DT115S Compression issue

[Kgamble]

Hello All,

New member here and hoping to get some feedback from the group. I have a 17ft Challenger bass boat with a 1997 DT115 EFI outboard motor. Have owned this boat and motor for nearly 20 years and have always taken great care of it. It has always run great and been problem free... until recently. The problem that I’m having is that it will get up on a plane and run great for about 2 or 3 minutes and then the engine shuts down and has to sit for about 20 minutes before it can be restarted. Once it restarts it’s the same thing over again. I did a compression check on all 4 cylinders and found that cylinders 1, 3 & 4 were all at 90 PSI but cylinder 2 was at zero. I’m being told by a local marina that based on the results of the compression test... the engine is bad and needs to be replaced. Is that right? Just like that it goes from being a great motor to a pile of scrap? Any feedback would be greatly appreciated. Thanks in advance.

[Solarman]

If the motor weren't so old, it may have been repairable.
There are only a few reasons that could cause loss of compression?
You have to determine why no compression in #2 cylinder before it is scrap now.
If the cause is head gasket, or Reed valves, it may still be repairable?

Those were great motors, but getting parts will be difficult. I have parts for dt140's, carb & EFI models. Many of these parts are the same as the dt115. I may even have a new set of head gaskets for the dt140's EFI.

If your problem is damaged rings, cylinder walls, or crankshaft related parts, then yes it is probably not repairable.

Find out what caused your problem, and post back here on this thread.

Your first step would be to inspect the areas around the injectors, for any signs of damage to the case, if the connecting rod on #2 piston broke, it might have broken the case around #2 injector?

If no signs of damage to case, then you can pull the #2 cyl head, yes you will probably break off some of the bolts, plan for it. Unless you have a way to visually inspect the cylinder without pulling the heads, then pulling the head will tell the most. If cylinder walls and piston are good, inspect the head gasket for damages allowing compression to leak by into water jacket.

Hopefully you get all of this work done quickly, because if water is getting into #2 cylinder, it won't take very long for that to damage the rest of the motor - from rust on rings, crank bearings, etc.


Good luck, post back on what you find out.

[Hoosmatroos]

Do a leak-down test first so you can determine where to look. This is not difficult and doesn't require disassembling of the motor. Look on youtube for guide lines.

Post back the results.

https://en.wikipedia.org/wiki/Leak-down_tester