Evinrude V4 looper Thermostat issues.

[sutor623]

Hey guys, some of yall saw my other thread talking about fouling plugs. Well, turns out I am fouling plugs because my starboard head isn't reaching operating temp at idle. If you run her hard port head will reach 130 and starboard 120. At idle port head hits 140 and stbd only hits 80 degrees!!!!

Now, as far as internal issues, I can assure you that there are none. Powerhead is newly remanufactured. Motor is very powerful and idles great after a long run. Compression is 150psi on all cylinders. I put a freeze plug in the cylinder head where the thermostat cup goes and started up the motor. The head heated up from 80 to 120 degrees in 30-45 seconds, another 10 seconds later it was at 140 degrees and I shut her down. The freeze plug was blocking any cooling water from entering the head at all.

I have changed out the thermostat, grommet, spring, cup etc. and swapped out different components and still can not get the temp to budge over 80. Other head is reaching 137 degrees. Most of these tests are done at home in a 55 gallon bucket.

Maybe the vernatherm isn't seating itself properly?? Does it take a good hard run for the therm to seat properly? This is driving me nuts, brand new motor, tons of work for the install and fuel/electrical system clean up and now this.

Stator and powerpack are brand new also, and spark is good and strong on all 4 cylinders.

Here is the diagram of the cylinder head/stats..........

 

[sutor623]

Oh, and some added info. When I had the powerhead off I went ahead and pulled the midsection apart, changed all the gaskets and grommets in there, and made sure everything was clean and clear.

 

[sutor623]

Soooooo,

I did another few tests today. I pulled the thermostats out of each head and ran the motor. Motor got up to 70 degrees on both sides, almost identical. At least I know both sides are running similarly.

Then, I swapped thermostats and I noticed a little burr inside the housing of the side that seemed to be overcooling. I cleaned it up a bit. It is unlikely that it was preventing the therm from seating, but very possible. Anyways, after I did this I swapped stats from one side to the other. Now, both heads got up to 100 degrees and stayed there. The themostat housings were both around 92 degrees. This only took about a minute or two. I let it run for about 5 mins. at idle and the temp did not change.

At least both heads were behaving similarly.

This motor was being run in a 55 gallon bucket with 40 degree well water being pumped constantly into it. This makes me think that if I were in 70 degree water (which is the temperature that Evinrude tells you to perform the temp tests at for accuracy) that the heads would actually reach their desired temperature. Does this sound accurate?

 

[Bosunsmate]

If it was properly restricting the flow then i would of thought the engine should of gradually got up to temp even with the lower temp of the intake water.
Hows the telltale behaving?
Id also fix up that bur on the weak one with some sealant of some sort, permatex aviation form a gasket perhaps. A little gap can let through a lot of water under pressure

 

[sutor623]

Thanks for the reply Bos. Telltale looks good with a nice solid stream. I cleaned up the bur with a file and cup seems to be seating properly.
I would have expected the engine to get up to temp too but I can't understand why it is behaving this way.

 

[Fed]

Wait until the bucket temp is up to 70 then check the motor.

 

[sutor623]

Wait until the bucket temp is up to 70 then check the motor.

Yea I think you are right. Unfortunately in the bucket with water constantly bubbling out and back in from the spigot I think that would be a timely/nearly impossible process. I am going to the lake this friday. Water temps are in the mid 60's, so I am going to run some extensive tests on the water, finish the 2 more hours of break-in, mix the remaining fuel at 50:1 (instead of the current 25:1) and see how she does. I am hoping at this point she will be running like a top with no more sputtering at idle and hard starting.