70 Seahorse

16ftsunbird

Seaman
Joined
Mar 19, 2015
Messages
59
I picked up this 70hp seahorse need to know for sure how to see if water is pumping. I fired the motor up ran for about 10mins or so kept cking the head seemed to be gettting really warm but never heard the warning buzzer help please
 

bonzoscott

Senior Chief Petty Officer
Joined
Jul 26, 2008
Messages
745
If you ran it for ten minutes and it didn't lock up, it's probably pumping some amount of water. How did you test the heat of the head? Should be able to touch it at least for a few seconds. Either way, you should replace the impeller, possibly whole pump if condition is unknown. As fireman said, model number will help.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
The telltale indicators first came out in 1978, the year after yours was manufactured. So, your engine does not have that familiar water flowing out of the lower cowling nozzle. The most accurate temp measurement is with a laser temp gun. You can also borrow/rent one and check the cyl head temps once it is warmed up. Not sure just what temp that stat should open on that model, but it probably runs under 150 degrees at idle.
 

16ftsunbird

Seaman
Joined
Mar 19, 2015
Messages
59
ok there is a sensor in the head with a lead wire coming out what would this be, it looks just like whats on my 85hp Johnson
 

fireman57

Captain
Joined
Aug 24, 2004
Messages
3,811
brown or tan wire is your overheat alarm sensor. You can install a telltale on it as I did on my'76 75hp. There are a couple threads on how to do it. It's easy and really gave me piece of mind. If you don't know when the impeller was last changed I would replace it.
 

16ftsunbird

Seaman
Joined
Mar 19, 2015
Messages
59
I really want to test this boat out over the wk end how can i test the alarm to see that it's working and i stated in my post earlier i ran the motor on muffs for around 10 mins i could put my hand on the head for a few sec's just could'nt hold it there for 2/3 mins
 

fireman57

Captain
Joined
Aug 24, 2004
Messages
3,811
Muffs don't tell you a whole lot as they force water into the engine. If you have a 55 gallon drum you can cut off (I use a blue plastic one) you can run it in it at idle. Once it warms up you should be able to hold a couple fingers on the head for a long count of 5. If you are not too far from a lake with a dock you can do it there.
 
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