Hi guys,
I've got a cooling issue that I can't sort. This outboard is what's called a 140hp International i.e. it's an export only model that's common here in New Zealand. Basically it's the same as the 2001 - 2005 150hp to 200hp 2.5L V6 Carb ones you guy are used to.
It will run hot at part throttle but is fine at the top end. The water pump was replaced but it was still running hot so I replaced both stats. I then had a better tell tail flow and thought the issue was sorted as it was running great initially, but we were running at 4 - 4500rpm.
At 3000 and lower it gets hot. The gauge will go to 1/2 way between the 3/4 and full marks. Water pressure at 3000 is about 15psi. It has about 3-5 psi at idle.
I checked the temp sender last night and it seems to be OK. Ranges from about 950 ohms cold (about 64 deg) to about 68 ohms at 212 deg. I put a 5k pot on the gauge to simulate the sender output and I'm now more concerned that I was. During the last outing I pulled the cover and checked the stat housings with an IR temp unit and both showed about 148 but the gauge was well round.
Simulating the gauge reading I had to have about 40 ohms to get the same reading. This is telling me the head temp was well over 212 deg but the horn remained silent?
So in short, it runs cool at high speed but heats up quickly at low speed, even 1200rpm. The water pressure looks to be good enough to rule out the pump. Both stats are new and look to be working correctly.
The motor has only 80 hours on it.
What else should I be looking at?
I've got a cooling issue that I can't sort. This outboard is what's called a 140hp International i.e. it's an export only model that's common here in New Zealand. Basically it's the same as the 2001 - 2005 150hp to 200hp 2.5L V6 Carb ones you guy are used to.
It will run hot at part throttle but is fine at the top end. The water pump was replaced but it was still running hot so I replaced both stats. I then had a better tell tail flow and thought the issue was sorted as it was running great initially, but we were running at 4 - 4500rpm.
At 3000 and lower it gets hot. The gauge will go to 1/2 way between the 3/4 and full marks. Water pressure at 3000 is about 15psi. It has about 3-5 psi at idle.
I checked the temp sender last night and it seems to be OK. Ranges from about 950 ohms cold (about 64 deg) to about 68 ohms at 212 deg. I put a 5k pot on the gauge to simulate the sender output and I'm now more concerned that I was. During the last outing I pulled the cover and checked the stat housings with an IR temp unit and both showed about 148 but the gauge was well round.
Simulating the gauge reading I had to have about 40 ohms to get the same reading. This is telling me the head temp was well over 212 deg but the horn remained silent?
So in short, it runs cool at high speed but heats up quickly at low speed, even 1200rpm. The water pressure looks to be good enough to rule out the pump. Both stats are new and look to be working correctly.
The motor has only 80 hours on it.
What else should I be looking at?