Merc high temp alarm?

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dbetterred

Junior Member
I finally got the V out today for the first time this year. Did a bunch of work this year. cleaned carbs, water pump, durabak, new swim platform, anchor roller, etc... I'll get some pictures out to you guys this week.

My problem is my 1993 135 hp merc/mariner was having some problems today. It never idled well (last year also, was hoping cleaning the carbs would help that) and today it idled decent in the beginning but than would die when idling out of gear. It will idle all day in gear (I trolled for an hour and no problems). it doesn't seem to be loading up it just dies. to start it you have to advance the throttle and it will start right up. When it died I tried to give it more fuel using the enriching switch (choke) this made it worse. The idle rpms are good at about 650-700 rpm.

As bad as this is this is NOT the bad problem. My main problem is the motor gets an overheat alarm if run around 3300 to 3700 rpm not below or above if I keep it above 4000 or 4200 it seems fine. trolling around it was fine. the pee stream was constant and plentiful at all times (once warmed up) and it did feel very hot during the over heat alarm (no temp gauge).
when the alarm goes off I just cut it back to idle and it would cool down rapidly (20 seconds).

All other times the motor runs tops. I saw 40 mph with full canvasses up today around 5400 rpm.

any ideas? I can understand if it was above a certain rpm but this slot type problem doesn't make sense to me.

I really don't want to take it to a mechanic and pay $ I can't afford, if you know what I mean. But it may come to that.
 
not knowing what you replaced in the water pump, I would check the water pump housing for warpage, also make sure you run a bead of silicon on the exhaust separator plate right behind the water pump to prevent exhaust from aireating the water flow. It wouldn't hurt to check the poppit valve while your at it
 
i would suggest checking the poppet valve on the side of the lower block, also you mentioned you changed a water pump. did you just do the impellor and not the housing? also t stats are a common problem. just hang in there, the real mechanics will be along................

man spare, you are a faster typer than i am great minds think alike.
 
I replaced the impeller and the bucket it comes in but not the plastic housing. I thought it looked straight... I might half to pull off the lower again to check.

Never heard of a poppet valve. what is it? what does it do? I'll look in manual after work and check it out.

I thought of the t-stats also, but wouldn't they stop the pee stream if they closed up? They are easy and pretty cheap. I'll get them anyway.

Thanks for the quick response!
 
I looked up the poppet valve and that made sense with the overheat symptoms. I pulled it off and it looks good. Disasembled and cleaned it and will reinstall when I get gaskets. I won't know for sure until I run it but that doesn't look like the problem.

Looks like I'm pulling the lower unit back off. :sad:

ordered t-stats also.
 
I may not have to pull lower off after all.
Pulled thermostats out (broke one bolt...:head:) and they were super crusty and rusty!
Looks like this may have been the problem. Fingers crossed!
 
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