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9 votes
Accepted

Does driving at top speed damage a car or stress the engine?

I've posted this graphic before, but I think it's pertinent here as well: This is an image of a graph which Carroll Smith put in his book, Engineer to Win. In the book, one of the sections talks ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
9 votes

Dealership's service dept drove my car 19 km

I see this completely normal and not a cause of concern. The service advisor's explanation is certainly a valid reason, but they could have needed to drive the car for a total of 19kms for many ...
WeakMech's user avatar
  • 944
7 votes

Hand-testing Shock Absorbers

"Hand priming" or actuation is effectively worthless as a gauge on the performance of a Shock/Strut Assy. Only when severely damaged or out of service will the activity show any truly noticeable ...
Jeep Cherokee Rescue Society's user avatar
7 votes
Accepted

Tie-rod final test

No - that's all you need to test. Now drive the car to a nearby garage and get them to do a front-end alignment on it - you won't have gotten everything exactly where it needs to be, so let them fix ...
PeteCon's user avatar
  • 8,702
7 votes
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The top speed in the my owner's manual seems to be too low. Is this normal?

In general, the max speed in the manual is a guide to tell you how fast it's capable of going. It's likely lower than what it's actually capable of since most buyers won't file suit if a maker under ...
cdunn's user avatar
  • 9,316
6 votes

Do no-name tires go through thorough testing?

Fun fact: the average mid-sized car tire sees ~800 revolutions per mile, so every component of a 50k mile tire must endure more than 40 million loading/unloading cycles! (note: some tires are not ...
MooseLucifer's user avatar
  • 6,037
6 votes

Do no-name tires go through thorough testing?

In the US, the NHTSA (National Highway Traffic Safety Administration) is the governing body that controls testing and specifications of motor vehicles. They mandate that a certain set of ...
JPhi1618's user avatar
  • 13.3k
6 votes
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What is surface charge and how does it affect battery testing?

I have often heard this term as well, but have never known the technical reasons or the actual root cause of what is known as a "surface charge". To figure it out, I took a gander at a website called ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
5 votes
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What do professional battery testers actually measure?

There are two things that professional battery testers can measure. One is to somehow based on the voltage measure the charge level. Another is to measure cranking amperes. Of these, the second ...
juhist's user avatar
  • 14.6k
5 votes

Is there a way to test ignition coils with built-in ICM?

Honda Coil Over Plug setups have three wires. As mentioned they have an internal Ignition Control Module. Pins 1 & 2 are power and ground while pin 3 is the control signal from the Electronic ...
Ben's user avatar
  • 10.7k
5 votes
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The Testing Procedure for the Mazda 626 Alternator in the WSM is Unclear

You'd backprobe the S and L terminals with the connector plugged in. So attach one end to a ground point and the other to the S or L terminal. Basically the S terminal is the Field terminal. The S ...
Ben's user avatar
  • 10.7k
5 votes
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How to test the function of a water pump?

I've been wondering this too as a lot of overheating related questions come up. There are 2 ways water pumps fail - leaks and impeller failure. Leaks can typically be seen, so they are easier to ...
rpmerf's user avatar
  • 8,443
5 votes

Hand-testing Shock Absorbers

Hand Priming Shocks of Various Dampeners/Struts is Urban Legend This myth has been perpetuated over time and has gained legs and therefore credibility. Yes, it's true that the gas and oil separate ...
DucatiKiller's user avatar
  • 32.9k
4 votes
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Have my tyres been tampered with?

Take the left side wheels off, bolt them on backwards, and turn the car upside down... Seriously, @spicetraders nailed this in the comment. the US DOT date codes [WeekWeekYearYear] are only hot-...
SteveRacer's user avatar
  • 12.4k
3 votes
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How to Tell No MOT Advisory Notes?

The owner does not post the reports or results of the mot on the gov website - it comes from the testing station and the tester. The tester may be able to exercise their judgement about posting ...
Solar Mike's user avatar
  • 34.7k
3 votes
Accepted

Should I do combustion gas test in radiator or reservoir neck?

