Home Mechanic Cock-up

Home Mechanic Cock-up

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NMNeil

5,860 posts

50 months

Tuesday 30th June 2020
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Brake job on an old Chrysler Imperial.
The wheel nut refused to budge so I ended up with a 1" impact driver turned up to maximum because no matter how seized the wheel nut was, this would shift it; and it did. The wheel nut came off along with the stud. Forgot that they were left hand thread.rolleyes

andygo

6,796 posts

255 months

Tuesday 30th June 2020
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Had just finished building my MK3 Escort Tarmac Rally car. It was converted to RWD, had a normally aspirated Cosworth engine in, good for about 270bhp.

Thought I would take it for a shakedown round the lanes.

Came flying down a hill, did a 90 degreee right with a stone barn straight ahead. another 30n yds, came to another 90 degree right, turned the wheel, steering impossibly light, not connected. Stopped up a farmers track, fortunately nothing in the way.

The nut from the pinch bolt attaching the rack to steering column had vanished. Could have been nasty...

Chris32345

2,085 posts

62 months

Tuesday 30th June 2020
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I took the rear light off my car to change a bulb a few months back
Put it ontop of the bit to get a screwdriver to take the bulb holder out turned my back then heard a crack

It had slid of the bin lid and hit the floor
£65 later all sorted

anonymous-user

54 months

Tuesday 30th June 2020
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As a boy I spent endless hours doing home mechanics on motorbikes and lawn mower engines etc.

Roll forward to age 18 and I had a Vauxhall Cavalier. My youthful confidence exceeded by ability. One Sunday afternoon I decided I'd de-coke the engine and grind the valves in.

So I carefully marked the position of the timing belts and all the pulleys etc it went round so when I reassembled it, it would have the right teeth in the right place.

Roll forward a few hours: Car struggled to start, eventually after many explosions from the exhaust pipe it limped into "life" of sorts. Set of 100 miles to my place of work and realised something was amiss when the usual 70 odd bhp was now maybe 10 tops. Every junction and roundabout comprised full throttle (with no load that gave about 3000 rpm) then careful clutch management and with much popping and banging the car would limp out of the junction and then proceed to "accelerate" to about 20mph in the next 15 minutes.

Needless to say after about 40 miles there was an inevitable meeting of metal parts that shouldn't meet and I had to get trailered to my destination. At the garage where the car was dropped off they diagnosed the cam belt was fitted wrong and how could that have happened. My best "really, no idea mate" face didn't cut it as it was bright red.

To this day I will not do any job that involves a toothed belt.

PS - I still have no idea why my carefully marked positions for the belt and pulleys etc which I followed scrupulously when re-assembling lead to this outcome. If anyone can throw some light on it I'd be interested.

Zoobeef

6,004 posts

158 months

Tuesday 30th June 2020
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MikeStroud said:
As a boy I spent endless hours doing home mechanics on motorbikes and lawn mower engines etc.

Roll forward to age 18 and I had a Vauxhall Cavalier. My youthful confidence exceeded by ability. One Sunday afternoon I decided I'd de-coke the engine and grind the valves in.

So I carefully marked the position of the timing belts and all the pulleys etc it went round so when I reassembled it, it would have the right teeth in the right place.

Roll forward a few hours: Car struggled to start, eventually after many explosions from the exhaust pipe it limped into "life" of sorts. Set of 100 miles to my place of work and realised something was amiss when the usual 70 odd bhp was now maybe 10 tops. Every junction and roundabout comprised full throttle (with no load that gave about 3000 rpm) then careful clutch management and with much popping and banging the car would limp out of the junction and then proceed to "accelerate" to about 20mph in the next 15 minutes.

Needless to say after about 40 miles there was an inevitable meeting of metal parts that shouldn't meet and I had to get trailered to my destination. At the garage where the car was dropped off they diagnosed the cam belt was fitted wrong and how could that have happened. My best "really, no idea mate" face didn't cut it as it was bright red.

To this day I will not do any job that involves a toothed belt.

PS - I still have no idea why my carefully marked positions for the belt and pulleys etc which I followed scrupulously when re-assembling lead to this outcome. If anyone can throw some light on it I'd be interested.
Did you turn it over by hand and then make sure the marks still lined up?

anonymous-user

54 months

Wednesday 1st July 2020
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Zoobeef said:
MikeStroud said:
As a boy I spent endless hours doing home mechanics on motorbikes and lawn mower engines etc.

Roll forward to age 18 and I had a Vauxhall Cavalier. My youthful confidence exceeded by ability. One Sunday afternoon I decided I'd de-coke the engine and grind the valves in.

