How much compression should a Cushman truckster with a omc engine have

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

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.

I would do a compression test of the engine. Spend about $40 for the gauge tester and do it yourself. Engine should be at operating temperature, remove all spark plugs, disable ignition by grounding the high tension cable from coil to distributor, screw in the gauge to one cylinder, hold the gas pedal to the floor-or hold the throttle at wide open, then crank engine for about 5 seconds. You will have a compression reading that should be somewhere between 100 psi and 200 psi. Anything below 100psi means not enough compression in the cylinder to produce power when running. Do each cylinder the same-crank the same amount of time for each cylinder( with wide open throttle). All compression readings should be fairly close-lowest reading must be within 75% of highest reading cylinder for a good, healthy engine.

If compression is low in any cylinder, it probably won't even fire the air/fuel mixture. Look for valve problems, valves not sealing (burnt valves cause this), or piston rings worn too bad, head gasket failure can cause low compression. Example, compression tested a Nissan, and readings were all 155-160 psi in all cylinders, so compression was excellent, engine was internally good. If you have good compression in each cylinder, look elsewhere like a plugged catalytic converter-won't let the engine breathe, or a problem with the ignition system-test for a snapping, blue spark when cranking the engine, on one of the spark plug wires. Others: check EGR valve for being stuck open, good luck, then.

It could be a problem in the valve train. For a car that old, before putting new parts in, you could buy a compression tester for about $30, and do your own compression test. It should tell you if the engine is good enough internally to warrant proceeding. If compression is low on any cylinders, that problem must be addressed first. If a valve is not sealing and causing the popping, that cylinder will show low compression.
For the test, the engine should be at normal operating temperature. Then pull all the plugs out, connect tester to #1 spark plug hole. Have a helper hold the throttle wide open while cranking the engine over about 5 seconds. Watch the gauge-the first revolution or two will cause the gauge to jump high at first, and successive revolutions during the 5 second span will cause the needle on gauge to climb a little each time. Record or note the compression on #1, then do each cylinder. Try to do the same amount of cranking on each cylinder, and keep the throttle wide open. What you want are compression readings on each cylinder that is well above 100 psi, and all should be close. The lowest reading should be within 75-85% of the highest reading cylinder. Example: say your highest reading is 135 psi. 85% of 135 is 115-so your lowest reading should be at least 115 psi. Some general guidelines: any cylinder with compression below 100 psi is definitely a problem-that cylinder will not have hardly any power output, even if it is firing. Worn piston rings or poor valve sealing is causing compression loss. A newer engine should have compression readings above 150 psi. As the engine wears, compression will drop. In general, for high mileage engines, you would want to see compression in the range of 125-150 psi, the higher the better, but remember, it should be balanced-the lowest should be at least 75% of the highest reading cylinder.
Post back if you have questions-good luck.

How could you be lost

You explained it perfectly

The shop did all the correct diagnoses,
seldom see that at all,they did great job
of finding the issue

If cylinder compression is too low, the car may not even start because of it. Have a shop do a compression test or a leak-down test to check the internal health of your engine. A good engine should have pressures of 150-200 psi in all cylinders and be close to each other. A worn or high mileage engine may have pressure as low as, say 125 psi, but if still balanced (close readings), would still run decent. Compression below that, especially below 100 psi, is serious trouble. ignition spark refuses to ignite the air/fuel mixture and you get a misfire-a non-working cylinder. Low compression can be caused by worn piiston rings or poor valve sealing. Low compression in 1 or 2 cylinders can be a valve problem, burned valves or valves not seating properly.
A leak-down test will check each cylinder and if there is a problem, the test will find the cause of the problem.

remove No. 4 plug add teaspoon of engine oil, compression test if compression rises 120 psi plus, points to broken piston rings, below 90 psi burnt or stuck exhaust valve.

Replacing a cylinder head gasket is a miss or a hit. In some cases, just replacing the gasket may work. But if the cylinder head is bend, dealer may ask to replace it, because "machined aluminum heads rarely works". In this case the cost may be more than $1000. It is a good idea to send the cylinder head for inspection, in a machine shop. They charge $150 for inspecting, checking, cleaning and if necessary machining the head.
If the timing belt will be replaced this is an extra cost. If someone will just replace the gasket, on a bend cylinder head, it is more likely to blow out again. This problem can be solved if the gasket be replaced properly, checking and taking care for the cylinder head too.
As the coolant warms up, it expands and for that reason you have two marks at coolant bottle. Down cold and up hot. It is normal for the coolant to overflow from coolant bottle, if it is filled to the upper mark with engine cold, way up the cold coolant mark. Let engine to cool down overnight and set the level at coolant bottle at the lover mark cold. If it will overflow again this is a bad sign. The pressure at combustion chamber varies from 75 in idle up to 150 or more in higher RPM. If the cylinder head gasket is blown, then gases are blown into the cooling system, increasing the pressure, the radiator cap pressure relief valve is open and coolant is discharged in the coolant bottle. In such cases it is common for the coolant bottle to boil. You can observe gases discharging in the bottle, mixed with coolant, from the cooling system. These are symptoms of a blown cylinder head gasket. Because you replaced it once, there might be a bad (bend, deformed) CYLINDER HEAD too.
To find it out you have to perform cylinder compression test on your car (PROFESSIONALLY).
1. Start with a normal ("static") compression test. To eliminate rings, valves, holes in pistons, that sort of things. A normal cylinder balance test is also helpful (so you know which, if any, cylinder is presenting a problem). Engine should be warm.
2. Put all spark plugs but one back in. Ground that plug wire to prevent module damage. Disconnect that injector on a port fuel system.
3. Put your compression tester into the empty hole. The test can be done without a Shrader valve, but most people recommended leaving the valve in the gauge and "burping" the gauge every 5-6 "puffs".
4. Start the engine and take a reading. Write it down
5. Now goose the throttle for a "snap acceleration" reading. Reading should rise. Write it down NOTE: Don't use the gas pedal for this snap acceleration. The idea is to manually open then close throttle as fast as possible while without speeding up the engine. This forces the engine to take a "gulp" of air.
6. Now write down your readings for at least the bad cylinder (if there is a single bad cylinder) and maybe 2-3 good ones. Make a chart like this: CYL STATIC COMPR IDLE -RUNNING COMPR - SNAP Cyl 1 150 75 125 Cyl 2 175 80 130 Cyl 3 160 75 120 Cyl 4 160 80 125
7. ANALYSIS: Running compression at idle should be 50-75 psi (about half cranking compression). Snap throttle compression should be about 80% of cranking compression.
Consult a professional with the readings. If the gasket is to bad, you may have very low compression at lease in one cylinder.
If you will get a positive confirmation for a bad cylinder head then you have two options:
REBUILD THE CYLINDER HEAD or REPLACE IT.

Minimum compression is 100 psi @ 200 rpm. The lowest cylinder reading should not be less than 80% of the highest reading. Perform the compression test with engine at normal operating temperature, spark plugs removed and throttle wide open. Normally I look for about 170 psi to 180 psi.