Notices
The Boating Forum

250 OX66 Running Rough

Old 06-25-2003, 06:27 AM
  #1  
Senior MemberCaptains Club Member
Thread Starter
 
Join Date: Apr 2001
Location: Texas
Posts: 531
Received 18 Likes on 10 Posts
Default 250 OX66 Running Rough

Need some help guys. I would like to keep from taking the boat in to a dealer this time of year.

My port engine is running extremely rough at idle. I just got it back from the dealer last week for what I thought was the oil adjustment rod. The oil is adjusted properly, however it smokes like crazy at idle, runs 3 to 400 in gear while on the troll and shakes like crazy.

It seems to me that it's getting too much oil at idle. It runs like a champ at high speeds. Could it not be getting enough FUEL at idle thus causing the over oiling? Again, oil adjustment is correct. I was thinking about decarbing and adjusting the idle speed but want to make sure I find the cause of the heavy smoking first. And yes, I use ringfree consistently.

HELP!

Reel Screamer
Reel Screamer is offline  
Old 06-25-2003, 06:47 AM
  #2  
Senior MemberCaptains Club Member
 
Join Date: Aug 2002
Location: St. Augustine, Fl
Posts: 22,385
Received 4,469 Likes on 1,800 Posts
Default 250 OX66 Running Rough

Rell screamer,
I just decarbed my 225 OX66. Afterwards I did not change my plugs. about 4 engine hours afterwards the boat would not hardly run at low rpm then at top end I lost at least 800 Rpm. It sounds silly but try new plugs it cured my problem. Carbon was clogging up the O2 sensor since the plug was fouled in the cylinder. Also if you pull the O2 sensor use acetone to clean it or a small propane torch to clean it. Check that O2 sensor. Good Luck (I am not a mechanic)

As a side note if you pull the plugs and one of them is grey, that is a melted/blown piston. A blown cylinder acts similiar.
Cracker is offline  
Old 06-25-2003, 06:54 AM
  #3  
Senior MemberCaptains Club Member
Thread Starter
 
Join Date: Apr 2001
Location: Texas
Posts: 531
Received 18 Likes on 10 Posts
Default 250 OX66 Running Rough

Cracker, Thanks for the advise. The first thing I did was change the plugs. None were fouled but needed changing anyway. They all looked the same. I don't think I have a cylinder down. Purrs like a kitten at high rpm's. That's whats got me baffled about the smoking at low rpm's.

Can you give me some instructions on how you decarbed? What product did you use? Also, it's not acting like an o2 sensor. I have had a couple of them go bad before and they usually surge the rpm's at high speed up and down.

Reel Screamer
Reel Screamer is offline  
Old 06-25-2003, 07:09 AM
  #4  
Senior MemberCaptains Club Member
 
Join Date: Aug 2002
Location: St. Augustine, Fl
Posts: 22,385
Received 4,469 Likes on 1,800 Posts
Default 250 OX66 Running Rough

Reel,
What I did was pour a bottle of sea foam and about half of bottle of yami Ring free in my gas tank that only had 25 or so gallons in it. Ran it for about two hours at various speeds. Then filled my tank up. The carbon apparently took a lil while to break free, as 5 hours later had fouling. I never had done a shock treatment before about 600 hour on engine, but I had always used merc and Yami oil with ring free. Good Luck
Cracker is offline  
Old 06-25-2003, 07:18 AM
  #5  
Senior MemberCaptains Club Member
 
Join Date: Jun 2003
Location: Deerfield Beach, Florida
Posts: 1,061
Likes: 0
Received 55 Likes on 36 Posts
Default 250 OX66 Running Rough

Reel,

Do your motors only smoke excessively at idle in and in gear? I have a pair of 250's that smoke when I go to a idle while in gear. I see very little smoke while cruising at 1000 - 1100 rpms. But when I drop the throttles back to 500 RPM they belch out the smoke. I assumed this was normal.. Maybe not? I have about 350 hours and have never de-carbed. I do run ring free and the WestMarine TCW-3 oil though. No yamalube.
FishEye is offline  
Old 06-25-2003, 07:30 AM
  #6  
Senior MemberCaptains Club Member
 
Join Date: Jun 2001
Location: Boynton Beach Fl (Pursuit
Posts: 5,541
Likes: 0
Received 5 Likes on 5 Posts
Default 250 OX66 Running Rough

If I am not mistaken, those engines should run about 650 rpm in gear. I would suspect that they adjusted your idle screw to get the pump rod adjusted. Turn the idle screw to get 650 in grear. The reason it shakes is that below 800 rpm you are running on 5 cylinders, the low idle pronounces the shake.
As far as smoking, mine smoke hardly at all even @ idle, or pulling back from a plane!
KevinM is offline  
Old 06-26-2003, 11:29 AM
  #7  
Senior MemberCaptains Club Member
Thread Starter
 
Join Date: Apr 2001
Location: Texas
Posts: 531
Received 18 Likes on 10 Posts
Default 250 OX66 Running Rough

Does yamaha make a decarb? Is there something in a can that I can spray into the intake or will I need to mix with my gas?

