1979 350 260hp manifolds running hot!

[knightowl]

Just trying to make sure im thinking right. Summarized my boat today (finally!)

Fired the engine, ran it for a little bit. The temp gauge says its around 145 to 160. However, my log style manifolds are around 210 degrees when 2k rpm!

To me it seems like my thermostat might be stuck? I did use that salt away product and pumped it through my system before winterization. Also before i removed my block bolts for winter drainage, i had to poke with through with a screw driver for water to drain.

Thats why i think i need a new thermostat. Or i should run salt away again to remove some of it.

I replaced the water pump 3 years ago, i also replaced the out-drive pump last spring as well as brand new thermostat.

Here is my flow through my coolant lines. All i know its like boiling water from the log style manifolds but the engine temp is around 160!!

Also the out-drive flow seems like its coming out pretty steady uh??? take a look at pictures below.

 

[bruceb58]

Re: 1979 350 260hp manifolds running hot!

The purpose of Salt Away is to run it though your engine after each use in salt water. Its not going to do you much good at this point. Time to pull your risers and see what the condition of the riser and manifold is to see how much corrosion you have in there.

Where are you measuring 210 degrees? At the riser?

 

[knightowl]

Re: 1979 350 260hp manifolds running hot!

My log style manifolds where replaced by brand new ones last year too. The raisers where replaced by brand new ones 3 years ago.

The raisers are at 140 degrees. The log style manifolds are at 200 +. Supper weird. Its like the water does exit fast enough. Do you think the thermostat does open all the way?


I was in salt water for a fishing tripe once, that's why i had to use salt away.

 

[knightowl]

Re: 1979 350 260hp manifolds running hot!

Additional note:

I also remember last year i had a similar problem. I replaced the water pump inside my alpha drive and replaced the thermostat and if fixed the problem.

How many vote its the out-drive water pump?

How many vote is the thermostat?

How many vote its something else?

 

[bruceb58]

Re: 1979 350 260hp manifolds running hot!

Depending on where you are measuring it sounds ok to me. Normally, the cooling water is sent to the manifolds first and then it travels up through the risers unless you have a seperate hose that feeds the risers as well.

 

[knightowl]

Re: 1979 350 260hp manifolds running hot!

this is what i have. Only 1 hose goes to each raiser. two for the log style manifolds.

 

[knightowl]

Re: 1979 350 260hp manifolds running hot!

one thing i do remember making mistake on. I had the out-drive lifted all winter long. So if their was any water in the out-drive pump, i think it froze and cracked or has some damage.

Does that water pump help bring in water to engine or release water from elbow? Doesn't it suck up water to engine? This is whats making this diagnostic so hard to decided on. Almost just want to replace both.

 

[intimidated]

Re: 1979 350 260hp manifolds running hot!

I think that sounds alright. i believe the system runs water through the block before being run through the manifolds, so the cooling water is already hot before it gets there and picks up additional heat from the manifolds. the elbows are being fed a blend of cool water all the time plus whatever is being rejected from the cooling system.

naturally the manifolds will run hotter than the coolant temp, and will be hotter than the elbows.

 

[knightowl]

Re: 1979 350 260hp manifolds running hot!

I was able to hold the water pressure of the raiser port in with my hand as well as the hose that connects to the raiser port while the engine was running. It doesn't seam like theirs a lot of pressure to force my hand from those port/hose.

However, when i release my hand, there seems to be a pretty steady flow.

 

[bruceb58]

Re: 1979 350 260hp manifolds running hot!

I am more familiar with mine where the manifold gets the inlet from the thermo housing and the risers get its water from the manifold(not with a seperate line). Very possible that the riser is getting more coooling water than the manifold. Would be nice if someone who has the same exact setup could measure temps for comparison.