Burning Smell, Very Hot And All 5 Lug Nuts Loose On Same Wheel

[NorbyG]

I felt a sudden heavy vibration in steering wheel on my gen7 Celica (especially after climbing hills). First I thought it was wheel balancing or uneven road surface (which is very bad in my area); but discovered later, burning smell from nearside front wheel, all 5 lug nuts loose and whole wheel very hot - couldn't touch (even tyre hot). I had driven about 15 miles on 2 occasions when I experienced the vibration. But the vibration wasn't there all the time - only at certain speeds and road surface, which made me think it was just wheel balancing; (checked other wheels everything ok). I don’t use the car often as I’m retired. It’s always kept in my garage; use it about every 2 weeks to do shopping about 2mls from my home and take it for the occasional 20-30 mls run to keep Battery topped up.

What could have caused the burning smell, wheel being so hot and nuts to come loose?

[Cyker]

I wonder if the nuts were already loose and the whole wheel was rubbing against the inside arch of the car and being dragged around slightly sideways on the road...?

[shellyvvti]

My guess would be either the pads are stuck in the caliper carrier or the piston is seized binding the pads to the disc. This maybe because the car isn't used that much Japanese car tend to suffer with this.

[NorbyG]

Had look at it yesterday: took wheel off - brake pads/disc were binding (need new brake pads, worn down to about 3mm) - took the calliper apart - push piston back but it wouldn't go right back, about 5mm still sticking out - refitted calliper - calliper is sliding as it should – break pads/disc free from binding - refitted wheel - went for a spin and noticed the binding started again and wheel got hot. I don't want to fit new brake pads until I get binding sorted.

Should piston go all the way back where it's flush with piston outer housing; or, should a bit of it still be sticking out? It seems the piston is not retracting under normal operation so causing the binding. It only goes (nearly) all the way back when it's push back manually. Why is that?

As to the nuts coming loose; if you think about it...because of the heat from the wheel (yes it was that hot) the nuts came loose. If you apply heat to tight nuts/bolts they normally come loose - that’s what mechanics tends to do when they find tight nuts/bolts are hard to shift.

[Cyker]

That is pretty hot!

[gazza1286]

If you can push the piston back using finger pressure the caliper can't be that bad. I've known calipers act strange at the limit of the piston range when the pads are virtually done. The piston being so far out of the caliper cylinder it distorts and locks up. Putting in the new pads allows the piston to operate with most of it within the caliper body thereby reducing the risk of locking. May be worth a try otherwise it's a rebuild or replacement. Btw the piston normally will compress flush to the caliper body - but there may be a build up of crud behind the rubber boot preventing this.

[armoredfist2002]

Sounds like the piston is sticking and causing the pad to be constantly touching the disc causing excess heat build up.

With the wheel getting hot you need to check the discs haven't been warped from the heat also, for the extra few ££ it would cost I would replace the discs when you change the pads just to be on the safe side.

If your not doing the job yourself go to a garage and get them to change your discs and pads and sort out the caliper at the same time. If your doing it yourself I would either find a second hand caliper in good condition or buy a refurb kit.

[NorbyG]

I felt a sudden heavy vibration in steering wheel on my gen7 Celica (especially after climbing hills). First I thought it was wheel balancing or uneven road surface (which is very bad in my area); but discovered later, burning smell from nearside front wheel, all 5 lug nuts loose and whole wheel very hot - couldn't touch (even tyre hot). I had driven about 15 miles on 2 occasions when I experienced the vibration. But the vibration wasn't there all the time - only at certain speeds and road surface, which made me think it was just wheel balancing; (checked other wheels everything ok). I don’t use the car often as I’m retired. It’s always kept in my garage; use it about every 2 weeks to do shopping about 2mls from my home and take it for the occasional 20-30 mls run to keep battery topped up.

What could have caused the burning smell, wheel being so hot and nuts to come loose?

I’m still trying to repair brake... Piston hard to push back into cylinder when bleed nut is locked, but easy to go back (all the way) without any resistance when bleed nut is released. But when applied brake again and again pads stays on; but when I tap calliper with a piece of wood the pads releases. I’m puzzled...as calliper is free and slides as it should when checked against opposite wheel. The opposite wheel is ok - pads on that still 6mm thick; while pads on problem brake are only 3mm thick. I noticed there’s a block under the bonnet where brake pipes are connected to. What is it, and its purpose? Could it be that something is wrong with that hence the problem?

By the way; the disc is not warped.

[gazza1286]

The unit is part of the abs system. It won't be related to your problem.

[NorbyG]

Thanks for all your help. I've booked the car into garage to have the whole brake system inspected/sorted.