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Car: Audi S5 4.2L 8 cyl, 6 speed manual

Purpose: I want to clean the carbon build up on the intake ports and valves.

The reason: Not all the valves are closed at the same time, and so the engine needs to be turned to open any remaining valves.

The issues:

  1. To crank the engine from the crankshaft pulley, a special tool is required which I don't have.
  2. The car has a push button start, so it's hard (not impossible) to crank the engine for a very short period of time (need to release the clutch very quickly for it to stop cranking)
  3. I tried putting it in 6th gear with the handbrake down and pushing the car (with 2 people), but it required a lot of effort (rocking the car forward) and not sure how effective it is.

What would be a safe way to crank the engine? I'm not sure how safe the releasing clutch method is. It also involves removing the spark plugs so the injectors don't pop out. Not sure of any other damage doing this a few times.

Regarding the pushing method, is there a reason why it was so hard to push in 6th gear? The car was off for about 1 hour, so I'm not sure if there would still be compression in the engine. Also, being such a high gear ratio, I'm not sure how far I'd have to push the car to close the open valves...

Thanks

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  • If any of the spark plugs were still in, almost as soon as the engine begins to turn, you generate compression.
    – anonymous2
    Nov 6, 2016 at 9:49
  • All the plugs were in, I'm currently weighing options on how best to turn the engine over. I always thought it was the gearing ratio that stopped the car from rolling, not the compression of the engine.
    – tgun926
    Nov 6, 2016 at 12:05
  • It's a combination of both. The engine compression makes the engine hard to turn (try turning a weedeater motor sometime with and without the spark plug in). Depending what the gearing ratio is, you will be more or less able to overcome that pressure.
    – anonymous2
    Nov 7, 2016 at 17:51

3 Answers 3

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Either use the tool probably with a crescent wrench since there is not much space unless you have the fans out and whatnot. Or get a remote starter like this one. Hook it up to the positive battery terminal and the positive terminal on the starter, then blip it until the valves you need to clean are closed.

Other things I can think of:

  • Possibly spinning an accessory pulley
  • Pulling all the spark plugs should make spinning it easier
  • Take a bar and put a couple bolts in it to catch the lobes the tool is supposed to fit into (I would spin it without spark plugs so you do not put undue stress on those lobes)
  • With the sparkplugs out use the remote starter switch which will make it easier to stop the engine at the spot you want
  • Painful but could spin it from the crank with a prybar but might need to take out the starter if there is no timing or dust cover in the bell housing
  • Could use compressed air after pulling the spark plugs
  • With the car in reverse gear pick up one wheel and use a lug wrench or breaker bar to spin the tire clockwise (tighten) I would suggest doing this with the spark plugs out. If you have a LSD or locked dif or 4WD you may need to pick up more wheels to do this
  • Sometimes you can pull the accessory belt with the plugs out and spin it that way but with your V8 this might not be possible
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  • 1
    Looks like most things become easier with the spark plugs removed. Cheers
    – tgun926
    Nov 6, 2016 at 12:06
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    Yes yes it is. with them out you could also just push the car in 6th gear and it should roll reasonably easily.
    – Cc Dd
    Nov 6, 2016 at 13:38
  • Engine was very easy to turn by the rear wheel jacked up and spark plugs removed. Thanks
    – tgun926
    Nov 20, 2016 at 1:40
  • @tgun926 Excellent good to hear!
    – Cc Dd
    Nov 20, 2016 at 2:36
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As @Cc Dd said: 'pull all the spark plugs'. This is by far the easiest method i think. It requires the least effort and you don't need special tools, unless your plugs are hidden away somewhere very unconventional. Because of the lack of compression with the plugs pulled, it's very easy to turn over the engine. You can also do so with good accuracy, which is often desired when working on the valves. Most of the time i jack up the rear and ask someone else to turn the wheel until the valves are in position, and i say stop. (or the front in case you have fwd)

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Pulling various suggestions together:

  • Pull the spark plugs, once they are out the engine will not build up compression and turning it over will be much easier. It will also be easier to position the engine where you want because the compression will not be trying to resist or move the piston for you.

  • For the work that you're doing it will probably be easier to turn the engine over while you are near the valves so that you can see them move into position.

  • When the plugs out you can probably turn the engine pretty easily with the accessory drive belt. You may be able to do it by just pulling on the belt, be careful as your hand gets near any of the pulleys that your fingers don't get caught between the belt and the pulley. That hurts...

  • If you can get enough purchase with just the belt a wrench on the pulley nut of one of the accessories should make it easy.

Regarding your question about pushing in 6th gear – then engine will (should) always build compression as you turn it over with the plugs in place.

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