2018 18 TRX Lost Top End Speed

[Bryanmc57]

The guy working on your motor is as good as they come. I'm sure he'll find the issue.

[JOE54]

we will know tomorrow

[barmour]

Update: I left my rig with Joe mid April and picked in up Aug. The thermostat alarms seems to be fixed and the speed in TX was 67. I only had half day to run the boat in TX, nor fish at lake fork and have ran the boat 2 short days other times in CO since and no Stat alarms. Being it's a dual console and it was a humid 85 degree day it's better than it was and a more normal top end than before. Joe found a plug was misthreaded and not seated as far down as it should (and likely crooked to the piston) & replaced the head cover on the port side. I'm thinking since the boat was new it either had a defect in the head since the boat was new causing the tstat alarm issue from day one. He checked several other areas and that's the only thing he found. I pulled all the plugs and either it was already misthreaded from tech in CO doing comp check or I did it, so either way the head maybe was the problem. Thanks to all on this site for assisting and a big thanks to Joe54 for spending the hands on time and effort to fix my issue.

[JOE54]

that boat would go 72-3ish here in few weeks

[barmour]

So after a few days of no alarms in spring 2022, now back to water temp to low or to high stb/port side then the sometimes on the hose and sometimes on the water random just in gear idling alarm and it comes and goes again since April 2022 same as before. Never been in a registered guardian mode. Do you guys know what the part # is to replace the port/starboard side water temp sensor in the heads or an overall water temp sensor that senses the alarm related to port/starboard water temp. Is is specific to my engine SN or just for a 2018 200 pro xs. tks. So many hours and effort and money spent and thinking maybe try something like a sensor. tks

[JOE54]

8m0148668

[EuropeanAM]

So after a few days of no alarms, now back to water temp to low or to high stb/port side then the sometimes on the hose and sometimes on the water random just in gear idling alarm and it comes and goes again since April 2022 same as before. Never been in a registered guardian mode. Do you guys know what the part # is to replace the port/starboard side water temp sensor in the heads or an overall water temp sensor that senses the alarm related to port/starboard water temp. Is is specific to my engine SN or just for a 2018 200 pro xs. tks. So many hours and effort and money spent and thinking maybe try something like a sensor. tks

Very unlikely to be a sensor. Have you checked to make sure that both banks are coming up to temp at idle (ie: thermostat cover at least 120 degrees F when checked with an infrared temp gun)?

It takes less than 1 second to such up some crap off the bottom and about 1 more second to send it to a thermostat where it lodges it thermostat open... especially problematic when it's the PORT side that's stuck open.

[lpugh]

Here's something to try... Instead of leveling the deck when you measure prop to pad, level the pad and then remeasure PTP after leveling the cavitation plate. See if you come up with the same number as when you leveled the deck.

Check level of flat surface the boat is sitting on and adjust Toung jack to level the pad of the boat to match the floor, then use trim to level the cav plate to exactly match the same, then measure.
mark the jack when set at 3 in. now you a reference permently.

[barmour]

Check level of flat surface the boat is sitting on and adjust Toung jack to level the pad of the boat to match the floor, then use trim to level the cav plate to exactly match the same, then measure.
mark the jack when set at 3 in. now you a reference permently.

Lol, Lpugh, I think you replied to a diff part of the thread. Tks tho, the center bottom of the boat with a level of PTP is 2.5 inches below center of pad with boat and cav plate level.

