Water control valve rework and results.

[j_k_bisson]

To start off I have a 1987 225 Evinrude that I rebuilt/restored. I just finished 3hrs of breakin and I am asking questions about certain things that have popped up. That is why this thread is being started.

The motor's water cooling system was rework as per Faztbullets suggestion to remove the whole water control valve and diaphrams, seeing some parts are not longer available, and replace them with a late 80's 70hp T-stats covers, spring and T-stats. This worked out great seeing it was already done to the motor when I got it. I replaced the springs and and T-stats and reused the covers.

I also installed the OMC Head temp sender and gage in the boat to motonitor the temp while running. I had an issue with this right off the bat seeing I bought the sender and gage separate from each other. When I first started it up, and the motor warmed up, the gage spirked to the limits. I found that the sender unit did not match the gage I was using. I have corrected this on the motor.

While out running the last time, while still in the breakin stage, I notice that the motors temps are around 165'f at idle, 650-700rps. This is high as per the service manual. Tha manual states that the temp should be 140'f +/-15'f. At 2000rpm approx the temp rises to185'f. That is untill the t-stat's unseat and the temps drop to 120-140'f.

I have talked to my local dealer and they are telling me this is not really an issue. I have gotten feed back from members on this site and they stated I should be concerned. That is why I am starting this thread.

First off I am asking anyone else that has this same setup what are you reading on your temp gages. Also what style is your temp gage are you running.

I am lead to believe that this could cause premature failure/wear to the motor with the sustained temps. I plan on using this boat in rough seas and the speeds I will normally use it at is 2500rpm rage. Basically just up on plane. So this could become a big issue for me.

The next question is how can I over come this issue? Or better yet how can I lower the temps? If it where a typical T-stat from a car I would just drill out the pee hole in the t-stat and call it a day. But these T-stat's are a bit different monsters. Is there different Verbatums thingy's for different temps? I am assuming the Verbatums are inside the t-stats.

Or am I making a big deal out this whole temp issue?

And yes I have replace the water pump as a whole. It is installed correctly and working correctly.

 

[j_k_bisson]

Re: Water control valve rework and results.

No one has done this change to thier motor?

 

[j_k_bisson]

Re: Water control valve rework and results.

Well seeing that I did not get a response to this thread. I descided to talk to my local Evinrude dealer about this rework. The old Evinrude mechanic stated that he had done this same rework many times and depending on the application of the motor, bass boat to offshore boat, that if the ower ran the boat in the mid throttles where this heat issue was a concern, he would cut off one coil from the spring. I though this was a bit strange but here is what he stated for his reasons for this change.

First the springs come off a 70hp 1987'sh motor. The thermostat to cover dimension is larger than the 200-225hp's. It around the 1.75" lenght for a 70hp and 1.5" on the 200-225hp's. This causes a greater force being applied to seat the thremostats at rest/idle on the 200-225hp's than what was originally required on the 70hp's.

As to the water pressure required to unseat them, with this great force being applied, it would take more RPMS to unseat. This is not a problem for the bass boat guys that have two speeds "on" and "full throttle". For us that venture in rougher water where we cruise any where from 12-21mph, or 2000-3500rpm's, then the spring rework needs to be done.

So getting back to the technicals. Seeing I did not have a 70hp motor to take the exact measurements from I made the follow assumptions and I am tresting it. The first assumptions is that at idle a 70hp water pressure is the same as a 200-225hp, around 3psi. Also the water pressure curves are the same from a 200-225hp as a 70hp through out the rpm-range. I don't think this is the case but they must be close. SO the same preload of the spring, the compression when assembled, must be the same. So for thew 70hp it was 1/4" compression, so I cut the springs down to 1.75" from 2.0", the orginal uncompressed length.

Seeing I did this after dark last night, I'm going to run the motor on muffs this afternoon to see what happens and test it out on the water after work one night this week.

So does anyone see any issue with what I have done?

 

[daselbee]

Re: Water control valve rework and results.

My loopers run 8 - 10 psi at idle. First discrepancy. Thirty + at WOT.

 

[j_k_bisson]

Re: Water control valve rework and results.

OK thats good to know. I was only quoting what the dealer said. I have not tried it, and will not this afternoon. The neighbours are having a family function. I don't need to smoke them out, as the wind is blowing that way.

I have a spare set of springs if this does not work. Also when I get to work on monday I'll start playing with the force guage to see what rates the springs respond at.

Anyway I can get the psi at say 1000, 1500, and 2000 rpms?

 

[daselbee]

Re: Water control valve rework and results.

No, sorry Jeff, I have never payed attention to the intermediate pressures at mid range throttle.
My boat is down now, transom and stringer replacement, and I will not have it back in the water for a month or so...

 

[j_k_bisson]

Re: Water control valve rework and results.

OK I'll tr4y this the old fashion way. Trail and dumb luck way. Tomorrow I'll see what happens on muffs. I'll report my findings.

I'm sure my neigbours will love this one.