Volvo Penta AQAD41a overheating

buli

Cadet
Joined
Jun 12, 2022
Messages
14
Hi! I am new in this forum, and i have read many useful threads. But now i have an issue and might need some help.

I got sunseeker mohawk with twin volvo penta aqad41a engines with 290dp sterndrives. After winter, engines started like a dream. I made maintenance (motor oil, oil filter, racor filter, fuel filter, sterndrive oils etc) and put boat on water. When i drive with lo rpm everything works well, but when i drive with full throttle, both engines starts to overheat. I changed impellers, and checked that water rises nicely in sea water filter but still both engines overheats when driving on plane. I also took thermostats off and tried to boil them and they opened like they should.

I found old thread (https://forums.iboats.com/threads/volvo-penta-diesel-overheating-problem.366960/) but pics and links in that thread doesnt work anymore.

Any help or ideas where to look for air leaks or maybe some other issue?

Sorry for my bad english :)

And greetings from Finland :)
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,469
Hi! I am new in this forum, and i have read many useful threads. But now i have an issue and might need some help.

I got sunseeker mohawk with twin volvo penta aqad41a engines with 290dp sterndrives. After winter, engines started like a dream. I made maintenance (motor oil, oil filter, racor filter, fuel filter, sterndrive oils etc) and put boat on water. When i drive with lo rpm everything works well, but when i drive with full throttle, both engines starts to overheat. I changed impellers, and checked that water rises nicely in sea water filter but still both engines overheats when driving on plane. I also took thermostats off and tried to boil them and they opened like they should.

I found old thread (https://forums.iboats.com/threads/volvo-penta-diesel-overheating-problem.366960/) but pics and links in that thread doesnt work anymore.

Any help or ideas where to look for air leaks or maybe some other issue?

Sorry for my bad english :)

And greetings from Finland :)
Ayuh,..... Welcome Aboard,...... What did the old impellers look like,..?? Any missin' bits,..??
How 'bout the impeller housing,..?? any scoring,..?? end plates,..??
 

buli

Cadet
Joined
Jun 12, 2022
Messages
14
Old impellers were fine, no missing bits. Didn't find any leaks from the impeller housing. sorry for my bad english, but what is end plate? pic or part no would help a lot.
 
Last edited:

Bondo

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Messages
70,469
Old impellers were fine, no missing bits. Didn't find any leaks from the impeller housing. sorry for my bad english, but what is end plate? pic or part no would help a lot.
Ayuh,.... The surfaces that ride on the flat sides of the impeller,....

Have you checked for good flows beyond the raw water pump,..??
Is the motor raw water cooled, or heat exchanger,..??
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
Messages
47,309
Make sure to look at the white metal fitting that is on top the H frame that the water inlet connects to. That fitting lasts 2 years in salt, and 5 years max in fresh water.

Also, the o-ring on the bottom of the H-frame pivot needs to be changed periodically

Those two areas are know issues with the AQ series of drives.

If your raw water pump needs replacing, the F6 bolts in place of the F5 Johnson pump and provides 20% more flow
 

buli

Cadet
Joined
Jun 12, 2022
Messages
14
Ayuh,.... The surfaces that ride on the flat sides of the impeller,....

Have you checked for good flows beyond the raw water pump,..??
Is the motor raw water cooled, or heat exchanger,..??
haven't yet checked flow. Both engines is with heat exchanger.
 
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