I have seen a couple of references to cylinder #2 (on an OMC V6) as being a bit different. For example, people mention problems showing up first in cylinder #2, as in "if you don't [do something correctly] you will blow cylinder #2."
Also, cylinder #2 apparently has different size high-speed jets (larger) in its carburetor.
Which cylinder is cylinder #2?
Why does cylinder #2 warrant all of this special attention?
Modified by jimh at 6:12 AM 9/20/2005
So it doesn't come apart at high speed and explode you block. I have the fragments of a '94's block and pistons on my kitchen windowsill. Of course, this was a problem for a limited #of engines for a limited time. Not all OMC V6's had the problem. Also, OMC stepped up big time and I am still running that replacement block, with the carb change.
'93 Ranger 392
'94 Johnson 200 Venom
26 Raker
65.4 MPH GPS @5950
You anecdotal information is interesting, but it does not answer my question.
What is special about cylinder #2 in OMC V6 engines that it need particular
attention?
I don't know what's special about it, but we had a brand new 225 H.O. E-tec blow #2 yesterday
Need to add something. This is definitely a fluke thing as far as the e-tec goes. We have bunches of them on the water, with no issues whatsoever. Very very low warranty claims on all of them.
Aaron
Modified by Aaron Swann at 6:59 AM 9/20/2005
As I understand it. in some motors, the #2 cly required extra cooling. The increased jet size allowed for this. This has been covered extensively in this forum, I'm sure you'll find the answers if you search the forum
Sorry if this is a Frequently Asked Question. I did not see the FAQ--Is there one?
A link to prior discussion would be welcome, too.
Searching on CYLINDER and #2 is a bit difficult because the search discards the argument #2 as being too short. But skimming through the search results from just CYLINDER gave me the impression that the #2 cylinder is more prone to overheating than the rest. Apparently re-jetting the carburetor helps give this cylinder more fuel, therefore more cooling.
Is this endemic of all OMC V6 motors or just certain models?
Is the re-jetting a factory recommended modification, or just a field modification developed by saavy repair technicians?
My 1992 motor is probably in stock condition, so I am curious if I ought to look at the carburetor jet to see it is the larger size or not.
I have a 2003 225 HO that blew the #2 piston. Coincidence? I don't know. I was told that my oil injector either stuck or quit working, the mechanic couldn't tell. I didn't notice the extra oil usage if it was stuck.
The cooling problem was due to a design flaw in the block.... You are correct in saying that the stepping up on #2( which btw if looking from the back of the motor is the top left....which the carb is on the opposite side in the front) helps cool it down... Not all the motors had this problem, and it is mainly when you turn them hard for a long run period that it shows it's head MOST of the time. If I had a 92, and it hasn't broke yet, I would leave it along.
Sage advice WD. If it ain't broke...
C
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jimh »</TD></TR><TR><TD CLASS="quote">I have seen a couple of references to cylinder #2 (on an OMC V6) as being a bit different. For example, people mention problems showing up first in cylinder #2, as in "if you don't [do something correctly] you will blow cylinder #2."
Also, cylinder #2 apparently has different size high-speed jets (larger) in its carburetor.
Which cylinder is cylinder #2?
Why does cylinder #2 warrant all of this special attention? </TD></TR></TABLE>
Most folks are not aware that #2 cylinder provides vacuum from its intake manifold to the top main crank bearing which then thru a rubber hose and check valve, "pulls" lube from the bottom main bearing to keep it from "building up" and to provide lube to the upper bearing. If a bottom crankshaft seal leaks, the vacuum from #2 will "suck up" water and deposit it in both main bearings, damaging them, and then damaging #2 cylinder, crank journal, etc. If the upper crank seal leaks, it draws in air and lowers the vacuum so the upper bearing gets less lubrication and ultimately fails whlle the lower bearing cavity is full of liquid lube that works it way into #6 cylinder and causes smoking and/or puffs of smoke, and possible plug fouling and carbon buildup.
If the motor is jacked to high and gets air into the cooling water, both #1 and #2 cylinders will run hotter due to aerated water not providing enough heat transfer as liquid water will.
This problem is only related to high performance boats and offshore wave jumpers.
Because #2 runs slightly leaner than the others and with aerated cooling water, it is more likely to detonate or run too hot and score the piston in certain situations. A bandaid is to richen up the high speed jets, and it does work in most cases.
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A Technical troubleshooter possessing more tools than talent !
Thanks for the explanation. Very interesting.
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