Overheat Warning

[ahill]

Thanks,
My 225 OX66's don't have any wiring on the housing.
After talking to some service mgrs while buying parts they all agree its the poppet valve. I had to go to 7 dealers to get the housings, gaskets and plastic mushroom.
If I knew acquiring the parts was that difficult I'd have ordered in advance from SIM.
Attacking it this weekend.
BTW have you ever used Loctite's new product Freeze & Release?
It replaces heat applied to nuts & bolts by reducing temp to -42 F degrees and has a penetrating oil in it as well.

 

[Tucker]

How'd you make out?? As you probably figured out, the connectors go into the ECU and are directly in you way. I've yet to find a dealer that had any parts in s tock other than thermostats and then they wouldn't have the gaskets. Thought Florida dealers would have better stock, especially of a part prone to failure.

 

[ahill]

I should have read your post about the ECU closer.
The boat is at dock so the job had to be done with the motors tilted full up.
Did unbolt the cover latch do aid in access.
All bolts came out easilly, added neverseize at reinstall.
Stbd. had the hose really expanded, enough to break plastic tie. Had to drill a hole in the valve to get a good enough grip to remove it. Port had almost no salt build up & came out by hand.
Vinegar did a better job on salt than Salt-A-Way, a lot cheaper to.
I didn't replace the housings yet due to the hose condition. Bought new hoses today & will attack in the next few weeks.
Stbd. hose bubbles a tiny amount even after installing new tie real tight. Probably been doing that a long time.
Ran the motors for a long time at idle with no overheating.
Local Yam service mgr said the old style valves could twist and not reseat as well as deform the grommet. That seems to be what happened to the port engine altho it had no buildup.
I'll need to remove the shrouds to replace the hoses, I'll do that on a flat or may put the boat on its trailer.
Thanks for your help, I'll report on the hose replacement later.

 

[Tucker]

Cheez Alan, you're a better man than I. I would have never attempted that job in the water. Bet it was a real site to see! Getting the valve, spring, housing, gasket and bolt holes to line-up requires both my hands and a lot of French. Did you replace the grommet? I've never seen the housings go bad, but I'm in brackish water here. Sorry about the hose. It's pretty cheesy to begin with and wondering if you had something rubbing on it. Sounds like a PIA job. And, wondering why you're even seeing a leak. Wouldn't think you would build up enough pressure to open the valve idling. Unless your hanging over the back of the boat on plane. Not a big fan of never-seize on boats. Seen it turn to white dust, not sure why. I use grease on everything. I even put it on gaskets to hold them in place while lining up the mating piece.
Also, some food for thought while you're getting dirty. Guy at my marina has a Marlin with 250's. Stb motor was starving for gas. Had mobile techs a bunch of guys looking at it. I went over and bypassed the check valve and she lite right up. I'm no genius by any stretch but remember reading about the check valve between the fuel filter and LP fuel pumps seizing up. I've removed them from every Yamaha I've had. Just an FYI...

 

[ahill]

Changed the grommet too.
With the motors tilted up you get a little gravity assist when reassembling.
I've used grease before but a Yam mech said use neverseize.
After changing the hoses & housings I hope I won't have to do this again.
Thanks for the fuel tip. I had a check valve at the fuel tank stick on my old Mako 17. Luckilly able to get it off without damage to the tank.

 

[ahill]

Final Update.
When changing the poppet valves I noticed that the hoses between the valve housing and block were distorted. Decided to change them while changing housings.
Pulled the boat out for that job.
My local service mgr. said to pull the apron and rear shroud to afford easy access. WRONG! all that did was waste time. It does provide access to the flush hose.
With my 39 yr. old son doing most of the work the hoses & housings were replaced. Extra long needle nose pliers make the job bearable. He has twin 250 OX 66s so the experience was valuable.
First one took an hour, second about 25 minutes after learning on the first.
While cleaning the pan I noticed the port oil control rod nylon fitting had split and the rod was hanging loose.
Checked the stbd and saw where it was split but not completely so it still functioned.
Downside to the rod being disconnected is that you burn oil at 45:1 at all speeds.
Replaced both and adjusted properly.
What started this whole problem was the port overheat alarm. Determined it was the poppet valve but the engine was idling at 500 after changing which leads to the overheat warning.
With the control rod connected to the oil pump oil is abbout 200:1. With proper oiling the idle now settles at 700 rpm.
Guess the overoiling fouled the plugs and caused the low idle and overheat condition.
Sheesh!

 

[Tucker]

Thanks for the follow up ahill. Don't think fouled plugs oroveroiling caused the low speed overheating. I believe you nailed it with the PRV valves; sorry about all the grief with the hoses. I would have also guessed that removing the lower cowl would help facilitate the job. There's a lot of tension on those plastic oil link clips. Wondering if they're a bit fatigued and purchasing new ones would be a good idea. Also, there's an adjustment for the pump. With the lower butterfly fully closed (throttle link removed) the clearance should be .010 between the pump lever and the stop. You may have fouled your 02 sensor. They changed the test procedure several times and the latest is done using a 5' test harness (about $40) that check the voltage readings on the fly. My stbd motor had a bad one and it drank gas like crazy.

 

[Tucker]

Thanks for the follow up ahill. Don't think fouled plugs oroveroiling caused the low speed overheating. I believe you nailed it with the PRV valves; sorry about all the grief with the hoses. I would have also guessed that removing the lower cowl would help facilitate the job. There's a lot of tension on those plastic oil link clips. Wondering if they're a bit fatigued and purchasing new ones would be a good idea. Also, there's an adjustment for the pump. With the lower butterfly fully closed (throttle link removed) the clearance should be .010 between the pump lever and the stop. You may have fouled your 02 sensor. They changed the test procedure several times and the latest is done using a 5' test harness (about $40) that check the voltage readings on the fly. My stbd motor had a bad one and it drank gas like crazy.

 

[ahill]

I think the fouling caused the low rpm & hence the overheat.
Do you have the test procedure for the O2 sensors?

 

[Tucker]

Yea, but I'm not smart enough to figure out how to post it here. I got it along with the test harness from Andy at SIM. I'm sure he'll send it, if not shoot me your email address. I can scan it and attach to an email. Have you been pulling it out and cleaning it every year?? Believe the book says every 200hrs or once a year? That includes the sensor, sensor tube, and housing.