Sealey CT951.V3 Instruction Booklet

instructions for

IMPORTANT: PLEASE READ THESE INSTRUCTIONS CAREFULLY. NOTE THE SAFE OPERATIONAL REQUIREMENTS, WARNINGS & CAUTIONS. USE
THE PRODUCT CORRECTLY AND WITH CARE FOR THE PURPOSE FOR WHICH IT IS INTENDED. FAILURE TO DO SO MAY CAUSE DAMAGE AND/OR
PERSONAL INJURY AND WILL INVALIDATE THE WARRANTY. KEEP THESE INSTRUCTIONS SAFE FOR FUTURE USE.

petrol engine compression test kit
3pc

model no: ct951.V3

thank you for purchasing a sealey product. manufactured to a high standard, this product will, if used according to these
instructions, and properly maintained, give you years of trouble free performance.

refer to
instructions

Wear eye
protection

Wear protective

gloves

Wear safety

footwear

Wear protective

clothing

1. safety

 Warning! ensure all Health & safety, local authority and general workshop practice regulations are strictly adhered to when using

tools.

8 Do not use tester if damaged.

9 maintain the tester in good and clean condition for best and safest performance.
9 Wear approved eye protection. A full range of personal safety equipment is available from your sealey stockist.
9 Wear suitable clothing to avoid snagging. do not wear jewellery and tie back long hair.
9 Account for all tools and equipment being used and do not leave them in, on or near engine.
9 When not in use, place in protective case and store in a safe, dry, childproof area.

9 Always refer to the vehicle manufacturer.s service instructions or a proprietary manual, to establish the current procedure and data.

2. introDuction

fitted with Ø65mm gauge having two scales (psi and kPa), reading from 0-300psi and 0-2000kPa. includes quick coupling 150mm rigid stem

with cone-type adaptor and 320mm exible adaptor with 14 and 18mm screw in adaptors. Supplied in carry-case.

3. operation

3.1. preparation.

3.1.1. run engine until normal operating temperature is achieved.

3.1.2. stop engine, loosen spark plugs one turn, with an air hose, blow dirt and debris from the spark plug wells.

3.1.3. remove all spark plugs.

3.1.4. If tted with a carburettor set the throttle valve wide open.

 Warning! the ignition system must be disabled. failure to disable could result in damage to the ignition system or ecu.

3.1.5. unplug the low tension connections to the coil. if you aren’t sure how to disable the vehicle ignition system then consult the
manufacturers service instructions or a proprietary manual before you start. it is also good practice to unplug the fuel injectors or disable

the fuel pump, especially on cars tted with a catalytic converter. This prevents unburned fuel getting into the exhaust system during the

test.

3.2. compression test.

3.2.1. Using the appropriate threaded adaptor, screw the tester into a spark plug hole (nger-tight - do not use a wrench) or using the

push tting, hold the compression tester rmly against the spark plug aperture.

3.2.2. Crank the engine until no increase in pressure is noted on the gauge reading; usually 3 or 4 revolutions is sufcient. Take a note of the
pressure reading.

3.2.3. Decompress tester by pressing release valve (g. 1) remove the compression tester from the spark plug hole and proceed to the next
cylinder. note pressure reading for each cylinder.

note: The actual gure in psi is not important. It is important that all cylinders have approximately the same compression pressures.
on high compression engines (150psi and higher) the pressure should not vary more than 15psi from the highest to the lowest
cylinder reading.
on low compression engines (under 150psi) the pressure should not vary more than 10psi from the highest to the lowest cylinder
reading.
note: compression readings are unbalanced when one or two cylinders are considerably higher or lower than the others.

3.3. causes of unbalance.

3.3.1. low cylinder compression is caused by leakage from:

a. Head Gasket - explosive sound when running engine.

b. Head Gasket between cylinders - compression will be low in two adjacent cylinders and water may appear in cylinders or crankcase.
c. Valves that are not seating properly.
d. Piston rings that are worn. Pour a teaspoon of oil into the spark plug hole to seal the rings. repeat test. if compression reading
increases, the rings are worn; no increase indicates a bad valve.

3.3.2. High cylinder compression is caused by accumulation of carbon in that cylinder. High compression readings in all cylinders is

caused by an even accumulation of carbon in all cylinders. This may cause detonation pinking that is difcult to eliminate.

© Jack sealey limited

Original Language Version

cT951.V3 | Issue 1 07/02/18

g.1

Parts support is available for this product. to obtain a parts listing please log on to

www.sealey.co.uk, email [e-mail] or telephone [phone]

enVironment protection

recycle unwanted materials instead of disposing of them as waste. All tools, accessories and packaging should be sorted, taken to
a recycling centre and disposed of in a manner which is compatible with the environment. When the product becomes completely
unserviceable and requires disposal, drain any fluids (if applicable) into approved containers and dispose of the product and fluids
according to local regulations.

note: it is our policy to continually improve products and as such we reserve the right to alter data, specifications and component parts without prior
notice.

important: no liability is accepted for incorrect use of this product.
Warranty: Guarantee is 12 months from purchase date, proof of which is required for any claim.

sealey group, kempson Way, suffolk Business park, Bury st edmunds, suffolk. ip32 7ar

01284 757500 01284 703534 [e-mail] www.sealey.co.uk

© Jack sealey limited

Original Language Version

cT951.V3 | Issue 1 07/02/18