If the system you are working on has a sealed radiator, with an expansion tank instead of a surge tank, with the only working pressure cap on the expansion tank, then yes, insert the tester in that ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
3 votes
Accepted

Emissions - High CO reading only

The Lambda readings are slightly lean but within the acceptable range for normal catalytic converter operation. The CO is in the normal output range for an engine that is running normally and within ...
Fred Wilson's user avatar
  • 11.6k
3 votes
Accepted

Is 12 volts safe for testing injectors?

Backprobe the injector signal wire and use that to activate the injector. Let the ECM or relay handle the power side of things.
Ben's user avatar
  • 10.7k
3 votes

Do no-name tires go through thorough testing?

In Europe, only tires with an EU Tire Label are allowed to be sold. Big brands were initially happy for the introduction of this label, but were disappointed about the results. Those "crap" Chinese ...
com2ghz's user avatar
  • 288
3 votes

The top speed in the my owner's manual seems to be too low. Is this normal?

The max speed a vehicle is rated for usually depends on the speed rating of the tires equipped by the OEM. The vehicle can move faster, but the tires are not rated to go faster.
rpmerf's user avatar
  • 8,443
3 votes
Accepted

Is propane test for vacuum leaks a fire hazard?

Anytime you use a combustible fuel in a manner not prescribed you are creating a fire hazard. The thing about using the propane tank (we're talking about a small propane torch, not hooking a hose to ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
2 votes

Is the diagnosis from a battery/starter/alternator tester meaningful?

This test is rudimentary, but efficient. Testing the battery voltage with the car off tells you the current state of the battery (can it hold a charge) Testing the battery voltage with the car on ...
tlhIngan's user avatar
  • 12.2k
2 votes
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How Long to Power the Injectors for a Fuel Pump Volume Test?

According to agcoauto.com the length of time that you are supposed to let the fuel flow is 15 seconds. In that period of time, you should have collected at least 1 pint of fuel. However, you should ...
procrastilater's user avatar
2 votes

Determining Expected Battery Voltage With Vehicle Running

No, there is no relationship between voltage and engine displacement or number of cylinders, except a larger engine may lead to more heat in the engine bay, necessitating lower voltage. A voltage of ...
juhist's user avatar
  • 14.6k
2 votes

Determining Expected Battery Voltage With Vehicle Running

There are slightly different methods of measuring voltages defined for each car / manufacturer. The one I show below is from the Jaguar X type manual page 2081 and I would take this info for my car ...
Solar Mike's user avatar
  • 34.7k
2 votes
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Will a carbureted engine have different fuel consumption rates based on external load, with the same RPM?

I disagree with the premise of the question. If you have the engine connected to wheels on the ground, it's going to put some load on the engine. That would slow down the rotational speed of the ...
juhist's user avatar
  • 14.6k
2 votes

Will a carbureted engine have different fuel consumption rates based on external load, with the same RPM?

In simplistic terms, the energy required to overcome a load must come from the fuel. RPM being equal, a loaded engine requires more energy than an unloaded one, to run at the same RPM. For a ...
Caius Jard's user avatar
  • 1,155
2 votes

How do I test the Door lock relay on a Dodge TIPM?

Have you found the physical location of the relay? If so, testing it is pretty easy. You have a power/ground which switches it, then there are the pass throughs. 87 & 87a will either/or be on, ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
2 votes

Testing piston ring

Basically, no. You're going to lose fluid past the rings no matter what, plus, how are you going to measure this anyways? This isn't how you test your piston rings. The way to test your piston rings ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
1 vote

How to figure the best state of tune for custom four-stroke single?

It is possible to check a few things with relative ease before taking it to the dyno: ensure air-tightness of the intake path Confirm there are no paths for intake air to escape through. Crank the ...
Zaid's user avatar
  • 39.2k

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