I have a 98 115tsl evinrude, 20 inch shaft, will a powerhead with the part number 398604, year 1988 110-115hp, bubble back, fit my motor? Does the term "C Drive" make a difference? Thanks for any help!!
A 98 tsl is indeed a crossflow as is the 1988. They are basicaly the same motor. There will be some wiring changes between the two but the powerhead is the same. Almost.<br /><br />The 1998 has the driveshaft O ring in the bottom main bearing seal plate. The O ring on the 88 is on the driveshaft. You can use the 88 powerhead but you will end up with no driveshaft O ring to protect the splines. A good coat of grease will help -- and it may never become an issue but personally I would prefer to use the 98 crank and lower seal plate in the 88 block. <br /><br />The term Sea Drive is a line of motors that OMC built that have a bracket built into the mid section to install on a full transom type boat. The 1.6 Sea drive powerheads will bolt to any V4 crossflow from 1978 and newer. Again the only real difference is how the power packs were mounted on some earlier blocks. Of course you still have to look at the driveshaft O ring issue. The Sea Drive will have some different cable linkage attachments and bosses that you wont need on an outboard.<br /><br />What wrong with your 98 that you want to change it?
My motor has around 115psi on each cylinder. It doesn't perform the way it used to and the replacement sounds very cheap, cheaper than a rebuild. It runs fine, I guess Im getting bored this winter.
I would try a decarb job while youre waiting for the outdoor heater to kick in and try compression again. Thats a bit lower than we normally see on that type motor but I havent been using your gauge either. The good news is that they are all even. Lets do the decarb.<br /><br />Now tell us what it used to do that its not doing now. Dont forget about any weight youve added, anything youve changed (prop, motor height, cylinder heads etc).
I have decarbed this motor a couple of times and have ran ring free through it, probably couldn't get much cleaner. In your opinion do you think this is a good idea with the o-ring issue. Or will I end up with a problem child for a motor?
We've seen it done this way and if you drop the gearcase every year to re-grease the splines, its probably OK. Youre gonna do a water pump about that often anyway. Naturally its more of a concern in saltwater than fresh. <br /><br />It would still be interesting to hear what it was doing that it isnt now and what was done to the motor. <br /><br />Good luck!
