Mercruiser 470 Temp

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yamhoss86

Petty Officer 2nd Class
Joined
Jul 17, 2013
Messages
116
I changed the heat exchanger from the 3" to the 4".
The engine does run a bit cooler and does cool down much faster with the 4" heat exchanger.
I am running about 180 at 3/4 throttle. Is that normal?
I did notice that at some moments when i did go 3/4 throttle the engine temp would go up to 180 then back down to 160 and stay there.
I don't understand...any help would be appreciated.

Thanks.
 
SDSeville

SDSeville

Lieutenant
Joined
Mar 19, 2010
Messages
1,481
Re: Mercruiser 470 Temp

Not an expert, but that sounds a little high. Mine runs around 150. How is your your impeller?
 
Eric 3.7LX Alpha 1

Eric 3.7LX Alpha 1

Captain
Joined
Mar 27, 2010
Messages
3,008
Re: Mercruiser 470 Temp

My 3.7 aka 470 with the 4" exchanger... will run at 160?F all day long.

Here is a list of the impeller Kits avail. from Mercruiser:

What year is your drive and I can give you the correct part numbers
 

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S

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,827
Re: Mercruiser 470 Temp

If it has been more than 2 years since the impeller was changed, change it! If your impeller is failing you are courting disaster.
 
Y

yamhoss86

Petty Officer 2nd Class
Joined
Jul 17, 2013
Messages
116
Re: Mercruiser 470 Temp

stonyloam said:
If it has been more than 2 years since the impeller was changed, change it! If your impeller is failing you are courting disaster.
Click to expand...

I changed the impeller this year, when the guy was replacing the impeller, i noticed that one of the fins was facing in another direction. Is that a problem?
 
Y

yamhoss86

Petty Officer 2nd Class
Joined
Jul 17, 2013
Messages
116
Re: Mercruiser 470 Temp

Eric 3.7LX Alpha 1 said:
My 3.7 aka 470 with the 4" exchanger... will run at 160?F all day long.

Here is a list of the impeller Kits avail. from Mercruiser:

What year is your drive and I can give you the correct part numbers
Click to expand...

Its a 1981 model
 
S

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,827
Re: Mercruiser 470 Temp

yamhoss86 said:
, i noticed that one of the fins was facing in another direction. Is that a problem?
Click to expand...

It should flip around when it was first run. Check for a restriction in the water outlet in the exhaust elbow. Pull the hose off and attach a garden hose to see if the water will flow out of the outdrive without restriction (no or very little backpressure). Also check your temperature with an infrared thermometer to make sure your gauge is accurate.

Just reread your initial post, if the temperature goes up then down your thermostat may be hanging up.
 
Last edited:
achris

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Mercruiser 470 Temp

Hey Terry, Try to send you a PM, but ya box is full... :facepalm:

Here's the PM anyway (OP, sorry to have to do this)

Hey Terry,

Been looking at dwell/tach digital meters for some guys.... There is a LOT of them out there, but check this one out.... Got the LOT! Dwell and tacho for 1,3,4,5,6,8,cylinders, all the usual electrical functions (V,A,Ω,diode,buzzer), capacitance, thermocouple and bipolar transistor tester... And here's the best part.... $26... and free postage!

Digital Tachometer Meter Tach Dwell Tester Multimeter Ship From USA | eBay

You really gotta get one of these!!!

Cheers.....
Click to expand...
 
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