AQ125 Volvo Penta Overheating!!

[Higgy-1983]

I have replaced the impeller, thermostat, and heat exchanger in my 4 cylinder Volvo Penta, and it still overheats. I dropped my lower unit into a metal wash tub and just sitting there the temp got to about 240. When I was out on the lake the temp read 260 and it began to cut out. I need a lot of suggestions. Do you think I blew a head gasket. I don't see any signs of the antifreeze leaking. Just sitting in the tub it pumps kind of irregular. Thanks

 

[jeff13601]

Re: AQ125 Volvo Penta Overheating!!

You will be lucky if it didnt do more then that at 260 degrees. Have you backflushed the cooling system and checked the exhaust flaps

 

[radglenn]

Re: AQ125 Volvo Penta Overheating!!

I have the same problem...I am LOST!! I have back flushed, cleaned the heat exchanger and replace the impellor. I don't have a clue what to do next!!!

 

[radglenn]

Re: AQ125 Volvo Penta Overheating!!

One other thing, when the boat is running, and you remove the cap on the heat exchanger do you get exhaust coming out of it? I do and am wondering the it is getting enough back pressure to kill the raw water pump...

 

[tommays]

Re: AQ125 Volvo Penta Overheating!!

if you have exaust gas in the heat exchanger you have a motor problem<br /><br />its a sealed system just like a car only water cools the exchanger instead of air like a car<br /><br />tommays

 

[Haut Medoc]

Re: AQ125 Volvo Penta Overheating!!

Exhaust in heat exchanger? Sounds like a blown head gasket to me..........

 

[Don S]

Re: AQ125 Volvo Penta Overheating!!

Tig, since you started this thread, have you checked the exhaust manifold? If it's plugged up, no water will go through it no matter how great the water pump is.<br />If it's plugged up, it's due for replacement.

 

[Higgy-1983]

Re: AQ125 Volvo Penta Overheating!!

I haven't gotten to try anything knew but the exhaust manifold replacement sounds like a good idea.

 

[Higgy-1983]

Re: AQ125 Volvo Penta Overheating!!

Last night I went through the whole cooling system clamps and tubes were tight. I noticed that the bottom copper tube (suction tube) was leaking a little bit. I theorized that when the pump was working that would cause air to be sucked up. After I put some sealant on the pipes and tightened everything else, and then I ran the boat for twenty minutes. The temp never went past 185, but thats just running from the water in a tub, the real test will be on the lake. I beleive I am going to go ahead and replace my water pump housing, the back seal, and the shaft to ensure everything is sealed. Any suggestions where I should buy these items. Thanks

 

[radglenn]

Re: AQ125 Volvo Penta Overheating!!

Tig,<br /><br />This is Glenn, the other guy with the AQ125 heating problem. I dropped mine it the lake and while at an idle I took the cap off the heat exchanger and it was like old faithful! I thought I had it fixed. BUT over 3200 RPM she overheated again! As soon as I slow down a but the temp goes right back to 185. I checked the thermostat but I think I am going to replace it anyway. I am at a TOTAL loss, I have no clue what else could be wrong with it....Tomorrow I am going to pull the thermostat out totally and see what happens, if it works I will post it for you....Good Luck<br /><br />Glenn

 

[Peter J Fraser]

Re: AQ125 Volvo Penta Overheating!!

DONT pull the thermostat out and run your engine. You will overheat the engine FAST.<br />The thermostat has a valve on it that closes the bypass circuit off, without that the water recirculates around the block only as that is the easiest path to take.<br />Make sure that the thermo is the correct type and it is operating properly.<br />If in doubt replace it with new.<br />Check your RWP suction lines to ensure you are not sucking air anywhere particually in the swivel area on the leg.<br /><br />Peter

 

[radglenn]

Re: AQ125 Volvo Penta Overheating!!

Tig, Mine is FIXED!!!!I replaced the goosneck on the outdrive, gasket, hose and clamps. Cost about 100 for the parts and 30 minutes to replace them. I found the top of the outdrive under the gasket very rough, so I filed it smooth, put a little (very) silicone and snugged it tight to the outdrive. Too tight and the gasket squeezes out. I replaced the hose and clamps too. I took her out and 180 at ANY speed!!!! I hope this helps<br /><br />Glenn