Burning Smell While Climbing Hills

[vancouver.matt]

Hey guys,

 

So, I've got this problem that I can't quite figure out - though I have yet to put much effort due to my work schedule.

 

I took the truck through the mountains for a weekend trip a few weeks ago. On the way up, I noticed the following:

- Strong burning smell, almost like rubber coming from middle of the truck.

- Brakes unresponsive when smell is evident (I push the brake pedal and nothing really happens, if I release the pedal and press again, just brakes fairly normally).

- Exhaust pipes/muffler extremely hot.

- Smell goes away after a minute of normal driving/downhill coasting.

- Truck smells "gassy" even after just driving around the city and getting back into my underground.

- Tranny fluid is up to level and still has good colour.

- Brakes/wheels are NOT hot when I pull over immediately to check around the truck once the smell starts.

- Smell is NOT emulating from under the hood.

- No smell on flat roads/hwys nor while downhill, even if I have to ride the brakes a bit.

- Engine temp (at least according to the gauge) is normal at all times and the engine doesn't feel excessively hot.

 

Now, I chalked this all up to the truck burning through some stuff since it hasn't really seen any mountain driving for quite a while. However, the problem got worse, then the truck threw a "service engine soon" light. I haven't had time to scan the truck for codes, so I understand there's not much you guys can do for me, but this is really starting to bug me. Just looking for any sort of insight/things to put on the list to consider.

 

Some ideas:

- Blocked cat

- Trans overheating (would maybe cause brake lines to overheat and give me the issues with braking?)

- E-brake sticking (causing burning drum pads, truck to work harder than it needs to, etc. - though as I mentioned, the wheels and hubs do not feel excessively hot).

- Truck running too rich and causing...?

- Something else?

 

I'm just guessing here, but I'm going to assume the SEL is because I fried an O2 sensor or 2 when the exhaust system was running extremely hot on trip up - I'm talking like surprised the whole system wasn't glowing red.

 

Thank guys, and I'll give any more info I can if you have further questions.

Edited August 2, 2016 by vancouver.matt

[rgallant]

Could be cats if they get really clogged they literally glow red, which is a bigger issue because they should not get that clogged. If you are in the Fraser Valley give Mission Auto tech a call, Andy there is an ex nissan mech really good at a reasonable price.

 

[ThaBigPerm]

Odd - on my 3 trips to CO with mine, I noticed something similar. After extended periods in 4wd and chugging away on steep climbs to altitude, mine also smells, but it doesn't smell anything remotely of "man-made" chemicals ... no burning oil, fluids, coolant, rubber, plastic, etc. In fact, the best way I can describe it is smelling like I ran over some mountain foliage and sage grass, and it began cooking on the exhaust. It's almost an overpowering perfume smell ... but with no associated flowers stuck in the exhaust (and definitely not the "hot pancake syrup" smell of coolant). It also goes away after cooling down, and never happens outside of my trips to CO. The only thing I can think of is pine sap has been tossed up onto my exhaust during the drive.

Edited August 3, 2016 by ThaBigPerm

[k9sar]

My 95 caught fire pulling a boat up a long hill. Floor pan under drivers side had rusted through and the hot exhaust ignited the carpet pad. You claimed the exhaust was really hot, perhaps something similar?

[vancouver.matt]

My 95 caught fire pulling a boat up a long hill. Floor pan under drivers side had rusted through and the hot exhaust ignited the carpet pad. You claimed the exhaust was really hot, perhaps something similar?

 

 

I mean, there is a good chance that that is what the smell is, but it doesn't explain why the whole exhaust system is so hot.

Would the pipes really be hot enough to feel it on my legs while standing next to the truck just from climbing?

Why would the check engine light come on?

Still doesn't answer questions about braking.

 

I think it's all related to overheating exhaust system, but I'm not sure why it's overheating when the engine runs at perfect temp. That's kind of why I'm worried it's cat related (I really don't want to dump money into replacing the entire system and/or cats).

[Remus92]

Well a cat does sit right below the master cylinder. The heat may be boiling or otherwise affecting the brake fluid.

 

And the heat on the legs... If its over heating absolutely! It can only release so much heat so fast going up through the engine bay. Out the sides of the vehicle would happen too.

 

What was the code?

[Slartibartfast]

How's the power feel? Our Cornbinder heated up the exhaust like crazy when the timing was retarded. I'm not sure exactly how the timing is set on the VQ, what sensors would have to go bad or out of alignment or whatever to make it do that. Or the ECU could be pulling timing and dumping fuel if it thinks you're pinging under load. Hopefully the code gives you a better idea.

 

Also, how's your brake fluid look? Level, condition? If it's old and sketchy, the boiling point could be lower than it should be--but they sure as hell shouldn't be heat fading when you're going uphill.

[vancouver.matt]

Well a cat does sit right below the master cylinder. The heat may be boiling or otherwise affecting the brake fluid.

 

And the heat on the legs... If its over heating absolutely! It can only release so much heat so fast going up through the engine bay. Out the sides of the vehicle would happen too.

 

What was the code?

 

Still haven't had time to scan it.. which is priority number 1 I suppose.

[vancouver.matt]

How's the power feel? Our Cornbinder heated up the exhaust like crazy when the timing was retarded. I'm not sure exactly how the timing is set on the VQ, what sensors would have to go bad or out of alignment or whatever to make it do that. Or the ECU could be pulling timing and dumping fuel if it thinks you're pinging under load. Hopefully the code gives you a better idea.

 

Also, how's your brake fluid look? Level, condition? If it's old and sketchy, the boiling point could be lower than it should be--but they sure as hell shouldn't be heat fading when you're going uphill.

 

Thank you, I will check brake fluid and level.

 

I'll also update once I pull the code.. just have to figure out a way to do it.

[LittleFR]

I'm kind of in tune with the load making the CAT superheat the brake fluid under a load. A hill should not affect your brakes... Ever.

 

On a side note transmission fluid always looks better on the dip stick than when you actually drain it. I'd be awful tempted to at least do a flush and fill.

[Aaron]

I'm assuming that you have done a full visual inspection of your exhaust system but the same exact thing happened to my pathy. The smell started while I was climbing the hills and I finally tracked it down to the failure of the final flange on the exhaust that least to the final muffler/resonator. The exhaust was leaking from a hole there and was shooting straight up to the rear floorboard and over a brake line. The brake fluid got cooked leaving me with a mushy brake pedal and a spot in the rear carpeting and matting melted leading to the horrid smell. Since the leak was after the main muffler there was no noticeable noise difference. I'd suggest getting under the truck and doing a thorough inspection.