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I cant seem to get the piston rings into the cylinder head they are fully compressed

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Hi,
use a ring comperessor, special tools, that u could buy in any tool dealer!

Posted on Apr 11, 2011

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Posted on Jan 02, 2017

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What should the psi compression be thanks.


It can vary between make and model of car. However, a general rule of thumb is that 135+ average is okay. Less than 85psi is pointing at something seriously amiss in the engine.

It can vary - some cars may have 125psi as 'average' compression.

Don't expect each cylinder to give the same compression reading as there will be a fluctuation. Another general rule of thumb is that there shouldn't be more than 10% variation between the readings. That is, if cylinder No1 is 135 psi, cylinder No2 shouldn't be less than '125 ish'.

If you suspect you may have compression issues, it's quite easy to do a bit of fault finding. Warm the engine first so that the pistons are expanded in the cylinders. Then do a dry compression (normal) test.

Here's some examples of compression tests on a 4 cylinder engine:
130 127 129 127

All compression readings are within 10% of each other. Fine.

Example 2:
95 95 129 127
Here, a low compression reading on cylinder 1 and 2 suggests a problem. It may be due to a faulty head gasket/cylinder head allowing compressed gases to be transferred via the defective head gasket from one cylinder to another.

Example 3:
130 80 129 127
Cylinder No2 has a problem. It's compression is way down. The other three cylinders are fine. So .. what is the cause of the low compression on cylinder 2? It could be a broken ring/cracked piston or a burnt exhaust valve.

This is where you do a second compression test - called the 'wet' test.

Squirt some light engine oil into each cylinder. Aim for the cylinder walls so that the oil can find its way down the walls and around the piston rings. Place a rag over each spark plug hole and spin the engine to expel excess oil.

The oil that you have sprayed into each cylinder will form a 'seal' around the piston ring. Do another compression test and note down the readings. Here's example 3 again:
Example 3:
130 80 129 127
.. with the low compression on cylinder 2.

If after carrying out the 'wet' compression test you have a reading along the lines of
130 100 129 127
suggests that the bore/piston rings in cylinder 2 are at fault. The compression has increased on No2 cylinder because of the oil forming a seal around the rings.

If there is no increase in psi on the wet test i.e
130 80 129 127
This suggests a burnt exhaust valve.

May 17, 2016 | Cars & Trucks

1 Answer

Compression cylinder low #2 and #3 cylinders.


there are only four possibilities left:
1: valves are not fully seating - adjust rocker arm / cam
2: piston rings are bad - replace rings
3: holes in pistons - replace
4: cylinders out of round - most complicated repair, bore / machine cylinders and replace piston rings with oversized rings.

of course you could just have 'gunk' on the valves preventing full closure........

Jul 23, 2014 | 2001 Hyundai Tiburon

1 Answer

What do i need to do to replace pistons and rings on a corsa utility


Normally would squirt some oil into the cylinder spark plug hole and check compression again. If it's better, then may be rings. But no compression seems more like a head gasket or stuck open valve.

Mar 01, 2014 | Cars & Trucks

1 Answer

Sluggish no power cant get over 90kms


this is caused by loose compression.

either worn out piston rings or cracks in the combustion chamber.

replace your piston rings and cylinder head gasket. then bring your cylinder head to a machine shop to have it resanded.

if cracks are present in the combustion chamber, then one of the best solution is to have it rebored (to widen the current diameter of the combustion chamber) and replace your pistons with the correct diameter of the new hole.

Jan 31, 2013 | 2008 Jeep Patriot

1 Answer

No compression on cylinder #2 after putting a new (remanufactured) cylinder head and pistons/rings


You did not mention about replacing a piston you said was broken? if you did not there is the cause of you low compression. either way if you did change it out and did not measure the ring end gap and put the right size ring in the hole then it looses compression, if you failed to resurface the cylinder and just put in a set of rings then they wont seat for a while. In addition. length of push rod? was cam follower collapsed? did you change? How about the connecting rod of the piston? the one that was in there more than likely got squashed and isn't coming up to full compression Sounds to me like you need to take the head off again and check out a few more things Sorry!

Sep 06, 2012 | 2002 Jeep Liberty

1 Answer

1998 nissan altima has low compression on one cylynder


Might be a bad cylinder head gasket at this cylinder. A radiator compression test can find the problem. Might be a bad valve, or a frozen (stuck) piston ring, or broken piston ring. To isolate the problem to the valves or rings, you have to add a little 30 weight oil inside cylinder through spark plug hole. Repeat the compression test. The oil temporarily seals the piston rings. IF the compression is still low then you have a bad valve. Good luck.

Oct 14, 2010 | Nissan Altima Cars & Trucks

1 Answer

#2 cylinde r head bad. how to repair low compression


First thing you need to do is determine why the compression in that cylinder is low. Four possible causes are 1. blown head gasket 2.bad valve(s) in the head 3. broken compression ring, piston ring land or burned piston. 4. rounded camshaft lobes
One other possibility is a fuel washed cylinder (from leaking injector)
You are going to have to remove that cylinder head and do a thorough internal inspection, possibly involving oil pan and piston removal.
Once the cause has been found you can proceed to make an appropriate repair. Or if the damage is beyond your ability, replace the engine with a used or new one.
There is no quick easy fix to restore compression.

Jun 09, 2010 | 2005 Chevrolet Colorado

1 Answer

Low compression on one side, one fowled plug


A compression leak down test would tell you where the compression leak is coming from, and you should call around to find a repair shop that knows what a compression leak down test is.

