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Engine temp on fake-a-lake


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I was getting my 07 VLX ready for the season (I know, WAY late, but...) and got a little concerned when the temp ran up to 180. It then recovered and went down to about 145, and then went back up to about 160 where it hung out for a while. This was over a span of about 5-10 minutes.

I figured it was just the fake-a-lake and not having enough pressure to really get the water flowing, so no big deal, but a mental note to watch the temp.

We took it out for a lake run the other night and it seemed to hold 160 pretty steady. Then, to burn out the old gas (ok, that's my excuse for running full throttle) I ran WOT for about 10 minutes and noticed the temp was back up to 170. There were otherwise no obvious problems w/ the maiden voyage. Water temp is about 65-deg.

After picking up some items from the dealer and mentioning this, he seemed to think that was classic impeller issues. Since it was 2 years old, I decided to replace it. The impeller was in perfect shape when I removed it.

Since the temp always seems to recover, I'm not THAT worried about it, but I am curious as to why it fluctuates so much. Other boats have been rock solid at 160 regardless of speed, etc... Is this 'normal'? Or does it sound like the thermostat is being stubborn?

I've read that replacing the thermostat can cause more issues that it solves. Since the impeller was in good shape, I don't really think it could be debris in the lines - especially since it recovers well.... or too well.

So, if you've made it this far, then you've obviously got an opinion, so please share it! My plan is to watch the temp closely and see if its more consistent at the lake. If it still fluctuates, then it will be time for a trip to the experts.

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I dont think you have anything to worry about. Small fluctuations will be normal.

As far as the WOT scenario, I would say thats normal as well considering the water pump is based of the engine rpms. Think of it this way. Your running 5200 RPMs generating lost of heat and the pump is keeping in balance by pumping faster with the increased RPMs. Now when you stop, all that heat is still built up in the engine and in the compartment and you just cut the amount of water being pumped by a fraction. So I would say your fine.

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I wouldn't be running it at WOT on a fake a lake, but that's just me. 2-3K rpms or so, but it's much better to have a load on the engine of your going to be running high rpms for that period of time.

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I wouldn't be running it at WOT on a fake a lake, but that's just me. 2-3K rpms or so, but it's much better to have a load on the engine of your going to be running high rpms for that period of time.

I was WOT on the water, not on the fake a lake. I don't take it above 2k on the FAL.

I'll look into cleaning the tranny screen. Hopefully I can find a link -- anyone have a picture handy?

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I've always found V-drives tend to fluctuate more than DD's, I think i has to do with the longer intake run.

I would say clean out the tranny cooler (its the first thing upstream of the impeller), looks like a black redbull can with two lines in it that go to the transmission. Pull off the downstream (water) hose and stick you finger up in there and clean out all the weeds and junk that build up.

-Chris

Edited by 99response
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I have seen older impellers take shape and not pump well. I have reversed the impeller and cooling was a solid as a new impeller. I still replaced the old impeller as soon as we got one but reversing the old one got us through the weekend. Put the marginal one away for an emergency.

I have never seen my boats run any different on a fake a lake as in the water. I do run more water than the boat can use on the fake a lake. The extra just squirts out between the haul and the fake a lake.

The old impellers showed no damage other than taking shape! If it has any damage put it in the trash!

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I wouldn't be running it at WOT on a fake a lake, but that's just me. 2-3K rpms or so, but it's much better to have a load on the engine of your going to be running high rpms for that period of time.

I was WOT on the water, not on the fake a lake. I don't take it above 2k on the FAL.

I'll look into cleaning the tranny screen. Hopefully I can find a link -- anyone have a picture handy?

Didn't read it carefully enough, but even so for that amount of time. I've done WOT for about 20-30secs max but not in the minute ranges, just me. The motors can take some abuse, they are LS1's :)

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