Suzuki DF140 O2 Bolt problem

[ianyoung77]

I have a 2003 with 240 hours and reading all the O2 bolt posts I looked at my bolt and it is corroded on the outside so I want to replace it. The casing is still ok from the outside. The problem is removing the old bolt. I could weld a nut or easyout but I am concerned this would damage the case causing a bigger problem. It may be safer to drill out the old bolt and use a larger aluminium bolt like

https://www.probolt-australia.com/al...ap-suzuki.html

What do people think the best solution is? Should I risk damage to the casing by trying to screw out the bolt or is there less risk to drill it out?

Here is the link to problem description

 

[tommarvin]

Don't take the bolt out unless you have too. do not weld a nut on a bolt on an outboard.

Corrosion on a bolt is ok, I have corrosion on all my bolts it's ok to have some corrosion it's an outboard,that's what outboards do.

If your looking for trouble,and you must, spray PB blaster on it three times, wait over night, lightly tap the head three times,get a breaker bar and take it out and put anti seize on the thread for easy removal next time.

If the bolt snaps off,cut the bolt 1/8th above, get a center punch and punch a indent so the 1/16 inch cobalt drill bit stays in indent, drill larger and larger until you use the correct drill size for heli coil insert, youtube explains it perfect.

 

[ianyoung77]

Thanks Tom. Are you familiar with this issue? The bolt corrodes the aluminium from the inside out and it blows a hole often taking out the electrics and costing two grand to fix.
As far as I know heli coils are steel so putting one in would restart the whole problem. What is the advantage of using a helicoil rather than just a bigger bolt? The hole is just for an O2 sensor and I was thinking that if ever I needed to do an O2 test I would heli coil or use an adapter temporarily then put the bigger aluminium bolt back in.

 

[tommarvin]

I'm not familiar with your issue. Why does the bolt corrode the aluminum from the inside out,I have never heard that.

The advantage of using a helicoil is there30% stronger and there stainless steel. and only one drill bit larger than the existing hole back to same bolt diameter maybe different threads per inch..

The hole is for an 02 sensor, is the sensor corroding the aluminum from the inside out that your worried about? If so take the sensor out and mount it some ware else, or zip tie it to something. Give us an update, so we can help and learn something.

 

[ianyoung77]

Hi Tom,

Did you read the link? Suzuki were going to install a permanent O2 sensor then changed their mind. To fill the hole where the sensor was going to go they put in a mild steel bolt. Since this is in the exhaust area the exhaust gases accelerate the galvanic corrosion meaning the aluminium around the bolt (plug) starts to corrode. In later models they removed the hole altogether so O2 sensing is obviously not critical.
If I buy a replacement housing it does not have the hole so I figure why not just put a bigger aluminium plug in. I was hoping people might have some experience in getting the old plug out.

 

[tommarvin]

Drill out the mild steel bolt/plug, and install an aluminum plug or fill the hole with two part epoxy.
You need to drill the old plug out with a 1/16 inch cobalt drill bit and drill larger and larger holes until big enough then two part epoxy, or tap for aluminum plug..