One Hot Riser

[searayray]

1998 4.3 L Mercruiser raw water cooled. Brand new OEM manifolds and risers. Starboard riser is to hot to touch after as little as 15 min. run time. Port side is cool. Old starboard riser was warmer than port but not to hot to touch. Outside of manifolds on booth sides are cool starboard is slightly warmer. Checked water flow into bottom of both manifolds seems to flow about egual maybe starboard is slightly less.New water pump both in the outdrive ( Alpha 1) and circulating pump on engine and thermostat. Engine temp sits at 160.
Thoughts anyone

 

[Bondo]

Re: One Hot Riser

How is the Flapper Valve on that side,...??..

 

[bjcsc]

Re: One Hot Riser

There was a post like this awhile back where someone had their risers replaced and the shop inadvertantly used the wrong gasket (no holes for riser water jacket). Could also be plugged with sealant if done incorrectly. I'd pull the riser and disassemble that side of the exhaust. Stuff like this is why I have a dual EGT gauge...

 

[bruceb58]

Re: One Hot Riser

I am interested in your EGT guage. What and where did you purchase?

Stuff like this is why I have a dual EGT gauge...

 

[bruceb58]

Re: One Hot Riser

Did you check the thermostat housing for blockage there?

 

[searayray]

Re: One Hot Riser

Thanks for the reply thermostat housing is clear, Riser gasket is correct. Flapper valve is what I will check next

 

[DHPMARINE]

Re: One Hot Riser

I think I'd invest in a pyrometer to find out how hot hot is. I have had countless times when I thought something was too hot (by hand) only to find it OK by meter or melt stick.

I add this as you say the temp guage stays at 160* .While it sounds like water blockage,it seems it's not overheating.

DHP

I have a snap on unit with a wand to hold on the surface, Well also ambient and fluid probes as well.But I am getting used to an infra red Sears unit that's not too shabby.Only $50.00 on sale.

 

[bjcsc]

Re: One Hot Riser

I am interested in your EGT guage. What and where did you purchase?

I purchased it from Livorsi Marine. It's their twin pyro gauge. I bought the kit with the thermocouples, wiring, backlit gauge, everything for the install. I had to swap thermocouples with them as the ones in the stock kit extended ~ 1 1/2" into my riser (3" thermocouple) which was not enough to clear the water jacket. I gave them the dimension for what I needed (6" total) and they swapped me out. Very nice, high quality stuff and I feel like it gives me that much more of an edge.

http://www.livorsi.com/catalog/pyrometers.htm#PYROMETERS_EGT_(Exhaust/Gas/Temprature)