HELP I'm Stumped is running hot!!!!!!!

[doubleDs]

First off hello everyone!!! i have a 21 glasstream with the mercruiser 350. the motor is newer like a 93 and an alpha gen 1 outdrive. The temp guage reads 150 all the time. when running you cant touch the exhaust riser on the port side so bad flow right. i replaced the exhaust manifold and cleaned the riser. i have one on order. so i checked the impellar and made sure i had good water flow into the manifolds and i do. so i hooked the ears on it with the hose running on the port side and the manifold didnt get warm. sooo problem fixed and i took it out. well the riser got hot as crap and vapor locked the motor i guess. it idled all day and ran good for a while but when i put the throttle to it it would die. i'm gunna check the thermostat tommrow and i also thought it could be a fuel prob so i replaced the fuel water seperator in fear it was cutting off due to water. i think the temp reads 150 cause its on the star side. any tips or anything???? thanks everyone. oh the water pump is new also.and its in the salt.

 

[Zackman]

Re: HELP I'm Stumped is running hot!!!!!!!

i replaced the exhaust manifold and cleaned the riser. i have one on order.

Not sure what you mean by cleaned the riser?​

Sounds like you might have blockage on the port side exhaust. Is your exhaust flapper still in place on the port side? Sometimes these fail and get lodged in the y pipe.​

Anyhow, don't do anything till you get the new riser installed and check it again. Did you install the correct gasket between the riser and manifold? See this service bulletin to be certain. http://www.boatfix.com/merc/Bullet/99/99_10.pdf​

 

[doubleDs]

Re: HELP I'm Stumped is running hot!!!!!!!

i soaked the riser in muratic acid and cleaned it up. ran water through and it didnt look like anything was blocked. i dont know what other flapper you are talking about eccept the one mounted on the outside of the boat. and one more thing when i hook the ears up to the boat and the water is running in on the port side it looks as though the port side is flowing domint and when the ears are on the star side that looks like it has more flow. anything to look for when i pull the thermostat housing? and what type of thermostat should i get. thanks

 

[slasmith1]

Re: HELP I'm Stumped is running hot!!!!!!!

if it hydro locked the motor you may have an internal leak.

 

[jerryjerry05]

Re: HELP I'm Stumped is running hot!!!!!!!

If 1 riser gets that hot then the thing is probably clogged(you won't be able to see the clog).Other things to look for:Bad impeller.melted flapper(regular exhaust)Do you have thru hull exhaust?
DON"T remove the thermostat!!!! You can cause serious damage if you do.
The manifolds and riser are probably bad.They can last sometimes 15-20yr
Or they can go bad in 10yr.J

 

[doubleDs]

Re: HELP I'm Stumped is running hot!!!!!!!

what damage could i do by pulling the thermostat and replacing it? the reason i thought it locked up is because the fuel water seperator and all the fuel lines are right by the hot manifod and riser. i have a new riser on the way. and yes it is a thru hull exhaust. thanks again! i checked the impellar and it was fine and i had a new one anyway so i replaced it anyway. how would i know it i had an internal leak or better how can i find it? It runs great for like the first 3 hrs then i ran it at idle for like 3 or 4 more and when i was ready to get back home as soon as i went to 3/4 throttle it dies out. and it will crank if i give it more gas but then dies right away and if i let it sit for 30 mins it will run for like 30 min and do the same thing! Is that hydro lock????

 

[Zackman]

Re: HELP I'm Stumped is running hot!!!!!!!

DD, I've never understood why some people try to clean their risers with muratic acid. Muratic acid will kill organic growth but disolves metal just making things worse, at best.

Don't know exactly how your cooling system is designed, but on mine, the cooling lines go from the thermostat manifold to the bottom of the exhaust manifolds. Water is always going to the exhaust manifold and the thermostat only controls circulation through the engine. Unless your system is different and your engine is not running too cool or too hot, I don't understand why you would replace the thermostat.

Sounds to me like the most likely culbrit is the riser you're planning on replacing.​

 

[Don S]

Re: HELP I'm Stumped is running hot!!!!!!!

You guys can create all kinds of problems by replacing A manifold or A riser on a V8 or V6 engine. Since both sides get the same amount of use, one side always goes first, but the other is right behind.
If you have 1 riser plug up, change everything, manifolds and risers, or you will be betting your engine on the other pieces you leave.