Compression test

- G
- Greg
  
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posted
20 years ago

Wed, Jul 30, 2003 1:49 AM

Is it ok to do a compression test with the exhaust manifold off and having the exhaust ports exposed? I'm going to try and rent a compression tester tomorrow and I'm also wondering whether I need additional equipment to perform a leak down test and does the chilton and/or factory service manual provide the info needed to do these tests? (I don't have either manual at my disposal right now but will tomorrow). The reason I ask is because I'm considering buying a new turbo and manifold but I don't want to put a lot of money into a '91 Talon that has over 150,000 mi. and is 13 yr. old unless I am sure the internals are in good shape. Btw, if my tests go well I'm going to get the 'small 16g' w/ 6cm housing -- swapping out a 13g w/ 5cm housing, does anyone have any opinions on my choice of turbo for this auto trans car?

Thanks in advance, Greg

- R
- Richie Rich
  
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posted
20 years ago

Wed, Jul 30, 2003 3:00 AM

Sure you can do your tests without the exhaust manifold on.

Make sure the coil is unplugged.

- S
- Steve Piette
  
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posted
20 years ago

Fri, Aug 1, 2003 10:15 PM

Yes, Since the engine isn't running and nothing is hot you don't have to worry about warping anything.

You can buy a compression tester for about $25 A leak down tester is a different tool, I bought mine from Summit.

these tests?

The factory manual covers the compression test but not doing a leakdown. I suspect Chilton's will give more detailed information on performing a compression test than the factory manual since mechanics are expected to know how. A leakdown tester requires access to compressed air to pressurize the cylinder, It measures the difference between the input pressure and the actual cylinder pressure and you calculate the leakage percentage.

Just remember that once you swap in a larger turbo your going to need other modifications too. The fuel injectors on the AT 1G are much smaller than the

1G MT (390 vs. 450 cc/min). I suggest you spend some time at the AT DSM web site

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Steve