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Author Topic:   Causes of Engine Failure
fester posted 01-09-2002 11:21 PM ET (US)   Profile for fester   Send Email to fester  
I spoke to my outboard mechanic and asked him what is the single most important thing in preventing outboard engine failures. He said that in addition to routine maintenance, it is preventing carbon build up in the cylinders. He went on to indicate that 90% of the engine rebuilds that he does are needed because of excess carbon. He explained that the carbon causes the rings the lock up with the result that a ring breaks or some other problem occurs in the cylinder.

His belief is that every 50 hours of use a can of carbon remover/engine tune should be run through the carburators. He felt this is the best and least expensive way to control carbon build up in the engine. While gas addatives are also helpful, he did not think they were as effective as the engine tune.

Since I have a carburated 2 stroke, I think his comments were intended to primarily address these types of engines.

Clark Roberts posted 01-10-2002 09:30 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Jeff, I think your mechanic is right!
Bigshot posted 01-10-2002 11:06 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Also carb failure. If a piece of varnish gets into a carb and leans it out, there goes your piston. I have heard on this and other forums hundreds of times that VRO is risky and that theirs "went bad" and blew "A" piston. Well just so everyone knows if "A" piston blows that is either due to a stuck ring or a lean oil mixture(from a lean carb). If oil injection goes, you will blow "all" your pistons, not just 1. So do not remove your pumps and mix gas because you are worried, the chances of that pump going is slim to none. Make sure your warning buzzers work and you will be fine.

Decarb that engine at least every 100 hours, preferably 50. You can also run ring-free in your gas which does the same(expensive).

george nagy posted 01-10-2002 12:03 PM ET (US)     Profile for george nagy  Send Email to george nagy     
I blew my 70 Evinrude twice that way!
fester posted 01-10-2002 03:08 PM ET (US)     Profile for fester  Send Email to fester     
Anything that has a tendancy to lean out the engine is also a big problem. I have heard of people having air leaks in their fuel systems which had the affect of leaning out the engine with disaterous results. I think routine maintenance is critical and one should make sure the fuel system including fuel lines are tight and do not suck air.
andygere posted 01-10-2002 04:23 PM ET (US)     Profile for andygere  Send Email to andygere     
Is there any danger in spraying a can of carbon remover into the carbs? For example, could this cause a chunk of carbon to dislodge from the head or cylinder wall and pop a ring off the piston?
Bigshot posted 01-11-2002 10:57 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
No! You should run it through carbs and then fill cylinders and let sit overnight.
lhg posted 01-11-2002 08:17 PM ET (US)     Profile for lhg    
To get rid of carbon deposits, the great engine killer, particularly the DFI's, there are two products: I am familiar only with the Mercury products, but I understand Yamaha sells equivalent ones. Either will work for you.

1. For carburated engines, Mercury "Power Tune". This is a spray-through-the-carb decarbonizer. Instructions on can, but engine/boat must be in the water where you can run it up to 4500rpms to clear it out after the application. You won't believe the crud it flushes out of your engine exhaust ports! Can't use this with EFI or DFI engines, since no way to spray it in.

2. For any engine, especially EFI/DFI, Mercury's "Kwick Cleen". It's a yellow liquid in a bottle, for addition to the gas, and costs about 12 cents to treat a gallon of gas. Use about every 3 tanks of gas. It will keep your engine totally decarbonized.
My Mercury mechanics say it is essential, and keeps engines running forever. I always use it, and once when I had head gaskets replaced on my Merc 200's, the cylinders and pistons were absolutely factory clean on inspection.

triblet posted 01-12-2002 02:41 AM ET (US)     Profile for triblet  Send Email to triblet     
lhg, I'm missing something here. EFI and
DFI engines have intakes. Why can't Power
Tune be sprayed in the intakes, just like
on a carbureted engine???


kingfish posted 01-12-2002 09:46 AM ET (US)     Profile for kingfish  Send Email to kingfish     
OMC has a product also; I used it late in the summer last year on my '92 Evinrude 225, blew a lot of crud out, but I don't remember the exact product name.

My motor is carbed and has a male bicycle-tire type valve on the oil injection circuit that allows a can of this stuff (or end-of-season fogging oil)with a similar female knurled nut to attach directly rather than spraying through or into the air intake.

BTW, seeing a similar-looking valve in approximately the same place on the Yamaha 225 FI motor on our other boat, I tried the same trick when winterizing. The FI pressure was greater than the pressure in the can, and actually started pumping fuel into the spray can before I caught on to what was happening and shut the motor down. I was told afterwards I was lucky I didn't blow the fogging oil can up.


Bigshot posted 01-14-2002 10:52 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
OMC's is called "Tune up in a can" or something as stupid. Great stuff too. Probably all made by Valve tech.
Bigshot posted 01-14-2002 10:52 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Any word on ring free or fuel injector cleaner to be used in 4 stroke EFI's?
lhg posted 01-14-2002 12:55 PM ET (US)     Profile for lhg    
Chuck - I don't know enough about EFI systems to answer your question. The Mercury "Power Tune" can says spray through carburetors while idling at 2000 rpms, until the engines load up and die. So I just assumed it couldn't be used on an EFI system. I've actually never even looked at how my EFI engines work. At 1200 hours, I've never had the hoods off except to change plugs. No tunes ups or adjustments, nothing. Maybe they're due for a check up!
Tom W Clark posted 01-14-2002 03:06 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
The OMC product is called "engine tuner"

My 13 oz. can has a price label of $5.75 on it.

