AQ 151C still overheating with new impeller

[Ark-86]

Hello again

I was not sure whether to start a new post, but it's been 3 weeks, and sort of a new problem. I'm sure one of you will let me know if this an etiquette
no no.

My newly installed impeller, shaft, and cross piece carrier etc seem to be circulating water through the raw water system. When I crack open the drain **** on the exaust manifold, lots of water comes out after I start the engine. I'm running it in the river (on the trailer) with the drive down, so I can't say for sure how much water is being pumped through.

The temperature gauge heads steadily to the red, and the manifold gets pretty hot. The new rubber exhaust hose coupler even got hot....then it all cooled, after I primed the pump via the strainer cap. Seemed like I had finally gotten past the ovheating issue. No dice, it started overheating as soon as I left the trailer and drove 100 yrds.

Now it overheats on the trailer again. She's teasing me and we've not even rounded 1st base... There does not appear to be any blockages in the flow of water, but I could do more thorough checking I guess? I read in one thread that the thermostat may have been ruined by the initial overheating? Guess I should take it out and test it? Does it sound like a thermostat? At least I can get one locally.

I'm rounding up some metric wrenchs, sockets, and extensions tomorrow to take a look, as I've had it with the SAEs not quite fitting. This is such a nice clean smooth running engine, it deserves a much smarter owner. Reminds me of the 3 old Volvo cars I've had...Any tips would be helpful indeed. I may have to hit the rum soon otherwise!

Tim

 

[captmello]

Re: AQ 151C still overheating with new impeller

Replace the thermo, easy enough to do. Yes that could be it. However the manifold should still be cooled even when the thermo is stuck. When the engine is running, you should see a lot of water running through the stainer even at idle.

 

[Ark-86]

Re: AQ 151C still overheating with new impeller

thanks captmello,

I wondered about the hot manifold, wasn't sure how it all works... maybe it only cooled it for a few minutes after I primed it . I checked the intake, it looks fine.

Will replace the thermostat and try again. After that I may have to get serious about finding a blockage.

 

[jerryjerry05]

Re: AQ 151C still overheating with new impeller

Did you test the pump for output after you changed the parts?
What condition is the wearplated on the pump?There is an eccentric cam in the pump that wears and can cause to not pump right.
How old is the manifold?They can look brand new and be full of crap.Do a flow test.You said new exhaust bellows,how did the end of the manifold look?
Any rust and corrosion means that the inside usually is bad.Inside the resivoir is a heat exchanger that can be clogged and not let enough cooling water to circulate.
Fill out your profile as there is a difference from salt and fresh water problems.J

 

[bruceb58]

Re: AQ 151C still overheating with new impeller

You may want to try installing a clear hose inline with the pump to see if you have an air leak toward the drive. Volvos of that type are notorious for corrosion where the hose connects to the gimbal housing and allows air to get in which causes you to lose suction.

 

[Ark-86]

Re: AQ 151C still overheating with new impeller

Thanks guys for your replies. I was away rounding up parts and vinyl for seats etc.... just saw the notes. Didn't know about the profile. Just filled in some info there. (boat has never seen salt water)

I will check the pump flow and the manifold. The impeller pump looks good inside. The cam really compresses the impeller fins, and shows no obvious wear. The timing cover was bent, (story in my previous thread), and may have held the impeller shaft at a slight angle or a millimeter off center. I can't imagine it affecting the performance, but I found another one and will change it anyway.

The water coming out of the manifold plug and oil cooler line etc is crystal clear. Perhaps there is a piece of an old impeller plugging up the flow somewhere?

I didn't change the exhaust bellows, only the rubber connector between the back of the mainfold and the ehaust pipe. as it had burned off. hard to see into the manifold from there, maybe a mirror and a light.

Not sure how to check for an air sucking issue. I can start it on the trailer in the water and listen or look for it I guess. Or try to hook up the clear hose

t