I disconnected the boost hose that runs from the intake manifold to the injection pump as NM requested. Reviewing the engine
manual, this hose feeds boost from the intake manifold to the injection pump boost compensator. As boost increases, it increases the fuel
being supplied to the engine
(as best I can tell). I removed this hose and fired the engine and let it warm up.
As the engine was warming, there was definite air pulsing out of this hole in the intake manifold. The air pulsed.
When the engine was up to temp, I put it in gear
here at the dock
. Figuring that the point of the test was to see if not having the boost pressure increase the amount of fuel
the injection pump would push would have an impact on the amount of smoke I am getting I determined that it would be best to test with the hole in the intake manifold closed so that the engine was getting all of the turbo boost. Otherwise, lots of boost would be blowing out this hole. So I taped the hole off so air would not blow out. I also disconnected the breather line from the air cleaner so I could look for pulsing air blowing out and smoke or such under load.
Here are the results.
: minor light to medium colored smoke, some air flowing out of the breather line but no pulsing and minor, air at the intake manifold boost hose had a decided pulse to it (was then taped over but the tape cover could be seen to still pulse mildly)
: A bit more smoke, still light to medium grey in color, the same amount of air coming of the breather line and no pulsing or smoke and the tape over the boost outlet on the intake manifold was pulsing more.
1800 rpm: The same amount of smoke and same condition at the breather line, more smoke of about the same color as 1500 rpm but not billowing amounts.
2000 rpm: Breather hose the same, no pulsing and steady pressure on the tape over the boost hose hole on intake manifold, lots more smoke and black in color, also a clear fuel sheen is being left on the water
and the exhaust water
2550 rpm.... Max throttle, engine under max load. Billowing black smoke, fuel sheen on water, exhaust
water is very sooty, pressure at the boost hole blew the tape off (after I checked the smoke) and when I cut the throttle and shut her down there was a tiny amount of light colored smoke trickling from the open breather line. I did not get a chance to put my finder over the breather line while the engine was at max load.
So... my conclusion would be that the issue is not something wrong with the boost compensator unless it is stuck way beyond its maximum fuel allowable settings or something. The lever on the back of the pump that allows the cutoff of the boost compensator for extreme cold weather
start does move back and forth relatively smoothly. The hose itself connecting the intake manifold to the injection pump has no obstructions.
Let me add another confusing bit of info to all this....
It appears the engine may still be making oil
. When I last checked the oil
with the engine cold several hours after running the oil level was just under the full mark. When I checked it this morning before running.... it was just over the full mark. It is hard to tell for sure, but it is possible I am somehow still diluting the oil with fuel.
I am more and more starting to believe that one cylinder has bad compression
, is not burning the fuel thus causing all the black smoke and soot and some of the unburned fuel is running past the rings and diluting the oil. Catastrophic....
..... after adjusting the prop pitch
we ran the engine about 25 minutes, testing and then motoring back over to the slip we are in. During that time we ran at different rpm's doing testing and it sure seemed we had the exact same issues just at a higher engine rpm.
Below the exhaust elbow
is a section of 4" exhaust hose that is only 3-4" long before a large 90 degree fiberglass elbow
. I have no issues drilling a hole in this for a fitting to test back pressure in the exhaust and then just replace the small section of hose. I am hoping to find someone who can help me with this on Monday. Where we are has no auto supply shops or marine
stores close and we have no car.
I do now have the name of a guy who can test the compression
and I hope to discuss monday morning having them come out and properly test the engine, both compression and exhaust back pressure.