn't pay attention to the bedding instructions. Ignore that. Or his caliper(s) is not backing off properly when releasing the pedal.

If you do buy these, you'll be buying the rears soon enough. LOL

JvG 01-09-2019 12:01 AM

I did a thorough from and rear bake job on mine last year.

The calipers can seize due to internal rust. You could buy a rebuilt caliper, or it is possible to rebuild them yourself by using a rubber seal kit. This costs a lot less.

Another possibility is that the brake hoses are delaminating from the inside out. That can create sort of a one way valve.. When this happens, there is still residual pressure in the caliper.

Either wsy, there is brake drag, creating the smell.

Determine which one is causing the problem by driving the car a few miles, then brake gently.
After waiting a minute or two, touch the wheel near the center hub. A hot wheel indicates brake drag.


​​​​​

Turbobink 01-09-2019 05:06 AM

Check your wheel bearings.

Shrout1 01-09-2019 06:07 AM


Originally Posted by JvG (Post 9192368)
I did a thorough front and rear brake job on mine last year.

The calipers can seize due to internal rust. You could buy a rebuilt caliper, or it is possible to rebuild them yourself by using a rubber seal kit. This costs a lot less.

Another possibility is that the brake hoses are delaminating from the inside out. That can create sort of a one way valve.. When this happens, there is still residual pressure in the caliper.

Either way, there is brake drag, creating the smell.

Determine which one is causing the problem by driving the car a few miles, then brake gently.
After waiting a minute or two, touch the wheel near the center hub. A hot wheel indicates brake drag.
​​​​​

Thanks for the pointer! I'll give that a try today. The smell wasn't there this morning, but it was also a lot colder outside so that could have subdued it.

It's a good thing I love driving this car so much lol...

JvG 01-09-2019 09:27 AM

Turbobink also has a good point. A bad bearing would also cause heat. I imagine that the noise would come and go on curves. While brake issues would be constant. I have not experienced wheel bearing issues on mine yet.

Shrout1 01-09-2019 02:16 PM

Well took it in for an oil change at lunch and told the shop to take a look at the wheels. Just got off the phone and they said they couldn't see anything wrong with them! The mechanic said he used an IR camera to check for heat from dragging parts after a short test drive and everything looked OK.

So at least I'm only out the diagnostic fee... I'm guessing we washed some crap onto a hot part when checking for leaks; I never noticed the smell before we ran the hose on it. So I'll be keeping an eye on it, but I'll take any good news I can get.

Thanks for the suggestions! Hopefully I'm just a car hypochondriac...

JvG 01-09-2019 06:08 PM

Sometimes symptoms appears slowly but progress over time.

Keep monitoring the situation.

Shrout1 01-10-2019 07:34 AM


Originally Posted by JvG (Post 9192459)
Sometimes symptoms appears slowly but progress over time.

Keep monitoring the situation.

Yeah I'm hoping it's not the clutch dragging or something. The car is behaving quite normally, so for now I'll keep it in the back of my mind and keep watching for symptoms.

She still has the occasional hard start (been doing that for 18 months now), needs a new sway bar bushing and has a bit of chain rattle on a cold start. But once I'm on the highway it drives like a new car, so no complaints. Hopefully that trunk leak is solved... We'll see!


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