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alph
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« on: July 10, 2009, 08:45:11 PM » |
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So I was on a ride with a buddy and I asked him if there was any white smoke coming from my exhaust? He informed me that there was a little when I accelerated. I figured that I either had a sticking valve, or worst yet a hole in my head gasket that would be letting in antifreeze into the combustion chamber. The best way to find out would be to do a compression test.
I figured an engine is an engine right? Wrong! First off I tried doing my compression test the same way I’ve done my car, truck and wife’s van, pull the spark plugs on a cold engine, hook up the tester, turn over engine till full compression is reached.
Did a little research and found that the compression rates should be about 171# per cylinder pretty simple on a F6 engine since all plugs are readily available. So I pull the plugs, crank the engine and got a very ugly surprise! I did each cylinder five times with two different testers and my compression rates were an average;
1-67
2-51
3-68
4-83
5-87
6-57
How on earth can this engine be running on such low compression? And all the numbers were not consistent! Everyone who said this engine was bullet proof was full of crap! (I thought.)
Here’s the skinny.
The most accurate reading will come with a warm engine, so start it up and let it idle for a while to normal operating temp (I ran mine till the cooling fan kicked on). Blow out any dirt that might get into your cylinder when you remove your plug, do this with the sparkplug in the engine! Undo your #1 sparkplug and remove it with a pair of needle nose pliers so you don’t burn your fingers.
When testing, you must also fully open the throttle. Turn off your engine fuel, and remove the spark plug cables for all spark plugs, you don’t want to run the engine.
Make sure all other spark plugs are in the engine, and properly torque to 12 Newton meters. Install tester in the number one, front right cylinder. Crank the engine over until the gauge reaches the maximum pressure of that cylinder. You now should have an accurate reading of that one cylinders compression. Repeat five more times for all the other cylinders, replacing the previous sparkplug.
After doing this procedure my new readings were much more accurate. They were;
1-137
2-138
3-134
4-133
5-134
6-134
Remember that you don’t want any two adjacent pistons to read more then 10 #’s difference, example if my number one cylinder read 130, and cylinder three was 141, then I would be concerned. That’s when you start putting teaspoons of oil in the cylinder to find out if it’s a valve, or a ring.
What I will need to do now is a valve clearance check, and my numbers will most likely come up even higher. But until then I’m now too concerned. One ordeal at a time!!
Al.
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