Author Topic: Magnetic oil drain plug warning  (Read 937 times)

FordPrefect8

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Magnetic oil drain plug warning
« on: April 16, 2020, 09:22:04 PM »
Didn't happen to my Jazz but Honda motorbike.
After draining oil, I've put new crush washer in and tried to tighten it to required torque spec of 30Nm when suddenly bolt started to rotate very easily... It snapped (see attached photo).

Spent next 30 mins carefully trying to recover remnants out of the sump, it was made of aluminium and magnet drill hole didn't improve its integrity. It's probably worth investing in something made of stainless steel.

culzean

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Re: Magnetic oil drain plug warning
« Reply #1 on: April 17, 2020, 08:00:35 AM »
Sounds like you had a nightmare, those large grains where the bolt broke make me think that it was not a good grade of aluminium or had work hardened / fatigued,  also the magnet has taken away a lot of the bolts strength.... aluminium is tricky stuff at the best of times as it does some odd things.

I am a convert to this for cars - https://www.amazon.co.uk/Sealey-TP696-5-5ltr-Manual-Extractor/dp/B000WZF74M  ( it has gone up about 20 since I bought it about 3 years ago ).

Just done 3rd oil change on two cars with it,  was a bit dubious at first that it would get all the oil out but every time I use it I decant oil into a graduated plastic jug a litre at a time ( cheap from Aldi ) and the exact right amount comes out.  It does help that our drive has a slope on it so that front of sump is the lowest point.  At least now I don't have to get the cars up on ramps or remove the drain plug,  just jack up drivers side and slip an axle stand in, remove front four screws ( of 6 ) from plastic under tray and let it drop out of the way,  replace filter fill up with fresh oil,  run engine for 10 mins to make sure filter is seated and refix undertray - jobs a goodun'.  ( Jazz is easy to do, our Civic is a bit of a PITA,  but it was even when up on ramps so no change there ( at least with reduced mileage these days I only replace filter every second oil change = every 2 years )

When I used to remove plug to drain oil I got some copper washers to replace aluminium ones,  if you need to you can anneal and re-use copper ones by heating up red hot - quenching in cold water - polish the face of scale with a bit of wet and dry on a piece of glass ( nice and flat ) and re-fit.   They were copper anyway on my motorbikes so I guessed they would be fine on a car and never had a problem.

I guess they use magnetic plugs on motorbikes because oil is shared with engine, gearbox and clutch so much more change of getting metal in the oil than on a car where oil only goes around engine.
« Last Edit: April 17, 2020, 08:15:47 AM by culzean »
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FordPrefect8

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Re: Magnetic oil drain plug warning
« Reply #2 on: April 17, 2020, 09:47:16 AM »
Sounds like you had a nightmare, those large grains where the bolt broke make me think that it was not a good grade of aluminium or had work hardened / fatigued,  also the magnet has taken away a lot of the bolts strength.... aluminium is tricky stuff at the best of times as it does some odd things.

My heart stopped for a good while! That would have been roughly 500 mistake :o

Quote
I am a convert to this for cars - https://www.amazon.co.uk/Sealey-TP696-5-5ltr-Manual-Extractor/dp/B000WZF74M  ( it has gone up about 20 since I bought it about 3 years ago ).

Just done 3rd oil change on two cars with it,  was a bit dubious at first that it would get all the oil out but every time I use it I decant oil into a graduated plastic jug a litre at a time ( cheap from Aldi ) and the exact right amount comes out.  It does help that our drive has a slope on it so that front of sump is the lowest point.  At least now I don't have to get the cars up on ramps or remove the drain plug,  just jack up drivers side and slip an axle stand in, remove front four screws ( of 6 ) from plastic under tray and let it drop out of the way,  replace filter fill up with fresh oil,  run engine for 10 mins to make sure filter is seated and refix undertray - jobs a goodun'.  ( Jazz is easy to do, our Civic is a bit of a PITA,  but it was even when up on ramps so no change there ( at least with reduced mileage these days I only replace filter every second oil change = every 2 years )

That's one of the things I miss in my garage. I'd still probably drain the oil normally but I'd more than happily use pump as well to get those very last, hard to get remnants :)

Quote
When I used to remove plug to drain oil I got some copper washers to replace aluminium ones,  if you need to you can anneal and re-use copper ones by heating up red hot - quenching in cold water - polish the face of scale with a bit of wet and dry on a piece of glass ( nice and flat ) and re-fit.   They were copper anyway on my motorbikes so I guessed they would be fine on a car and never had a problem.

Good idea in case of emergency, at the moment I've got stocks of both MB and car oil drain bolt washers, I use copper on MB and aluminium on Jazz. I mean, they sell them by 50 or 100 for less than tenner :D

Quote
I guess they use magnetic plugs on motorbikes because oil is shared with engine, gearbox and clutch so much more change of getting metal in the oil than on a car where oil only goes around engine.

Precisely. Also my particular engine does not have actual separate oil filter, instead it has an oil strainer that looks like a little sieve. I've installed magnetic plug about 4 years ago when I got the bike and changed oil about twice a year. With each change I would see smaller amount of filings stuck to the magnet in a form of a cute and terrifying tiny hedgehog :o

I don't have one in my Jazz but until yesterday I did consider using one for gearbox drain bolt. Not so much now.

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