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Cobalt_drill_bit

cylinder leak-down test

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Cobalt_drill_bit

Hi guys,

 

I would like to pursue an cylinder leak-down test on my TU1M engine. Because I suspect a blown head gasket.

 

I have to say that I already made up my mind to go for a leak-down test. What I would like to ask about is something I read in the Haynes manual regarding the related compression test. As Haynes doesn't have a section regarding leak-down test.

 

Ok, for the compression test on the TU they refer back to chapter 2A*3 (for X engines) because the instructions are likely identical.

Step 3 of the compression test read:

 

Disable the ignition system by disconnecting the ignition HT coil lead from the distributor cap and earthing it on the cylinder block. Use a jumper lead or similar wire to make a good connection.

 

My question is what are they trying to achieve there? As I have an engineering background I'm very annoyed by these loose instructions. I have to understand what I am doing.

 

Despite my annoyance at Haynes I appreciate people who use this forum to help out other members.

 

Best regards,

Maarten

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jackherer

I would imagine they are ensuring there are no stray sparks when you might have e.g. fuel hoses disconnected. Also I think it is possible to damage a coil if they have no path to discharge to ground.

 

Personally I would unplug the LT side of the coil...

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Ozymandis

Best to take the main high tension lead off, then loosely lay it against  the cylinder  head casting or engine block/crankcase, connect your test apparartus, then IMMEDIATELY before you crank the engine over, liberally douse the whole thing with 98 octane gasoline, 4.5 liters or a gallon should be sufficient, place propane gas cylinders in each footwell, one in Your lap helps a lot, 12kg cylinders are sufficient.

Then crank away on the starter. It`s best to do this inside in an enclosed space, a wooden garage is best, but be sure to close and lock the doors before You attempt this. As I have a terrorist insurgent background it does annoy me so much when people DONT lock themselves in the  building first.

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jackherer

Even if you did all that the chances are it wouldn't ignite! The air/fuel ratio needs to be within a very small range for a spark to actually do anything.

 

Haynes still have to cover themselves though for that 1 in a million chance that could get them sued.

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Cobalt_drill_bit

I didn't appreciate the parody by Jay. I wasn't opinionated regarding safety. I just don't accept instructions that completely fail to communicate the idea behind it.

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Ozymandis

Is your engineering background with Lego?

 

 

  • Haha 1

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