Overheating Issue

[twincaman]

1993 175 hp Merc. OK at low speed and high speed, overheats, 170+, at medium speed (2500-3500rpm), then cools if speed is increased to high (over 4500+ rpm). Water pump and both thermostats have been replaced and water stream looks good. Any thoughts? Poppet valve?

[XstreamVking]

Not a legit fix, butt....I cut 2 coils off the spring in the poppet on my 2.5 200. It had the same symptoms. Runs 145 now all the time. Instructor at merc school said it might fix some engines. You might also try a new spring? The problem occurs when the poppet is taking over for the stats. Poppet just opens easier with less water pressure needed.

[rgsauger]

Not a legit fix, butt....I cut 2 coils off the spring in the poppet on my 2.5 200. It had the same symptoms. Runs 145 now all the time. Instructor at merc school said it might fix some engines. You might also try a new spring? The problem occurs when the poppet is taking over for the stats. Poppet just opens easier with less water pressure needed.

Does cutting the spring increase or decrease water pressure? Or does it impact water flow?

[XstreamVking]

Water press seemed to stay about the same. It runs about 20 psi at wot. 12 or so at 3500 cruise.

[tlwjkw]

water stream looks good. Any thoughts? Poppet valve?

need a gauge.. tha "cut spring" might/might not work but it will actually masked tha problem that might/might not return....

pump.. kit or jus impeller?.. poppet kit before ya start changin' junk..

[twincaman]

need a gauge.. tha "cut spring" might/might not work but it will actually masked tha problem that might/might not return....

pump.. kit or jus impeller?.. poppet kit before ya start changin' junk..

Just impeller. the rest looked good.

[Merc 2.5]

Just impeller. the rest looked good.

The base plate wears out and cant really tell if it's bad until it starts letting water in. Need the whole kit , when was last time u replaced ALL of it? Did u put metal plate back k in correct?

[tlwjkw]

no mater what tha rest "looks like" best ta replace it all.. tha stainless parts (cup in tha housing and tha ride plate) will look jus fine but still be wore.. same with all gaskets.... jmo.