AQ271c overheating

[jhetrick55]

Hey, I was given a 1989 Carver Montego 23 with an '89 V-P AQ271c. Currently the boat will run and sounds healthy, but it is overheating. I've replaced impeller and circulating pump and I've checked as much of the system as I know how to make sure water is able to move through the engine. Does anyone have suggestions of what else I could check? Also, i've run on muffs and I've filled a tote of water under the outdrive. I also have replaced the hose that runs through the transom and the fitting connected to that hose which runs into the lower unit. Thanks for any help!

 

[kenny nunez]

The “O” ring that seals the lower gearhousing to the suspension fork is drawing in air when the boat is on plane.
Drain the oil. The only tools needed is a set of fractional allen wrenches.
Sierra# 18-3888 lower gear unit seal kit.
Sierra# 18-2778 water hose connection kit with power trim
Sierra# 18-2777 “. ” without power trim
Sierra# 18-2775 water hose.
The #s ending 2278-2777& 2775 are for the aluminum connection which is notorious for breaking under the hose clamp so look at it closely.

 

[jhetrick55]

Thanks kenny nunez. I've never had the boat on the water, so I've never had it on plane. I've also already replaced parts you've mentioned... should have mentioned that.

 

[Scott Danforth]

check the pot-metal fitting on the top of the H-frame pivot. the one where the cooling water hose connects to

even in fresh water that fitting only lasts about 3 years

 

[jhetrick55]

Thanks Scott. That was one of the pieces which have been replaced. Yeah, the old one was bad!

 

[Scott Danforth]

the cooling system is simple. if that fitting is good, the only other place it can suck air is the o-ring at the bottom of the H-frame.

to replace that o-ring, the drive should come off so you can split the case

however if you tried to run from a tote under the drive (as you posted in post #1), you toasted the new impeller. pull the impeller and put a new one in

if your pump is sloppy, replace it (they are about $150 from Johnson pump)

you need to run on muffs (and plug the bottom pickup hole) or you need to have the whole boat in the water.

 

[jhetrick55]

Ok. I'll be going back through things tomorrow, and then hopefully taking it to a launch to try it in the water. It may be a simple fix, maybe just something I overlooked. If anyone has any other ideas, let me know!

 

[Scott Danforth]

only other thing it could be is the PS cooler is plugged and you are not getting water flow. back flush from the raw water pump would cure that.

 

[kenny nunez]

There is something else worth looking at, there is a metered orifice in the thermostat housing which is the bypass when the thermostat is closed.
Sometimes they are so blocked up that you cannot see it. If you have a blasting cabinet would be good.
The earlier Volvo power steering coolers had small tubes which could get blocked up like Scott suggested.

 

[QBhoy]

Thanks kenny nunez. I've never had the boat on the water, so I've never had it on plane. I've also already replaced parts you've mentioned... should have mentioned that.

Try it in the water first. These sometimes struggle to pull water up from muffs on the drive. I only know of one set of muffs it can manage it. Other than that…check the power steering cooler on the intake hose isn’t drawing air.