Tag: compression tester

How to Use a Compression Tester

BER5252NEWThe compression of your car’s engine is a very important characteristic for proper functioning. Poorly sealed cylinders can lead to serious issues that may eventually result in the rebuilding of the engine. Checking the engine’s compression involves an instrument called compression tester.

What is a Compression Tester?

The compression tester checks the valve and rings of the engine and it detects excessive carbon. There are two varieties on the market.

The threaded screw tester is screwed into the spark plug opening.

Alternatively, you can use a hand-held compression tester. If you choose this possibility, you will have to work with another person. Your helper will have to crank the engine while you are performing the test.

The traditional compression tester consists of an indicator dial gauge, a testing tube and a spark plug holder or a rubber tip in the case of a hand-held piece.

According to professionals, threaded screw compression testers provide more accurate readings.

How to Check the Engine’s Compression

The engine manufacturer will provide you with the correct compression reading. You should use it as a guideline while performing the test. Keep in mind there could be variations in compression engine readings recommended by different manufacturers.

You first need to remove the spark plug from the engine cylinder you are about to test. Never attempt removing a spark plug at working temperature because it will lead to severe burns. Locate the distributor cap and pull the centre coil wire. By doing this, you will be preventing the engine from starting but still building compression to perform the test.

Get your spark plug compression tester. Install it in the hole of the spark plug. Hand tightening is usually sufficient to position the tester accurately. Hand-held testers have a rubber tip that has to be pushed into place.

Crank the engine and take the compression tester’s measure. For best results, perform the test a couple of times and calculate the average or choose the test reading that appears most often. Use the manufacturer-supplied information to compare the  results.

Press the release valve to release the compression from your car’s engine. You are done! After you are done testing and reinstalling spark plugs, run the engine to make sure that everything functions properly.

HIL85420002A Few Additional Tips and Considerations

If you own a hand-held compression tester, you may be interested in creating a better seal for more accurate readings. Grease can be used to achieve that goal. Just use your finger to apply a little bit of grease on the rubber tip.

There could be specific compression testing procedures for particular engine models. It may be a good idea to familiarise yourself with the process before getting started. Manufacturers may suggest different methods of creating engine pressure, so make sure that you are informed.

Checking the engine compression is a simple, yet highly beneficial procedure. Every vehicle owner should have a compression tester. Perform the test whenever you experience any problem like the loss of too much oil or a general lack of engine power. Compression testing will help you figure out what the cause of the problem  is.

Author – Tony Heywood

Tony Heywood

Tony Heywood is a ‘Retail Troubleshooter’ with 40 years experience in the retail industry, specialising in e-commerce over the last decade. He has his own consultancy firm and is MD of  ’e sell it’, an on-line store selling tools and auto-care products worldwide.

For tools & auto-care products at trade prices, please visit: www.esellit.com

Or call: 020 8201 0588


How to do a Compression Test on an Engine

WHY DO A COMPRESSION TEST?

The engine’s compression reveals much about the state of the engine. Low compression caused by a faulty valve or worn piston ring could mean a lack of power or blowing smoke from the exhaust but can also help you rule out some of the more serious faults.

WHAT IS A COMPRESSION TEST?

If your engine is running smoothly there should be a compression in excess of 100 psi per cylinder with no more than a 10% difference between the highest and lowest cylinder test.  As a general rule a compression of 135 PSI or better is excellent, and a compression of 85 PSI or lower is not good at all. If this is not the case it is likely that your engine valves, their valve seats or piston rings need replacing.

 

BEFORE USE

Compression Tester with Quick Disconnect for Petrol Engines

Compression Tester with Quick Disconnect for Petrol Engines

  • Identify the size of fitting that is required for the engine to be tested.
  • This compression testing kit includes fittings suitable to replace injectors and glow plugs.
  • Refer to the table for details of fittings and thread patterns.
  • The battery and starting system must be in good condition to ensure an accurate test.

 

WARNING:-

  • Always keep well away from any hot / moving engine parts.
  • Take care to keep compression tester from becoming entangled in moving parts.

 

OPERATION

Compression Tester for Diesel Engine

Compression Tester for Diesel Engine

  •  Allow engine to reach normal operating temperature. Stop engine, remove all glow plugs or injectors (refer to vehicle manufacturers manual).
  • The compression tester (with correct fitting attached) can now be screwed into a glow plug or injector hole. Ensure that fitting is screwed in securely.
  • Disconnect the fuel shut off solenoid to disable the fuel injection pump.
  • With the throttle in the wide open position, turn the engine over 6-8 revolutions.
  • The dial gauge will automatically record the highest pressure reached.
  • To release the pressure, and reset the gauge, depress the bleed valve button.
  • The compression tester can now be unscrewed, and the next cylinder tested.

 

 TIP

  • If you find that one of the cylinders has a compression of under 100 psi then pour about a teaspoon full of oil in and retest.
  • If the reading increases then it’s likely to be a piston ring problem. If not, it’s more likely the valves need replacing.

 

IN SUMMARY

  • For an engine running normally compression builds up quickly and evenly to the specified compression for each cylinder.
  • If the Piston Rings are leaking: Compression is low on the first stroke but builds up after further strokes but does not reach normal. However, the compression improves considerably when you add oil.
  • If the Valves are leaking: Compression is low on the first stroke and does not normally change much after further strokes and does not improve much by adding oil.
  • If two adjacent cylinders have lower than normal compression and adding oil into the cylinders does not increase the compression, it could be that the head gasket is leaking between the cylinders.

 

MAINTENANCE

  • Keep your compression tester clean.
  • Ensure that screw threads do not become dirty.
  • If necessary clean with a wire brush.

 

CONCLUSION

  • With the correct equipment a compression test can be done in around 20 minutes but can save you £100s in garage fees.

 

 

Author – Tony Heywood

Tony Heywood

Tony Heywood is a ‘Retail Troubleshooter’ with 40 years experience in the retail industry, specialising in e-commerce over the last decade. He has his own consultancy firm and is MD of  ‘e sell it’, an on-line store selling tools and auto-care products worldwide.

For tools & auto-care products at trade prices, please visit: www.esellit.com

 


Copyright © 1996-2010 e sell it - tools and auto-care tips and tricks. All rights reserved.
iDream theme by Templates Next | Powered by WordPress
Visit Us On TwitterVisit Us On FacebookVisit Us On Google PlusVisit Us On PinterestVisit Us On YoutubeVisit Us On LinkedinCheck Our Feed