Helicoil and the motor - DIY or take it in?

[ampersat]

I took chinookjinxd and his dad out with me on Saturday in the army boat, eventually. Some of you may remember my quandry with bolt sizes on the Evinrude. Well, four cranks on the starter and my bolts popped back out enough that I was forced to pull start the big motor. The trip home for tools looked promising at first but after we got up on anchor, I pulled the cover and the bolts had worked back out again.

Diagnosis: threads are shot (gee, whodathunkit :smirk: ).

So, I'm going to look into what it would take to upgrade to a more appropriate motor (boat is rated for 60hp, current is 35hp) but considering that's probably out of the question, I'm researching repairing it.

What scares the bejeezus out of me is it's aluminum. A friend has a tap and die kit and I thought about tapping new threads myself. A quick google says aluminum is fussy about being tapped and the advice I came across was to use an insert. But that still means having to tap the aluminum.

I'd pay a few bucks to have someone else do the work for me if it's worth it. Considering the nature of the work, any shop would do, not just an outboard shop.

Recommendations? Advice? I'm all ears.

[ICHTHYDEMON]

I put a couple helicoils in an old (late 60s)Evinrude 18HP.

After 20+ years the changing sparkplugs the threads finally gave out.

I followed the directions with the kit and everything worked out fine.

[Rod Holder]

Helicoils are a pretty straight forward do-it-yourself task. You do need to get your hands on the installation kit and that can run ~ $30-40 bucks, I'd suggest pricing out the kit and also getting a quote from a shop to have it done, it may not cost much more to have it done

[wwjetboater]

here in Gresham Ed's auto parts have a machine shop they will probaly do it.

[1pump]

What size and pitch are the bolts? I might have an old HC kit laying around here somewhere. I don't know if there would be enough inserts left in it, but at least you could use the tap and install tool, and just get new inserts for it. Much less $$.

[skybuster]

A friend and I tried to helicoil a stripped out spark plug thread on an older merc 115 a few years back. We got the helicoil in and were finishing up the rebuild of the motor.

We fired the motor up in the street in a garbage can to make sure it sounded right before we took it to the river. This was about the fifth or sixth time we ran it since the helicoil. Well the thing fired up and was purring like a kitten when all of a sudden there was a loud noise and something shot out of the motor right between us. Apparently the helicoil didn't take very well and the helicoil and sparkplug shot right out of the engine, across the street, and embedded in a telephone pole. Luckily neither of us was standing directly behind the motor because it may have killed us.

We ended up taking the motor to an old timer for advice and he welded a spark plug to a Ford 460 into the hole. It ran fine after that.

[or.hunter]

I think you would be better off to use an insert rather than a Heli-coil.
The inserts are solid with 4 pegs that you drive in after installation. You would have to drill the hole out larger and still tap it but you would have a nicer finished product.
Aluminum is finicky and using the insert would give more contact area on the back side of it rather than just the spiral portion of a Heli-coil.

Mike

[ampersat]

When I was researching tapping aluminum, I ran across Keyserts and agree wholeheartedly that they would be better than Helicoils. Any idea where I would find them retail in the east PDX area?

[As yet un-named]

Ampersat, you can get either the helicoil or the keyserts at Fastenal, go to their website to find the location nearest to you. Also a good place to get those hard to find stainless nuts and bolts etc. etc.