165 running hot

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25'k&c

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165 mercruiser running hot not impeller or thermostat took it out still hot. heat exchanger or water pump?
 
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stonyloam

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Re: 165 running hot

Probably not the engine waterpump (nothing to go wrong there except the seals), pull the ends off of the heat exchanger and take a look (only raw water will come out, antifreeze is sealed inside). Check the antifreeze, should be about 50/50. Make sure the water passage in the exhaust elbow is clear, if not it could restrict the flow of water from the exchanger. Check the temperature with either an IR thermometer or a radiator cap thermometer to double check your temperature gauge.
 
cr2k

cr2k

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Re: 165 running hot

Closed cooling or sea water? Put the thermostat back in. By not being there you will run hotter than normal and have hot spots in the block. How do you know it's not the impeller? Is it brand new? Was the old one in pieces? You need to take a look at the heat exchanger, pieces of a damaged impeller hide out there blocking flow. Other things are; bad manifolds or risers, flappers stuck it the Y tube or elsewhere in the exhaust blocking flow. What you are calling the water pump (on the front of the engine) in Marine terminology is a Circulation Pump.
 
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25'k&c

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Re: 165 running hot

stonyloam said:
Probably not the engine waterpump (nothing to go wrong there except the seals), pull the ends off of the heat exchanger and take a look (only raw water will come out, antifreeze is sealed inside). Check the antifreeze, should be about 50/50. Make sure the water passage in the exhaust elbow is clear, if not it could restrict the flow of water from the exchanger. Check the temperature with either an IR thermometer or a radiator cap thermometer to double check your temperature gauge.
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I pulled the riser off the water passage is clear heat exchanger looks good. seems to olny run hot under load I have 2 seperate gauges and both read hot. How much flow should I have coming from the impellar? Looks like about the same amount as a kitchen tap with the motor at an idle.
 
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stonyloam

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Re: 165 running hot

How hot? The 165 normal operating temperature is 165-200 F. Does the temperature stabilize, or does it keep going up? How long since the impeller was changed? Sounds like everything else is in pretty good shape and you have decent flow.
 
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AzFisherman84

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Re: 165 running hot

I'm having a similar problem with my 1977 165 running hot too. I recently had to replace the upper unit seal because I founded oil in the u-joint bellow. So I figured I would replaced the bellows and impeller why I had the drive apart. I install everything as describe in the service manual, I the only thing I did differently was install exhaust tube instead to a bellow. Now I'm running hot, so my question is could the exhaust tube be the problem or could it be that impeller is not circulating water correctly?
 
achris

achris

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Re: 165 running hot

AzFisherman84 said:
I'm having a similar problem with my 1977 165 running hot too. I recently had to replace the upper unit seal because I founded oil in the u-joint bellow. So I figured I would replaced the bellows and impeller why I had the drive apart. I install everything as describe in the service manual, I the only thing I did differently was install exhaust tube instead to a bellow. Now I'm running hot, so my question is could the exhaust tube be the problem or could it be that impeller is not circulating water correctly?
Click to expand...

You have an entirely different problem. Please don't hijack someone elses thread, start your own...
 
achris

achris

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Re: 165 running hot

25'k&c said:
I pulled the riser off the water passage is clear heat exchanger looks good. seems to olny run hot under load I have 2 seperate gauges and both read hot. How much flow should I have coming from the impellar? Looks like about the same amount as a kitchen tap with the motor at an idle.
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When was the last time the heat exchanger was cleaned out? They should be done every 2-3 years... That could reduce your flow... The other thing to also check (I mention this one a lot because people overlook it) is the Water Pocket Cover in the bottom of the top box of the drive. Not sure what that is? -> http://forums.iboats.com/showthread.php?t=556903&p=3825409&viewfull=1#post3825409

Chris.....
 
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AzFisherman84

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Re: 165 running hot

Excuse me, it wasn't my intention to as you stated hijack someone else thread. But it seemed like we were having the same issue that why I posted I this tread instead of starting a new forum on the same issue. But anyways point taking, thanks.
 
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25'k&c

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Re: 165 running hot

stonyloam said:
How hot? The 165 normal operating temperature is 165-200 F. Does the temperature stabilize, or does it keep going up? How long since the impeller was changed? Sounds like everything else is in pretty good shape and you have decent flow.
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I took the leg apart to double check the impeller and found the seal in the top of the impeller housing was damaged dont know if thats the problem so I will replace it next week on days off. It was running at about 200 I dont know if it leveled out I got scared and let it cool down. I will let you know how it goes thanks for the help
 
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stonyloam

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Re: 165 running hot

Yeah that's too hot, shutting down was wise;). At this point I would recommend that you replace the whole pump, housing and all with OEM Mercruiser parts. I know OEM is more expensive but in the case of the 470 I think it is well worth it, and it is a whole lot less expensive than a head gasket. Good luck.
 
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25'k&c

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Messages
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Re: 165 running hot

stonyloam said:
Yeah that's too hot, shutting down was wise;). At this point I would recommend that you replace the whole pump, housing and all with OEM Mercruiser parts. I know OEM is more expensive but in the case of the 470 I think it is well worth it, and it is a whole lot less expensive than a head gasket. Good luck.
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replaced the pump everything seems to be working great thanks for the help running right around 165
 
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