temp of exaust

[Davidmerc140]

Hello forum iam diagnosing trouble starting on a mercruiser 140 3681706 i am wondering what temp would the exaust manifold come up to at idle? There is a leak between the exhaust wall and cooling water wall wanna make sure this is my problem before ordering this pretty expensive part

 

[HT32BSX115]

Re: temp of exaust

Hello forum iam diagnosing trouble starting on a mercruiser 140 3681706 i am wondering what temp would the exaust manifold come up to at idle? There is a leak between the exhaust wall and cooling water wall wanna make sure this is my problem before ordering this pretty expensive part

Howdy,


The temp of the riser won't tell you if it's defective (leaking)

If it's getting hot at idle, it's most likely due to either a failed raw water impeller, blockage in the raw water circuit or a fully rusted riser that doesn't allow water to flow out.



If you're getting water into the exhaust manifold, it's either due to a failed manifold, riser, or riser gasket.
If you're getting water into a cylinder on shutdown.......(won't crank after shutdown, and you get water out of spark plug holes) it can come from the failure above.

The only way to tell is to separate them and inspect. If it's a salt water engine and the manifold/riser is more than about 5-7 years or so old and If they're rusted to the point of blockage, you cannot 'clean" them safely. it's time to replace.

Regards,


Rick

 

[Davidmerc140]

Re: temp of exaust

Ok thanks for the reply let me update I removed the exaust and determined it had a leak between the exaust /raw water wall in the manifold i sealed the leak only to find out if this was my problem. After putting exauast manifold back, I still got back fire through carb. So im still not sure replacing the exaust will get the boat back on the water

 

[HT32BSX115]

Re: temp of exaust

Ok thanks for the reply let me update I removed the exaust and determined it had a leak between the exaust /raw water wall in the manifold i sealed the leak only to find out if this was my problem. After putting exauast manifold back, I still got back fire through carb. So im still not sure replacing the exaust will get the boat back on the water

A leak in the exhaust manifold water jacket WILL seriously damage your engine though, regardless of how you "sealed the leak".......and understand. If you have a leak in any cast iron manifold, sealing the leak can only be temporary at best......(and you may not have "sealed" it at all!)

Backfire through the carb can be caused by several things. Ignition and valve timing, stuck/burned valves, severely "carbon'd" plugs, pistons, combustion chambers etc.....

 

[Davidmerc140]

Re: temp of exaust

Ok so my problem is the manifold and matbe valves if u pull the cover anhow do i go about dianosing which of those it maybe

 

[Bondo]

Re: temp of exaust

Ok so my problem is the manifold and matbe valves if u pull the cover anhow do i go about dianosing which of those it maybe

Ayuh,... Start with a Compression Test...

 

[Davidmerc140]

Re: temp of exaust

On my way to swap out my reverse gear puller for a compression test kit and a timing light( pep boys rent a tool)