Ask the Car People.SM


A Mechanic's Life - Tales From Under the Hood

2868 messages,  Last post on May 22, 2013 at 8:19 AM

You are in the Maintenance & Repair Forum.

What is this discussion about? Auto Repair, Hatchback, Truck, Sedan

     This topic is primarily for professional mechanics, current or retired, or ardent amateurs who would like to share the suprises, victories, tricks and challenges of working on the modern automobile. All Forums members are invited, of course, to ask technicians about their work, or comment on your own experiences dealing with mechanics.
 
If you have a maintenance or repair question about your vehicle, please use search to find one of our Maintenance and Repair discussions, or ask a question in Edmunds Answers.

Messages Page 61 of 288

#596 of 2868 Re: Online advice [xwesx] by thecardoc3

Dec 03, 2012 (12:50 pm)

Replying to: xwesx (Dec 03, 2012 11:06 am)
As for my tester, I think it goes that small. it switches between a mV reading and V reading automatically, and displays tenths in the mV setting, so theoretically it will. It's only a $35 Innova unit, though, so I'm not sure how accurate it'll be.
 
You should be using a meter with an accuracy of .1% +1

#597 of 2868 Re: Online advice [thecardoc3] by srs_49

Dec 03, 2012 (2:39 pm)

Replying to: thecardoc3 (Dec 03, 2012 3:05 am)
On measuring parasitic current draws-
 
You said to measure the voltage drop across the fuse, then calculate the current from that and the resistance of the fuse.
 
Question - how do you measure the resistance of the fuse without removing it from the circuit? Do you just measure a fuse in the parts bin, and assume it's close enough to the one in the vehicle?
 
If you have to remove the fuse from the vehicle, then aren't you right back at the issues you raised with opening up the circuit to insert a current meter? Unless you jumper around the fuse before pulling it out to measure it's resistance.
 
Could use a non-invasive current (Hall Effect) probe, providing you can clamp it around the wire of interest.
 
Just thinking out loud...

#598 of 2868 Re: Online advice [thecardoc3] by obyone

Dec 03, 2012 (3:24 pm)

Replying to: thecardoc3 (Dec 03, 2012 3:05 am)
Even if I bring her on and fix this for her history has shown that she is not likely to be come a permanent customer. She started out at the parts store with this problem because everything the consumers have ever been taught is how the cheapest price is all that really matters, right up until that routine fails. Then in some ways it doesn't matter what we charge, "it's too much" so the only way we ever see them again is in five or six years when they have another nightmare that no one else seems to be able to solve.
 
I think you've answered your own question though you won't know for sure unless you go ahead and repair it. On then will you be certain whether she will be a loyal customer or not as we never judge a book by its cover.
 
In this case, I'd agree and unless it's real slow I'd pass on it.

#599 of 2868 Re: Online advice [srs_49] by thecardoc3

Dec 04, 2012 (6:18 am)

Replying to: srs_49 (Dec 03, 2012 2:39 pm)
Question - how do you measure the resistance of the fuse without removing it from the circuit? Do you just measure a fuse in the parts bin, and assume it's close enough to the one in the vehicle?
 
 
Actually what I said was.
 
A fuse is a resistor, so any parasitic drain will cause a small voltage to be measurable across the fuses terminals. Do you have a voltmeter that is accurate into the 10,000ths of a volt or smaller? (.000XX) That is how you go about locating what circuit the drain is on. A low amps probe allows a technician to measure the drain on the car without opening the electrical system and clearing out all of the memories as well. Some of those are accurate down to about 5ma (.005 amps).
 
Could use a non-invasive current (Hall Effect) probe, providing you can clamp it around the wire of interest.
 
So the answer is yes, measure the current draw, and if it's excessive use can use the voltage drop technique to identify the circuit.
 
Question - how do you measure the resistance of the fuse without removing it from the circuit? Do you just measure a fuse in the parts bin, and assume it's close enough to the one in the vehicle?
 
It is possible to measure the resistance of a fuse with the correct tools but a regular ohmmeter isn't the correct tool. Besides, it's easy to calculate the fuse's resistance by measuring the current through it, and the voltage drop across it. The fun part about this is the fuses resistance isn't fixed. Like anything else the temperature of the fuse makes quite a difference in it's resistance, which of course explains exactly how they work when you think about it for a few moments.

#600 of 2868 Hello all. by bartbarter

Dec 04, 2012 (1:44 pm)

I read this entire thread and wanted to say thanks for all the great info.
 
