Pelican Parts Forums

Pelican Parts Forums (http://forums.pelicanparts.com/)
-   911 Engine Rebuilding Forum (http://forums.pelicanparts.com/911-engine-rebuilding-forum/)
-   -   compression test recommendations? (http://forums.pelicanparts.com/911-engine-rebuilding-forum/457246-compression-test-recommendations.html)

70SWT 02-14-2009 04:29 AM

compression test recommendations?
 
EDIT to clarify: looking for tips on how to do a compression check on an engine on a stand i.e. out of the car, if possible, and without taking it to a shop, and recommendations for specific products available at a reasonable cost.

Thanks, Al

nimskov 02-14-2009 06:18 AM

I recently tested the compression on my car. I simply bought a compresstion tester at a local parts shop. It's no big deal.

The only slight problem with my tester is, that it can be bard to screw the hose in the plug hole, since the tube its flexible.

Other than that, remove all plugs, disconnect fuel pump, always test with full throttle, and run on the starter the same amount of revolutions for each cylinder tested.

Good luck :)

70SWT 02-14-2009 08:53 AM

Thanks for the tips! Original post edited as above.

nimskov 02-14-2009 11:05 AM

Normally the engine has to be at operating temp. when compression test is performed.

Not sure if it's a good idea to do it on an engine stand... there's no oil pressure and the temp is too low.

If you could rig a temporary oil tank, so the engine would get some oil, it could perhaps be done.

Hooking up a battery and making a temporary start switch should not be a problem.

70SWT 02-15-2009 03:54 AM

How about leakdown - doable on the stand, or similarly also only practical in the car?

911pcars 02-16-2009 12:53 PM

Posts above neglect to mention the starter motor needs a mount to rotate the engine. That means either a partial or full gearbox housing, and the required real estate for this gets a little tricky the way most engine stands are configured.

As suggested, the engine should be be close to normal operating temperature for accurate compression and cylinder leakage results, but while one shouldn't necessarily compare cold test results with factory specs, it's close enough for a very rough estimate.

Cylinder leakage testing requires the test cylinder to be positioned @ TDC end of compression. That task is the same with the engine installed or on an engine stand. Accessing the plugs and fishing loose spark plugs that fall out of the socket is easier on a stand, but that's quite minor. Preventing the crank from rotating is easier on a stand (lock flywheel in place), but for more accurate results, the engine should be at normal operating temperature.

Sherwood


All times are GMT -8. The time now is 07:25 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2025 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website


DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.