How do you tell if the water pump (raw water) is failing/Weird high temp readings

[ers906]

I think I may have a bit of a problem, but I am not sure. Here is the situation...
Over the winter I put on a fresh air exhaust, since I have done that, when I am in neutral the temperature gauge start inching up from the normal 160 up as high as 230. This does not happen every time I am in neutral, there seems to be no rhyme or reason to when this happens. As soon as I put it in gear and engage the throttle to about 5 mph (or even just give it gas out of gear, although the temperature drop is not as dramatic) the temperature drops, sometimes even below the 160 mark down into the 145-150 region. I am not sure if the raw water pump may be failing and having a difficult time overcoming the pressure of the water in the FAE, or if something else is wrong. Larry Mann (owner of FAE) has been very helpful, but he thinks there may be something wrong with the boat. According to him, this should not be happening. So I am trying to find out if there is a part that is not working properly (possibly thermostat?) or if a part is on the verge of failing (water pump). The boat is running great, no misfiring, abnormal noises, etc. However, when the temperature is at the 230 mark, the boat does accelerate and RPMs do not go above 2000 (my guess is that it goes into limp mode) but as soon as I ease off the throttle and put it in neutral for a few seconds, it drives just fine. Appreciate any pearls of wisdom or advice.
Thanks - Sorry if I rambled on a bit
Also, Impeller was replaced three weeks ago, but I am going to be rechecking it this weekend. Fluids and plugs replaced two weeks ago. 8 hours on since.

[Quinner]

After checking your impeller, go through the raw water hoses and tighten all your hose clamps with a nut driver not a screwdriver, also check that your strainer has a seal and it tightly closed. Sounds like you could be drawing air in somewhere, maybe??

Good Luck

[ers906]

THanks
Hadn't even thought of that, although it would make sense. I think I am going to run it on the Fake-a-lake to see if that causes for the temp to fluctuate. I also do have a flush kit that I will look for any cracks etc.
Has anyone had any failures in the thermostat which caused intermittent fluctuations?

[WakeSlayer]

Quinner's advice is more than likely the solution to your problem. Just for the future, go on Amazon and buy one of these.

Minitemp

This will pinpoint hotspots and tell you if you have a real problem or a fake one.

If your impeller failed you can get chunks of it stuck in various points in your engine. They need to be located and removed.

[WakeSlayer]

THanks
Hadn't even thought of that, although it would make sense. I think I am going to run it on the Fake-a-lake to see if that causes for the temp to fluctuate. I also do have a flush kit that I will look for any cracks etc.
Has anyone had any failures in the thermostat which caused intermittent fluctuations?

You should check your hoseclamps annually at the least, and as Chris said, use a nutdriver, not a screwdriver. They do loosen up at the connections. Have not expereienced it, but I believe thermostats fail period, not intermittently.

[ers906]

I was going to pick up an infrared thermometer today. But not sure where I aim it at the engine to give me the most accurate and important readings

[WakeSlayer]

They are pinpoint accurate. Point it everywhere. Block, heads, intake, hoses, manifolds, temp sender, prop shaft, stat housing, your beer, your girl, everything. Move it around and you can see transitional temps just holding the trigger down.

[ers906]

My girl is hot or cold depending on imaginary inferences of what I have said (v. what I meant v. how she wants to interpret it at that second), and unfortunately been more cold lately than hot, so may be time for a different model. What should the engine temp be? the same temp as reading on the thermostat I assume, or is there some dissipation by the time the exhaust reaches it?

[WakeSlayer]

Ha. They'll do that. It is a design flaw.

It will vary depending on the water flow. Your stat is 160*, you shouldn't really see it exceed that anywhere but the exhaust, which is extremely hot right at the heads, but cools immediately thereafter. Temp will build in the intake until the stat opens and then drop. The exhaust manifolds will be cooler, and you should be able to hold your hands right on them for a few seconds. One side may be warmer than the other.
I actually have not done this much on my 502 as it has never given me any trouble. I have done it a lot on our 289 in the Mustang as I had several issues. No stat being the first one. Backwards stat for a day because I was an idiot. A couple wrong temp senders when I replaced all the gauges. The incorrect sender would show a temp of mid 200's and my laser showed low 100's. While freaky seeing the gauge, at least the laser is being honest and let's me know it is a fake problem.

I still think your problem is loose hose connections, but get the RayTek anyway.

[johnboyy7]

If you have a flush pro, make it isn't sucking air where the water hose goes.

[johnboyy7]

If you have a flush pro, make it isn't sucking air where the water hose goes.

Also let me know how you like your FAE please.

[Chexi]

My girl is hot or cold depending on imaginary inferences of what I have said (v. what I meant v. how she wants to interpret it at that second), and unfortunately been more cold lately than hot, so may be time for a different model. What should the engine temp be? the same temp as reading on the thermostat I assume, or is there some dissipation by the time the exhaust reaches it?

Eric, are you dating my wife?

[ers906]

Chexi, hopefully I am not dating your wife, but it is scottsdale so that is always a possibility (it is amazing how many women go out without wedding rings here, has gotten me in trouble more than once unfortunately). Turns out that the strainer connections were loose and sucking air through those. Ended up replacing the connections, and while I was at it, also placed a new gasket in the impeller housing. Runs great now (until my next mis-adventure at least)

[WakeSlayer]

Sweet. Glad to hear it.

[75Tique]

Don't bother with the fake a lake. It won't tell you anything about yoru RWP as it will push water through your engine. The only way to test the pump is to pull the hose off your thru-hull water pick up, extend the hose as needed to reach into a bucket, keep a flow of water going into the bucket and see if your RWP draws the water out of the bucket.