And insight. I'm a backyard hack, but a stubborn one, so I only use a garage occasionally. But when I do I'll look at it a little differently now.
 
The only thing I have to add is, don't buy the cheap rotors!! Even if you're lucky enough to not get the ones that shatter, I was buying $13 fronts for my old 97 Grand Marquis and had to replace them more often than the pads! Also, while the rotors on my 03 are hatless, because they are so much bigger than the 'hatted' rotors on my 85 Town Car they seem to weigh about the same.
 
Bartbarter

#601 of 2868 Re: Hello all. [bartbarter] by stickguy

Dec 04, 2012 (5:46 pm)

Replying to: bartbarter (Dec 04, 2012 1:44 pm)
good point about the parts, and I will bet that "doc" will agree. Not worth buying cheap parts, unless you like to replace them and do your own work. and have lots of spare time.
 
but when you are paying to have a job done, usually (or at least often) the labor is the biggest part of the job. So saving a few dollars on an inferior part seems counter-intuitive to me.

#602 of 2868 Why is getting wheels balanced so difficult??? by oldbearcat

Dec 04, 2012 (9:31 pm)

Where I live, the past few times I've replaced the tires on my vehicles, I've had to take the car back 3 - 4 times for a re-balance for the shop to get them properly balanced. I've had this problem with local independents and national chain tire dealers as well. My most recent experience - I recently replaced all 4 tires on my Honda CRV. I've had the car back to the shop 3 times for a re-balance and they still didn't get it right. Monday I took the car into my local Honda dealer for a brake job, and, had them balance all 4 wheels as well. The Honda techs got the wheel balance right on the money. Is there a shortage of folks who know how to mount and balance tires correctly? Around here the only places that I currently know that will get it right the first time are my local Honda and Mercedes Benz dealers. I'm tired of sitting in waiting rooms for hours while they make multiple attempts to balance the tires correctly.
 
Regards:
Oldbearcat

#603 of 2868 Re: Why is getting wheels balanced so difficult??? [oldbearcat] by stickguy

Dec 04, 2012 (9:45 pm)

Replying to: oldbearcat (Dec 04, 2012 9:31 pm)
My guess, a combination of poorly trained low paid techs, the need to get them done quick, and the ever increasing size and weight of the wheels/tires all come into play.

#604 of 2868 Things that are out of balance by thecardoc3

Dec 05, 2012 (7:11 am)

My guess, a combination of poorly trained low paid techs, the need to get them done quick, and the ever increasing size and weight of the wheels/tires all come into play.
 
Many of the chain stores pay their techs an hourly wage, plus a bonus based on productivity. Then they turn around and exclude some items from the list from which they accumulate productivity. Guess what one of those items is?
 
In essence, the techs are "punished" for doing tires, unless they upsell other services from the tire replacement. Then in the case like bearcat, since techs are not paid for a "comeback", they are in effect punished again. The only recourse is for the techs to minimize the personal financial hit by not being paid for installing tires and that happens with speed. When everything goes correctly, nobody else cares what actually happened inside the shop.
 
Now as far as balancing the tires, there are problems with some wheels on some balancing machines. The wheels have to center correctly in order for the machine to be accurate and many manufacturers have an uncanny ability to make sure their wheels don't mount up without specific adapters. My machine (Snap-On) doesn't do a lot of the 3/4ton truck wheels as easily as it does any car steel wheel. Some of the Jeep mag wheels force me to be very creative in double, and triple checking the wheel/tire assembly which often means that I have to spin it to measure it out, add the weights to balance the assembly and re-spin it to check it. The I have to break it loose, turn it on the spindle and then tighten it up and re-check it again. There have been a number of times that I have found that I have to use different adapters between individual wheels from one car. If the wheel is balanced correctly, I should be able to take it loose, reposition it, and tighten it back up and end up with "0's" again.
 
The advantage for me is that I don't have to rush through a job like this. I'll take whatever time I need to and in some cases I have had to buy additional adapters for my machine.

#605 of 2868 Re: Things that are out of balance [thecardoc3] by obyone

Dec 05, 2012 (11:47 am)

Replying to: thecardoc3 (Dec 05, 2012 7:11 am)
Notice the difference?
 
Snap On
 
The competition

Messages Page 61 of 288

To POST a message, please Sign In.

Advertisement

Browse by Category

Browse by Vehicle
   View All Vehicles

Browse by Board
Browse by Topic
View All Topics

Edmunds Community

Advertisement