1988 Mariner 60 HP Overheat alarm

[fishinhardwater]

My 1988 mariner 3 cylinder 60 HP engine's overheat alarm goes off on the throttle control box. This beeping occurs at Wide Open Throttle only. The dealer sugggested new impeller, did that, problem still occurs at WOT. Tell tale is strong at all speeds. When i drop the throttle back to slow or neutral beeping stops, and engine stays cool entire time even when its beeping. By the way its a continuious beeeeep, not a beep beep beep, which would be for low oil. I can also run engine at 1/2 and 3/4 throttle all day and beep does not occur. thank you

 

[Laddies]

Re: 1988 Mariner 60 HP Overheat alarm

I believe you engine has one of the small senders right next to the top spark plug and if it does they are prone to causing that type of problem.

 

[fishinhardwater]

Re: 1988 Mariner 60 HP Overheat alarm

Thank you Laddies, my motor does have this wire. its a tan wire about 4" long. i guess its worth a shot to replace it, what do you think?

 

[marty53]

Re: 1988 Mariner 60 HP Overheat alarm

yea.. that bad boy is like $40-50 bucks. its either that or you could have a stuck poppet valve. those are cheap.

 

[fishinhardwater]

Re: 1988 Mariner 60 HP Overheat alarm

just bought the temperature sensor/sender?? 90 bucks.. had to order it. the one that Laddies said.(right next to top spark plug) hopefully it will be in by friday. parts counter guy said also might be sand/dirt inside water pump.. i guess ill do it one piece at a time. (hopefully i can fix the problem myself in less money then it would cost to pay someone to fix it) Both of your inputs are much appreciated! thank you.

 

[fishinhardwater]

Re: 1988 Mariner 60 HP Overheat alarm

Got the new switch assembly, its much more sensitive then the old one. alarm goes on at full throttle but stays on longer as i back down on the throttle. Went home shoved a garden hose in the coolant lines blew out all the lines i could without dropping the lower unit. then i went back out and the alarm sounded 4 times at full throttle.. then all of a sudden it didnt sound anymore. i drove around for 20 minutes full throttle and never heard it again! I think clearing the coolant lines with the garden hose may have solved my problem? or maybe just pushed it down the line for trouble later? but i hope i solved it for good. thanks the piece i bought is number 3 on this chart. http://www.crowleymarine.com/mercury_parts/1991/250.cfm

 

[fishinhardwater]

Re: 1988 Mariner 60 HP Overheat alarm

update:
alarm is coming back on again! i cant figure this out. IS THERE any way possible that i am getting this alarm because of AIR in a fuel line? or maybe i should mix oil RICHER then 50:1 ?? any suggestions?

 

[Laddies]

Re: 1988 Mariner 60 HP Overheat alarm

Have you disconnected the auto blend sender and ran the engine to make sure that its not causing the horn. Your engine does not have a thermostat or popit so that can't be the problem. When you changed the impeller was the old one all in one piece or could there be pieces loose in the cooling system, were the pump base gaskets in good shape sometimes they will allow exhaust into the cooling system.

 

[fishinhardwater]

Re: 1988 Mariner 60 HP Overheat alarm

yes sir, autoblend is disconnected and i mix 50:1. (do u think i should try to mix richer?) when i changed the impeller, the old one looked good and all in one piece. however, i did not change the whole water pump kit, just the impeller, maybe i gotta do the whole thing... another quick question: after i "flushed" the cooling lines with the garden hose it finally ran WOT without beeping so maybe i just pushed the problem down the line further until it got stuck in something again? thank you for your help, Laddies, its much appreciated.

 

[Laddies]

Re: 1988 Mariner 60 HP Overheat alarm

No the 50 to 1 oil mix is not the problem, I have been checking parts bulletins and they say not to use a 96829A1 switch as a replacement use 12415 the early number was a 260 degree switch and cost $85 and the replacement is a 285 degree switch and is less than $20 but you have to buy a wire thats $30 or just make one up heres a link http://www.mercruiserparts.com/Show...260.png&inbr=336&bnbr=90&bdesc=Cylinder+Block Item 38. Both Bam marine and US Boat supply have the new number listed in their parts books, did the place you bought yours cross the part to a new number or just ship the 96829 to you? That could be the problem I suppose. If you engine is a salt water engine removing the exhaust cover to check for debris could be a problem.