Reel Screamer
Reel Screamer is offline  
Old 06-26-2003, 02:12 PM
  #8  
Senior Member
 
Join Date: Feb 2003
Location:
Posts: 438
Likes: 0
Received 41 Likes on 28 Posts
Default 250 OX66 Running Rough

You can get Deep Creep. It is the spray version of seafoam. Yopu can get it through NAPA auto stores.
IRock is offline  
Old 06-26-2003, 03:51 PM
  #9  
Junior Member
 
Join Date: Jun 2003
Location: Pawleys Island, SC
Posts: 21
Likes: 0
Received 0 Likes on 0 Posts
Default 250 OX66 Running Rough

Reel Screamer...Yamaha makes a product called Combustion Chamber Cleaner. This product is good and will not hurt the o-2 sensor. Some of the products out there are not good for the 0-2 sensor. O-2 sensors are not cheap and can not be cleaned if contaminated with some off the shelf chemicals.
You say the oil is adjusted correctly. How do you know it is? Sounds like the oil link rod has come loose from the oil pump causing a rich condition or the engine RPM is too low. The engine should run a about 600-650 in gear and I have seen them run at 500 ok, but this is too low for extended trolling. The engine idles on 5 cylinders when out of gear and all 6 cylinders when put in gear. Idle the engine up and check the oil link arm to make sure it is connected to the throttle arm on the carb and the oil pump on the port side of the engine. Good Luck and Good Fishing
knotwanted is offline  
Old 06-26-2003, 04:35 PM
  #10  
Junior MemberCaptains Club Member
 
Join Date: Feb 2003
Location: Palm City Fl
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
Default 250 OX66 Running Rough

How often should you decarb these engines?
Norman Clature is offline  
Old 06-26-2003, 06:22 PM
  #11  
Senior MemberCaptains Club MemberPLEDGER
 
Join Date: Apr 2001
Location: 22 Riddick Bay
Posts: 1,934
Likes: 0
Received 0 Likes on 0 Posts
Default 250 OX66 Running Rough

Wow, advice is all over the place. Here is my take based on the info you give. First off the 250 OX66 shake and smoke some at idle all the time but since you refer only to your port engine I am assuming it is more than normal. If you are in gear and the rpm's are only 3-400, your problem is probably the idle adjustment is too low. In gear you should be around 600 rpm. Not hard to fix. As KevinM points out the motor is running on 5 cylinders at that rpm range so running at 3-400 REALLY makes it shake.

Now on the smoking, oil that is. It sounds like you have never decarbed the motors. IMHO that should be done every 50 hours, 100 hours max. Cracker is correct that decarbing the motor can cause spark plugs to short out as loose carbon can get on the electrode. May want to use old plugs for the actual decarb. As far as the how, go by your local NAPA store and buy 3-4 cans of Deep Creep (says right on the can, O2 sensor safe). Warm your motor up on the muffs, spray a can into the throttle bodies of all cylinders, let sit for a while, start up and at fast idle spary the remaining cans into the motors. Mine smoke and spit out black crap but once they are done they idle smoother.

Cracker talks about the O2 sensor. Here is a great link that will tell you all you need to know about the O2 sensor.

http://www.thebassguide.com/home/News/05-30-2002-01.htm


Ain't it a bitch when then run but not as smooth as you want!!!!!!!!!!!

Good Luck,

Kirk

www.geocities.com/reel_time_fishing_team/
Tsunami is offline  
Old 06-26-2003, 07:19 PM
  #12  
Junior Member
 
Join Date: Jul 2002
Location:
Posts: 4
Likes: 0
Received 0 Likes on 0 Posts
Default 250 OX66 Running Rough

be careful if you shock treat with ring free. the excess carbon will foul your 02 sensor and cause you more problems. if you shock the fuel to will need to pull and clean the 02 sensor after you have run it a while.
grinder is offline  
Old 06-27-2003, 07:39 AM
  #13  
Senior MemberCaptains Club Member
 
Join Date: Jun 2001
Location: Boynton Beach Fl (Pursuit
Posts: 5,541
Likes: 0
Received 5 Likes on 5 Posts
Default 250 OX66 Running Rough

knotwanted, the ox66 V6 225 and 250 do not go to 6 cylinders when in gear, in fact it runs on 5 cylinders in or out of gear up to 800rpm, 4 cylinders from 800 to 2000rpm in or out of gear.
Above 2K rpm all 6 are in.

