Overheat or Oil...Back To Square One!

[imported_barlow46]

Thought we had this one whipped but problem cropped up again today. Engine is 2000 VMax 150 on Hurricane Deckboat...aftermarket gauges. History: Engine has 49 hrs. (all freshwater except for last 10). Water pump was just replaced by dealer after I bought the outfit used and I got my first alarm after boat sat for 6 months. Dealer water tested (30 min) with no alarms. Alarm went off a while back (first trip after dealer service on WP) and RPM's dropped back. Shut engine down and restarted about 10 min. later....no alarm until RPM's get above 3500. Thought I had an overheat problem (see earlier post by Barlow46). Removed tstats and checked in pan of water with candy thermometer. OK. Removed and cleaned popit valve. Checked overheat sensors with water, candy thermometer and digital multimeter. OK. After posting my original problem, it was suggested that I may be dealing with an oil issue rather than overheat since my IR gun was showing no higher than 170's (if I remember correctly on last post). Removed remote oil tank, cleaned, replaced filter. Removed engine oil tank, cleaned, bled system. Also found plastic trim lever on tube under steering housing was broken and replaced it. Trim meter now works. Took out for test run. No alarms! Problem solved...Nope! Went out today and alarm is back. While alarm was sounding, I removed engine cowl and disconnected pink wire on sensor (right bank)....alarm stopped....reconnect wire....alarm continued again. Stopped engine. Removed sensor from right bank and moved it to left bank and put left bank sensor in right bank. Started up agaiin and went to 4000 RPM's. About three minutes into run, alarm starts again. Went back and removed pink wire from right bank sensor,,,alarm stopped...replace wire and alarm started again. I didn't have my IR gun with me but I placed my hand on top of right bank and then left bank. Left bank was cooler, I could hold my hand on indenfinitely. I had to remove my hand after about 7 seconds on right bank, not scalding hot but definitely warmer than left bank. After alarm sounds and engine is dropped down to idle, alarm shuts off after 3 or 4 minutes. Not sure where to check next but want to rule out oil if possible. I have ordered a Yamaha tach with oil/temperature, etc but I have to also put in new harness and switch as Godfrey Hurricane used their "own" harnesses to save a few bucks. I do have the 704 binnacle controls, so I do have that harness. Should I just wait until I get the tach installed and go from there or should I look at some other things while waiting on my stuff to get here? Thanks

 

[Shrek1]

Re: Overheat or Oil...Back To Square One!

I bought a used Yamaha that alarmed everytime it went over 3000 rpms. the engine ran rough until the alarm resolved, and was advised by a Yamaha dealer that is the engine protecting itself, by shutting down to 2000 rpms. I also tested the thermostats, and sensors all was well. I thought it also may be an oil issue. When I took out the thermostats it was caked inside with residue from years of salt water use. I was advised to put some On & Off Acid in the block where the thermostats were, let it stand for a few minutes, then flush with fresh water. I did this three times, and also treated my thermostats with On Off to get the gunk off them also. Just took it out this evening, and ran 4800 rpms for a solid 10 minutes, then did various rpm ranges for the next hour, with no alarms. It could be a blockage in the block. for $11.95 it solved my problem. It is called On & Off hull and bottom cleaner for Fiberglass.

 

[JUSTINTIME]

Re: Overheat or Oil...Back To Square One!

sounds like a blockage in the right bank
time to flush it