Clark Roberts posted 01-14-2002 03:12 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Here is a simplistic explanation of how the Merc EFI works (hope I get it mostly right!). The system is analgous to an auto's "throttle body" fuel injection in that the fuel is sprayed (injected) into the intake just aft of the air "butterfly" valve, hence "throttle body" injection. This is opposed to injecting the fuel into the cyls. individually... this is called "Direct Injection" , "Piston Port Injection" ect... hence Direct Fuel Injection a'la Optimax DFI..etc..etc.. So the basic EFI system throttles the air, the fuel is injected aft of throttle and ahead of reed valves and the timing and amount is controlled electronically by a processor (ECM/Engine Control Module). Now, once the fuel/air mixture passed through the reeds all is the same as a carb engine.. So, I think spraying the decarbonizer in the air intake will work! Hey, I'm not recommending it or discouraging it, I'm just throwing this stuff out and like I said, hope it's mostly correct... I don't see why it wouldn't work with A DFI Opti/HPDI or Ficht since the stuff will find its way into combustion chamber... The ECM program may be such that some anti-knock sensor may go haywire, however .. just don't know ... maybe a check with company tech rep would be a good idea.. Nickle knowledge and that's about what its worth... clark.. Spruce Creek Navy
where2 posted 01-14-2002 04:51 PM ET (US)     Profile for where2  Send Email to where2     
Fuel Injector cleaner for a 4-stroke? Isn't that called Techron. That's what my Bosch Fuel Injection books recommend for keeping the little German injectors clean. Of course, Honda and all the other 4-stroke manufacturers will have their own bottle just like the VW dealer does. Same stuff, but Wal-Mart will sell me two bottles of Chevron's Techron for the cost of 1 at the VW dealer.
Clark Roberts posted 01-14-2002 06:13 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Whereto, you're onto it!
The Quicksilver "Power Tune" and
Yamaha's "Combustion Deposit Cleaner" (identical products) are made by Chevron and contain Techron as the prime ingredient! I use Chevron gas (all three grades have Techron additive) in all my ourboards and other engines whenever I can get it.
PULLNIT posted 01-15-2002 05:13 AM ET (US)     Profile for PULLNIT  Send Email to PULLNIT     
I just purchased a 1989 Johnson 150 VRO.I have heard the VRO pumps can go and kill the motor.How many are still running with pump?Horn works !should I still worry?
Tom W Clark posted 01-15-2002 12:43 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

I have only owned four Johnsons with VRO, and the last one I owned (1990 150hp) was only ten years old when I sold it, but I had absolutely zero problems with the VRO systems. I believe them to be highly reliable. I wouldn't worry about it if I were you.

where2 posted 01-15-2002 12:54 PM ET (US)     Profile for where2  Send Email to where2     
Main problem with VRO pumps is actually air leaks in the hoses for fuel and oil between the tanks and the engine. Keep them from drawing air, and find out if the pump is using the latest diaphragm materials, and they work fine. See Trailer Boats Magazine article in late '99-early '00 issue.
Bigshot posted 01-15-2002 02:52 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I've posted this before but seems timely here again.

Yamaha dealer friend told me he learned this in Yamaha school. If you really want to decarbonize and clean a carb this is how it is recommended:

If "non" VRO mix oil into gas. Take a gallon jug and fill it 1/2 way with gas. Pour a whole bottle of techron in it and drop fuel line into jug. Run engine (on muffs or in water) until mixture is gone(took 35+/-mins on my 90hp) and shut it down before she runs out of gas. Let it sit overnight. Run it to blow out any risidual crud. It really plugs looked great. This can also unstick a ring due to carbon buildup.

I would recommend everyone to do this with a "new-to-them" outboard. This will give you the confidence that your engine is decarbonized and carb is clean.

jay posted 01-17-2002 06:48 PM ET (US)     Profile for jay    
Bigshot, if I've got a VRO, do I just take 1/2 gallon gas and 1/2 bottle of techron and drop the fuel line in?
Bigshot posted 01-18-2002 10:40 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
That's what I did, VRO will pump the oil. If you wanted to put a drop or 2 in the gas it can't hurt but probably unnecessary.
Hank posted 01-19-2002 12:45 AM ET (US)     Profile for Hank  Send Email to Hank     
What's the volume of a bottle of Techron ?
How many ounces per gallon of gas/oil mixture?
The procedure sounds like a good idea.
mattius1969 posted 10-12-2007 11:12 AM ET (US)     Profile for mattius1969  Send Email to mattius1969     
I have a 89 vro150 that ive been running for about 2 yrs now and have never had any trouble with it except that its really cold blooded. I did replace the vro pump because of all the forum discussions about the alchohol resistant diaphrams and how the old pumps would fail if there were too much alchohol in the gas. Other than that the motor has been running great. Im not sure that my motor has ever had any kind of carbon deposit remover ran through it so its probubaly pretty loaded up. guess ill have to get on top of that one. thanx for the tips on cleaning it out
jgkmmoore posted 10-16-2007 08:19 PM ET (US)     Profile for jgkmmoore  Send Email to jgkmmoore     

Do it for sure.Use the OMC 'Engine Tuner'. It will feel the next day like you scooped up 15 xtra ponies (after it gets thru smoking).Do run it at WOT during the cleanout to blow the crap out. You will have a nasty exhaust area for a couple of hours (black, oily). If your motor is cold blooded, this may fix that too. After you blow out...good idea to renew the plugs. It's cheap, and good insurance.Your motor will run like a watch after this treatment if it's halfway decent to begin with. I do it at the beginning of the season, right after I run the fogging oil out of the engine. Then your plugs will go the whole season (for most owners). Do the treatment every 100 hours at most, every 50 hours if it's convenient.

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