1970 25 hp - fixing starter mounts on block?

[BF]

Hi all,<br /><br />Well that old 25 hp I picked up seems to run nice and strong... idles down nice too, although it's a bit louder at idle than my 15 hp... I think having that biggish exhaust hole on the leg gives it the louder "putt putt" sound of the older motors. It also seems to like the dino juice! Burnt about 7 gallons of gas without tryin' too hard... but that's fine, as long as it runs good, I'm happy.<br /><br />Now for the problem, it has electric start and 2 of the mounting points on the block had previously been broken off and repaired (previous owner). Well, the repair job sucks. The original mounting holes have been welded and then tapped. But the threads are poor and the bolts vibrate loose in no time, even with locktite and lock washers. I removed those 2 bolts, tightened the other 2 (threads are OK on those) and used the rope start with no problems last weekend, but it'd be nice to fix the mounts of the electric start properly.<br /><br />First thought was to drill out the cruddy holes and put in two helicoils. But... the last 1 cm or so of the rear mounting spot on the side (port) is broken off. It's the last bit of a kind of a finger projecting off the block, it looks like it was all added material and probably was a poor tig job at that.. So, maybe I should put a stud in that location? That way I can put a nut onto it and have the starter bracket sandwiched between 2 nuts? Otherwise there would be no backing for the bracket to be tightened against.... I can't place studs in both problem holes, because one faces forward and the other one port - bracket couldn't be slipped on if there were 2 studs. I'd just as soon avoid more welding. <br /><br />Anyone had similar probs?<br /><br />Thx in advance.<br /><br />Brent

 

[R.Johnson]

Re: 1970 25 hp - fixing starter mounts on block?

First off! if you have'nt already, fix, or replace the prop. That starter is quite heavy, and is mounted outbound from the engine. A damaged prop will give any engine guite a shaking. It will loosen bolt's, and even break bolt's as in the case of you starter.The only fix I can think of is to grind back the damage, and fix by welding, if possible.

 

[BF]

Re: 1970 25 hp - fixing starter mounts on block?

Hi,<br /><br />The prop is in excellent condition... only the paint worn off the tips, no damage. The previous owner told me the damage to the starter mounts was originally done when a guest to his cabin pulled the rope enough to engage the recoil, and then hit the starter button. As a result, the starter engaged the flywheel that was being already engaged by the recoil, and bang... the starter broke free. Seems plausible, especially the part about how a guest ends up bustin' your stuff. <br /><br />thanks for the warning though.<br /><br />Brent

 

[BF]

Re: 1970 25 hp - fixing starter mounts on block?

^

 

[BF]

Re: 1970 25 hp - fixing starter mounts on block?

Thought I'd do a "what I ended up doing" post in case someone ever finds this thread in the archives...<br /><br />I drilled out the 2 problem mounting holes, tapped the now bigger holes and installed a "Keen" insert in each. These are little tubes (about 5/8" long) that are threaded on both the outside and inside. I used the ones which had 1/4"x20 threads inside (same as the original starter mounting bolts). That meant I needed a "Q" drill bit and tap the block with 3/8"x16 tap. They can tell you what drill bit and tap to use where you buy the inserts. Basically its the same idea as using a helicoil, but mucho cheaper. The inserts I bought were $2.36 each. I had the drill bit and tap. The minimal helicoil kit to do 2 holes of this size was $42. Helicoils use there own "special" taps so unless you have a master kit already (or have access to one) you need to buy the tap (and probably insertion tool, and tang breaking tool) in order to install them. <br /><br />The Keen inserts just thread into regular threads, and have 2 little tabs that you tap (they go down into the outer threads and lock the insert in place). I used red locktite (permanent) on the outside threads when installing.<br /><br />One thing I noticed was the aluminum mounting areas of the block were a little cruddy near the the outside edge, so I opened up the first 1/4" or so of the hole up bigger with a dremel to allow me to screw the insert in further to get a bite of better aluminum deeper in the hole. Normally the lock tabs on the insert bind the outside threads when the insert is flush with the edge of the hole.<br /><br />I let the locktite set up (ended up being 2 days) and put the starter back on last night. I used blue locktite and the star kind of lock washers on all bolts. It went on great, and the bolts tightened down nicely... with the poor threads in aluminum it had before, the bolts felt spongy when tightening them down, and they vibrated loose after using the starter a few times, and also just from regular (not excessive) engine vibration.<br /><br />Hopefully they'll hold tight now!<br /><br />Brent