[barmour]

My man Joe spent a lot of time on this motor tween Apr 2021 and Aug 2021 and thought it was fixed but only for a few days for "5" years since the boat was brand new, have had this nagging problem and I'm no mechanic but I know when something fishy here. People are looking for the obvious and it's not the obvious. It's random different sides of the motor alarming either temp to low or temp to high and it's not because stuff is plugged up. I had temp alarms again in 2022 on random days then in Apr 2023 ran it for first time on muffs Sep 22 and got a stb temp to low within appx 5 min, verssel view mobile, did not have a laser gun in hand and cleared the alarm, turned off engine started again and for 15 min on muffs no alarm and could see vessel view mobile water pressure 3 psi, temp going tween 117 and 130 as if stats opening/closing. No I didn't sit on the laser gun but other mechanics have and they work & open close as designed. This never alarms on pad ever, only slow to fast idle "in clean water". Test drove on lake next day for some 5-15 idle in gear and full runs off on for an hour, no alarm. It's just friggin random. I've backflushed, it's got good water psi always above 12 psi above 4000 rpm, 22 psi WOT, 3psi at idle on muffs/on out of gear in lake, checked the plastic lower left side cowling plastic filter, pulled stats, replaced multiple stats, "known good stat by mechanic", people shot laser at it during checks. So that's why I'm tired of spending time & money, frustration of chasing this ghost. It's never been in guardian mode for this or anything. Now if I want to sell it gotta deal with this problem and warranty is over 1 May. I'm ready to cut ties, but now motor is at 128 hrs and still this issue after 5 yrs. I feel like it's a sensor or sensors or the item that monitors these sensors. Mercury dealers won't fix anything on their dime cause keep blaming it on "normal wearable" stuff. Thoughts?

[barmour]

PN for sensor 8m0148668
tks Joe.

[barmour]

8m0148668

To make my failure complete should I get 2 (1 for each side) or is it total? Any chance my ECU needs to be updated/reflashed with any updated software? Tks All

[JOE54]

yes replace both they dont come in pairs , possible pcm may have update , ser number please ????

[barmour]

SN 2B533330

[Savage]

"This never alarms on pad ever, only slow to fast idle "in clean water"

The above statement tells me that you do NOT have ANY temperature sensor problems. You do have re-occurring thermostat issues. Just because you are "in clean water" when the alarm occurs, doesn't mean that you didnt drag the lower unit through debris, after you shut the motor down. Most of these alarm problems are thermostat debris related and will continue, until you make an effort to keep the motor trimmed up and barely under the water, when you are on the trolling motor, in the shallows. Your problem will never be FIXED for good, because thermostat related alarms are a maintenance issue.

[barmour]

Great advice "I've followed that for 18 years tho already" Come on guys throw me a bone here, I realize the 2005 175 optimax I put 550 hrs on is a little different than a 2018 200 pro xs 2 stroke with the front cone low water pickups, but I run the same waters the same way and this is not stuck stuff in the stats. If it was it would not be this random and only during idle. At some point it would stay stuck open or stuck closed. Are we sure it can't be something defective since brand new bought and ongoing randomly for 5 years and 130 hrs, only during random days at neutral or in gear idling. ECM, poppet, sensors?

[barmour]

Think something we haven't check that we/is still bad from the factory new in 2018 and still there, installed upside down, slightly defective intermittent temp reads that are only few seconds out of tol, but only idle related assuming its "not" plugged or bad stats, not bad water pump, not operator error and never 18mph to top end.

[apdriver]

I had some funny stuff happening at idle. Temps wouldn’t come up to 130 and cycle. Would stall, climb very very slow, stall again. I cleaned, tested, then replaced the stats. No change. Then I decided WTH and replaced the poppet. Solved my issue. My guess is it was weak, sticking, something. It’s relatively inexpensive and prolly worth trying. Mine never alarmed.

[lpugh]

I had some funny stuff happening at idle. Temps wouldn’t come up to 130 and cycle. Would stall, climb very very slow, stall again. I cleaned, tested, then replaced the stats. No change. Then I decided WTH and replaced the poppet. Solved my issue. My guess is it was weak, sticking, something. It’s relatively inexpensive and prolly worth trying. Mine never alarmed.

Poppit sticking open would cause very low or no water pressure at idle.

[JOE54]

G3 diagnostics will verify source of warning horn , low voltage ,low temp , high temp, low block psi ,...... etc