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

Low compression on cylinder number 1 and cylinder number 2 on a 2000 Toyota Solara 2.2L engine could be caused by a few different issues. Here are a few possibilities:

1. Worn or damaged piston rings: The piston rings seal the combustion chamber and maintain compression. If the rings are worn or damaged, they may not be able to seal the combustion chamber properly, resulting in low compression.
2. Damaged or worn valves: The valves allow air and fuel to enter the combustion chamber, and allow exhaust gases to exit. If the valves are damaged or worn, they may not be able to seal the combustion chamber properly, resulting in low compression.
3. Damaged or worn cylinder walls: The cylinder walls are what the pistons move against. If the walls are damaged or worn, they may not be able to maintain proper compression.
4. Head gasket failure: The head gasket seals the combustion chamber and prevents compression from escaping. If the head gasket is damaged or blown, compression can escape, resulting in low compression.
5. Leak in the intake or exhaust system: a leak in the intake or exhaust system can cause low compression.

The dry compression test you did on cylinder 1 and 2, 80 PSI and 60 PSI respectively, are not within the normal range and indicate low compression. The wet compression test results are also not within the normal range, 95 PSI and 85

Are you sure it's actually a plug?
Are you getting oil on the plug?
The plug may be firing but you may be losing compression which gives the symptoms of a misfire. As you've changed the plug, lead and coil this points to to a problem elsewhere.

Your first course of action should be to get a mobile mechanic carry out a diagnostic check for you.

To put your mind at rest, do a 2nd compression test using a light oil squirted into the bores:

Doing a Compression Test
Warm the engine. Remove all the spark plugs.
Get a pencil and piece of paper to note down the readings.
Put the compression tester into the No1 cylinder and crank the engine for 10 seconds.
Note down the compression reading.
Repeat process for all cylinders.

Here's an illustration of what you may expect on a 4 cylinder engine:
Cylinder 1 2 3 4
psi 125 122 120 124

125 is the uppermost figure for that engine. Here, this engine is fine. There's a slight variation in psi figures, but that's perfectly normal.

Here's the same engine:
Cylinder 1 2 3 4
psi 110 112 114 112

The psi reading is down. However, as all the figures are pretty much equal it doesn't indicate head /gasket problems. It may point towards worn pistons or burnt valves.

Now consider these psi readings:
Cylinder 1 2 3 4
psi 125 84 86 124

There's more than a 10% drop - a difference - between cylinder 1 and 2, and cylinders 3 and 4.
The compression readings for cylinders 2 and 3 is down; low. There's something clearly wrong.

It suggests that there is a defective head gasket between cylinders 2 and 3 or a crack in the cylinder head. The rising piston compresses the gases which escape into the adjoining cylinder via the defective gasket or cracked head.

However, it could also mean that there is a problem with the valves (burnt/not seating properly) or perhaps piston / ring problems.

A burnt valve - it's usually the exhaust valve as they bear the brunt of the combustion - can cause a reduction in engine power simply because the combustion process isn't occurring properly. Compressed air/fuel gets squeezed out of that cylinder because of the damaged valve . There even may be a misfire - a surge as the car runs.

Worn or broken piston rings allow compressed gases to leak past into the crankcase. A compressed crankcase can force oil out of the dipstick tube. The pressure in the crankcase will leak to atmosphere anywhere it can find an outlet.

The 2nd Compression Test
The second compression test is known as a 'wet test'. The first compression test was the dry test because no oil was added to the bores. The second 'wet' test can give an indication of whether it is the rings or valves at fault (though bear in mind rings and valves do not cause overheating or water in the coolant symptoms).

Spray a liberal amount of light penetrating oil into each cylinder - aim for the cylinder walls, not the centre of the piston. You want the oil to run down the cylinder wall and around the piston to form a seal.

Place a rag over each spark plug hole and spin the engine to eject the surplus oil.

Then carry out a full compression test noting down the results.

Here's the previous results with the 2nd compression readings added:
Cylinder 1 2 3 4
psi 125 84 86 124
Wet 128 112 110 126

The readings have increased. This because the oil sprayed into the bores has formed a temporary seal around the piston, thereby enabling the compression to be raised. It also indicates that the bores/rings are worn on cylinder 2 and 3 - the 'oil seal' has increased the readings but is still low in comparison with cylinders 1 and 2.

This could also indicate that in addition to worn rings there is also burnt valves. Oil cannot form a seal around a valve. A worn or split valve will cause a low compression reading and misfiring symptoms.
Compressions readings should be taken in conjunction with other symptoms. It will help you identify the problem:

Low compression readings between two adjoining cylinders point towards a head gasket/head fault if your vehicle has shown signs of coolant loss, coolant in the oil system - mayonnaise, overheating, rough running and lack of power.

If those symptoms are not present it points towards burnt valves/piston rings. A worn engine may be difficult to start and pressurise the crankcase, but it doesn't cause overheating problems.

you have a bad head gasket or a crack in the block or a bad valve seal

Well, there are a few causes for low compression....bent valve, broken rings, worn cylinder, broken/ chipped valve, blown head gasket, cracked head, cracked block/ cylinder, broken/ cracked piston......as you can tell, none of which are good and always means going into the engine to repair. A lot of times it is quicker, cheaper, and easier to exchange the engine for either a remanufactured or good salvage yard engine.

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........

IF YOU REPLACED THE HEADS WITH REBUILT/NEW HEADS:
A side effect of increasing compression when you bolt on fresh heads, is broken piston rings. It's beneficial to replace the rings & bearings and at least remove the ring ridge at the top of the cylinder wall if not re-bore when replacing heads due to the higher compression that will cause.


If you just put on a set of used heads.

There's also the chance that the new headgaskets didn't seal completely, (usually due to a problem with surface prep or a warped head/block), but if you've got high mileage, it's usually the rings.

A set of rings can be replaced, but you'll want to make sure they haven't cut into the bore so much as to cause blow-by once new rings are installed. Eliminating the ridge by carefully using a ridge reamer at the top of the cylinder to prevent breakage of the top ring from impact.
Hone the cylinder walls gently & reinstall pistons & new rings!
Good luck.

did you take a compression check on these cylinders compare to 1 & 4, possible causes for such a symptom are as listed:damaged head gasket between 2 & 3, a cracked cylinder head between 2 & 3, faulty injectors, bad plug wires or coils(direct ignition), a warp cylinder head, intake or exhaust valve are losing compression,damage or sleeping piston rings.

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.

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 :)

Lost of compression is due to either leaking head gasket, valves not closing and seal properly or piston rings are worn and need replacing. One can tell if you have bad head gasket, oils contaminated by water when looking at dip stick, bad valves cause some smoke and run rough, worn piston rings will cause lots of blow-by and will cause white smoke heavily and also runs rough. Being 1968 original motor and never have been rebuilt will probably have over 100k mile will be needing tear down and rebuilt. Rebuilt it correctly will get another 100k plus. being 1968, doing your head and valves job or replacing head gasket if that is the problems and you can get by it. worn rings, I would rebuilt it completely instead repairing one or two cylinder unless you plan to get rid of it.