Realscreamer:
Personally I think as I previously stated, when your mechanic adjusted your oil injection rod, they adjusted the idle setting to get it properly adjusted. They never ran the engine in the water. As you know once in the water the idle usually drop due to back pressure. This is where you really need to adjust the idle and in gear. Try adjusting to 650 in gear while in the water, in gear and see if the shake goes away!
I probably will start a riot with my next statement, but I am convinced that different oils have different properties by the way of additives. Some use additves that lower smoke and provide other benefits. Not knowing what oil you use maybe that is something to look at.
Next, take a look at the puddling lines. These lines pull excess oil away from the various locations to be pulled through the crankcase.
If these lines are not pulling the excess oil, you can possibly get an over rich oiling situation at startup and at low idle. These keep those pools of oil from draining when the engine sits. Sort of like recycling unused oil.
The puddling lines are those clear plastic lines that are attached to each cylinder and areas of the crankcase and air silencer.

[This message was edited by KevinM on 06-27-03 at 09:50 AM.]

[This message was edited by KevinM on 06-27-03 at 09:51 AM.]
KevinM is offline  
Old 06-27-2003, 07:58 AM
  #14  
Senior MemberCaptains Club Member
Thread Starter
 
Join Date: Apr 2001
Location: Texas
Posts: 531
Received 18 Likes on 10 Posts
Default 250 OX66 Running Rough

Kevin,

Thanks for the reply. I think that's exactly what the dealer did. I will adjust the idle up this weekend.

Kirk,

I guess I'm gonna try the decarb thing. I am a little concerned that this may foul the o2 sensor though. Those things are not cheap to replace! I can't fathom why this motor is smoking so bad though. The starbord motor only smokes a little during start up which is normal for these. However, this dam port motor smokes all day long. Could a new power head be in my future? Are there any early warning signs I should be looking for? I guess I will just decarb and hope for the best. Just like you said Kirk, not runnig bad enough to warrant a trip to the dealer, but just bad enough to worry about before the next King Tournament.

Thanks again for the advise guys

Reel Screamer
Reel Screamer is offline  
Old 06-27-2003, 08:20 AM
  #15  
Senior MemberCaptains Club MemberPLEDGER
 
Join Date: Apr 2001
Location: 22 Riddick Bay
Posts: 1,934
Likes: 0
Received 0 Likes on 0 Posts
Default 250 OX66 Running Rough

It is possible to foul the O2 sensor but probably remotely so. If you have lots of carbon, a small peice could break off and get stuck on the O2 sensor. Unlike a spark plug however, the O2 sensor is designed to burn off any carbon that might get to it. In fact the sensor heats up on its own to something like 600 degrees which should cook any carbon. Just be sensitive to any O2 sensor symtoms particualry surging of rpms. Not fatal as the motor will run but it is aggravating.

Not sure what if anything you can make out of one smoking more than the other. I assume they are burning the same amount of oil? The best way to tell if you are headed down the blown powerhead path would be a compression check. That is easy to do and would give you a pretty good indication on the condition head/rings. If you get a shop to do it it should only cost $50-75 I would guess. The only other thing that comes to mind is something Dunk once said about how he has seen two motors on the same boat, same oil, same gas. One will choke up with carbon and the other will be clean as can be. It has to do with the varinaces in porting and such.

I agree with KevinM on the oil. Hopefully you are using Yamalube or one of the premium oils. They have 2-3 times the carbon inhibitors. Kevin's other point on the puddling lines is worth taking a look at as a source of your smoke.

Good luck

Kirk

www.geocities.com/reel_time_fishing_team/
Tsunami is offline  
Old 06-28-2003, 06:59 AM
  #16  
Senior MemberCaptains Club Member
Thread Starter
 
Join Date: Apr 2001
Location: Texas
Posts: 531
Received 18 Likes on 10 Posts
Default 250 OX66 Running Rough

Bought the Yamaha combustion chamber cleaner yesterday. I going to give it a try this morning. I will post the results later on today. I appreciate the help.

Reel Screamer
Reel Screamer is offline  
Old 06-30-2003, 10:45 AM
  #17  
Senior MemberCaptains Club Member
 
Join Date: Jan 2003
Location: Porter Tx USA
Posts: 360
Likes: 0
Received 0 Likes on 0 Posts
Default 250 OX66 Running Rough

Reel Screamer,
What is the out come on the motor. I hope it is running fime now.

Team Binnion
Fish Hard or Go Home/24 Cape Horn
Team Binnion is offline  
Old 06-30-2003, 04:37 PM
  #18  
Senior MemberCaptains Club Member
Thread Starter
 
Join Date: Apr 2001
Location: Texas
Posts: 531
Received 18 Likes on 10 Posts
Default 250 OX66 Running Rough

Although I won't know for sure until I water test it, I do know that a lot of black sh#$ came out of the prop exhaust while decarbing. Seems to run and idle quite a bit smoother too. Again, only a water test will tell but if nothing else got quite a bit of built up carbon out. I also sped up the idle to 800 in neutral. Should be around 650 to 700 in gear with a load on it.

For those of you who have asked many questions about decarbing but have been reluctant to do it, DO IT. It's a breeze.

Thanks to Kevin and Kirk for the words of advise.

Reel Screamer
Reel Screamer is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.