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AQ125 overheating problem

J

jaxworks

Member
"I have a 1985 Bayliner Ciera

"I have a 1985 Bayliner Ciera with an AQ125 Volvo Penta engine. It functions perfectly until you decide to cruise somewhere and then the temp slowly climbs to 200F and I drop it back to idle and it immediately cools off.
It has a new raw water pump and it squirts water straight up out of the cap at idle, so it's working fine. The engine water pump spins free and at idle you can see the water moving in the tube under the cap. The thermostat is new (and it did the same thing with the old one) All the hoses are clean, the o-rings are new, the raw water filter is clean. It has fresh water/glycol mix in the engine. The timing is set correctly, it has the correct plugs etc. It shoots plenty of water out of the exhaust port in the sterndrive. I have tried several different pitch props in case I was loading the engine..all the same problem with any of them.
I have taken the heat exchanger apart and cleaned it with Muratic acid to remove the scale, picked out the 3 or 4 small pieces of junk in the fins.
So what now...any suggestions?"
 
"Have you checked the raw wate

"Have you checked the raw water hose connector in the outdrive? If it is corroded/perforated, the pump will suck air instead of water when the boat is on the plane.

Also, remember that the normal operating temperature for your engine is 180ºF-198ºF, so it is not unusual or abnormal for the temperature gauge to climb up to 200ºF as long as it does not go higher than that."
 
It climbs much higher if I let

It climbs much higher if I let it...and I just checked the hose and fitting and all seems well.
Does a 270 outdrive have o-rings anywhere inside the outer housings that could go bad or need replaced?
 
"You may want to check the con

"You may want to check the condition of the exhaust manifold, for if it is corroded and with scale in the water passages it will severely restrict water circulation. Also, you may want to check inside the intake grids in the outdrive for marine growth (barnacles) and to make sure the grids are clear.

When it comes to the raw water hose connector, those things usually go in 5-7 years. Even if from the outside it looks OK, you may want to remove the hose clamp and pull the hose out (if you haven't done so) just to make sure the hose connector is not the culprit."
 
"Nope, no oil cooler in the AQ

"Nope, no oil cooler in the AQ125, unless someone wanted to complicate his life and added one."
 
I have removed the suction hos

I have removed the suction hose and both the water connection and the hose are in good shape. I have filled a container with water to an inch above the top intake grill and the raw water pump will not prime and pick up water even if water is poured in the outlet tube of the raw water pump to help prime/lube the pump. The pump is working so well it even makes a bit of pressure if you cover the outlet hole down in the plastic fitting with the cap on it.
Should it be able to prime in this this situation?
 
"I bet it's the exhaust ma

"I bet it's the exhaust manifold...My boat was operating 210 degrees till manifold was replaced this week(more on that latter).Now it's operating at 200 degrees.And no back pressure.Before mani was changed higher RPM's meant more water spitting out under strainer cap.The mani. was last on things attended to in my boat,at least it's done now."
 
Thanx for all the suggestions

Thanx for all the suggestions but I found the problem. I taped the inlet grid in the lower drive closed and poured colored water in the hose going to the raw water pump and found the leak. The area under the water hose connection in the stern drive was corroded and it was sucking air when the boat was on plane.
I have the entire outdrive off now and am replacing all the gaskets and o-rings.
 
"Hello all. I came across thi

"Hello all. I came across this forum after searching the internet, after having the same problem.

Thanks to a post that came up from....August 5, 2007...reference "AQ170/270 outdrive overheating problem"

El Pescador gave the solution to my problem.

I have a 1986 Bayliner Capri, 2.1 Volvo Penta, with 270 outdrive.

I rebuilt the entire engine, and started up real quick, runs smooth. I was watching all the gauges, and noticed the temp gauge was at 175 degrees and then to 180 degrees.

I had the outdrive, minus the prop of course, sitting in a large storage tub, filled with clean water, and noticed there was not much water circulation, or hardly any water coming out of the exhaust port.

Through my reading of Raw water pumps, which I placed a brand new impeller, a suggestion was posted, to place a clear re-enforced hose between the 2 raw water intake tubes, so you can see the water going through the intake tubes. After I installed the hose (has to be thick enough so it does not collapse under high RPM), I noticed hardly any water going through.

El Pascador...posted to duct tape the water intake grids and plug up the drain hole on the bottom of the outdrive. ( I used an expansion plug)

He suggested to disconnect the raw water suction pipe (as discribed above), then connecting a garden hose to the section of the pipe that leads to the outdrive.

I barely turned on the hose, and found the LEAK!

It was oval gasket, that is located below the hose connector.

Thanks for the easy way to find out where a leak may be!

My next step would be to remove the lower gear section and replace both the OVAL ring gaskets and the hose connector assembly.

Thanks for having this website/forum here, for everyone to ask questions and get answers !! Keep up the great work !!"
 
"I did the same thing except i

"I did the same thing except instead of a garden hose I used colored water and poured it in the same intake hose to the engine using a funnel and found the leak in the same spot...under the gasket. Apparently the housing corrodes away just enough to suck air, so when the boat is on plane the engine starves for raw water."
 
"Life is good....now to start

"Life is good....now to start taking apart the outdrive...
At least there are manuals for that. Thx Jax for the reply. You got your seal all fixed then?"
 
"yes...I traded an old shotgun

"yes...I traded an old shotgun for a complete 270D outdrive many serial numbers and many years newer than mine and swapped them out after replacing all the steering and lifting bushings since I was in there anyway. All new o-rings etc, all lubed up with water resistant red grease prior to assembly. Tested it today and all is well. Now to head into the Columbia River this weekend to try for some fall run salmon!"
 
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