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SA200 Engine Compression Testing For the Complete Idiot

Engine compression is the number one test to evaluate your engine's health and longevity. Excessive piston ring wear, leaking head gasket, burned valves, and worn valve guides will affect the piston compression.  

If you have, say, a 1987 SA 200, as the best we can determine, it is the last year they were manufactured; the engine is 39 years old. The average American drives approximately. 14,000 miles a year. If you bought a car new in 1987 and as an average driver, drove it it 14,000 miles a year, it would have over 500,000 miles on the engine

 

So you will have internal engine wear. Every item in that engine that moves-wears. 

Reading Your Compression Gauge; Tips and Tricks

1. You can check compressionhot or cold. There will be a slight difference, but in the real world, it should tell you pretty quickly if you have a problem.

2. Turn the ignition switch off.

3. Remove each spark plug and lay it next to the cylinder it came out of.

#4 cylinder (closest to the fuel tank) runs hotter than the rest. We normally see more exhaust valve wear than the rest. #1 cylinder runs the coolest. 

4. The first thing to look for is an oily, black foul, your burning oil, the first sign of a worn engine. Because the oil-bath air cleaner is inefficient, dirt gets into the oil and acts like a grinding compound, accelerating engine wear. This chart is open source, copy the image onto your smart and study it.

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Typical Industrial Engine Vacuum Tester

5. With all four of the spark plugs out, your starter will not have to fight the compression of the other three cylinders. 

6. You can styart with any cylinder, I always start with number 4 (cloest to the fuel tank).

Write down each cylinders compression.

7.  There are differenting opions, but I look for a minimun of 105 pounds per cylinder. Anything above 125 pouinds you have carbon build-up in the cylinder.

8. If one or more cylinders have low compression, you may have worn rings or leaking valves. Do this: get a squirt-type oil can with 30 wt oil. Squirt three or four hard squirts into the clyonder. Recheck the compression; if the pressure comes up significantly (10 pounds or more), you have ring problems. If not, you need to have the valves checked.

All cylinders should have 10% compression.

9. If the rings are worn, it's time for major engine repair. The least expensive way to do the motor is to remove all external components: water pump, thermostat housing, alternator, governor, manifold, and idler solenoid. What you end up with is a core, the engine block. oil pan, head, and front motor mount. This is what an engine machine shop wants to see. They normally do not have time to do anything else. Most of these machinists live in their own little world. Don't ask them to get out of their comfort zone.

10. If you are going to become technology self-sufficient, and you need to decide whether you want to or not, this is a good project to start with. Look for a rebuildable engine. The continental f163 out of a Miller Big 40 would be my place to work. They never degraded like the engines in Sa200's. They had a large paper air filter that kept dirt out of the engine. I have seen Miller Big 40's, 40 years old, no seal leaks! Most Lincoln welders never gave me a second look, but I have had customers give me their Lincoln welders. You can;t fix stuip, but you profit from it.  If you want more information email me; m5090c@gmail.com

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Need your own compression tester-yes, you do, they are cheap and a lifesaver.

Need those special tools that no one knows where to buy? Click on this Link.

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