[Jeepwm69]

As some of you already know, I've torn into an extra 350 Rancher motor I had in the shop, with the intention of swapping in a rebuilt crank, thoroughly cleaning out the cases, and swapping in a later style shift drum. Upon tear down I discovered a stripped drain plug.

So, we've all gone through this before. Easy answer is "replace the case" and I can get used cases for about $50, but if I go that route, I will then have the problem fixed, but the inherent weakness in the design hasn't been addressed. Sure, I can be careful in the future and not over-torque the plug, and it will likely be fine, but if I'm going to fix this, is there not a way to improve on it?

Option 2 would be a Fumoto valve put in with loctite. There are threads there. I can screw a plug in and it isn't loose, but it won't tighten down, so I could screw a Fumoto in with loctite and let it sit, and it work, and afterwards I wouldn't have to worry about the worn threads anymore. I've done this on a 420 and it worked fine, but to be honest I don't like the way the Fumoto hangs down. While it does not protrude past the skid plate, I still have concerns that debris could end up flipping the lever, draining the oil, and bad things would happen.

Option 3 is using a helicoil in the case. I have a set of Helicoils, and while I know that the 420 and 500 cases don't have enough material to hold one, this 350 case looks thick enough, and I think the steel thread insert would actually be stronger than the factory threads, so I'm wondering if that wouldn't be the way to go.

Option 2 and 3 will probably both require trimming down the valve or Helicoil to make sure they don't protrude up into the crankcase, not allowing all the oil to drain, but since I have the cases apart now anyway that shouldn't be a problem.

Thoughts?

 

[retro]

Since it is already apart (and you have the tools) I would fix it with a helicoil. What is it... a 13mm thread I think?

 

[Jeepwm69]

12MM x 1.5

I'm pretty sure the helicoil kit I bought goes up to 12mm so I think I'll already have the bit, tap, and coil.

Will have to dig it out. LOL

 

[Jeepwm69]

Welllll, not much luck on the helicoil.

I discovered that the helicoils are about 3x longer than the thickness of the case, so that's going to require cutting down the helicoil.

The problem is, when I cut down the helicoil, what was left didn't have enough to it to thread up into the case without distorting the coils when I tried to screw in the drain plug.

So bottom line, the design of the 350 case doesn't give me a way to do what I had originally intended, which was to screw the helicoil in, then cut off the top of the helicoil with a dremel and cutoff wheel. Cutting down the helicoil before installation makes getting what's left threaded into the case dang near impossible without screwing up the helicoil.

I MIGHT be able to pull it off if I wanted to go through several helicoils trying to get one in just right, but I think what I'll do instead is just order a used set of cases from PSN.

 

[Jeepwm69]

I'm wondering if there will be enough threaded area to hold a helicoil. That said, if I use red loctite and can get one in there, it would definitely be stronger than the stock aluminum threads. Maybe I'll give it another shot before I order a used case....

 

[wheelsquad]

I'm wondering if there will be enough threaded area to hold a helicoil. That said, if I use red loctite and can get one in there, it would definitely be stronger than the stock aluminum threads. Maybe I'll give it another shot before I order a used case....

have any pics of the case where the drain bolt is? trying to think of ideas and pics tend to help me think of various things.

 

[wheelsquad]

Without seeing exact pics of yours, in general this is the kind of solution I would lean most too, as done in this post here: https://www.hondaatvforums.net/foru.../45961-broken-drain-plug-hole.html#post533921 especially since you already have the motor apart. Find someone you can trust to weld aluminum well, weld the spacer on, drill and tap new and much deeper threads.

 

[Jeepwm69]

Well I don't mind buying a used case. That's what I've always done in the past. That said, this is obviously a weak spot so if I can strengthen it for the same cost I'd rather go that route.

I live in BFE so not any welders around here that I would trust with welding up the bottom of an aluminum case.

As you can see in the pic, there is a dome and a crossmember right above the drain plug hole so that pretty much limits what you can do from the inside of the case.

 

[wheelsquad]

Well I don't mind buying a used case. That's what I've always done in the past. That said, this is obviously a weak spot so if I can strengthen it for the same cost I'd rather go that route.

I live in BFE so not any welders around here that I would trust with welding up the bottom of an aluminum case.

As you can see in the pic, there is a dome and a crossmember right above the drain plug hole so that pretty much limits what you can do from the inside of the case.

Bummer about nobody locally to weld for you like in that other post. If you were near me I have a couple guys that can do this lickety split.

These here are much better than helicoils: https://www.amazon.com/TIME-SERT-1-50-Metric-Drain-Repair/dp/B003SER3PA and would make the case better than new. But unfortunately the cost is also more than a used case. I think if you can get a fitting lock-tighted in well, that may be your best option and I would try that before getting a used case.

 

[Jeepwm69]

Well I don't mind buying a used case. That's what I've always done in the past. That said, this is obviously a weak spot so if I can strengthen it for the same cost I'd rather go that route.

I live in BFE so not any welders around here that I would trust with welding up the bottom of an aluminum case.

As you can see in the pic, there is a dome and a crossmember right above the drain plug hole so that pretty much limits what you can do from the inside of the case.

Bummer about nobody locally to weld for you like in that other post. If you were near me I have a couple guys that can do this lickety split.

These here are much better than helicoils: https://www.amazon.com/TIME-SERT-1-50-Metric-Drain-Repair/dp/B003SER3PA and would make the case better than new. But unfortunately the cost is also more than a used case. I think if you can get a fitting lock-tighted in well, that may be your best option and I would try that before getting a used case.

We used a Time-sert on my sister's Toyota van when a spark plug blew out of the head. Put it in about 100K ago and it's still holding fine.

 

[wheelsquad]

@Jeepwm69 is there room in the area to drill and tap to slightly larger to use an M14 drain plug similar to this? https://www.napaonline.com/en/p/NDP7041370 then at least you are starting with full and new threads. or this stubby one: https://www.napaonline.com/en/p/NDP7041361

 

[Jeepwm69]

Toodeep suggested doing that on a 300 pan. Even gave a Honda OEM part number that still takes a 17mm socket.

https://www.hondaforeman.com/130-foreman-500/71918-oil-drain-plug-size-2.html#post3072162

Problem is,, I don't think there's room to go that big. If I wallow the hole out much more it's going to get into that rib that runs up through the case.

 

[Jeepwm69]

Sometimes I want to kick myself for overlooking the obvious.

I got a helicoil in there, more or less. I had my doubts that it had enough contact surface to stay put, but then the drain plug still wouldn't go in.

Looked and my 12mm helicoils are 1.75 pitch instead of 1.5 (part of a kit with several different sizes).

Think I"m going to take a break from the front crankcase half and try to get the new crank, shift drum, and transmission back in the rear half of the crankcase while I decide what to do. At this point I've pretty much decided to just order used cases from PSN, but I know I'll still end up trying to helicoil this one just because.....LOL. At least with a used case I can go ahead and get the motor back together.

Picked up my 350 Foreman axle tubes this morning with Don Oglesby's brackets welded to them to install on the 300's. Might try to get one of the 300's on 4 wheels this weekend while the weather is nice and I'm not confined to the shop.