Overheating and Sticky Shifter

Couple problems I'm hoping someone on here can assist me in resolving on my 1987 Saltare with the 454:

-When I launch the boat, I power it off the trailer (in reverse) where it sits running while the truck and trailer get parked. I come back to the boat, go to take off, and within seconds the overheat light comes on. It's done this every time I've launched the boat and I've been able to just increase my speed through the water and it cools back down, but this most recent time, I tried to cool it down with no luck. I ended up opening up the water intake line in the engine bay and blowing through the line that goes down to the impeller. I blew pretty hard and it felts as though something blew out, but it's hard to say. I then hooked it back up but it still would not draw water into the engine. So I opened the line up again and poured water in the line going to the engine and the line going down to the water. After hooking it up and speeding through the water again it finally began to draw water and cool the engine back down. Is it normal for it to overheat right after launching or is there something wrong? My best guess for what happened today is that the line got air-locked when I blew through the intake line. Is this possible? Do I need to look at replacing the impeller?

-The other problem I'm having is with the throttle/shifter lever. It takes a LOT of force to get it out of neutral, and it's sloppy feeling in between neutral and drive once I manage to get it out of neutral. Is there any way to adjust this? Do I need a new throttle shifter or is it more likely something in the transmission itself?

When was the last time you replaced the impeller? If it has run dry for any length of time you will fry it. Sounds like it needs to be replaced. Make sure all your intake clamps are tight, and check your transmission cooler for any debris. Do you have a water strainer?

2nd on the impeller. They need to be replace every couple of years even if you haven't run it dry. Cheap/easy fix.

The throttle cable may be bad. Disconnect it at the controls and see if the throttle lever moves freely -- if it does, time for a new cable.

Make sure all the clamps are tight and hoses are in good condition from the pump to the hull (suction side). For the time it takes in the garage it is always a good idea to remove and inspect the intake side of the cooling system every spring and have a spare thermostat and impeller onboard.

As for the cable, remove the linkage from the trans and try it. Sometimes there can be a kink in the stainless section of the cable where it was stood on by accident.

if the shifter is still sticky once you've disconnected the other end of the cable your brass pivot pieces might be wearing out. check this thread: https://forum.supraboats.com/showthr...ighlight=brass

you'll have to pull the throttle unit to inspect. there's a trick to it...not sure if i remember but with the engine off put the throttle into forward gear and then wiggle the unit away from the wall. (it might be reverse gear)

If you replace the impeller and it still hover heats there is a seal in the pump housing that should also be replaced every couple of years, if the seal is allowing air to be sucked in it will not have enough suction to pull the water in. What year boat and size engine?

So new problems today...seems like everytime I fix something and take it out, something else breaks. Anyhow, so I took the boat out and after about 10 mins on the water at a mediumm speed, nothing WOT, it made a popping noise followed by a hot/burning rubber smell. Turns out the exhaust hose connecting the manifold to the exhaust pipe burst on the outer part of the hose. There was a pea size hole in the fabric part of the hose. It's very confusing to me because my temp was great the whole time and never had any other problems. Here's a question though, how much water should travel through the exhaust hose? After the burst there was only a mild spray of water coming out of the hole when I rev'd to about 3k. And yet another question that I have to admit I'm embarrassed to have to even ask, but is my impeller on the block run off a belt? I have looked through several threads and cannot find where the placement of the impeller is. And I cannot find any other place except where the main water line comes in from the bottom of the boat and then up to the water pump. Is there an easy way to take the housing apart to replace the impeller? Thanks all! Oh, and an update on the throttle cable/shifter cable, the throttle cable is like brand new and moves freely, the shifter cable on the other hand is stubborn as heck and can't move it by hand. I have looked along the whole line of the shifter cable, and can't find a kink or pinch, so I'm thinking I just need to replace. Is this a simple replacement or is there any trick to it? Thanks again all.

Hopefully you didn't melt any of the exhaust today near the transom. You still have flow issues WRT the impeller, this is why the exhaust burst. No flow, means no cooling, resulting in steam and the big melt down. The impeller is on the starboard side of the engine driven by a belt. Yours is toasted and shrapnel is more than likely upsteam from here. Time to do some research and repair.

Are there any threads out there that talk about how to clean out the water lines post impeller? Or is this something I should have done by a marina? What kind of exhaust parts could be melted in the transom area?