Tail pipe under water = burnt valves?

[bmohan55]

I pretty new to off-roading and was told that if I get stuck in a water-crossing with the tail pipe under water that I should keep the engine running. A mechanic here a work told me that this will result in burnt valves from the increased back pressure on the exhust. So who's right?

Is it that the people telling me this had Discos (in fact I was on the trail in the Disco at the time) and their more powerful engines wouldn't labor as much as a 2.25 Series engine?

[LaneRover]

Don't know about the burnt valves, but the reason to keep the Rover running when stopped during a water crossing is to stop water from coming up the tailpipe when the truck stalls. If this happens then the Rover won't be able to re-start because of the increased back pressure with the water up the pipe.

[graniterover]

Are you sure they didn't say 'bent valves'?

[jac04]

^^ Does it matter? You're not going to bend valves by having your tailpipe under water.

[yorker]

^^ Does it matter? You're not going to bend valves by having your tailpipe under water.

I think he is thinking about a hydrolocked engine.



Keep it running unless you have injested water into the intake. You aren't going to burn valves by running with the exhaust submerged.


some neat fording info:

http://www.cj3a.info/sibling/cjv35u/evolution.html

http://www.cj3a.info/sibling/m38vent/vent.htm

[rovers2a]

horsesh!t.... a friend of mine is a lisecensed mechanic and he dosent know is ass from a hole in the ground. there are alot of bad mechanics out there so take what he says witha grain of salt.

[greenmeanie]

I don't know much about modern boats but the WWII elco 80ft PT boat of presidential fame had six exhaust stacks. These could be run open off the stern of teh boat for speed but could also be routed under water for a bit of stealth. They had many problems with engines due to poor fuel and other nasties but not burned valves due to an exhaust exiting under water.


Incidently, with three big packard V12 marine engiens it is one of the coolest sounding machines ever. Oh well, after these obscure and barely realted facts we can get back to the regular programming about Land Rovers.

[graniterover]

Yes, that's what I thought someone might be referring to.

I think he is thinking about a hydrolocked engine.



Keep it running unless you have injested water into the intake. You aren't going to burn valves by running with the exhaust submerged.


some neat fording info:

http://www.cj3a.info/sibling/cjv35u/evolution.html

http://www.cj3a.info/sibling/m38vent/vent.htm

[yorker]

Yes, that's what I thought someone might be referring to.

Who knows? maybe that was what his mechanic was thinking of! Burned Bent whats the difference- a lot of today's mechanics have probably not seen either. A lot of them are nothing more than parts changers today.

[jac04]

Burned Bent whats the difference....

......Valves, Connecting Rods, what's the difference?

[bmohan55]

To stick up for my friend...he's not a professional mechanic (well yes he is at the plant) but an old timer who's worked his whole life on anything and everything (restores tractors and keeps dozens of old cars running as a hobby), not a "parts changer". If not for him my truck would be for sale as I'd have gotten in over my head. This advice came from the fact that after a recent valve job on his old jeep his son got it stuck with the tail pipe under water, engine running, for about 40 minutes. Afterwards the valves were shot, hence his warning to me.

Again, possibly it's the fact that the smaller engines would be damaged by the increased back pressure but the larger displacement ones can over come it?

[thixon]

To expand on Gregors comments, the ski boat I grew up skiing behind had a ford v-8 that was exhausted underwater. Never a burnt valve.