A burnt or bent intake or exhaust valve, warped cylinder head or faulty head gasket, or a damaged piston or piston compression ring could cause a compression leak, and a leaking intake manifold gasket that allows oil to enter the intake through the lifter valley could foul out a spark plug, and also it could be a damaged piston or broken piston rings that is fouling out the spark plug.

Jun 06, 2010 | 2005 Ford Explorer

2 Answers

Spark to but No compression in 2nd cylinder


The most common cause of your problem would be a sticking or burnt valve the only way to know for sure is to remove the head and check then it will need a valve grind and head machined before replacing you may find it cheaper to hunt around for a good secondhand engine to have fitted in your car.
The head of the piston in each cylinder is designed to compress fuel so that it is combustible (explosive/flamable) when it is ignited by the spark plug. The compression is maintained by O-rings on the piston which do not allow fuel to escape past it. In your case, either an O-ring is damaged or the piston itself isn't working properly and it is not compressing the fuel as it should.
Hope this helps, best regards :)

Nov 21, 2009 | 1995 Ford Escort

3 Answers

Oil leak?


Whoa whoa ... You've said that the car takes 7 quarts of oil. That's 14 pints. Depending on which engine variant is fitted, engine oil capacity is either:
  • 5.75 litres + 0.4 litre if the oil cooler is drained
  • Turbo - 3.85 litres + 0.6 litre if the oil cooler is drained
  • These figures are for a UK 3 litre version of the 960
If you've filled the car with 7 quarts of engine oil that's almost twice as much oil as should be in the engine. Did you mean pints when you wrote quarts?

If you've filled it with 7 quarts it's overfull. Way too full. Check your oil dipstick - remove it, wipe it clean and then dip the oil level. At the bottom of the dipstick there is a flattened wider part. The oil level should not be below the bottom of this marker, and nor should it be above it. If the oil level is way above the flattened marker bar - you're overfull and will have to drain some oil out of the engine. An overfilled engine will try and blow oil out from wherever it can as the oil system will over-pressurised.

Ok .. so there's no problem with the engine compression. The crankcase isn't overfilled with oil (the crankcase is known as the oil sump in the UK). There's no oil fouling of the plugs and the car isn't burning oil, just leaking it. There's no misfires or running

If the engine isn't overfilled with oil there may be a problem with a broken/sticking piston ring or piston/cylinder. That high oil loss you mention seems severe. A problem with a piston/ring/cylinder can allow the compression to leak past the rings/piston into the engine oil sump and pressurise it. Under pressure, the oil will try and leak to atmosphere from anywhere it can.

A blue smoky exhaust is also an indication of piston/ring problems. A quick check is to start the car. If there's a cloud of blue smoke at start up which clears quickly, it's like to be worn valve guides. If, when driving the car with a warm engine there's blue smoke on acceleration - it points to a problem with rings/piston.

A quick check is to remove the spark plugs. Is there engine oil on one or more of them? An oiled up plug indicates that the engine oil is finding its way up past the rings/piston - and if oil can find its way up to a spark plug, then exhaust gasses/compressed fuel/air can find its way into the engine oil sump and pressurise it.

Another quick check is to start the engine and remove the oil dipstick. If fumes are 'chugging' out of the tube or oil is spitting out, that's another sure-fire sign that the oil sump is becoming pressurised due to a piston ring/piston/cylinder problem.

If you possess or can borrow an engine compression tester there is a further test you can do yourself to confirm whether or not there are piston/ring problems. Basically, a compression tester is just a gauge that screws into the cylinder head in place of the spark plug.

Warm the engine for 5 minutes so that the pistons expand fully in the bores.
Remove the spark plugs
Fit the compression tester into No1 cylinder and crank the engine for 10 seconds. Make a note of the compression reading on the gauge.
Do the same for each cylinder.

Here's an example of what you might find (the figures are for example only)
Cylinder Reading
1 115
2 120
3 118
4 95
5 96
6 117

Figures vary, but there should not be more than a 10% difference between the readings.
In the example above you can see that cylinders 4 and 5 have readings that are well below those of the other cylinders. This is indicating problems within those two cylinders. The lower compression could be due to a head/gasket fault or piston ring/piston problem. A split or worn exhaust valve in the head may cause low compression, a misfire and uneven running but it won't cause the engine oil sump/crankcase to pressurise. Now, some fine tuning to locate the exact problem:

Put a liberal squirt of oil into each cylinder - something like Redex, WD40 or engine oil.Put a cloth over each spark plug hole and spin the engine to get rid of the excess oil. The idea is that the oil you have squirted into the piston bores will form a 'seal' around the outside of the piston/rings.

Do the compression tests again and note the readings. If the readings go up significantly it indicates that the rings/pistons/bore has a problem. Readings that go up significantly are due to the oil forming a seal around the piston which raises the compression whilst testing. Here's an example:Cylinder Reading on 1st test 2nd test
1 115 118
2 120 121
3 118 120
4 95 110 Significant rise - more than 10%
5 96 98
6 117 119

Ok .. all this means is that cylinder 4 has compression problems due to the rings/piston/bore. The 2nd compression reading (with the oil squirted in) is higher simply because the oil formed a seal. Cylinder number 5 still has a low reading which didn't increase significantly on the 2nd 'wet' (when oil is added) test. This suggests that the problem is an exhaust valve/head gasket/head problem.

If there had been no significant increase in the reading on number 4 cylinder, this would suggest valve/gasket head problem. Low readings on adjoining cylinders (and which don't increase with the 2nd compression 'wet' oil test) would indicate a faulty head gasket between those two cylinders.

I'll continue this article ... ran out of word space

Jun 24, 2008 | 1996 Volvo 960

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