"Parmas" Motor - Toyota Yaris Forums

cdydjded · 03-03-2010, 01:00 PM

Here is a good article:
http://www.carcraft.com/techarticles...ter/index.html

My car is @ -22 so -20 is not that different. You low compression issue could be one of the following problems:
Piston ring end gap wrong
Piston to cylinder wall clearance wrong
Valve to valve seat problem
Crack or broken ring lands
These are just a few that I can list. Im not saying it has to be one of these, but its a possibility.

Parmas · 03-03-2010, 03:27 PM

Quote:

Originally Posted by cdydjded

Here is a good article:
http://www.carcraft.com/techarticles...ter/index.html

My car is @ -22 so -20 is not that different. You low compression issue could be one of the following problems:
Piston ring end gap wrong
Piston to cylinder wall clearance wrong
Valve to valve seat problem
Crack or broken ring lands
These are just a few that I can list. Im not saying it has to be one of these, but its a possibility.

Nice test I didn't know about it since now. Interesting tool ... what brand do you recommend?

cdydjded · 03-03-2010, 05:07 PM

Quote:

Originally Posted by Parmas

Nice test I didn't know about it since now. Interesting tool ... what brand do you recommend?

I dont have a specific prefrence, here are a few:
http://www.google.com/products?hl=en...ell=1&oi=spell

rob323 · 03-03-2010, 05:10 PM

If you have a compression tester, you can easily tell if it's the rings or the valves which are causing the problem. Run the compression test as you would normally and take note of the reading.
Then remove the compression tester fitting and drop a teaspoon of oil (any normal mineral oil will do, castor oil, motor oil, doesn't really matter as long as it is thin (ie. not gearbox oil)) down the spark plug hole and then repeat the compression test. The oil you put down the combustion chamber helps the rings to seal better. If the reading is the same as before the oil was added, then the problem is in the head (valves, valve guides etc). If the reading is dramatically better than without the oil, then you look towards your pistons and rings for the problem.
If the reading is only slightly better than before you added the oil, but still low compared to the other pistons, then you possibly have a bent rod.

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03-03-2010, 01:00 PM	#1
cdydjded Drives: Yaris LB Turbo Join Date: Aug 2006 Location: Miami FL Posts: 782	Here is a good article: http://www.carcraft.com/techarticles...ter/index.html My car is @ -22 so -20 is not that different. You low compression issue could be one of the following problems: Piston ring end gap wrong Piston to cylinder wall clearance wrong Valve to valve seat problem Crack or broken ring lands These are just a few that I can list. Im not saying it has to be one of these, but its a possibility.

03-03-2010, 05:10 PM	#4
rob323 Don't drive it, RALLY it! Drives: 1999 echo PRC rally car Join Date: Oct 2008 Location: Joyner, Brisbane Posts: 321	If you have a compression tester, you can easily tell if it's the rings or the valves which are causing the problem. Run the compression test as you would normally and take note of the reading. Then remove the compression tester fitting and drop a teaspoon of oil (any normal mineral oil will do, castor oil, motor oil, doesn't really matter as long as it is thin (ie. not gearbox oil)) down the spark plug hole and then repeat the compression test. The oil you put down the combustion chamber helps the rings to seal better. If the reading is the same as before the oil was added, then the problem is in the head (valves, valve guides etc). If the reading is dramatically better than without the oil, then you look towards your pistons and rings for the problem. If the reading is only slightly better than before you added the oil, but still low compared to the other pistons, then you possibly have a bent rod.