Cooling issue... '89 VP AQ271C

[jhetrick55]

I have the engine I mentioned in the thread. I'm having cooling issues. Here is what I've done so far:
1. Replace the connection from the drive to the hose which runs through the transom. This includes removing the upper gear housing and replacing the seals on the bottom of the gear housing before replacing.
2. Replace the raw water hose running through the transom and made sure the flange on the hose sealed up tight to the transom.
3. New impeller/seal and checked housing for leaks.
4. New engine water pump.
5. New thermostat.
6. Cleaned the manifolds/risers.
7. Reverse flushed as much as I could from the system.

The boat will run fine with an adapter hose I made which the garden hose screws into then goes directly into the impeller housing. When I have water pressure to it while the engine is off, I can hear water flow through the engine and out the bottom of the drive as it should. This leads me to believe is something on the raw water intake side of things, just simply not pulling in enough water.

It WILL NOT run on muffs, and it did get hot, although slower than on muffs, the one time I've had the boat on the water. I did another post wondering specifically about the power steering cooler, but I checked that out and it looks fine.

I don't know where to go from here. I'm one last step away from taking it to a mechanic. Thanks for any help you may be able to offer!

 

[dubs283]

I would back flush from the sea water pump inlet hose through the transom and out the drive. Check for a restricted flow/leaks

 

[jhetrick55]

Thanks dubs283. I should have mentioned that I have done that and all went well. That was part of checking into power steering cooler. I may try again, however.

 

[QBhoy]

Hi. If this is the engine I think it is…are these not normally an engine with closed water cooling ? If so…have you looked at the internal closed cooling system for being the issue?

 

[jhetrick55]

Qbhoy, I have considered similar. This is raw water cooled, not a closed system, but I assume maybe you mean have I considered from the water pump (not impeller) on? As I mentioned, I did add a new internal water pump. I guess it's possible it's not good. Water seems to flow well from all the passages, like the engine drains and plugs in back of the manifolds, and if I pull hoses there always seem to be water in them. What else should I check?

 

[Scott Danforth]

Did you replace the fitting on the H frame swivel?

Did you replace the O-ring at the bottom of the H frame pivot tube?

When running on muffs, are you plugging the lower pickup

 

[dubs283]

Did you replace the fitting on the H frame swivel?

Did you replace the O-ring at the bottom of the H frame pivot tube?

When running on muffs, are you plugging the lower pickup

I took this to be #1 in the original post. OP also says will overheat in the water as well, not just on muffs

OP, have you verified temp with an IR temp gun at the sender/various places on the engine?

 

[jhetrick55]

Dubs283 and Scott Danforth... Yes I am plugging the lower pickup when on muffs. And yes I replaced the Hframe fitting. I plan to get an ir gun this morning and check the temp with it today. I will report back.

 

[jhetrick55]

I picked up an infrared therm. Before I started the engine, I back flushed the water intake hose, back through the power steering cooler and transom and then finally through the hfram fitting and out the lower unit. Good flow, no leaks anywhere I could see. I then ran water from the garden hose directly into the impeller housing through the contraption I made up. First I opened the drains on the engine and let the water run to flush anything I could. Closed them, started the engine and it ran up to 162 and then cooled off to between 156-160.pretty normal in my understanding.

Next, I put on the muffs, made sure the bottom pick up was plugged and started the engine again. This time it climbed up to 190 at the temp sensor before I called it off. No signs of slowing...

So, that's where she sits right now. I'm just at a loss. Don't know where to go from here.

 

[dubs283]

What brand sea water impeller do you have?

 

[jhetrick55]

Volvo penta, from the nearest dealer. I'm kind of wondering if this isn't the wrong one. On the other picture from keypart.com, there is one for the 6 hole cover, which is what I have, and the impeller is a touch wider.

 

[dubs283]

I'm kind of wondering if this isn't the wrong one. On the other picture from keypart.com, there is one for the 6 hole cover, which is what I have, and the impeller is a touch wider.

It's quite possible. Volvo used/uses many different styles of sea water pumps/impellers. Best bet is to go oem (which you have) but verify by eye the style, number of vanes, hub style, length, etc....

Have no idea the exact p/n for your six bolt/screw cover impeller but can say I've replaced that style very recently, so it is available

 

[Scott Danforth]

What brand of muffs do you have?

 

[jhetrick55]

I've done some other checking and it does appear the other impeller will work and fit tighter and create more suction. I'm going to try the other impeller and see how that goes...why not at this point? Plus I've always felt that the impeller I got from the dealer was looser and didn't fit as well as other impellers I've used, I just chalked that up to having worked on outboards more. My muffs are the round ones, but they actually seal up pretty well.

 

[jhetrick55]

Great news... I got the boat out today after installing the new impeller and the boat ran great and didn't get hot even a little! Thanks for all the help, I also fixed a couple things with your advice!