4.3 l mercruiser one piece exhaust manifold temp senor install

[kazek]

Hi there crew. I acquired 19 footer monteray with 2001 4.3l mercruiser equipped with one piece exhaust manifold. Iron testing, starboard manifold was getting hot, compared to port. I cleaned the water ports as much I I could and it helped. Both manifolds were same temp ( to touch), but when I shut engine off, starboard side was hot again. I am thinking of installing temp sensors with separate gauges for each side. Where would be a best spot to drill for sensors. Also thinking of using a JB weld to attach a coupler to screw in sensors.
Q 1what is better way?
2 if drilled...which location?
Thanks in advance

 

[Lou C]

Those are prone to failure due to casting flaws, I’d get rid of them & convert to the 2 piece system before they hydrolock the engine

 

[Scott Danforth]

Q 1what is better way?

Upgrade to the 2-piece and get rid of the failure prone batwings

 

[kazek]

Thank you for responses. I would like to keep it in org state. I do realize that one piece will rust out from the inside. Just want to keep an eye before it does. Thus the question at what point. I would think....Given that all other components are in working order and maintenance is being done... temp gauge would make a good indicator of failure of the part

 

[kazek]

Thank you for responses. I would like to keep it in org state. I do realize that one piece will rust out from the inside. Just want to keep an eye before it does. Thus the question at what point. I would think....Given that all other components are in working order and maintenance is being done... temp gauge would make a good indicator of failure of the part

Does anyone has a diag or Pic where water meets exhaust

 

[Lou C]

Thank you for responses. I would like to keep it in org state. I do realize that one piece will rust out from the inside. Just want to keep an eye before it does. Thus the question at what point. I would think....Given that all other components are in working order and maintenance is being done... temp gauge would make a good indicator of failure of the part

The engine is 24 years old, and those manifolds were only made for 3 years because Mercruiser couldn’t get the wall thickness consistent so there were a lot of failures. When that happens it will let water in the cylinders which can ruin the engine. Merc & Barr both make conversion kits to convert it to the two piece. I had a similar system on my OMC Cobra and while I never had a failure I converted it to the later 2 piece style.

 

[Scott06]

Thank you for responses. I would like to keep it in org state. I do realize that one piece will rust out from the inside. Just want to keep an eye before it does. Thus the question at what point. I would think....Given that all other components are in working order and maintenance is being done... temp gauge would make a good indicator of failure of the part

Temp has nothing to do with how these fail.
they are double wall so drilling in and JB welding the bung is a fools errand . Aren’t there a few threaded ports on the manifolds already ? Another t where the cooling water comes in

 

[Bondo]

Thank you for responses. I would like to keep it in org state. I do realize that one piece will rust out from the inside. Just want to keep an eye before it does. Thus the question at what point. I would think....Given that all other components are in working order and maintenance is being done... temp gauge would make a good indicator of failure of the part

Ayuh,....... It's got nothing to do with rust, those were junk the day they were brand new,......
They quit making them for a reason, core shifting, during the casting process,....
Yer idea of drilling them is even dumber than not replacing then now, before they fail, which they will do, destroying yer motor,......

 

[kazek]

I do have a spare set of 2 piece. Since one piece is junk.. where one would install temp sensor. I haven't taken manifolds out yet
Don't know what is the inside shape.

 

[kazek]

Ayuh,....... It's got nothing to do with rust, those were junk the day they were brand new,......
They quit making them for a reason, core shifting, during the casting process,....
Yer idea of drilling them is even dumber than not replacing then now, before they fail, which they will do, destroying yer motor,......

 

[kazek]

Please elaborate..... seems that ol 2 piece is preferred. Casting is pretty much simple process. Is it one ( bad mould) that constitutes for all to be bad? I get that quality of iron used may be questionable ( worked in steel heat treating)

 

[Scott Danforth]

To get a double wall casting, there are two sand cores. They would shift during the process.

You don't need a temp sensor

 

[Lou C]

If you really want to monitor temps just get an IR temp gun to leave on the boat, that’s what I do.