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Starboard side exhaust elbow running hot

S

Stevefish

New member
Hi all, i have a problem with the temperature gauge temp running higher than normal. I have replaced the impeller (slight damage) but still the same. I noticed that the starboard exhaust elbow was running hotter than the port side after a short run (60 SB/30 P degrees celsius). i removed the water inlet fitting onto the manifold (stainless elbow) and found it partially blocked. I cleaned it and tried again but same result. Am i looking at a blocked manifold on the starboard side or should i be looking elsewhere. Any help greatly appreciated. Steve
 
Maybe post the engine details, history details - year, serial number, engine size, Carbed or EFI or TBI, history of any issues or repairs that may be related, raw water cooled or closed cooling (heat exchanger), anything else that may help.....

When asking about an issue always include as many specific details as possible.

Also under normal running conditions a variation of 20-30* F at elbow from one side to the other is not uncommon.

Picture this, I ask you why my truck wont start, It has a stainless steel key which always works, Any ideas why it wont start?
 
Lack of engine information seems fairly common with new members. It seems like common sense, but Perhaps the site admin could add a note regarding such on the Sign Up Page.
 
I once recorded my temps with an IR gun idling after engine (2002 5.0 MPI) was run on plane for several miles. Hottest spot on starboard elbow 154 degrees F, port 107 degrees F. I suppose it's been that way since new. Now has 1600 hours. Now I have heard that a shiny black surface can confuse an IR gun but readings taken in and around the thermostat housing are dead on with a 160 degree thermostat.
 
Thanks for the replies and apologies for lack of information!.
Mercruiser 5.7L V8 1994. I have since removed the manifold and riser. The female/male stainless elbow on the water inlet had partially blocked, whilst the brass hose fitting screwed into the stainless elbow was completely clean!. On separating the riser from the manifold, i found that the ports either side of the gasket at that point had blocked (hard black deposits, really stain anything that touches it). The manifolds are 3 years old, i run the boat on long trips every couple of weeks. On inspection of the walls, they appear healthy. I was planning on refitting them and see if the temperature improves?
I noticed in the gasket parts kit; it comes with a plastic elbow with drain point for the water inlet to the manifold. Can anybody tell me if the plastic is better than the stainless elbow which appears to be attracting a buildup of black deposit?.
Regards Steve Fish
 
Stevefish said:
Can anybody tell me if the plastic is better than the stainless elbow which appears to be attracting a buildup of black deposit?.
Click to expand...
Ayuh,...... The plastic drainable fittings work just fine,....
Donno what the deposits are, maybe something in the water you boat in,....
 
Stevefish said:
Thanks for the replies and apologies for lack of information!.
Mercruiser 5.7L V8 1994. I have since removed the manifold and riser. The female/male stainless elbow on the water inlet had partially blocked, whilst the brass hose fitting screwed into the stainless elbow was completely clean!. On separating the riser from the manifold, i found that the ports either side of the gasket at that point had blocked (hard black deposits, really stain anything that touches it). The manifolds are 3 years old, i run the boat on long trips every couple of weeks. On inspection of the walls, they appear healthy. I was planning on refitting them and see if the temperature improves?
I noticed in the gasket parts kit; it comes with a plastic elbow with drain point for the water inlet to the manifold. Can anybody tell me if the plastic is better than the stainless elbow which appears to be attracting a buildup of black deposit?.
Regards Steve Fish
Click to expand...

Long trips, at what speed? Fresh water, brackish, or salt?

You used 'whilst'- British? are you using the boat on the canals? Low speeds can cause sediment to settle at the lower areas in the water jacket and other parts of the cooling sysytem- I'm not sure the plastic would make a difference over stainless. The deposits being black may be from decaying vegetation, including algae in the system.
 
jimn said:
Long trips, at what speed? Fresh water, brackish, or salt?

You used 'whilst'- British? are you using the boat on the canals? Low speeds can cause sediment to settle at the lower areas in the water jacket and other parts of the cooling sysytem- I'm not sure the plastic would make a difference over stainless. The deposits being black may be from decaying vegetation, including algae in the system.
Click to expand...
(Whilst) thats funny! Yes, I'm a Brit but boating in Australia. I think you have hit it on the head, i do run at low speeds down bracken water canals to get to open waters. They are shallow and muddy!
Going to stick with the stainless fittings.
Thanks for your thoughts on it.
Steve
 
Mercruiser 1994 5.7L V8 Engine number: OF418132. I have cleaned the manifold and riser ports. The condition of them is good the main issue appeared to be sediment blocking the ports.
My question now is which is the correct gasket between the manifold and riser. The riser and manifold have a long slotted port on all four sides, whilst the gaskets offered vary. Some have the four long slots, some have two slots with just a pilot hole on the other two sides. Although it appears obvious, i read a post, mentioning recirculation in the block with the four slot gasket ?.
Again any help, much appreciated.
Steve
 
kghost said:
1988-1995 5.7L with STAINLESS STEEL ELBOW
There also is cast iron ELBOWS

Link to parts diagram- Item 9 (only) (Items 8 and 10 are used for Closed cooling designs)
It also shows the orientation of the gasket.

Click to expand...
kghost said:
1988-1995 5.7L with STAINLESS STEEL ELBOW
There also is cast iron ELBOWS

Link to parts diagram- Item 9 (only) (Items 8 and 10 are used for Closed cooling designs)
It also shows the orientation of the gasket.

Click to expand...
Thanks for the info Jack, they are cast iron, the engine has a coolant heat exchanger. Raw sea water through the manifolds and riser, is this considered a closed or standard cooling circuit?.
Steve
 
kghost said:
1988-1995 5.7L with STAINLESS STEEL ELBOW
There also is cast iron ELBOWS

Link to parts diagram- Item 9 (only) (Items 8 and 10 are used for Closed cooling designs)
It also shows the orientation of the gasket.

Click to expand...
Hi Jack, they are cast iron. The engine has a coolant heat exchanger, the sea water runs through the manifold and risers, does this mean it is a closed cooling circuit or standard.
Steve
 
Stevefish said:
Thanks for the replies and apologies for lack of information!.
Mercruiser 5.7L V8 1994. I have since removed the manifold and riser. The female/male stainless elbow on the water inlet had partially blocked, whilst the brass hose fitting screwed into the stainless elbow was completely clean!. On separating the riser from the manifold, i found that the ports either side of the gasket at that point had blocked (hard black deposits, really stain anything that touches it). The manifolds are 3 years old, i run the boat on long trips every couple of weeks. On inspection of the walls, they appear healthy. I was planning on refitting them and see if the temperature improves?
I noticed in the gasket parts kit; it comes with a plastic elbow with drain point for the water inlet to the manifold. Can anybody tell me if the plastic is better than the stainless elbow which appears to be attracting a buildup of black deposit?.
Regards Steve Fish
Click to expand...
I have a 1983 5.7 Mercruiser and the starboard exhaust manifold - at the top - typically runs ~20 degrees hotter. Even after cleaning out the manifolds. I suspect the water pump favors one side. It's not a big deal.
 
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