2004 496 HO Running Hot
 

I have a 2002 Velocity VR1 with a 2004 496 HO. The boat is new to me. Two weeks ago had the impeller replaced and was told the impeller is pumping good. Took the boat out for the first time and it ran decent - temp was 160-165. One week later took the boat out and it started to overheat (190) as I was leaving the dock. Also, appeared to be pushing some steam. Brought the bought back to the dock, let it sit for about 30 minutes, started the boat, no alarm and idled out of the no wake zone temp around 160. Brought the boat up on plane and it started creeping back up to 190. Put the boat on the trailer. Initially thinking thermostat....any thoughts?

you are going to have to check your block heat exchanger and oil cooler to see if there are pieces of the impeller blocking the raw water cooling. It doesn't sound like a Tstat prob

Thanks, I'll start doing that now....this is a little different from my old 4.3LX!

You can take the output hose off of the sea pump & the inlet hose off of the heat exchanger. Put a hose on the inlet hose to back flush the line, I had to do that a couple of times to clean out the p/s & oil coolers. That's easier than crawling around trying to get to the coolers. If the problem persists I would look into a sea strainer. Randy

No obstructions in the oil cooler. I guess its time to start removing the heat exchanger.

I'll try the back flush before I pull the heat exchanger. Ok, here's where you know I'm new to this type of boat engine. I'm not 100% sure I have a sea strainer.

What kind of shape was the waterpump housing in? they have a problem with galling out the ends & losing pressure. The p/s cooler is behind the engine & is the first cooler water goes through, then the oil cooler, and finally the heat exchanger. If you have any blockage the p/s cooler is where I would look but is the hardest to get to. That is why I suggested back flushing the line. The heat exchanger has bigger holes inside so chances are that is not where the problem is. Ask whoever installed the impeller what the housing looked like. A strainer would be installed on the inlet side of the pump & is usually easy to get to so it can be cleaned out. Randy

Randy, thank you for your response. I was told the housing was ok, but i did not see it. I pulled the hoses off the p/s cooler and oil cooler I did not see any blockage in either.I will still try to back flush tomorrow. I've seen pictures of the sea strainer, but I do not see one on my boat. I'll keep looking. I may just replace the housing and impeller myself so I can rule out that part. He did say it had good water pressure and infact we ran it with no issues for 30 minute in the lake and about 1 hour on lake allatoona when I got home with no issue. It was the third time we took it out and I did notice some steam (more than what I'd seen before). But it started overheating while at idle heading out of the no wake zone.
Thanks again, Don

Interested to know what you find. Randy

I back flushed and noticed no debris. I'm going to change the impellar. See if that helps.

when you back flush. This going to sound bad. BUT fill the hoses up with water and then suck and blow in little jerky motions and the water could dilodge some peices. i have had to do that before, and 3 empellar vynes came out. that did not with just the water.

Had the impellar and housing replaced. Heating issue got better, but not there yet. 4000 RPMs boat runs about 170 degrees (according to the gauge). 5000 RPMs engine gradually heats up to 190 and hard alarm encountered. Seems like the more trim I add at the higher speed the hotter it gets.

Still encountering two beaps every minute. I've replaced a few sensors and plan to replace a few more.

Saltwater boat? Might have a restriction in the transom assembly from corrosion.

was a saltwater boat before I purchased....now freshwater.

Do you have any alarms going off?
Do you have a water pressure gauge?
Do you have even water flow out of each exhaust pipe?
If you have a sea strainer, it would look like a cross between a washing machine and a coffee can, somewhere low in the bilge. It more than likely has as a clear lid so you can see if the basket is full of garbage and would need cleaned out. If you have strong water pressure you more than likely do not have an issue here. An example of a sea strainer is below.





I bet this is it though...
Is the antifreeze bright peach/pink colored or is it getting dark and metallic colored? If the latter, its old antifreeze and its silting up in the closed part of the cooling system. Max life of AF is about 6 or 7 seasons. Its been discussed here on OSO in the past and some info should come up with the search tool.



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A scan tool would be helpful here. You can measure seawater pump pressure at any RPM as well as port and starboard manifold temperature with one.

Also you can use a cheap infared thermometer to check each manifold and riser temp. That would help isolate the problem to the fresh or seawater side

Regardless of the main problem I agree that an antifreeze change is warranted if it's never been done on a 2004 engine. Finding and getting to the block drains can be a challange however.

www.rinda.com

Probably the best money one can spend on any boat with a SmartCraft engine.

Have you pulled the end caps off the heat exchanger and cleaned out all the little tubes in there?

Thanks for all the replies. I have the heat exchanger off now and will inspect later this evening. Checked the old TSTAT and seemed to be working. I have a new (160) ready to go in. Agree on the Rinda scan tool (visited thier web site) and priced the IR Thermometer on Amazon

You can pick up an IR thermometer also known as a laser pyrometer; at Lowes and Home Depot, and the like.

End caps are off - only a few tubes required cleaning. The seal on one end was in pretty bad shape with holes and just wore out. I ordered two new seals and they recommended I use radiator flush and run trhough the heat exchanger. Its off the engine so I don't know how productive that will be. Also, replaced the coolant sensor while I was down there.

trying to drain coolant from block...I think I've located the drain on the side of the block where the power steering pump is located. Is this the only one and does it require a special allen wrench (size?).

found them....looks like 17 MM hex on front bottom of block

No, they are near the rear of motor mount. One on each side. Just above the oil pan mounting surface. On the side with the starter I had to move the single point drain valve to see it.

They're 18mm hex plugs that have an allen pattern also in the head.

found the port side, but just can't see the one on the side with the starter. I must be blind!

Like I said I had to undo and shift that drain valve out of the way. It's almost behind the oil dipstick tube but essentially in the exact same spot on the block as the port side.

Ok, this may sound dumb but have you tested your thermostat? I was having very similar issues and found my thermostat was barely open at 170 and not fully open till 195..and it took forever for it to fully open too. This was a 160 degree thermostat. Pretty much the same issue though-ok at idle and low speeds but when you start pushing it then it slowly gets hotter and hotter-shut it off for a couple minutes, start it back up and temp would drop to 150 and then repeat the whole cycle again. Brand new impeller with no pieces missing on the old one and system was back flushed.

Maybe this will help a little. Test the one you have now.

Dave

Thank you, I replaced the thermostat, flushed the engine and heat exchanger, added new coolant. The impeller is new (2 weeks). The boat did run cooler, but when you run it up to 48-50 RPMs still creaps up towards 190. I did not let it get to that point. Runs great at 50 mph.

Salt water boat - does it have a bravo one drive? could be the dreaded bravo one cooling hose restriction as mentioned above. My boat had the same symptoms.

Do you have a fresh water flush fitting where you attach a garden hose for flushing the salt out of the sea water side of the cooling system?

No flush fitting. It's a 2004 Bravo 1 X (0W224912). Could it possibly be the exhaust manifolds restricting the water flow?

Have you checked the water intake tube from the drive to the SWP for corrosion/restriction?

No I have not. I guess that would be next...thanks.

You say it creeps towards 190 at 5000 RPM? That's not that bad. Mine will to and you also need to scan that engine to see what the real temperature is. That dash gauge my not be very accurate.

Ever figure out what was wrong bc my 2003 36 ft baja outlaw with tiwn 496 hos is doing the exact same thing new impeller ... had backplate of pump resurfaced cleaned and check hest exchanger changed coolant .....?

well, im having the same problems. did yall figure it out? i have done everything except changing out sensors