Volvo aq130c Overheating Please Help

" I have a 69 volvo 4cyl aq130

" I have a 69 volvo 4cyl aq130c. Over the winter I pulled the engine because one of the pistons was bad. I couldn't find the same size pistons so I had the engine bored 30 over. I installed 4 new pistons,rings,bearings and full gasket set. Then put boat in the water and it ran great for a month and now it is overheating before I back out from the pier. I installed a new t-stat and impeller for the water pump, still no fix. I checked the flow of the water pump and thats working fine. I don't know alot about this engine but any info may help or web sites I can look at. Thanks, Shane "

"How do you know it's over

"How do you know it's overheating? If the gauge is the only indication, I'd put a meat thermometer in the exhaust water and see if it agrees with the gauge. If the exhaust water is flowing normally but too hot, see if you can localize the heat. After starting the motor cold, feel different parts of the head and exhaust manifold for too quick heating.

You may have a blockage in the cooling system. This is frequently caused by a chunk of rust or sediment dislodged from the water jackets or exhaust manifold during the rebuild. Did you flush the block & head water jackets and clean or replace the exhaust manifold?

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" Croozertoo, Thanks for the i

" Croozertoo, Thanks for the info. I do think the gauge is working normally, because in the front of the head there is a rubber freeze plug I took out and ran the engine, to see if water was flowing (it was). But when I shut the engine off I looked inside the head where this plug goes and the water was boiling. So the gauge must be working.


If I have a blockage somewhere how would I free it up? How do I flush the system? "

"Well, it's not as bad as

"Well, it's not as bad as a needle in a haystack, but you still need to try to localize a hot spot if you can. An infrared thermometer can help with this. If you can't, you'll have to start removing suspect pieces like the exhaust and intake manifolds, check all hoses, etc. You're working your way down to the block and head.

Other thoughts: is the raw water pickup clear? Try running off a garden hose to see if the overheating still happens. Are you sure your thermostat and hose routing is correct? Basically just work your way through the cooling system looking for any blockage or restriction. Invade the block and head only as a last resort.

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" Hopefully you found the prob

" Hopefully you found the problem by now, but I just went through the same thing. In addition to the items above I would check to see if all connections in back of the boat are properly connected. After I replaced my thermo, raw water impeller amd removed my circulating pump I found that my problem was the small hose going to the outdrive popped off and I was sucking air in even though it was underwater and I was getting some water through the engine. Also Are you sure the tne new thermostat is properly working. I ran mine without it just to see if the temp would go up without it. If none of these probably a blockage. "

" I have a 72 aq130c it runs l

" I have a 72 aq130c it runs like a champ, but it seems to have a lot of blow by. oil comes out of the dipstick when runnig hard. where should i get rebuild kit. is my only problem the rings. "