Oil transfering into the coolant on a chevy optra. lugs look good, compression is equal on all cylinders.

Only 2 and 3 injectors are firing on my Chevrolet optra,I checked and see that there is no injectors pulse on number 1 and 4 injector,can anyone help please

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.

The only way for oil to get into the coolant is for some type of leak to happen. As stated above, could be bad block, may be bad head gaskets, but the only way to really find out will be to remove the heads and look for signs of leaks. Regardless of the compression test results, you need to find out how the coolant is getting polluted with oil and resolve it.

Perform a compression test on all cylinders. Unfortunately one of the only things that will cause oil and coolant to mix is a blown or failing head gasket. Good luck.

sounds like possibly head gaskets, when you overheated probably warped heads causing coolant in oil and coolant in cylinders therefore partially hydrolocking...antifreeze does not compress like fuel vapors .check oil and see if looks like creme to light chocholate color. this means coolant in oil, this is very ******* bearings, eats them up and if thats the problem you loose oil pressure cause bearings are sloppy from being worn. Bottom Line.you might be looking for another enj.or rebuild

Hi and welcome to FixYa!

It's definitely a damaged head gasket. If the head gasket is damaged you'll have an oil and water mixture that's milky in appearance. You will need to have it replaced and be sure that you check if the head itself has cracks. If it has, a machine shop will be helpful.

Hope this helps and thank you for using FixYa! Have a good one!

ANTI FREEZE GOING INTO CRANKCASE GETTING IN THE OIL.YOU HAVE BLOWED HEAD GASKET.

Are you blowing white smoke that looks like steam that is a sign of a blower head gasket . Chevy has a problem with over heating the engines don't take it well . Check for oil in your antifreeze if you take the radiator cap off you will see it floating on top alos check your engine oil for a white fromey build up on the dipstick they bolth mean oil and antifreeze are mixing inside the engine. The most likely thing that happened is the intake manifold gasket is leaking coolant goes through it and is sealed between it and the heads but it flows between them. If you don't have the white smoke its likely what is leaking its just not getting into the cylinders yet its a cheaper job to repair then head gaskets but hard to tell with out a compresstion test then would show low compresstion on 1 or 2 cylinders still if you want to keep it you need to fix every thing wrong wish you luck and don't ever let a chevy over heat

Oil in the coolant,or coolant in the oil.Excessive smoke/steam from the exhaust that smells sweet,or coolant going low and no sign of leeks.Start your motor cold and make sure the radiator is full and cap off.Watch for excessive bubbles,but stand back due to the posibility of eruptions spewing coolant.These are all signs of a blown head gasket.You can also do a compression check on the cylinders and if two adjasant cylinders show low compression.Well hope this helps and good luck.

The ONLY way coolant can get into the crankcase is through a crack in the cylinder head, block, or head gasket. THE ONLY WAY!.

Checking compression was a good idea, and you've confirmed that is not where the leak is. It could be somewhere else within a head, the block, or head gasket.

Any gasoline engine will blow steam from the exhaust pipe on start-up and a few minutes running. May even stink, depending on how sensitive your nose is to smell.

I think your going to have to dig deeper into this, if you truly had coolant in the oil. But to tell you exactly where to look is not going to be easy.