Overheating question 94 Sport

[hep]

I'm stumped on this one. Everything is fine at idle and low speeds but when you go full throttle for awhile it starts to overheat but cools again when slowed. It hasn't been an issue because we usually just wakeboard, surf and ski behind it and keep the speeds low. Impeller is good, thermostat was changed last year. I checked for any old impeller particles from before I bought the boat last summer and everything looks clean. Cleaned and tightened the strainer (rubber O-ring is still good). I'm starting to think it may be electrical like a bad ground or something. At normal speeds it sits around 170-175.

[mf01]

How long at full throttle?

Mine almost always sits at 160-165. I wakeboard at 22-23 and cruise at 27-29. It sounds like it can't pull enough water, so it could be your strainer or impeller. When was your impeller last changed?

[teamseal]

Your boat is a 94 that meens it is nearly 20 years old (well over 15 anyway). I have seen the inner liner of the raw water inlet hose colapse under similar situations. also it may be time to inspect an flush out the exhaust manifolds, risors and engine block as sand and sediment can build up in all the water passages.

[hep]

How long at full throttle?

When was your impeller last changed?

It only takes a minute to start getting hot. The impeller was changed recently and I checked it again today and it still looks good. Even though it's old the boat only has 150 hours. It sounds like I might need to do a thorough flush in the manifold and block. What's the proper way to make sure I clear out all the sediment or build up?

[areford]

Overheating question 94 Sport

I would try hooking a garden hose on the intake to the raw water pump an run in the driveway. That way u can eliminate the hose and strainer constraints. Flushing the manifolds involves removing the drain plugs at the rear of each. If u still run hot after the hose test then maybe ur thermostat could have gunk in it. Good luck!

[areford]

Overheating question 94 Sport

And my 93 sport stays between 145 and 155 on the water so u are definitely running way too hot. Also make sure the right thermostat is in it. You can always test it on the stove in a pot of water as well.

[pdxCC]

Which thermostat are you runing? the 143 or 160? If your are running the 160 and your gauge is a bit off and reads high you may be OK. I have the 143 installed and I run between 155 and 165 on my 93' which has the same setup. When I had the 160 in it ran too hot for my taste.

Lots of guys here swear by the laser temp gauge to check the true block temp. This might be a good item to "borrow" from a friend.

[mf01]

If you're fuel injected, then you need to have the 160. The fuel injection will run it rich until it gets warm and the 143 won't bring the temp high enough. If it's carbed then you can run the 143.