5.7L risers, one running cool the other pretty hot

[tfret]

I installed new risers this spring and a new impeller kit in the alpha 1 drive over the weekend. Temp gauge reads normal all the time now, however I noticed by touch that the port riser runs cool and the starboard is hot. I can only keep my hand on that one for about 2 or 3 seconds. The manifolds looked good and leak checked good when I changed the risers. Why would temps be so different between risers?

 

[Fordiesel69]

Re: 5.7L risers, one running cool the other pretty hot

In the t-stat housing, there is a ball/spring valve to balance the flow to each riser / manfold. Inspect for proper operation, these likely seize up or break apart.

 

[tfret]

Re: 5.7L risers, one running cool the other pretty hot

Thanks for the reply. All I see on the diagram in the manual is the T-stat housing. Is this balancing valve inside, and is it servicable?

 

[Bondo]

Re: 5.7L risers, one running cool the other pretty hot

Thanks for the reply. All I see on the diagram in the manual is the T-stat housing. Is this balancing valve inside, and is it servicable?

Ayuh,... What Vintage, 'n drive..?? Ya may not have 'em...

 

[nikon]

Re: 5.7L risers, one running cool the other pretty hot

Mine was doing the same...same balls n' springs in the t-stat housing...loosened the assembly to its max and everything is good now.

 

[conk3416]

Re: 5.7L risers, one running cool the other pretty hot

I would disconnect the hose that runs from the t-stat to the riser on both sides and run water thru them. Check to see if the water flow is the same on the starboard side as it is on the port side. if not you may have a clog in the system somewhere.

 

[tfret]

Re: 5.7L risers, one running cool the other pretty hot

Sorry I didn't include year, it's a 1984 Mercruiser. Nikon mentioned loosening the assembly to the max(?) Is there an external adjustment screw on the T-stat housing? I will also pull the hoses to ensure they are clear of debris.

 

[nikon]

Re: 5.7L risers, one running cool the other pretty hot

It's internal, but I don't know if your year has them.....do try doing what conk said and run water through it.

BTW, are you checking this when your just idling around? A friends boat did the same thing till you gave it some gas and put a little more water through the system, then they both ran cool.

 

[Don S]

Re: 5.7L risers, one running cool the other pretty hot

Sorry I didn't include year, it's a 1984 Mercruiser. Nikon mentioned loosening the assembly to the max(?) Is there an external adjustment screw on the T-stat housing? I will also pull the hoses to ensure they are clear of debris.

He has a completely different setup than you do. Now that we have a year of your engine, the question is, do you have the log style manifolds or center rise.
Do you have your engines Merc serial number handy?

 

[tfret]

Re: 5.7L risers, one running cool the other pretty hot

It has the center rise manifolds Don, sorry I do have the serial written down at home but not with me right now. I can't find anything about the "ball and spring" valve in my manual.

 

[Don S]

Re: 5.7L risers, one running cool the other pretty hot

I can't find anything about the "ball and spring" valve in my manual.

That's because they didn't exist in 84.
Does the riser cool down if you raise the rpm up a few hundred rpm?