Exhaust Manifold at 200 degrees

[Backyardhockey]

Hello. Mercruiser Alpha 1 w/ Chevy 305. Lake water cooled. Runs fine. 160 at the thermostat. Cheap IR gun says 209 degrees on starbord Exhaust manifold. Thing on top of that (risor?) is only 90degrees. Slight burning smell every once in a while. Thoughts, comments?

 

[Apollo75]

Re: Exhaust Manifold at 200 degrees

It is a little warm but nothing to panic about yet. Need to know if this boat is closed cooling or half closed or raw water cooled ? What is the engine temp ?

90 degrees is a little cool ---- nice but cool --- how are the other readings while this engine is under load ?


OFM

----------------------------------------------------------------------------------------------------------
The big thing in the rear that consumes gas is an engine, the other big thing in the rear that makes gas is my brother-in-law.

 

[bds85466]

Re: Exhaust Manifold at 200 degrees

210F doesn't seem too hot. I would expect the manifold to dissapate more heat than the riser, hence remain hotter. What's the Port-side read? If they're extremely different you may have some flow blockage on the SB side...

It would be nice to know if it's fresh, raw, or closed.

 

[Backyardhockey]

Re: Exhaust Manifold at 200 degrees

Sorry, cooled by lake water. Didnt have a working pen with me, but other side was 180? Might have been lower. 160 at thermostat. That burning smell had me concerned. Its not a big smell. Usually comes after slowing or when stopped. Kind of rubberish. Thanks.

 

[Apollo75]

Re: Exhaust Manifold at 200 degrees

A 20-degree difference from side to side is not unusual. Both readings are high for a raw water cooled engine ----> unless you have a boat load of people and party favors blasting across the lake at full throttle ----> then it would be normal temp.

I would start at the impeller and go from there.


OFM

------------------------------------------------------------
If the boat is not sinking or on fire, Relax.

 

[Bondo]

Re: Exhaust Manifold at 200 degrees

That burning smell had me concerned. Its not a big smell. Usually comes after slowing or when stopped. Kind of rubberish.

Ayuh,... How long ago was the raw water Impeller changed,..??
Sounds like it might need it...

If it's not moving enough water at hi-speeds,..
You're probably smelling the rubber exhaust parts Burning...

 

[Backyardhockey]

Re: Exhaust Manifold at 200 degrees

A minimum of 4 years on the impeller. Dont actually know, but I bought it from a guy who was a maintiance freak. I watch the dash gauges like a hawk so I figured I'd let it go untill I saw numbers go up.

Thanks for the reply Bond-o. How do I inspect these exhaust parts you mentioned?

 

[Bondo]

Re: Exhaust Manifold at 200 degrees

How do I inspect these exhaust parts you mentioned?

Ayuh,... Loosen the Big hose clamps on the exhaust ferules,+ pull the Big elbow at the Y-pipe connection...
Then Look,...