Temp issue remains, beyond stumped

[jerzia]

Optimax 250 Pro XS 2B360847 - Last summer, I chased a temperature issue the whole season. It was constantly struggling to get up to operating temperature. I went through four OEM thermostats to finally get it where it appeared to be working correctly. I just got my injection/fuel rails back from service, and got everything installed, including new impeller. Before going forward, I removed compressor strainer and back flushed the motor for a good 15 minutes. I then did an oil prime, and got it running on the muffs with good water pressure. Compressor temp was holding at 86 degrees. Watching both port and starboard temps using Diacom software, neither side would get up to proper operating temp. The highest one side got was 122 for a brief moment before dropping down to 116-118, and the other never got past 116-118. I ran it for a good 10 minutes plus, and it never got warm. I'm thinking if it was a thermostat issue, at least one side would warm up close to temp, but since neither side did, maybe I'm missing something? Honestly, I'm at a loss with this one. Any ideas??

[lpugh]

What was the exact water pressure at that time
If you pinch off the thermostat dumps hoses, will the temps rise to 140 plus rapidly.
Have verified the poppit valve is sealing?

[jerzia]

What was the exact water pressure at that time
If you pinch off the thermostat dumps hoses, will the temps rise to 140 plus rapidly.
Have verified the poppit valve is sealing?

Pressure was 3-4psi and no I didn't pinch dump hoses or check poppit. I thought poppit wouldn't come into play until psi and RPM increased.

[Savage]

The dump hose test tells the tale. Pinch off a hose at the moment the temperature stops climbing on a cold motor. Temperature rises, then thermostat is leaking by......easy peazy

[jerzia]

The dump hose test tells the tale. Pinch off a hose at the moment the temperature stops climbing on a cold motor. Temperature rises, then thermostat is leaking by......easy peazy

I will try that. The thing that puzzles me though is, I was experiencing that same exact issue last year. I replaced both thermostats twice ($$) and the issue remained. The odds of getting four bad OEM thermostats has to be pretty high I would imagine, but then again, with my luck, not impossible. I also just checked the poppit, diaphragm, etc, and everything seemed fine, but for the price of parts and ease of doing it, I'll probably replace everything there as well.

[lpugh]

thermostats can get Debrie in them in one outing, could have would chips stuck various places such as lower unit passage
If this proves to be the case with the pinch test. remove stats and leave covers hanging, remove the compressor strainer, drop the lower and inspect carefully, cut the fitting off a garden hose and connect it to the pipe in the mid that connects to the water pump, turn the water on high for a few minutes,
3to 4 psi at idle indicates the poppit valve is sealing if it is not a new water pump.

Stats are very easy to test with hot water and a thermomitor. be sure they close completly within about 15 seconds when moved to cool water,

If you are picking up sand in shallow water, causing this replace them as they cannot be saved!

[jerzia]

thermostats can get Debrie in them in one outing, could have would chips stuck various places such as lower unit passage
If this proves to be the case with the pinch test. remove stats and leave covers hanging, remove the compressor strainer, drop the lower and inspect carefully, cut the fitting off a garden hose and connect it to the pipe in the mid that connects to the water pump, turn the water on high for a few minutes,
3to 4 psi at idle indicates the poppit valve is sealing if it is not a new water pump.

Stats are very easy to test with hot water and a thermomitor. be sure they close completly within about 15 seconds when moved to cool water,

If you are picking up sand in shallow water, causing this replace them as they cannot be saved!

They are both clean as a whistle. Remember, I had the issue last year, two brand new T stats, same issue, two more brand new T stats that I thought solved the problem, apparently not. Water psi is on the muffs. I don't want to drag it to the launch without fixing this issue. Going to replace all poppit components anyway, been chasing this stupid problem far too long, and way too many wasted trips to the lake. I hope I don't have to drop the lower again. Getting that hose and small connector into the lower unit when installing is a major PITA.

