Burning Out Valves Due To Loss of Exhaust Back-Pressure?

[Chaldaean]

My Y-Pipe fractured and I was at an exhaust shop yesterday to get quotes on a stainless system.

The manager of the shop advised that I shouldn't drive the truck around because I'll burn out the valves due to the loss of back-pressure.

Is there validity to this advisement on the 1FZ-FE?

Thanks.

.

 

[Frankencruiser]

He's either a big idiot, or just trying to get work. You won't burn exhaust valves because you don't have backpressure.

 

[specialk396]

I would not return to the shop you went to. Pressure tactics like that are a big warning sign.

 

[Kief]

I have heard of warping valves due to cold air getting in due to no exhaust system being in place. It may not be common but then again most people get stuff like that fixed. I suppose it is a little loud? I would be more worried about Carbon Monoxide poisoning... But yeah, you should not drive it like that.. It definitely should be fixed. I would do my best to convince you to fix it if I owned an exhaust shop..

 

[Offroads4x4]

First your getting a bid to fix your rig so your on the right track.
As far as burning your valves most valves are burnt from timing issues, running too lean and bad valve adjustment. All of which take time to burn the valve. Back pressure not so much it's not like running an engine with out any manifold and pipes. Back pressure is compression issuse related. Your cracked Y pipe is minimal short term to your valves.

 

[Pin_Head]

most valves are burnt from ..., running rich ....

Running lean burns valves.

 

[Cattledog]

No chance of burning the valves. The truck is going to run so stupid rich due to the ecu being in limp mode that the exhaust valves will be fine.

I would agree on the carbon monoxide coming back into the cab. That would be the only reason not to drive it.

Wow I am feeling really bad about suggesting that shot to you. Sorry

 

[Offroads4x4]

Running lean burns valves.

True sorry brain fart!

 

[Ebag333]

I drove for a couple of weeks with my Y Pipe detached. The bus full of nuns it still there.

No problems with it,in fact I didn't notice a change in fuel usage.

Run with the window cracked so you get fresh air, and hope no cops hear you as most states have noise laws.

 

[RockDoc]

I drove from Northern Cali or Southern Oregon back to Edmonton Alberta with one downpipe detached at the manifold on my 3FE with no issues. Made it easy to one-up people who like to honk their horns in tunnels.

 

[Offroads4x4]

If you want a good trail fix for your pipe now just clean up the area to repair and mix up some Lquid Steel. Be sure to cover the crack real good and go all the way around the pipe so it holds in place better. Next let it harden up and drive as normal.

 

[specialk396]

There is no chance of air(cold or otherwise) getting into the cylinder head through the end of the cracked y pipe of a running engine.
Not running an exhaust manifold could possibly cause that scenario, but I have seen engines with no exhaust manifold run(albeit roughly) with no lasting effects.
Definitely get the exhaust fixed(so as to save your brain cells and hearing), but you won't injure your engine running it that way.

 

[JohnR]

Agreed. No possible way of 'burning' exhaust valves with a cracked manifold. Race cars run open headers all the time. Just a pressure tactic to make money. Find a new mechanic.

 

[NKP Garage]

Too much backpressure on a turbo or supercharged engine may burn exhaust valves. Too much timing, not enough timing, or running lean may burn exhaust valves. Having a disconnected exhaust will not burn exhaust valves.