port side riser overheating

[jbauman4306]

I have a 2004 volvo penta 5.7gxi-e and the port side riser gets extremely hot and sets off the alarm when cruising between 3500 and 4500 rpm, the starboard side is fine. It doesn't when cruising under that.the risers are new and there's no blockage in the hose that goes to the exhaust manifold. Any suggestions.

 

[alldodge]

Howdy

Are you sure it's getting extremely hot? Have you checked the temp with a Infrared temperature meter?
When was the last time the impeller was changed?
Is this a closed or open cooled motor?

 

[Bondo]

and sets off the alarm when cruising between

Ayuh,... The alarm sensor is in the T-stat housin', not the manifold or riser,.....

As AllDodge asks, How long ago was the impeller changed,..??

 

[skydiveD30571]

Hi Bondo, the 5.7GXi-E does have an exhaust overheat sensor on the back of each riser. It will trigger an alarm.

I would IR the riser and see what temperature it is actually getting to.

 

[Bondo]

Ayuh,.... My bad for thinkin' it'd be like every other boat motor built over the last many decades,.....

 

[jbauman4306]

It is a open cooled. I change the impeller every year and I have not put a temp gun to it yet but it's hot to where you can't touch it for more than a few seconds but the starboard side you can put your palm on and leave it there.

 

[bruceb58]

You may have an obstruction in the thermostat housing or your riser/manifold is clogged on that side.

Saltwater boat? If so, have you ever changed your manifolds and risers?

 

[alldodge]

It is a open cooled. I change the impeller every year and I have not put a temp gun to it yet but it's hot to where you can't touch it for more than a few seconds but the starboard side you can put your palm on and leave it there.

You might not have an issue other then your alarm, the starboard side is always cooler then the port, just the least resistance to water flow. If you can touch it and not burn your self it's not that much hotter. Need to check the temp to be certain

 

[jbauman4306]

When the alarm goes off the boat also slows down, I figured the alarm triggers the computer to go into low rpm mode. After a few seconds at low rpm's the alarm stops and I can start cruising again, but then it will happen all over again.

 

[BRICH1260]

Pull the hose from the thermostat housing going to the manifold, start the engine and check for water flow volume from hose. Do it on a cold engine and do not let engine run for long, just long enough to check water flow. If low flow of water check pump output or blockage in housing or hose. If flow good, blockage in manifold/riser probably your problem.

 

[alldodge]

When the alarm goes off the boat also slows down, I figured the alarm triggers the computer to go into low rpm mode. After a few seconds at low rpm's the alarm stops and I can start cruising again, but then it will happen all over again.

Agree, it's doing what it should do. If ECM finds an overheat issue it will reduce power, once overheat is gone it will allow more power. Just need to know if it's the sensor or an actual overheat

 

[skydiveD30571]

You might not have an issue other then your alarm, the starboard side is always cooler then the port, just the least resistance to water flow. If you can touch it and not burn your self it's not that much hotter. Need to check the temp to be certain

I agree, my starboard side riser I could hold all day long. The port side riser is hot to the touch and very uncomfortable after a second or two. I've had a legitimate blockage in the hose from the t-stat to the riser before...the alarm went off shortly before the exhaust rubber parts started smoking and boiling :blue:

 

[user-name]

I would pull the manifolds. I just bought a doner boat raw water cooled california boat I don't believe the PO ever removed the rear MF plugs, The MFs were full of sand

 

[jerryjerry05]

Changing the riser without doing the manifold isn't the way it needs to be done.
They should be changed as sets.
​You can pull the riser an see the flow ports and they may look clear but that's just the top.
The crap and crud in the manifold could be blocking the flow??

 

[jbauman4306]

So I temp the risers and the port side was around 196f and the starboard side was around 176f. Does that sound right?

 

[jbauman4306]

Also I changed the thermostat and thermostat housing but it's still setting off an alarm. Could it be an alarm to something else? Maybe the fuel pump if it has one?

 

[skydiveD30571]

Have you done anything with the exhaust overheat sensors on the risers that were mentioned? The fuel pump does not have an alarm. You have alarms for low oil pressure, exhaust temperatures, and coolant water temperature. You also have senders for oil pressure and coolant water temperature which feed the gauges on the dash but do not trigger alarms.

 

[jbauman4306]

No I haven't, should I look into replacing them, Does the temp I posted sound right? I guess I should look at oil pressure also but I don't think its that because it takes a while for the alarm to finally go off and go into low rom mode.

 

[jimmbo]

They both seem to be too hot. You said you could hold your hand on the starboard side. 176f is almost the temp for well done beef

 

[jbauman4306]

Yeah I think when I did that the boat was back at idle so it cooled down. I tried it again right after the alarm went off and they both were real hot. I read on other posts about air getting in could that be it? The engine temp gauge is only around 120f What should the risers be at?