[lpugh]

They are both clean as a whistle. Remember, I had the issue last year, two brand new T stats, same issue, two more brand new T stats that I thought solved the problem, apparently not. Water psi is on the muffs. I don't want to drag it to the launch without fixing this issue. Going to replace all poppit components anyway, been chasing this stupid problem far too long, and way too many wasted trips to the lake. I hope I don't have to drop the lower again. Getting that hose and small connector into the lower unit when installing is a major PITA.

Easy peasy as Joe says, use a pick with a 90 deg bend to push the retainer down and pull the tube out before dropping the lower, put it back in place after bolting the lower in place.
Did you do the pinch test, positive conformation of a stat stuck open

[jerzia]

Easy peasy as Joe says, use a pick with a 90 deg bend to push the retainer down and pull the tube out before dropping the lower, put it back in place after bolting the lower in place.
Did you do the pinch test, positive conformation of a stat stuck open

So here's what I found. First off, I removed poppit, inspected everything which looked ok and put it back together. (still going to replace it) Removed both stats just to be double sure they were still clean, they were. Ran the motor again on muffs. This time starboard did get up to temp and open thermostat, port did not (114-118) Pinched dump hose and it did rise. (looks like thermostat #5 on the way) Now with starboard side temp swung up and down between 124-116. It would settle on 120 for a few moments and then once again started up and down. It did manage to cycle t-stat twice, so that was a good sign, but still wondering about that temp swing.

[1ranger487vs]

Had my share of thermostat problems also. If that helps any. Never had a thermostat problem before my opti.

[jerzia]

Had my share of thermostat problems also. If that helps any. Never had a thermostat problem before my opti.

Same here, my old EFI was bulletproof.

[jerzia]

Easy peasy as Joe says, use a pick with a 90 deg bend to push the retainer down and pull the tube out before dropping the lower, put it back in place after bolting the lower in place.

I've tried that and could never get it in from the top. The hose has zero play in it. If you saw how I had to do it with that hose so short, you would shake your head.

[lpugh]

already shaking my head, just pull the tubing down as there is more in the cowl, may be zip tied up and will pull a little hard, I never have an issue doing this on the gearcases used on that motor unless some one has it pinched between the lower cowls and that is an easy fix
Use hot water and thermometer to test cycle the stats. many times you will not notice that .015 gap or the contaminants, when they open shakem a bit and look in the container to see what came out

Unless you insist on having a operational pressure operated speedo, you don't even need to connect that tube!

[jerzia]

Did water test when I got them, and things were good, open and close as normal. The same thing with the others I tried, but the low idle temp remained. That tube on mine has to be stretched to even get close. I just assume eliminate it, would water spray from pickup be an issue? I get speed from gps. Can I cut it and just zip tie it off? It sure would maje things so much easier .

[lpugh]

Sure can, or under the cowl in front you can pull it out

[SilverFox579]

Unless you insist on having a operational pressure operated speedo, you don't even need to connect that tube!

+1!

Did the same thing and just left the tube hang in same spot as before but not connected, no issues with water spray.

[chad202]

I find mine doesn't get as high on the hose as it does in the water. I attribute this to higher pressure on the house hose than what the impeller puts out sitting in the water therefore since the Tstats are not a complete seal, you will have more water flowing through it on the house hose keeping your temp on the low side.

[JOE54]

hose temps are likely cooler than surface

[jerzia]

I kept pressure no higher than 3.8psi on Smartcraft, and water is cold, but not freezing. I would think the motor should reach proper temp regardless.

[EuropeanAM]

One thing I can assure you, you most likely DID have thermostat problems before your Opti. The engines you were running prior simply weren't smart enough to tell you about it (at least not COLD engine scenarios). Prior to the Optimax triple-nickle electronics, there simply was no "thermostat fault strategy".

So that meant you just ran it until it blew in most cases.

Jerzia: I'm wondering if you don't have sand built up in the recess at the center of the tuner/adapter plate. See a few like that and they were CONSTANTLY getting sand into the thermistor pin, causing binding and improper thermostat operation/closing. Like Leon said- sand will destroy them.