HELP!! 2001 Volvo Penta SX running hot

[Searay205]

Ok guys 2001 Volvo Penta 5.7 liter. Boat starts to overheat as soon as I get on a plane, idling and revving in neutral to 3000rpm in water and temp stays at 160F. As I get on a plane the temp climbs to 180F then I back off let it get off plane and it cools back to 160F. If I don't back off it would go to 200F quickly (verified with IR gun).
New engine, new manifolds, new thermostat, replaced nipple in outdrive (trying to eliminate any vacuum leaks on suction side), rebuilt sea water pump, engine circulation water pump new with zero improvement. Was overheating prior to original engine failure. With ear muffs on i can find no leaks going to seawater pump. Does anyone have a clue or troubleshooting suggestion. Is it even possible my suction hose is collapsing when getting on a plane.

 

[Senior B]

Water tube in the lower unit?

 

[Searay205]

I noticed with the ear muffs on hose on engine off water drips out of the 4 little holes near the cavitation plate. Is this normal, or should water only drip out the holes when engine running?

 

[BRICH1260]

Might pull the water intake line at the pump with the muffs on and water flowing to make sure no obstructions in the intake to the pump. Then pull the large water out line from the pump to the thermostat to make sure the thermostat housing is getting adequate flow out from the pump.

 

[Searay205]

Yea they both look good. Again past the seawater pump everything is brand new. I am beginning to think water tube in lower unit, besides it the only thing that hasnt been replaced.

 

[Scott Danforth]

check the fitting at the drive that the hose connects to. if its cracked, you start sucking air as soon as you are on plane

 

[Searay205]

I pressurized from pump suction back to outdrive with garden hose and didn't see at leak transom fitting. How fun to look behind the engine, lol. Tomorrow I will drop lower half and replace seals, why not, its a tradition with this boat to replace everything.

On a side note ran like crap finally got carb rebuilt but was still popping under quick throttle. I drained 3 year old fuel and put in my car (15 gallons). car ran perfect. put new fuel in boat and it runs perfect now. can't believe a carburetor is more sensitive than fuel injection but in this case it is.

 

[Searay205]

So I had success in replacing the water pick up tube seals in lower outdrive. Ran like a scolded ape on plane off plane for 15 minutes. gauge at 160F. I thought problem solved. I did a high speed pass and temp climbed to 190F and I brought to idle and temp cam down to 160F. Now I have the opposite if I go 30 mph on plane temp is perfect at 160 (before it would overheat), If I go faster than 30mph temp rises to 190F or higher. Now if I idle I am at 170F vs 160F when the tube seals on lower half were shot. what a **** show....... Again all manifolds, engine water pump(s) NEW.

 

[Searay205]

Well this is officially old. I went ahead and replaced seawater pump with brand new factory assembled unit. So everything is new. Idle temp came back down to 160F at idle, that was a win, at 3K rpm still 160F, 4800 rpm climbs to 190F where I shut it down. EVERYTHING is new. I can't wait to get back in a mercruiser.....

 

[Scott Danforth]

Check the fitting at the drive?

 

[akaBoB]

Check the fitting at the drive?

Well this is officially old. I went ahead and replaced seawater pump with brand new factory assembled unit. So everything is new. Idle temp came back down to 160F at idle, that was a win, at 3K rpm still 160F, 4800 rpm climbs to 190F where I shut it down. EVERYTHING is new. I can't wait to get back in a mercruiser.....

I had an issue like this a few years back in my previous boat. Take cover off where the shifter cable adjustment is. There’s a rectangular plate lower left with 4 screws. This plate covers the water passages. The gasket failed and it was sucking air in when on plane. When off plane this is under water… was a quick fix with some gasket material. Took me several hours to figure this one out.

 

[Searay205]

i replaced the fitting in the outdrive which eliminated the overheating when on plane at 3000 rpm. I can run all day at 3000 rpm with at 160F before i replaced the fitting I could not get on plane without overheating. Now my issue is at 3500rpm and higher temperature slowly climbs to 190F and I slow down

 

[Horigan]

There's a water tube between the lower and upper unit that can corrode and create the symptoms you're having. See item 47 below.

 

[Lou C]

There's a water tube between the lower and upper unit that can corrode and create the symptoms you're having. See item 47 below.

View attachment 361742

that, and the water tube grommets can deteriorate and suck in air

 

[Searay205]

Yes I replaced 47 and seals and that eliminated the problem with it overheating once on a plane. Before I replaced it I would overheat at 3K rpms while on plane now I can run all day at 3k rpm. I am starting to think I may have a blown head gasket, cracked head or block and that what causing the overheat at higher rpms. I going to put some see through hose on my thermostat to manifolds and see if I can see any air bubbles.

 

[akaBoB]

I was to the point of doing putting some clear hoses on. I still have the hoses, but never made it that far. That will definitely let you know if air is getting into the system. Here’s a picture of the plate I referenced. It’s the plate with 4 screws… just happens I pulled the foot on my current boat Monday. You could still be sucking in air here. Good to see the reference to 47 in the diagram as I’ll remember this as something to keep tabs on in the future. As for going back to mercruiser. Once you pull an alpha 1 foot and replace boots etc, you’ll realize how much better the Volvo is designed. Not to mention they shift so much better. Anyway, I hope you track it down and let us know what ya find.

 

[Horigan]

@Searay205
Did you replace the water nipple also, item 18 below?

 

[Searay205]

Yes I replaced it before #47 with no change. #47 definelty improved the situation. I have a clear hose on the seawater pump discharge and I don't see any bubbles. Its hard to watch the clear hoses when you are driving but tomorrow I have a buddy going with me so he can drive while I watch. In the driveway on flush ears I do see some small bubbles on the Starboard clear hose from thermostat to manifold. If they get worse tomorrow then I will do a leak down test on starboard side cylinders

 

[kenny nunez]

If you have a leaking head gasket you will see the water in the incoming hose disappear because the combustion pressure leaking will be more than the sea water pump can overcome.

 

[Horigan]

Yes I replaced it before #47 with no change. #47 definelty improved the situation. I have a clear hose on the seawater pump discharge and I don't see any bubbles. Its hard to watch the clear hoses when you are driving but tomorrow I have a buddy going with me so he can drive while I watch. In the driveway on flush ears I do see some small bubbles on the Starboard clear hose from thermostat to manifold. If they get worse tomorrow then I will do a leak down test on starboard side cylinders

What about #18? Was that replaced?