I noticed as I came online to type this post that there is another thread going right now about a GM series and bad compression
in one cylinder. I dont mean to clutter the board with repetitive posts, but my issue is a bit different. I know this is long, but hopefully I can save us some time with our troubleshooting.
Brief history on the motor:
Installed in a 1970 Morgan
in 1980 by an active sailor who regularly maintained and used the engine
for a solid thirty years. By 2010-2012 he didnt use it as much and I bought it from him in 2012. I've used it regularly, but never running more than a few hours per week on average. Over the last two months, I've been running this engine
like mad on my trip through the ICW
, probably around 200+ hours over that time period. Oil
changes regularly, generally well maintained.
: About a month ago we noticed the engine wasn't starting very well when cold, and the problem was getting worse over the next week of running it. We first thought air in the fuel
lines, so we bled up to the cylinders with success each of the next few days, allowing us to get the hell out of Morgan
City and further East where we thought we'd find more help. We noted a LOT of white smoke from the exhaust
when the engine finally did start, and a slight sheen in the water
. No black, dark gray, or blue smoke. We could hear one cylinder taking an additional 2 seconds or so to crank up to speed.
Through a couple of weeks of troubleshooting, we three rookies figured a leak in the fuel injector pump
, then we figured a leak in the fuel filter
, then maybe a buggered injector release valve thats allowing air in somehow. Another train of thought was maybe backwashing from the exhaust
from running the starter so much during troubleshooting, but we really doubt it given how well she seems to run when shes going. Still another train of thought was the fuel may be flooding a cylinder (lots of white smoke) with a faulty pump or injector valve, preventing even compression
and making it hard to start the motor
* We tried decompressing one cylinder at a time and found the middle cylinder to be doing most/all of the work starting the motor. #2 works very well, but #1 and #3 are not getting compression on their own well at all.
How we've tried to fix the problem:
Following the suggestions of many Yanmar
mechanics, and with the help of Charlie at Bell Marine
(this guy knows everything about Yanmars and has access to virtually all parts
old and new, I very strongly recommend him), we switched the injector valves out. No luck.
* During this process, we very slightly opened up the fuel lines at the injector valves to check fuel pressure, and the aftmost cylinder is shooting more fuel that we'd like, the other two are pushing consistent drips. Also, we ran with the oil
cap off for a bit to check for any smoke in the top cover. Nothing, she looked great.
Our strategy today:
We're going to pull the injectors again and check the gaskets (we reused some since they didnt come out with the injector and we didn't see any damage), re-check all the valve rods and springs under the top cover for bends (none of them are sticking), and then move on to checking the fuel pump
I really hope its a bad gasket
, I expect its going to be a faulty fuel pump
, and I'm terrified to think it could be some kind of hydrolock thats ruined the bottom end of the engine.
If ya made it this far reading, thanks very much for your time! Do you by chance have any suggestions or input to give?