So I carefully marked the position of the timing belts and all the pulleys etc it went round so when I reassembled it, it would have the right teeth in the right place.

Roll forward a few hours: Car struggled to start, eventually after many explosions from the exhaust pipe it limped into "life" of sorts. Set of 100 miles to my place of work and realised something was amiss when the usual 70 odd bhp was now maybe 10 tops. Every junction and roundabout comprised full throttle (with no load that gave about 3000 rpm) then careful clutch management and with much popping and banging the car would limp out of the junction and then proceed to "accelerate" to about 20mph in the next 15 minutes.

Needless to say after about 40 miles there was an inevitable meeting of metal parts that shouldn't meet and I had to get trailered to my destination. At the garage where the car was dropped off they diagnosed the cam belt was fitted wrong and how could that have happened. My best "really, no idea mate" face didn't cut it as it was bright red.

To this day I will not do any job that involves a toothed belt.

PS - I still have no idea why my carefully marked positions for the belt and pulleys etc which I followed scrupulously when re-assembling lead to this outcome. If anyone can throw some light on it I'd be interested.
Did you turn it over by hand and then make sure the marks still lined up?
No I didn't. I made sure the marks lined up then jumped in and after a minute or two of cranking it limped in to life then all the above sorry tale happened.

Is that the key thing to do that a professional would do?

In a way it was quite amusing as I have never heard so many different pops, bangs, strangulated wheezes etc come from an exhaust as I drove along.

Zoobeef

6,004 posts

158 months

Wednesday 1st July 2020
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MikeStroud said:
No I didn't. I made sure the marks lined up then jumped in and after a minute or two of cranking it limped in to life then all the above sorry tale happened.

Is that the key thing to do that a professional would do?

In a way it was quite amusing as I have never heard so many different pops, bangs, strangulated wheezes etc come from an exhaust as I drove along.
You may have had some slack on the opposite side from the tensioner so once rotated the tensioner would have taken that out but found the marks were a tooth or so out.

Another reason to turn over by hand is to check it rotates and you don't get any valve on piston contact. You'll find it by feel and can recheck rather than the first turn of the key where it bends everything.

Pit Pony

8,483 posts

121 months

Wednesday 1st July 2020
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There are 2 versions of brake for the B6 omega.
Solid disc and vented.
I looked through the wheel and saw a solid disc, so bought and had fitted 2 solid discs and 4 pads. Months later I noticed a spongy brake pedal. Stopped for petrol in Buxton. Was heading to the M6 via the cat and fiddle.
There was smoke from the brake fluid and trapped pad. Turned out mine was supposed to be vented discs and the out board pad had popped out and got stuck hence lots of heat and the fluid was seeping over the disc because the piston had come out too far too. and all over the wheel.
RAC took 3 hours to send a suitable truck to take me home.

AW111

9,674 posts

133 months

Wednesday 1st July 2020
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Oil change on my 4wd Express.
Pulled the sump plug, watched the golden oil pour into the dirty catch tray. It didn't smell right.

Replaced the diff drain plug and borrowed my mates car to go and pick up more oil for the diff.
Then drained the sump.

anonymous-user

54 months

Wednesday 1st July 2020
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Zoobeef said:
MikeStroud said:
No I didn't. I made sure the marks lined up then jumped in and after a minute or two of cranking it limped in to life then all the above sorry tale happened.

Is that the key thing to do that a professional would do?

In a way it was quite amusing as I have never heard so many different pops, bangs, strangulated wheezes etc come from an exhaust as I drove along.
You may have had some slack on the opposite side from the tensioner so once rotated the tensioner would have taken that out but found the marks were a tooth or so out.

Another reason to turn over by hand is to check it rotates and you don't get any valve on piston contact. You'll find it by feel and can recheck rather than the first turn of the key where it bends everything.
Thanks for good explanation. Still I learnt the limits of my mechanic abilities.

UnluckyTimmeh

3,450 posts

213 months

Thursday 2nd July 2020
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I fitted my own tyres to my race bike before a trackday at Cadwell Park.

Couldn’t identify what the vibration was I was getting over 100mph. I didn’t have any tools with me so I just removed the wheel weights, which improved things slightly and carried on just a bit slower and spent the day learning my lines.

Back at work, handed the bike to the techs and asked for their opinion. First things first were spanner checks.

I’d left both wheels only hand tight. Obviously thrown them in and not torqued them up eek

Luckily for me they are quick release endurance spindles, so reverse thread and would have been tightening up if anything.

