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Volvo-Penta 4.3 GXi-D Runs Hot Above 3000rpm

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rholling424

New member
Gents,
I have a 1998 Four Winns 180RX with a Cobra SX outdrive. In 2003 I replaced the original carbureted engine with a new V-P fuel injected 4.3L GXi-D. It has run strong until last summer when it began running hot. Over the winter I replaced the rubber impeller which showed no wear and the thermostat. It runs at a steady 170 degrees up to 3000rpm. If I run above 3000, the temp runs away to 200, 220 and overheat. Can you help with this one?
Thanks for your help, Holly.
 
Something to try, I had the same experience on the 3.0gs .
There is a flapper valve that prevents flooding into the engine during a fast launch. flapper on the exhaust riser coming up from the SX drive broke off and was stuck at the lower end of the exhaust pipe. Removed the Zinc on the leg and it fell out.
Did not replace it and is not needed on my boat.
This cleared the exhaust and problem fixed. At lower rpm the engine temp was noermal, but due to the restriction on the higher rpm it overheated.
This is a quick easy check to do before you strip off the riser, replace impellar, replace stat, etc like I did.
Hope this helps
 
Thanks Mr. Carvalho. What is the 'zinc' and where is the 'leg' from which you removed it? I'll give it a try. The original stat opened in boiling water - seems to work fine. It is possible a small piece of the original stat gasket fell into the manifold as I was scraping it off, even though I stuffed a rag in the opening. Backflush exhaust water jackets is an option but I need a Cirque de Soleil gymnast for that! Both side feel like they warm up and maintain same level of heat. I could check the new impeller however as you know, access is a pain and while I've replaced them every other year, none has shown wear. Sound like it may be easier to access the flapper. Where do I start?
 
I would tend to agree that the back-flow prevention flappers would be something to look into.
However, they are to be in place for much more than a launching issue!
The flappers are there to help prevent surge and back flow during low RPM, and/or perhaps when the engine is OFF.

I'd not run without these in place.
Volvo Penta installed these for a good reason.
 
Thanks Rick. Where can I find the flapper? I'm a pretty good tinker but on the outdrive, I've only worked on the shifter link and replaced the lower section of the drive. Thanks, h.
 
Back flow preventers on the Volvo Penta I have are obsolete and no longer available.
Besides that, hope you eleiminate this as your overheating problem.
my apologise, zincs also known as sacrificial anodes and theone i mentioned is at the exhaust outlet, on the gimbal housing, easy to remove with the leg raised.
Good luck.
 
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