to rebuild or not to rebuild? 84 OMC V4

[Jamar]

Evinrude 90 hp has been sitting for years. Last fall i started the rehab but got tired of waiting on myself so i took her into the shop for a carb rebuild, impeller, and overall check up/get her running. Compression test yielded one cylinder going out at 95#, other three at 120/125. Local wrench says roughly a grand 2 bore/rering. Didnt pull heads or look any further because i said just get her running and lets see what happens. We discussed OMC engine tuner and will run that through when she is actually running bt so far dont have those results.<br />I believe his price to be fair, i know there are lots of things he may find that could lower/raise the cost, and that sometimes you should do certain things while you are in there.<br />I just wonder if the engine is worth putting 1500 into. I'd rather sink that down on newer, bigger engine with better compression. Or maybe just a powerhead off another engine with bad lower. <br />How risky is it to run this engine till she drops? If i am looking at that kinda money i may as well replace the engine/pwerhead anyway right?<br />Would appreciate any/all advice to consider before deciding what to do. just cant afford another grand right now.

 

[ledgefinder]

Re: to rebuild or not to rebuild? 84 OMC V4

Do the decarb first. <br /><br />If compression is still low, it'll PROBABLY die slowly if you continue to run it, but be sure you fix whatever caused the cylinder to go bad in the first place (lean mixture due to dirty/gummy jets, timing, etc..). Higher chance of it dying suddenly on you now, so plan carefully. On the other hand, I had a 100hp V4 98/120/120/88 compression that ran 42mph.

 

[Chinewalker]

Re: to rebuild or not to rebuild? 84 OMC V4

If the decarb doesn't bring the compression back up, I would consider going for the rebuild - unless you really have your heart set on a bigger motor and the cost of a newer motor isn't an issue. If that's the case, trading in a running motor, albeit with issues, carries more weight than a motor that is toasted...<br /><br />The problem with running it into the ground is that at present it may be as simple as a hone and re-ring or a bore and new piston, where as running it into the ground my result in a more catastrophic failure involving one or more of cracked block, damaged heads, bad crank, bearings, etc. The low compression may be caused by a lean condition in one carb throat, which could also lead to burning up other parts in that sub-system. You won't know until you get into it...<br /><br />One other thing to consider is that running it until it dies rarely results in the motor dying just as you're coasting back into the dock after a day on the water - rather it'll die when you're trying to negotiate a crowded channel as a 42-footer is bearing down on your transom. That's Murphy's law at work....<br /><br />Bottom line is that it's up to you and your checkbook...<br />- Scott

 

[Jamar]

Re: to rebuild or not to rebuild? 84 OMC V4

UPDATE - finally got boat back fromt he shop. Runs reasonably well, we'll see for how long. Little bit of noticeable power loss and top end but could pick up with use i am told.<br />Also had a problem on the test run (by the shop)with a shifter pawl breaking in the foot. Replaced that and seals for 300 now there is a knock coming from the foot, even when you spin the prop by hand. Anyone got any ideas?

 

[Jamar]

Re: to rebuild or not to rebuild? 84 OMC V4

.....my apologies....a simple linkage adjustment fixed my problem. Thanks to this forum i ranted and researched and realized my problem, even found a solution. Glad i didnt upset my mechanic.