Volvo penta 2003 5.7 GI-DP Over heating a certain trim and rpm ranges

Perdido jim

Recruit
Joined
May 18, 2016
Messages
2
I have read post discussing similar problems and the post advised checking for o ring or water supply hose sucking air may be the problem. I plug the hose feeding the raw water pump and I block the water inlet on the lower unit and then connected my water hose to the flush connection and then pressurized the water intake to the raw ware pump and no leaks. I then connected all of the water supply hose and put water flush ears on the lower unit and discovered that the engine exhaust bllew down thru the anode just in front of the lower unit sea water intake, I feel that this may allow air into my raw intake has anyone exsperanced this before?
 

dypcdiver

Lieutenant Junior Grade
Joined
Nov 1, 2005
Messages
1,043
Perfectly normal it is the part of the exhaust system, it is commonly call the relief port.
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
18,146
IF??? it's overheating at the higher rpm's?? And the system's not sucking air and the impeller is new??
​Then more than likely the risers or manifolds are clogging?
IF?? you run in shallow water and you pick up sand?
You could be full of crud.
Or the cam in the pump might be worn? (probably not but possible)
 

Perdido jim

Recruit
Joined
May 18, 2016
Messages
2
The water pump impeller is new, new OEM thermostat I have not removed risers but blow thru the hose and found not resistance. The motor can ideal all day at 165 degrees, if I get up on a plan and run 3500 rpm no over heating but slow down for an ideal zone and the temp climes up to 275 very fast , UR
 

bajaunderground

Lieutenant
Joined
Apr 18, 2008
Messages
1,401
I'm dealing with the same stuff. I've replaced the thermostat, fuel cell (other issue), impeller, risers. did you clean out your thermostat housing? When I replaced my impeller and thermostat, I found 2 of the old vanes wedged in the thermostat housing (one port side riser outlet and one in the starboard side riser outlet). Still had the issues of intermittent over heating. I thought it might be the seawater hose was getting 'folded' when I trimmed all the way down...it seemed to run normal temps when I was trimmed up a little. I concluded today that it is the thermostat housing, the by-pass inlet was clogged or corroded, hindering flow. I found another piece of impeller vane wedged in the inlet side of the housing (I drilled it out and cleaned all orifices with a wire brush. If this doesn't do it, I'm getting new factory manifolds. I'm also ordering a new 'o' ring and fitting for the outdrive...
 

kccoe

Seaman
Joined
Jul 4, 2015
Messages
62
Could be bad seal on lower unit water pick up tube or crack water nipple on the gimbal housing allowing air to enter raw water coolant system when up on plane. When down on plane all of these parts are under water and no air can enter.
 

kccoe

Seaman
Joined
Jul 4, 2015
Messages
62
Also you can get about a 6 inch piece of clear vinyl pipe one and quarter inch diameter with a plastic nipple and clamp and clamp it on to the intake of your raw water impeller pump and connect the other end with nipple to the raw water pipe . Then do a sea trial with a friend to operate boat. You can while on plane check for air bubbles coming thru pipe. If any present you have a bad seal or hole in the water line between the impeller pump and outdrive or the outdrive itself. There is 2 water pick up tube seals in the lower outdrive unit. You have to separate upper and lower outdrive to replace these. Air will not allow water to be pump efficiently to cool engine.
 
Last edited:

bajaunderground

Lieutenant
Joined
Apr 18, 2008
Messages
1,401
Also you can get about a 6 inch piece of clear vinyl pipe one and quarter inch diameter with a plastic nipple and clamp and clamp it on to the intake of your raw water impeller pump and connect the other end with nipple to the raw water pipe . Then do a sea trial with a friend to operate boat. You can while on plane check for air bubbles coming thru pipe. If any present you have a bad seal or hole in the water line between the impeller pump and outdrive or the outdrive itself. There is 2 water pick up tube seals in the lower outdrive unit. You have to separate upper and lower outdrive to replace these. Air will not allow water to be pump efficiently to cool engine.

He states, the same as my issue, at 3,500RPM it runs at the correct temp. I suspect there's some blockage and under higher (RPM's flow) it has enough pressure and flow to run normal?

I bought all the clear hose/hose clamps/etc...I have yet to do that test, but I am today. I would suggest the same. I do plan on replacing both my plastic nipple and 'o' ring between drive and gimbal housing, just to rule it out.
 

kccoe

Seaman
Joined
Jul 4, 2015
Messages
62
He states, the same as my issue, at 3,500RPM it runs at the correct temp. I suspect there's some blockage and under higher (RPM's flow) it has enough pressure and flow to run normal?

I bought all the clear hose/hose clamps/etc...I have yet to do that test, but I am today. I would suggest the same. I do plan on replacing both my plastic nipple and 'o' ring between drive and gimbal housing, just to rule it out.

Good idea . My water inlet nipple was crack and had a bad seal on water pick up tube in lower unit
 
Top