Excalibur 330 overheating at speed, not at idle

[lfadam]

My 04 210 with Excalibur 330 is not off to a good start this season. She stays at the normal ~160ish when idling but when I plane out immediately the temp starts rising up to 175 and beyond. Not normal and enough to trigger the “Eng hot” warning. I thought it might be the impeller so I replaced that but still no dice. Normally with a failing impeller it’s the opposite where it overheats at idle but OK at speed. The other thing that’s weird is it seems to start smoking before it reaches 175 like only a certain part (eg one manifold) isn’t getting water which makes me think it may be a blockage? If so, how do you backflush this thing?

Strainer is tight and o ring is present. Picking up a little crud but nothing that looks like an obvious clog causer. Heater is working. I winterized it myself but no sign of cracks or dripping from any of the drain plugs or hoses I disconnected. Any ideas?

[biacs]

When I did the impeller this year, I had had the backing plate fall out of the impeller housing into the bilge.

I didn't notice until running it on the hose in the spring :-) take a look under the engine to see if there's that round plate that sits behind the impeller when you insert it. The cooling system wasn't building of pressure to pump water out the back, which is why I started taking a closer look.

[Rednucleus]

Check your thermostat 1st before spending time chasing possible blockages

[lfadam]

Thank you both for the quick replies. I think I cracked the case. For any future troubleshooters...let's start with what it wasn't.

1) Impeller / impeller backing plate. The old one wasn't terrible but put a new one in and it appears the plate that biacs mentioned is in place in the first pic. Rednucleus — thermostat was next to investigate but given it held a nice 160 at idle, seemed less likely.

2) What I tried next today was removing the hose just past the strainer as well as the hose going into the top of the impeller and blowing to see if there was a blockage. I was hoping they were two ends to the same hose but it doesn't appear that is the case as I was unable to blow the water through. The water circulation diagram from the PCM manual is very confusing as nothing is drawn to scale and they leave out many elements (e.g. the strainer, heater loop, etc.). But it seems the hose going into the top of the impeller is the output, the input is underneath. However the output hose is at least 6 feet long and disappears under the engine like most of these hoses so I have no idea where it goes next. What's highlighted in green shows how it should be based on the manual...a small connection to the thermostat area, but again my hose is at least 6 feet long and goes under the engine. And not sure where the purple (post-strainer) hose leads to. Maybe the bottom of the impeller (input)? So blowing / tracing didn't get me anywhere.

3) Well tracing did get me somewhere...the raw water valve at the bottom of the boat. It appears that either myself or my winterizing buddy attempted to close the valve last November to get the engine to suck up the antifreeze we were dumping in just before the strainer as it was coming out the bottom of the boat at first. It's in a tight space so I guess it didn't close completely, only partially. So my engine was sipping out of a coffee straw.

I opened the raw water intake valve all the way and did a very quick test at speed. It never got above 165-170 at ~25mph so I think that was (hopefully) the issue. It still smelled a little "burned" when I came back to the ramp but given the temps it may have been leftover from earlier. However, it started making some squealing / whirring noises at around 22+ mph...so I'm worried I might have burned up my water pump bearing while troubleshooting or my transmission fluid is overfilled again and causing weird vibrations (it happened once before).

So...success (I think). We'll see if the weird noises persist next time out. Hoping I'll be able to finally get a set in!

[bturner]

Thanks for posting your post mortem.

One thing I teach when doing any maintenance with new boaters is to create documents for each procedure they perform. Doesn't have to be crazy but these days everyone has a camera on their phone and at a minimum google docs to create a "how to" punch list or video of all the steps and procedures of the process. I have one for my boat that includes which steps are preformed when and what tools are needed for each step and where they're used. I also have a punch list that I run through before launching the boat for the first time in the spring, takes maybe 10 minutes to run through. One of the items on this list is verify all seacocks are in the open position. When you're bent up like a pretzel reaching things during the winterization process it's really easy to bump something or disconnect a wire or connector.

Glad to hear you're issue wasn't costly and you've moved past it.

[jpwhit]

If you ran it much with the seacock mostly closed, you may need to check the impeller. They overheat and get damaged in less than a minute w/o proper water flow. That may be the source of your noise.

[shag]

Good job in tracking it down.. And yes, I would re check that impeller. That rubber will quickly degrade with a lot of heat for a period of time... That one in the photo is defineatley F'd up, although I have seen worse lol

[lfadam]

Thanks shag / jpwhit — will take a look at the impeller this week