exhaust manifold.

[mauro.]

hey Iam back,

I just had the leg off for servicing bellows and was running the engine for a short period without fresh water just coolant and noticed that out of the exhaust manifold drain plugs and the fresh water hose had a steady stream of air/ exhaust gasses coming out. Is that normal? they are log manifolds.
when I just run it with the manifold on but no elbow it doesn't do it.
Gaskets are brand new and don't leak.

thanks in advane
mauro

 

[Bondo]

Ayuh,....... That's normal when run dry,......

 

[Scott Danforth]

is this a heat exchanged motor? Raw water cooled motor?

without running fresh water, your exhaust temps are 900-1100. so any rubber in the exhaust system gets burned to a crisp and any water vapor in the exhaust manifold gets turned to steam

 

[mauro.]

it is a heat exchanger model I made sure nothing got hot.
so I guess I am alright then? with the gasses?

 

[Bondo]

it is a heat exchanger model I made sure nothing got hot.
so I guess I am alright then? with the gasses?

Ayuh,....... With no raw water, the exhaust is running hot, 'n dry,....

 

[mauro.]

so it's normal for a bit of the exhaust coming back out the water jackets? from back pressure I guess?

 

[Bondo]

so it's normal for a bit of the exhaust coming back out the water jackets? from back pressure I guess?

Ayuh,...... With no raw water,..?? Yes,....

 

[mauro.]

perfect thank you. whew so I am all good to go for the season.
thanks again
mauro

 

[Scott Danforth]

perfect thank you. whew so I am all good to go for the season.

running the motor without the raw water flowing means that you burned up the rubber flappers and the couplings in the exhaust.....

those little rubber bits have a maximum temperature of 250F. your exhaust with water flowing is normally 200F. however without water, you were between 900F and 1100F.

how long does a bit of rubber take to burn with a blow torch on it.