1979 Chrysler Outboard Model 1154H9A - Lower unit bolt won't seat

[hokers]

Hi all,

I bought this motor from a friend who had a problem with the lowest drain screw on the lower unit, now it's my problem. :facepalm:

He was able to easily remove the screw, drained and changed his lower gear oil, and was unable to get the screw back in. He instead used an epoxy that sealed the hole off to keep the oil inside, but I want a more permanent fix.

I am not sure how much extra metal is around that area to be able to retap a slightly larger hole so that a new slighlty larger screw would fit there. As of now, every lower gear oil change, I will have to chip off the epoxy (or maybe break it down with some acetone/paint thinner), change the gear oil, and then re-epoxy the bottom drain plug to keep the oil in the lower.

Anyone got any advice?

Thanks!!!

 

[Frank Acampora]

Re: 1979 Chrysler Outboard Model 1154H9A - Lower unit bolt won't seat

Well, it depends upon the drain screw: Chrysler used three different types--a 5/16 set screw. a regular drain screw and a 1/8 NPT pipe plug. If it was the 5/16 set screw, you can retap to the regular drain plug (3/8 X 16 flat head) But you must spot face the top of the hole so the gasket will seat properly. You can also retap to 1/8 NPT which is probably more desireable. Just don't tap too deeply as the hole and plug are tapered. If you do tap too deep, the plug will not seal.

If the plug is in the bottom front of the nosecone, there is enough metal there that you could also tap as large as 1/4 NPT. If it is on the side of the skeg, then yeah, you probably could go this big but I have never done it so I can't say if it would be satisfactory. Again, with any NPT tap, don't go too deep. Do it in stages, testing the plug until you get it deepenough to not cause drag yet still seal. And do use either teflon tape or anti-seize.

If the drain plug is 3/8 or 1/8 NPT, then you are pretty much limited to re-tapping 1/4 NPT. 1/8 NPT MIGHT retap the 3/8 hole but it will be close. Again, this is one I have never done so you need to measure twice before trying to tap.

 

[fucawi]

Re: 1979 Chrysler Outboard Model 1154H9A - Lower unit bolt won't seat

Is there a helicoil option ? or tap a new hole adjacent to the old ? Or epoxy in a threaded T shaped sleeve as an adaptor .