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BF100 Fuel Pump Leaks Oil at mount to engine

S

steverhnm

New member
"So I go to replace my fuel pu

"So I go to replace my fuel pump and it appears there is no gasket between the fuel pump and the housing. I replaced the pump and the motor works great. After running for 10 min in a barrel of water, oil will start to drip from the bottom of the mating surface of the pump and motor. The motor ran fine (except for fuel problem at higher speeds), this is all I did and the manual does no show a gasket, am I missing something. The faces are clean. Screws tightened down very tight. What am I missing?"
 
"Found my problem. There is a

"Found my problem. There is an O-ring, its just that he motor I scavanged the pump from did not have one. Fortunatly I didn't throw out my old one, there was an oring on it.


So anyway, My motor blows oil (smokey) out the exhaust, anybody have an opinion on what I can do to fix it. Is it a valve adjustment or deeper than that?"
 
"Hopefully the valves have bee

"Hopefully the valves have been adjusted regularily in the past. The Honda exhaust valves have a tendency to go out of adjustment during a seasons use...closing to 0 gap, hard on valves and cam."
 
"What color is the smoke?
Blu

"What color is the smoke?
Blue would be oil, black would be excessive fuel.
If it's a fuel problem, could be that the floats in the carbs are set to high, or the floats are fuel soaked. Ether condition will cause both symptoms."
 
"The smoke is blue, definatley

"The smoke is blue, definatley oil. I can assure you the 5 years I have owned it and the 7 it sat in the previous owners yard (in the desert, hot but no rust) it was never worked on. I changed the oil & gear lube, ran some gumout through the carb and it works great except for the smokey exhaust. It did have a problem with fuel starvation at higher speeds, I thought it was the fuel pump and I found a parts motor for $150 with a new fuel pump and carb on it. So I have the Clymer manual. Is it possible to fix this problem? any suggestions on what I could do? Thanks, I appreciate your help."
 
"I would think that ether the

"I would think that ether the rings are worn or that the valve guide seals are bad/broken. The rings can be tested with a compression test. Do both wet and dry test per you manual. If the compression tests good, then the valve guide seals would be my next guess. The other thing that comes to mind, is that the oil is being diluted by excess fuel from a rich mixture. Try measuring the oil level before and after a run on the water. One more thing that just hit me, look at the Thermostat, (you have to remove to test)if the t-stat is not closing the motor will run cold and allow excess fuel to collect in the oil, causing it to smoke."
 
"The oil level will change, th

"The oil level will change, there is more smoke cold than warm, but I usually never run it very long, it's on a 26' sailboat on a small lake. 30 minutes would be long. Is there a way to check the oil for fuel? Is that the level check you mentioned? Should I expect it to change significantly? The oil still feels like oil, not like water, which is what I would expect if there was gas in the oil-wouldn't there be a point at which the oil would really be affected by the fuel, to which the oil would be more like water? I have used the "oil thickener" stuff (aka motor honey) and it definatley helps -almost eliminates the smoke- but the effects don't last as long as you would expect (leading me to think more about the fuel in the oil issue maybe) The rich mixture is a distinct possibility, the carb has not been professionally adjusted so it has been adjusted to "run smooth"..... meaning I don't know what I am doing....

By the way, I am at 5,000 ft altitude. I have this extra engine that has what looks to be a rebuilt carb (lighter gray paint-looks like the new fuel pump color). I know the guy that had the engine had it in a shop for tuneups regular. But then something broke (water return tube?) and they quoted $600 to R&R he said enough was enough and bought a new motor. So I have a motor (that doesn't smoke) with a bad cooling system (and the charger output wire shorted), but has a bunch of new parts on it

Checking the thermostat is within my abilities. Fixing a ring or valve guide problem is not (or at least I don't think it is at this time). Is there a spec on the torque for re-installing the cover? I didn't see one in the manual. Should I order new gaskets before I take it apart or is there a chance they can be re-used?"
 
"Regarding the T-stat, I just

"Regarding the T-stat, I just did a quick test and the water from the pee hole starts cold, goes warm, and alternates during warm up, time frame is a couple of minutes. After 5-10 min it runs pretty smooth. T-stat seems to cycle OK and the body by the spark plug warms up reasonably quickly. Do you think I still need to check the thermostat?

I did notice something though. Is it normal for water (droplets) to come out of the bottom exhaust hole (there are two)? Thats where the smoke is coming from (can't tell if the smoke comes from both or just one) It seems to be a cold-blooded beast, but when warm works great. The smoke is still annoying."
 
"You seem to be satisfied that

"You seem to be satisfied that the t-stat is good. I would think that if you had fuel in the oil, you should be able to smell it. Wait till no one can see you then see if you can get a sample and smell it! The water in the exhaust I suspect is normal, since it's the water that keeps the exhaust from getting too hot. The t-stat is very simple to test, if you can get the small bolts out. The gasket can be re-used if it is not damaged on removal. A little silicone seal will go a long way. The cover bolts just need to snug enough to hold the water from coming out.
Next step would be to do compression test.
Nick"
 
"Steve - don't know anythi

"Steve - don't know anything about carborated BF 100's, BUT, it sure sounds like you might have a clogged up breather tube. Even the tightest rings allow a little pressure to slip by, which pressurizes the oil pan. If that pressure is not relieved through some sort of breather, it forces oil up by the rings. Check your manual, find the breather tube, and make sure it's clean."
 
"At a 5,000' elevation, a

"At a 5,000' elevation, a standard carburetor Main Jet (#88) would be too rich.

The Honda Shop Manual does not say anything about elevation, just that #88 is "Standard Jet" (for sea level).

If you look on boats.net, you will see that they stock five Main Jets from #88 down to #72.

http://www.boats.net/parts/search/Honda/Outboard%20Engine/0/parts.html

If you remove float bowl, you would see the jet number stamped on the Main Jet. I don't know what number would be appropraite for your elevation, but it would not be #88."
 
"Hi guys, I went back and re-

"Hi guys, I went back and re-adjusted the carb to the manual specs, leaned it a little, being careful not to overlean it. Pilot is at 2 turns. I started it up and then opened the oil dipstick while it was running to check for backpressure. Seems like there was quite a bit, I tightened and loosened it several times. Not sure if it was the carb adjustment or fooling with the oil filler cap but she is not smoking anymore. I checked the manual and it does not have a crankcase breather tube, so that was out. I have a feeling it was way too rich on the carb (3/4 turn too much)

Anyway, you guys are great, I appreciate your help. I have a B100L1700000 series SN motor that is a parts motor if anyone needs a hard to find part let me know."
 
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