OMC 2.3L dies, won't crank

[rogerm]

I have a 1988 OMC Cobra 2.3L. It has been running great until recently when, on the lake, it suddenly died at WOT. When I tried to restart the motor, it wouldn't turn over. No crank, just a CHUNK sound. It was more than just the relay, as the whole boat and engine shook, but still, it wouldn't turn- like it was stuck against something. I looked at and fiddled with it for about 5 minutes, and when I tried to start it again, it turned once, and then back to the CHUNK. So I waited some more, probably another 5-10 minutes and it started up. I idled it, and then put it in gear and headed back. <br /><br />Then it did the same thing- completely and suddenly died at speed, and would not turn over, just the CHUNK- like the starter engaged but couldn't turn the flywheel.<br /><br />So after another 10 minutes of waiting, it started up. That time, while it was running, I checked the temperature gauge, and the temp definitely went down while running implying that it was indeed cooling and not overheating. But this time, it ran for an even shorter time and I was not able to restart it. (I was towed in.)<br /><br />Trailered it, took it home, and charged the battery to make sure that wasn't the problem. It still wouldn't turn over- just a "chunk" that would shake the whole outdrive unit and jerk the steering wheel. I pulled out the three easily accessible spark plugs and looked in the cylinders. No obvious bits of rings or valves there. It now starts up, but may be backfiring a little. <br /><br />Prior to this incident, the only change I can think of was that the day before this problem began, the boat got pretty wet in a rainstorm while towing it on trailer. When I got to estination, I covered it, but the next morning there was a puddle in the cover that ripped the cover and probably sent 4 inches of water through <br />the bilge. This might have been enough to get the starter wet.<br /><br />My first guesses are <br />1) perhaps the starter or starter solenoid is malfunctioning<br />2) something (like a rod or a ring) broke in the block and causes the engine to sieze.<br />3) The timing belt has slipped.<br />4) Transmission problem??<br /><br />Any suggestions are greatly appreciated. Thanks.

 

[akriverrat]

Re: OMC 2.3L dies, won't crank

pull the spark plugs and look for signs of water.

 

[rogerm]

Re: OMC 2.3L dies, won't crank

AK, thanks. I pulled 'em and didn't see anything<br />egregiously wrong. The piton heads and <br />cyl. walls are a blackish brown, but they are all <br />consistent. Nothing was wet. I'm still stumped.<br /><br />Is it possible for the engine to sieze even though<br />the temp guage seems to indicate temp OK?<br /><br />Should I be looking at the cooling system?

 

[akriverrat]

Re: OMC 2.3L dies, won't crank

anything is possible. well almost. only 2 things come to mind. first, hydrolock. seems to fit except no sign of water in cylinders. no water in oil? second would be gimbal bearing overheating and siezing. but that should have given some noisy warning? i would check gear oil for water and chunks. its easy. then pull outdrive.

 

[sea wolf]

Re: OMC 2.3L dies, won't crank

are u sure the engine didn't overheat before it quit? it sounds like it started after it cooled down some, then overheated & quit again. ever checked the impeller or anything else in the cooling system?

 

[rogerm]

Re: OMC 2.3L dies, won't crank

OK, Here's where I'm at right now.<br />I got a better look at cyl. 4 (brought a borescope home from work), <br />and I *might* be able to convince myself that there was some <br />wetness in there, though it also might have been fuel.<br />I have read some about hydrolock, and AK, you are right, it <br />does seem to fit the bill. I pulled the fuel filter and emptied it into<br />a pan, but didn't see anything that looked like water beads. Next, <br />I will drain the oilpan and look for water. Ditto the fuel tank.<br /><br />I have read differing procedures for recovering a motor from <br />hydrolock. In particular, there is contrary opinion as to whether <br />or not to put oil in the cylinders during open cranking.<br />Any advice there?<br /><br />Checked the upper gear case oil level, and it was slightly low, <br />but on the lake, I didn't hear anything that sounded like <br />a bearing going out. (Doesn't mean it didn't happen). But <br />everything sounded completely normal- and then completely <br />silent.<br /><br />Seawolf, I also agree that it could have been an overheating <br />problem. I have not yet checked the impeller but will. However, <br />after it started the 2nd time, I did make sure that the temp went<br />down while running. But I don't know exactly where the temp sensor<br />is, so is it possible to get a safe temp reading and yet have a portion <br />of the engine overheat?<br />If it is an overheating problem, what is the safest way to proceed?<br />1) check w/p impeller?<br />2) check thermostat?<br />3) if it was an overheating problem, is there other damage that <br />could have been caused which I should look for?<br /><br />Thanks very much to both of you!

 

[akriverrat]

Re: OMC 2.3L dies, won't crank

enough water to hydro motor probably came from some where other than fuel. more likely cracked/rusted out manifold or head. i overlooked where you said it jerked the steering wheel. that realy points to behind the motor. pull drain plug in lower unit and look for bits of metal bigger than fine filings/water.

 

[rogerm]

Re: OMC 2.3L dies, won't crank

Here's what I found.<br /><br />The dipstick showed the oil low. Pulled <br />the upper gear housing cover and the oil was <br />indeed fairly low and not covering the gears completely. Next,I drained the lower unit, and <br />did find some small filings (mostly on the <br />apparently magnetic drain screw tip). A few small silvery flakes in the oil that came out.<br />The oil was otherwise clean with no sign of<br />water.<br /><br />I agree with you that the problem appears to be <br />in the stern drive esp, since the moter cranks <br />and runs with no strange noises now. I wonder <br />if the set gears in the upper gear housing got<br />hot and froze together or got tight and stalled <br />the motor, then cooled and let it restart.<br /><br />I turned the gears all the way around, and there<br />are no obvious signs of destruction like chips<br />or fractures. They appear rather clean, and I <br />could only see very small flecks of any metal in <br />housing.<br /><br />Should I reassemble, fill with oil, and go <br />run it? Checking of course for an oil leak <br />somewhere which may have led the unit to get <br />low in the first place.<br /><br />At this point is further disassembly warranted?<br /><br />Thanks.

 

[akriverrat]

Re: OMC 2.3L dies, won't crank

i still suspect gimbal bearing overheating and siezing up. where are the omc guys?

 

[rogerm]

Re: OMC 2.3L dies, won't crank

AK:<br />I located some info on the Gimbal bearing in the SELOC book, and found the following:<br />"If the bellows are defective and leak, water <br />will find its way into the boat, cause damage to<br />the U-joint input shaft bearing, and possibly<br />short out the trim sending unit."<br />I mention this because, though I thought it was unrelated at the time, my trim sending unit did stop working about 2 trips before the last failure.<br />What is the best way to assess the integrity of the Gimbal bearing?<br /><br />thanks.