135 V - 6 Mercury Maximum Temperature

[KennyKenCan]

I have a 1994 Mercury 135HP V-6 that is running at 170 degrees when running without thermostats. With the thermostats installed, the temperature goes as high as 195 degrees. Is this normal? There are no blockages and the water pump is new.

 

[AndyL]

Re: 135 V - 6 Mercury Maximum Temperature

I would suggest you check or renew the poppet valve as if it is weak you will be losing water pressure from the block thru the exhaust. This would be particularly noticable at idle when the water pump is struggling to maintain pressure. The sensors for temp are at the top of the block so will "feel" the hottest part of the engine.

 

[KennyKenCan]

Re: 135 V - 6 Mercury Maximum Temperature

I guess I forgot to mention that I already have serviced the poppet valve. It was replaced.

 

[Dhadley]

Re: 135 V - 6 Mercury Maximum Temperature

I have seen motors that the poppet valve spring was actually strong enough to hold water in the block too long. It seemed the overboard water discharge was under tremendous pressure. We cut one round off the spring and it helped. Being in warm water we cut off another round and ended up with perfect temps. By the way, the temps were just like yours. Be VERY careful of heat in a motor with top guided rods.<br /><br />Good luck!

 

[KennyKenCan]

Re: 135 V - 6 Mercury Maximum Temperature

Many thanks to AndyL and Dhadley for their advise. I will try trimming the spring tonight and hope that is the cure.

 

[Dhadley]

Re: 135 V - 6 Mercury Maximum Temperature

Be sure and let us know. <br /><br />Good luck!

 

[Wellcraft 89]

Re: 135 V - 6 Mercury Maximum Temperature

Are you running in saltwater?<br />i noticed the location in your sig.<br />and has the motor been flushed regularly?<br />if not you may have little flow to the top of the motor.<br /><br />Just my $.02<br /><br />Rich

 

[KennyKenCan]

Re: 135 V - 6 Mercury Maximum Temperature

Thanks for the feedback Wellcraft89, but I always flush the cooling system. When I changed the head gaskets earlier this year, the internal components of the cooling system looked better than new with absolutly no salt deposits detected. I always flush out with "Salty-Away" after every use. Any other suggestions are still greatly appreciated.<br /><br />Kenny

 

[KennyKenCan]

Re: 135 V - 6 Mercury Maximum Temperature

Hey Dhadley, what are top guided rods?

 

[Dhadley]

Re: 135 V - 6 Mercury Maximum Temperature

Thats the style rods you have in your motor. Most rods are centered or guided by their location on the crank. Yours are centered by their location in between the wrist pin bosses.<br /><br />Did the temps come down?

 

[KennyKenCan]

Re: 135 V - 6 Mercury Maximum Temperature

Hi Dhadley, Thanks for that info on those connecting rods, it was informative. Unfortunatly we had very heavy rain last evening and did not have a chance to work on engine. Forecast is horrible for this weekend, but I am going to get to it no matter what, the fish are calling me<br /><br />Ken

 

[Dhadley]

Re: 135 V - 6 Mercury Maximum Temperature

Thanks for the update Ken. I hope your weather gets better for the long weekend.<br /><br />Good luck fishin!

 

[AndyL]

Re: 135 V - 6 Mercury Maximum Temperature

Just a thought that was suggested to me when I had a similar problem was that the tube that carries the water from the pump to the block is apparently seated in a rubber seal in the powerhead. If when the water pump was serviced and the lower leg replaced the tube was misaligned, it could have broken the seal in the powerhead causing serious leak past. I am sure someone more technically knowledgeable could say whether this would be likely or even how to effect a check. <br />Fishing is not up to much in this part of the world if that make you feel any better.

 

[KennyKenCan]

Re: 135 V - 6 Mercury Maximum Temperature

Hey Dhadley, hows it going. Thanks for the info on the poppet spring. Before I went ahead and cut the spring down, I went to the dealer who advised me that they have a tropical spring for my application, so I bought one and guess what, now it runs perfectly, 145 degrees to 150 degrees. I really appreciate the help you gave me with this problem, hopefully I can return the favor somehow. By the way fishing was super, 1 striped bass weighed in at 37 1/2 lbs. Thanks again.<br />Ken

 

[Dhadley]

Re: 135 V - 6 Mercury Maximum Temperature

Excellent! Was the tropical spring shorter or a smaller wire size? It sounds like they have run into this quite often.<br /><br />Thanks for the update!!

 

[KennyKenCan]

Re: 135 V - 6 Mercury Maximum Temperature

Hey Dhadley, sorry I did not respond sooner, but I had to go to work. Anyway, that tropical spring has a smaller wire size and appeared to be about the same length.

 

[Dhadley]

Re: 135 V - 6 Mercury Maximum Temperature

You're like me.....work keeps getting in the way of this important stuff.<br /><br />Thanks for the info. Thats very good to know. I would much rather change the spring like you did than cut one. Did you happen to get a part number for that new spring?<br /><br />Happy boating!