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capt. Troy

1999 mercury 225 dfi

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Good luck! After working on my own 03 135 Optimax, I can sympathize with you. Overall its been a pretty good motor and I have about 750 hours on it but you can do very little on your own other than replace parts and guess. The mechanic has so much more information available if it is hooked to a Merc laptop- I have had occasions where the temp guage showed running a little warm when the computer showed port side normal and starboard side running dangerously hot. A good shop/mechanic means almost everything! Trying to figure out a heating issue that began in the Gulf, I replaced and cleaned everything I could think of and then 3 shops failed to fix it. I even spent a lot of time with a Merc tech on the phone and finally ordered the repair manual where I found there was a screen leading into the air compressor. It turned out that we had somehow sucked in some kind of broad leafed aquatic week and packed it full (thats the bad shops). I now use Coopers in Ashland since he's not too far away but he has really worked to find some things such as a sticky poppit valve and has been really fair if I had to take the motor back. Overheating while trolling has been my main problem- so far nothing related to ethanol (knock on wood). I hope you get your problem straightened out so you can catch the tail end of the warm season and get out and go rockfishing!

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VBSF.net | Fishing Reports From Virginia Beach VA To Hatteras NC 

Good luck! After working on my own 03 135 Optimax, I can sympathize with you. Overall its been a pretty good motor and I have about 750 hours on it but you can do very little on your own other than replace parts and guess. The mechanic has so much more information available if it is hooked to a Merc laptop- I have had occasions where the temp guage showed running a little warm when the computer showed port side normal and starboard side running dangerously hot. A good shop/mechanic means almost everything! Trying to figure out a heating issue that began in the Gulf, I replaced and cleaned everything I could think of and then 3 shops failed to fix it. I even spent a lot of time with a Merc tech on the phone and finally ordered the repair manual where I found there was a screen leading into the air compressor. It turned out that we had somehow sucked in some kind of broad leafed aquatic week and packed it full (thats the bad shops). I now use Coopers in Ashland since he's not too far away but he has really worked to find some things such as a sticky poppit valve and has been really fair if I had to take the motor back. Overheating while trolling has been my main problem- so far nothing related to ethanol (knock on wood). I hope you get your problem straightened out so you can catch the tail end of the warm season and get out and go rockfishing!

 

KD - I have done my fare share of research on these motors. One thing that i continue to hear from the fleet of service men is that thse motors were not meant for trolling between 2000 and 2500 rpms. ANd that puts you at the 8 knot for tuna trolling.

About that screen though. I have heard of people cleaning them and then thier problem of over heating goes away. Where exactly is that? Maybe we can all check our and be relieved from the over heating saga.

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The mechanic ran the diagnostic test on it with his computer and says he is going to replace the two throttle sensors that relay the info to the ecu's. wish me luck

Wishing you luck CApt. Troy. Please let us know, maybe that is all of our problems and dont even know it. I am still guessing a clogged filter since we are staving of fuel.

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DoubleH- the strainer is easy to clean but a b--, I mean bear to get to! You have to remove the mid-section of the cowling. One screw is easy to get to out of the 4 you have to remove. It is located outside the middle cowling on the front of the motor, accessed from the port side. There is another up front, inside and center way. The worst one is the rear center, inside the cowling at the bottom below a couple of lines. The final one is inside the cowling, port side rear. If you don't see them, email me and I will try to scan a diagram for you. Do this on a day when you are not in a hurry and are feeling patient! Once you can lay the port side piece aside you will see 2 water lines feeding from the port head, under the fuel rail. One hose enters the air compressor a little higher than the other- remove the lower end of this hose and you will find a screen. It is not a very fine screen and how it can get stopped up I haven't a clue but mine has had some weeds in it a couple of times.

 

While you have the cowling off (by now you know you don't want to do this often) you may as well inspect and clean the poppet. It is located on the starboard side, at the bottom of the block. It is a silver dollar sized (if I remember) round access atached to another, smaller round plate that screws it to the block. The poppet can get sticky and cause low to mid rpm overheating.

 

You may as well remove and check your t-stats since you are working on cooling- this can be done after you cuss and get the mid-housing section re-installed. They are located on each side at the top of the heads and slightly under the fuel rails. The starboard side can be removed with just the 2 housing bolts- on the port, you will need to loosen or remove the fuel rail (again, 2 bolts if I remember and easy to do. I like to nuke some water pretty hot and insert both t-stats and see if they open about the same time. If you buy t-stats I think you need to order the rubber gaskets separately- merc doesn't provide them.

 

Hook her up to a set of muffs and start her up (better safe than sorry).

 

While looking at my service guide, I notice that the water coming out the tell-tale is the same water that must pass through the screen for the air compressor/port side head. It is listed as a possible cause for overheating/poor stream through the tell-tale(pisser).

 

Other than the water pump/impeller, I don't what else to check unless a sensor is bad. And as most of you know, always change the housing when installing an impeller- the shaft is just off center and carries the impeller around like an excentric. This motion is actually what pumps the water and not just the impeller blades. The housing gets worn and even with a new impeller may not pump water properly. The cost isn't much different and you already have it apart- fix it right!

 

I hope this helps- its a job, but then what isn't??

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Yeah I will be sure to let you all know how it goes. it just sucks this boat has run me 2000 in repairs this summer to pretty much still keep me off the water. A few cobia are about all ive got to show for it ha.

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Took the Grady out today. Bought new fuel water separaters and still had the problem. But it sure ran smooth!!! Made it to the beach to drop anchor and enjoy the sun, breeze and some bruskies. As I was sitting on the bow thinking that there could be nothing wrong, it hit me. I had one of those clear inline fuel filters in front of my sending unit for the fuel management. Low and behold that darn thing was sucking air. The moment I remove that darn thing, I was up on plane for miles on end with no issues. That was the one thing I was overlooking, it was not leaking and it was clean. Just never thought it would have been that and I hope that was the ture fix. Happy boating and hope fo you to get back on the water.

 

Double Headache

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Hope that was the fix! You missed some summer boating but you are ready to rock now- get out there all you can!

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Looking back in history... That crappy filter was the root cause. I have not had any issues since then. Have you solved your issues?

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I still have issues but mostly heat related and mainly at trolling speeds. I believe the poppet valve may be the culprit as I am setting a heat alarm while showing only 150 to 160 on the gauge. It could be a t-stat and only one side heating though I pulled them and they looked good. Cleaned the poppet once before and seemed to help for a while. It has never stopped me from fishing but is a pain, still.

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Yeah I replaced my impellers this year and still have that issue. Only the starboard motor runs warmer than the port when trolling 6-8 knots offshore. But not hot enough to set off the alarm. Just havent found the time to work that issue, not that it is that important. Maybe in the fall when it cools off I will get around to it.

 

Tight Lines!!!

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