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