Slt 780 overheat

[John8]

Hello I have a Slt 780 with 120 x3 compression, rebuilt carbs,new triple outlet fuel pump,new fuel lines, running it probably richer than I should. My issue is after about 10 minutes of wot I have an overheat issue. I noticed the pto cylinder had slight scoring so I opened the fuel screw about 1/4 turn. It runs awesome other than that. I replaced the rubber exhaust tubes and checked all water passages, no thermostat, I also don't have the luxury of an mfd. The only difference in what I have been doing is some stabil gas treatment I put in before when I was going to let it sit for the winter. Then it warmed up and I took it out a few times. Could that be the cause of the problem? Thanks.

[xlint89]

Welcome to the Hulk.

First, make sure the screen in the jet pump venturi is clear. That's the supply for the engine cooling.

Next, make sure the cooling tube and hoses from the pump to the engine are clear, unobstructed and not kinked.

Then, I would possibly look at the head gaskets to make sure they are oriented properly. There is a certain way they are supposed to be installed.

Inspect the 3/4" cooling hose that connects to the exhaust pipe. On some SLT's there were prone to rubbing/wearing a hole in them. You would prob notice water inside the hull if that were the case though.

Check this stuff out and report back

[John8]

I have new exhaust and cylinder and head gaskets coming. I'm currently trying to wire a high temp led. I'm a truck and specialized equipment tech so parts for that will be easy to find. I'm using an 2" red led marker light. I've been checking all of the coolant lines and had already checked the screen. I'm waiting for the gaskets to arrive before taking heads off. Thanks to all of you who post and answer problems on here. I've got a long way on my own just looking at past posts.

[K447]

How much current is that large LED red warning lamp going to draw?

[xlint89]

Do you not have a functioning MFD? It has it's own LED light to warn of overheat.

[John8]

I do not currently have a mfd. I have however hooked up a 2" red led light for overheat. I believe my problem is gone. I brought it to sunny Jacksonville FL and have had lots of wot time with no issues. I replaced the head gaskets, exhaust manifold gaskets, tested and reinstalled the thermostat to help with getting to operation temp also cut about one third of the spring from the plastic water valve in the thermostat housing. The light should be roughly.260 amps. I installed a 2a fuse.