 

[fishinhardwater]

Re: 1988 Mariner 60 HP Overheat alarm

#38 measures water temperature. i got that sensor once, and thought i had the wrong one. then i went back to the dealer and brought the 96829A1 with me and they ordered it for me. if i go back and buy the 12415, do i unhook the 96829A1 wire and put the 12415 wire back on instead? or leave both on?

 

[Laddies]

Re: 1988 Mariner 60 HP Overheat alarm

I don't have the serial number of your engine but if you use it on the Bam web site you need the sender the parts manual lists for your engine.

 

[fishinhardwater]

Re: 1988 Mariner 60 HP Overheat alarm



My Serial ob248347 1988 Mariner 60 hp 3 cylinder.
Heres what i have learned
Part # 12415 is for water temperature.
Part # 96829A1 is for metal temperature. (which is set to 260 degrees)
Now theres another part listed #96829a2 (which is the same as 96829a1, but its heat is set to 285 degrees) but my serial numbers not listed under that one. number 14 on here- http://www.mercruiserparts.com/Show_pictures3.asp?dnbr=%2016404&ivar=IMAGES/COMMON/19261.png&inbr=336&bnbr=100&bdesc=Exhaust+and+Manifold+Covers

>Was wondering if i put #12415's wire on the same place where 96829a1's wire goes?

>and do i disconnect 96829a1 completely and only have #12415 as my temperature sensor, or do i put both sensors on?

Thank You

 

[fishinhardwater]

Re: 1988 Mariner 60 HP Overheat alarm

ok, heres what i did. its probabaly not right, but i took off the very last hose that goes to the tell tale and put a fatter hose on there with out the small hole to pee out. running like this, there is no more overheat alarm. maybe the water wasnt going thru fast enough and was getting too hot? i dont know but it works now

 

[rhurt]

Re: 1988 Mariner 60 HP Overheat alarm

Wow.... Reading this thread was like De Ja Vue (spelling)... This is exactly the same thing my '88, 60 Mariner is doing. Only at full throttle and only after you are just up to speed and enjoying the ride..... I usually cut back to 3/4 and it will go off, but sometimes it takes a few minutes. The stream of water looks weaker and it has always been very slow to pump right after starting the motor. So, I too am planning to change the water impeller and possibly the entire pump. But I think I may also look into this sensor wire described and I will definitely look at increasing the size of the P tube!!!!

How have things worked out for you and what do you feel like the real issue was?

Thanks for such a great thread and real socratic discussion of the issue, good stuff!

 

[DuckOfDeath]

Re: 1988 Mariner 60 HP Overheat alarm

I had the same symptoms a year or more ago. Removed the water jacket cover to clean off the scale buildup and discovered my telltale hose was partly obstructed. The telltale stream looked good beforehand so I never suspected an obstruction there. I tried to convince myself that it could have been the scale buildup causing the alarm to justify all the time I put into cleaning it up. Truth is it was likely the simple 3 minute fix of clearing the telltale hose that really solved it. This was after 2 water pump installs and troubleshooting the sensor too. Doh!

 

[fishinhardwater]

Re: 1988 Mariner 60 HP Overheat alarm

Wow.... Reading this thread was like De Ja Vue (spelling)... This is exactly the same thing my '88, 60 Mariner is doing. Only at full throttle and only after you are just up to speed and enjoying the ride..... I usually cut back to 3/4 and it will go off, but sometimes it takes a few minutes. The stream of water looks weaker and it has always been very slow to pump right after starting the motor. So, I too am planning to change the water impeller and possibly the entire pump. But I think I may also look into this sensor wire described and I will definitely look at increasing the size of the P tube!!!!

How have things worked out for you and what do you feel like the real issue was?

Thanks for such a great thread and real socratic discussion of the issue, good stuff!

after installing the fatter hose at the telltale, it has never overheated, and the alarm has never turned on since!

 

[AEROCOOK]

Re: 1988 Mariner 60 HP Overheat alarm

Dont mean to hi-jack your post but there are 2 of you with the same motor as mine and I posted a while ago on a similar topic with little response.
My question to you is how long does it take for water to come out your tell tale after a hot restart? Mine seems to take around 5 seconds or so even after I replaced the impellor. Never heard an over heat alarm.
Just looking for a little reassurance that this is normal for these motors.

 

[fishinhardwater]

Re: 1988 Mariner 60 HP Overheat alarm

i never timed it, but it does seems to take about the same (5 seconds, maybe even a little longer)

how long does it take for water to come out your tell tale after a hot restart? Mine seems to take around 5 seconds or so even after I replaced the impellor.
Just looking for a little reassurance that this is normal for these motors.