AQ130C Overheating Help Please

[bwingler]

I need some help, i don't have a manual yet. I just removed the thermostat now i have water flow. Before i did not. I am not running on ear muffs, i connected the garden hose straight to the water pump on the engine. The temp gauge goes up slowly and gets up to 160 then it bounces around down to 140 and finally up to 200. This is without the tstat, i could not get the tstat to move at all by pushing on the spring so i know its bad. I open the drain **** on the block and i have clean hot water.
Shouldn't the engine stay cold without the stat and water coming in the water pump from the hose? And when it climbs to 200 it is real fast. Could the sending unit be bad? This is with the engine idling, if i rev it up alittle it does not make a difference. I have water coming out the exhaust also. I have replaced all the hose's on the engine. I would like to try the lake this weekend.

Thanks in advance

 

[Don S]

Re: AQ130C Overheating Help Please

Did you connect the hose to the raw water pump or the engine circulation pump? Makes a big difference.
Perhaps the exhaust manifold or elbow is plugged up.

 

[bwingler]

Re: AQ130C Overheating Help Please

I would guess it is the raw water, its like a 5/8" hose. Where would the other one be for the other pump? This engine is not a closed loop like a car. No radiator.

 

[Hermyboy3000]

Re: AQ130C Overheating Help Please

I have an AQ130 and I had the same problem earlier this season. My thermostat was locked in the open position and my motor was still overheating. I replaced the thermostat and that fixed my problem.

 

[Don S]

Re: AQ130C Overheating Help Please

I was thinking 131 when I ask which pump, as the 130 only has a single pump.
Look at the picture below. I marked IN as where you have the hose. If that is correct, my best guess is that you have something plugging the thermostat housing (item #3) or the tube (#4) that goes into it. Then all has to pass thru the thermostat.
If you have the boat bow down, it could develop air locks and prevent proper cooling.

 

[bwingler]

Re: AQ130C Overheating Help Please

Yes Don that is where i got the garden hose connected. I have the tstat out and i looked in the housing and block but did not see anything. What temp should that motor be running? Yes i am a noob, first boat and i dont know anything so please bear with me. Which manual should i order? The two copper tubes coming out of the tstat housing get real hot to the touch all the way down them. Now the water coming out of the exhaust is cool to luke warm.

 

[bwingler]

Re: AQ130C Overheating Help Please

I tested the tstat in water today and it opened at 140 degrees. I rodded out the oil cooler. The engine at idle goes to 160 then 200 then 160 and finally climbs to 200 + then i shut it down. I do have hot water coming out of the exhaust. Is it possible that the sending unit or the gauge is not reading correct?

 

[bwingler]

Re: AQ130C Overheating Help Please

Still overheating - Here is what i have done so far, checked impeller, replaced all hoses, rodded out oil cooler, rodded out exhaust manifold, checked thermostat in pan water, ran engine without stat still running hot, pulled out temp sensor and have water flow, has water flow out the exhuast, bought a mechanical water temp guage and it confirms the overheating, did compression test 1-170, 2-150, 3-180, 4-180. Water is hot coming out of the exhuast, water can burn you coming out of temp sensor hole. I am total out of ideas. Anyone please temp went up to about 220 before i shut down.

also the water like surges out of the outdrive like old faithful, no bubbling or surging out of the temp sensor hole just a steady steaming hot stream.

 

[spanner]

Re: AQ130C Overheating Help Please

I had a similar problem with a customers Volvo 4cyl with closed cooling showing symptons as yours. It turned out to be in the very final section of the exhaust manifold where the raw water cascades into the exhaust elbow rubber. The cast iron had rusted/swollen and was backing up the water in the block & manifold causing it to stay around and get too hot, when sufficient pressure had built up it would surge out of the exhaust but by then it was too hot to touch. Sometimes at WOT it would blow the lid off the filter strainer! Replaced the manifold and all was good. Whilst the manifold is off, check the exhaust port on the cyl head around No4 for signs of corrosion as these engines are prone to it and you may end up replacing the head as well.
Hope this helps.

 

[Robj]

Re: AQ130C Overheating Help Please

Barry, just do what they suggested marineengine.com site where you also posted this problem. El Pescador knows what he is talking about.

Have a great day,

Rob.