Even so, what should have been 50 and 90nm was about 30 and 40 when we undid them!

If they had been normal spindles it could have been a much more exciting day!

anonymous-user

54 months

Saturday 4th July 2020
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UnluckyTimmeh said:
I fitted my own tyres to my race bike before a trackday at Cadwell Park.

Couldn’t identify what the vibration was I was getting over 100mph. I didn’t have any tools with me so I just removed the wheel weights, which improved things slightly and carried on just a bit slower and spent the day learning my lines.

Back at work, handed the bike to the techs and asked for their opinion. First things first were spanner checks.

I’d left both wheels only hand tight. Obviously thrown them in and not torqued them up eek

Luckily for me they are quick release endurance spindles, so reverse thread and would have been tightening up if anything.

Even so, what should have been 50 and 90nm was about 30 and 40 when we undid them!

If they had been normal spindles it could have been a much more exciting day!
I think you need a change in username yikes

UnluckyTimmeh

3,450 posts

213 months

Saturday 4th July 2020
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JDB96 said:
I think you need a change in username yikes
Yeah. That’s not a bad shout... hehe

Paule2359

60 posts

80 months

Thursday 16th July 2020
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I have also done the front brake pad round the wrong way on a BMW I used to own, but not as bad as the time I pushed my Escort down the ramps that I had been using to work underneath the car then suddenly remembering the axle stand that was under there, had fun welding the floor pan where it came through.

underwhelmist

1,857 posts

134 months

Thursday 16th July 2020
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I've made many cockups over the years. This was what made me finally buy a torque wrench:

UnluckyTimmeh

3,450 posts

213 months

Friday 17th July 2020
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Is that a fork pinch bolt? We’re you aiming for FT?

underwhelmist

1,857 posts

134 months

Friday 17th July 2020
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Yes, fork pinch bolt. Dunno what I was aiming for but I think I thought "just a little tighter and it's done"!

Edit: My local bike shop had a genuine replacement in stock even though they're a Yamaha dealer and this was a Suzuki. Can't beat having a good local bike shop, or a torque wrench.

Edited by underwhelmist on Friday 17th July 01:39

UnluckyTimmeh

3,450 posts

213 months

Friday 17th July 2020
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underwhelmist said:
Yes, fork pinch bolt. Dunno what I was aiming for but I think I thought "just a little tighter and it's done"!

Edit: My local bike shop had a genuine replacement in stock even though they're a Yamaha dealer and this was a Suzuki. Can't beat having a good local bike shop, or a torque wrench.

Edited by underwhelmist on Friday 17th July 01:39
Very lucky!

I once had a customer who over tightened a fork spindle pinch bolt. It pulled all the thread out of the billet alloy stanchion and we weren’t happy to try and put another thread into it (neither was he). So over £1000 later it was all sorted. Ouchies!

Evercross

5,937 posts

64 months

Tuesday 21st July 2020
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Jakg said:
Last one - couldn't work out why the headlight washers weren't working. Took the front bumper off before I realised they only worked with the ignition in position 2....
Did something similar once with my E90 330i that I was retrofitting Xenons to. New headlamp clusters, ballasts, ride-height sensors and adjusters all fitted. Coded the ECUs for HID lights and everything and then tested them but was still getting a 'bulb out' warning.

Removed, rechecked and refitted everything and went through the coding procedure a second time. It was only several hours later that I realised the car was telling me it was the foglight bulbs that were out because I'd been testing everything with the bumper still off (with the foglights in).

xjay1337

15,966 posts

118 months

Tuesday 21st July 2020
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My car has a self contained nut and bolt on the battery clamps.

My last car, if you un did it too much it came apart fully. So you can thread it through a hook type wire connector typical with trickle chargers (what I was fitting).

So I got my socket set and went to undo the nut on the negative lead. But it didn't come off fully. So I undid it more and more and more. It got harder and harder. Then I realised... it's not coming off .....so wanted to do it up ... wouldn't go back up !!!

Cross threaded. Amazing. Been a long time since I did that.
Luckily Ebay came through with a next day negative battery cable and battery monitor sensor. (80 quid for a brand new one?!?!?!?!?! For a 6 inch cable fk off. I paid 19 quid).

Still have an issue - as I can't connect the bloody negative lead from the trickle charger as I need to put a nut on top of the existing factory nut to sandwich the trickle charger lead between the nuts, and spare nuts don't have the right thread pitch so I've had to hit up amazon and buy a huge collection of 75 Wing nuts to try instead. When I actually need 1 nut laugh

Piece of st.