Volvo 125aqa overheat

[salmoneer]

I have a volvo 125aqa whitch overheats and squirts engine coolant out of the holding tank. I have replaced the engine water pump, thermostat, seawater impeller and exhust manifold. The engine still runs at 200+ degrees at any over 3500 rpm forces coolent out from under the tank cover can anyone help solve this problem? The boat is a 1983 Renken.

 

[Dunaruna]

Re: Volvo 125aqa overheat

Hi salmoneer, welcome to iboats!<br /><br />Do a compression test. A workshop can also perform a 'combustion detector' test of the heatexchanger. I think you have a headgasket problem.<br /><br />Aldo

 

[salmoneer]

Re: Volvo 125aqa overheat

Aldo,thanks for the reply and suggestions to fix my overheating problem.In addition to the work imentioned i have also had some pitting on the head filled planed and replaced the head gasket.This past week i reset the head bolt torque to spec 66 ft lb, but I'am not sure I did it right. I didn't first loosen the bolts and then reset the torque,I just checked to see if they were still at 66ftlb, should I have done it differantly. IN all, todate Ihave cleaned the heat exchanger core [just as you would an auto radiator,replaced the exhust manifold,replaced the thermostat,the sea water impeller ,the engin water pump and all the seals and the engin coolent holding tank cap.Something Ididn't mention is I take take the sea water with a through the hull port,not through the outdrive.This is my second try to respond to you,I'am not sure if the first message ever made it,I hope I did this right Once agan thanks for the help and if you can please sent more about the heatexchanger combustion detector test I'am not all sure what that is or how it's done or who can do it for me. BEST regards Salmoneer

 

[Dunaruna]

Re: Volvo 125aqa overheat

Why did you do the headwork/gasket replacement? What problem did you have?<br /><br />With heatexchangers, just flushing with a hose often will not get them clean, they need to be dismantled and 'rodded out', the gunk inside becomes hard and difficult to remove.<br /><br />Headbolts and their coresponding threads need to be spotlessly clean, then lubed with a light oil including under the head/washer of the bolt. Then torque in stages according to specifications.<br /><br />As with a car, when a headgasket blows, exhaust combustion gasses enter the cooling system (a closed cooling system on a boat). A 'cooling system combustion' test will detect exhaust gasses and therfore verifying a blow gasket. You may have a different name for this test in the U.S. - dunno.<br /><br />Pressure is building up inside the exchanger, it is pushing past the cap. Could be a fault cap.<br /><br />I'm still thinking headgasket.<br /><br /><br />Aldo

 

[salmoneer]

Re: Volvo 125aqa overheat

Aldo" Thanks for staying with me on this problem.I oringinaly replaced the head gasket because of the overheating .First I replaced the head gasket and removed the heat exchanger core cleaned it by soaking it in a bath of 20% muriactic acid diluted 50/50 with water.I let it soak for about 5 min and flushed it with clear water to stop thea acid action and blew it dry with compressed air,it looked like new,I then ressembled the heat exchange unit with all new seals.I still had the overheat problem ,so Itore it down again and had the pitting around the rear most cylinder filled and had the head resurfaced and replaced the head gasket for the seconed time. At that time I replaced the exhust manifold,the exhust rubber bellows and the sea water impeller I also replaced the thermostat and the tank cap.After all I have done I'am still running on the hot side {200 plus and still loose coolent from under the tank. I'am sure your right I'am getting presure back through the heat exchange system,but I kown wtat to do next. I'am leaving for the lake in an hour or so and will see if I can find any other possible causes for my problem. If I run about 3500rpm with a moderate load I can get by with it,but I would like to run a little harder and not have to constantly watch the temperture gauge Thanks again <br />'Salmoneer"<br /><br /><br />[

 

[salmoneer]

Re: Volvo 125aqa overheat

Aldo' This past weekend I changed the engin oil thihking that if the head gasket was bad or completly blowned I would have signs of water in the oil,that millkey white look,but it was clean.I just got a new compression gauge and my next step is to re-check the compression in each cylinder.I had checked before,but Ididn"t have a gauge that could really reach well into cyinlder plug opening and couldn"t get really good accurate readings.If the compression is good it should prove the head gasket is OK ,then I'am completly losed I be looking for a new/rebuilt engin or possibly a short block. Posibly I could replace it with aq125b or an aqa130. I think either would marry to my 270 outdrive.ALDO,or anyone else,any other thought.THanks Sslmomeer WD40 is the universal cure for all mechanical ill's.