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496 ho temp issues
Hey guys, I have a 496 ho. This spring it did raw water pump rebuild, new manifolds and all new gauges. Took it out yesterday for a ride and temp was creeping over 210 on the gauge. And actually got to 220 when running wot for a minute maybe. It would cool back to 205-210 while running at cruising speeds. Alarm never went off. Manifolds felt nice and cool plenty of water coming out exhaust and coolant hoses and exchanger were hot but not crazy hot. Like to me the thing did not feel like it was running that hot. Is it possible the new gauge is not reading correct. Where dose the ecm get its temp from. It must have its own sensor to set the alarm off correct? Should the alarm go off at like 200 regardless of what the gauge is reading? I replaced the stock lavorsi gauge with auto meter pro comp marine. Any help would be appreciated
thank you |
sounds like a sender gauge incompatibility,,as for the ecu,,it has its own temp sensor,,its a 2 wire w/ yellow and black wires.
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I believe #7 is for ecu and #8 for your gauge. Check with livorsi what sender of theirs is needed for your gauge
https://cimg7.ibsrv.net/gimg/www.off...9b5c946d01.png |
Thank you, so you believe the alarm would be going off if I was running at 210-220 correct. Autometer does have their own sender. I’m ordering that now. Hope this cures it
thanks again. |
When was the last time you opened the heat exchanger, inspected, cleaned, and replaced the rubber end cap seals.
The end cap seals fail internally over time and then block cooling passages, which will cause hotter running temps. When was the last time you replaced the coolant? What does the color look like? Is it still bright pink? The pink coolant has to be replaced every 6-7 years, or when it starts to "silt" up, turn dark and metallic a bit. This means coolant isn't flowing as well due to jus being old, and full of crud as it doesn't have a filter. This will also cause hotter running temps. There have been a LOT of posts on this topic. |
Originally Posted by Sydwayz
(Post 4929019)
When was the last time you opened the heat exchanger, inspected, cleaned, and replaced the rubber end cap seals.
The end cap seals fail internally over time and then block cooling passages, which will cause hotter running temps. When was the last time you replaced the coolant? What does the color look like? Is it still bright pink? The pink coolant has to be replaced every 6-7 years, or when it starts to "silt" up, turn dark and metallic a bit. This means coolant isn't flowing as well due to jus being old, and full of crud as it doesn't have a filter. This will also cause hotter running temps. There have been a LOT of posts on this topic. |
Originally Posted by Sydwayz
(Post 4929019)
When was the last time you opened the heat exchanger, inspected, cleaned, and replaced the rubber end cap seals.
The end cap seals fail internally over time and then block cooling passages, which will cause hotter running temps. When was the last time you replaced the coolant? What does the color look like? Is it still bright pink? The pink coolant has to be replaced every 6-7 years, or when it starts to "silt" up, turn dark and metallic a bit. This means coolant isn't flowing as well due to jus being old, and full of crud as it doesn't have a filter. This will also cause hotter running temps. There have been a LOT of posts on this topic.
Originally Posted by ashipshow
(Post 4929071)
^ this... PLUS might want to check your power steering cooler on the back of the engine and flush it.. it can get clogged with debris and chunks of old impeller.
Originally Posted by Seth437
(Post 4928966)
Hey guys, I have a 496 ho. This spring it did raw water pump rebuild, new manifolds and all new gauges. Took it out yesterday for a ride and temp was creeping over 210 on the gauge. And actually got to 220 when running wot for a minute maybe. It would cool back to 205-210 while running at cruising speeds. Alarm never went off. Manifolds felt nice and cool plenty of water coming out exhaust and coolant hoses and exchanger were hot but not crazy hot. Like to me the thing did not feel like it was running that hot. Is it possible the new gauge is not reading correct. Where dose the ecm get its temp from. It must have its own sensor to set the alarm off correct? Should the alarm go off at like 200 regardless of what the gauge is reading? I replaced the stock lavorsi gauge with auto meter pro comp marine. Any help would be appreciated
thank you Oil cooler is the first thing in the raw water tract after the seawater pump. That's where I found the debris on my engine while pulling it apart to rebuild. A full raw water backflush is always a good idea. I fully second the input about the gaskets on the ends of the heat exchanger. I found mine to be almost entirely caved in. Between this and the oil cooler blocking off a significant amount of raw water flow, I was starting to run pretty warm. Change them. they are cheap and easy to replace. Thanks. Brad. |
If it was over 200*, you should have gotten an overheat alarm.
Need to run it with a scan tool to see what the actual temp is. |
I'd suggest using an IR thermometer to help troubleshoot.
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Griff is correct, the 496HO will go into limp mode if you were really running that hot.
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Thanks for the input. Sorry for late response as I just had back surgery and was down and out for a bit. Seems the 2 wire sender controls the gauge. After replacing the sender with an autometer sender the gauge was still reading in the 210 range. Checked it with an infrared and it was around 165-170 so at least I know I’m not over heating. I unplugged the one wire sender and gauge was still reading 210 then I unplugged the 2 wire sender and alarm went off and gauge went to 0. So I’m not sure what to do now. I thought the 2 wire sender was for the ecu and the 1 wire sender was for the gauge. Well not on my boat lol. Maybe autometer has the 2 wire sender to match the gauge?? I am at a loss. At least I know it’s not over heating but I would really like the gauge to read correctly?? Any help is always appreciated
thanks |
Your assumption is correct... The one wire port side temp sender is for the gauge.. The 2 wire starboard side sender is for the ECU.
I don't know whats going on with your setup.. The only thing I can think of is you have a digital temp gauge that is using the ECU signal and the 1 wire sender isn't being used anymore?? On another note... Hardin sells a temp sender specifically for Livorsi gauges, so I wonder if they use a different resistance range than what you have.. https://www.cpperformance.com/p-1307...si-gauges.aspx |
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