elr
Seaman
- Joined
- Aug 6, 2011
- Messages
- 57
Hi Folks,
I have a '80 Starcraft SS 16' (love the boat) with a '79 Mercury 90hp inline 6 (love the motor). I've had for maybe 15 years and made many happy memories with it.
Synopsis of problem:
In the spring of '17 we brought it out of storage aiming for the lake. Motor ran but not the best. We took it out and gave it a seafoam treatment thru the carbs trying to get it to clear up. It seemed like it wasn't running on all cylinders all the time. Gave up for time being and came home.
2nd time out same story except that it settled down to only running on 5 cylinders by the end. Came home and had a friend do a compression test... Don't remember the numbers except that top cylinder (#1) was dead. Pushed it back under a tarp and moped about it for the next two years.
Fast forward to now... I pulled it out, cleaned it up and did another compression test. This test was done cold because I couldn't get it running. I did spray fogging oil in all cylinders before and during compression test. Did each cylinder a couple times and following are averages in reverse order:
Cylinder #6 (bottom): 145
#5: 135
#4: 136
#3: 134
#2: 129
#1: 31 !!!
So pretty much confirmed what I knew. I was pleasantly surprised with 5 of the cylinders. Looking in the spark plug hole of #1 you can see scoring on the cylinder wall.
I'd like to rebuild it. I've never rebuild an engine but am mechanically inclined. (seeing as how I've recently started the 30-month apprenticeship route to becoming an A&P mechanic, I should be) So my questions...
#1. Does it even make sense to try it? I.e. Are parts still available for a 40-year old motor? If so, ballpark cost for most likely scenario?
#2. Also If so, how likely to need bored out and oversized? Or is there even much difference labor or parts-wise between that and just honing and new rings?
#3. How involved is it? Does pretty much everything need to come apart including all the bottom end stuff like connecting rods, crankshaft, etc.?
#4. Anyone willing to venture a guesstimate on # of hours required to bring her back to life?
#5. Why did it happen in the first place and what can I do to make sure it doesn't happen again?
I have received good help in the past from iboats for numerous odds and ends on this boat and would love to hear from folks like Chris1956, OldMercsRule, Gomer50, achris, and whoever else knows what they're talking about. Thanks.
serial number (on outside, can't find it on the engine block)
I have a '80 Starcraft SS 16' (love the boat) with a '79 Mercury 90hp inline 6 (love the motor). I've had for maybe 15 years and made many happy memories with it.
Synopsis of problem:
In the spring of '17 we brought it out of storage aiming for the lake. Motor ran but not the best. We took it out and gave it a seafoam treatment thru the carbs trying to get it to clear up. It seemed like it wasn't running on all cylinders all the time. Gave up for time being and came home.
2nd time out same story except that it settled down to only running on 5 cylinders by the end. Came home and had a friend do a compression test... Don't remember the numbers except that top cylinder (#1) was dead. Pushed it back under a tarp and moped about it for the next two years.
Fast forward to now... I pulled it out, cleaned it up and did another compression test. This test was done cold because I couldn't get it running. I did spray fogging oil in all cylinders before and during compression test. Did each cylinder a couple times and following are averages in reverse order:
Cylinder #6 (bottom): 145
#5: 135
#4: 136
#3: 134
#2: 129
#1: 31 !!!
So pretty much confirmed what I knew. I was pleasantly surprised with 5 of the cylinders. Looking in the spark plug hole of #1 you can see scoring on the cylinder wall.
I'd like to rebuild it. I've never rebuild an engine but am mechanically inclined. (seeing as how I've recently started the 30-month apprenticeship route to becoming an A&P mechanic, I should be) So my questions...
#1. Does it even make sense to try it? I.e. Are parts still available for a 40-year old motor? If so, ballpark cost for most likely scenario?
#2. Also If so, how likely to need bored out and oversized? Or is there even much difference labor or parts-wise between that and just honing and new rings?
#3. How involved is it? Does pretty much everything need to come apart including all the bottom end stuff like connecting rods, crankshaft, etc.?
#4. Anyone willing to venture a guesstimate on # of hours required to bring her back to life?
#5. Why did it happen in the first place and what can I do to make sure it doesn't happen again?
I have received good help in the past from iboats for numerous odds and ends on this boat and would love to hear from folks like Chris1956, OldMercsRule, Gomer50, achris, and whoever else knows what they're talking about. Thanks.
serial number (on outside, can't find it on the engine block)