Water keeps shooting out of tiny hole on top of smart head only when the pump is on. what is causing it and how can it be fixed?

not the oil pump
most likely a leaking injector causing a hydraulic lock where the fuel sitting on top of the piston is not allowing it to go over tdc
pull all the injectors
turn it over and push the fluid out the injector holes
have the injectors professionally serviced
bad news if you get water out of the injector hole as that indicates a head gasket or cracked head allowing water into the cylinder

I'm sorry but I believe you have this posted in the wrong product category. Please re-post the question in the proper category This is the car and truck problem category

OVERHEATING CAN BE CAUSE BY MANY THINGS LIKE FAULTY THERMOSTAT AND FAULTY RADIATOR PRESSURE CAP,TOO MUCH WATER IN COOLANT SYSTEM NEED 50 / 50 WATER AND ANTIFREEZE.LOOK FOR WATER PUMP WEEP HOLE LEAK, IF COOLANT LEAKING OUT WEEP HOLE WATER PUMP BAD NEED REPLACING.CHECK FOR LOW COOLANT LEVEL, YOUR RADIATOR OVERFLOW JUG SHOULD HAVE COOLANT AT THE FULL COLD MARK IF NOT KEEP ADDING COOLANT INTO COOLANT OVERFLOW JUG UNTIL COOLANT STOP DROPPING AND FULL COLD MARK, IF OVERFLOW COOLANT JUG WAS EMPTY RADIATOR IS LOW ON COOLANT.WHICH CAUSE AIR IN COOLANT SYSTEM KEEPING THE ENGINE COOLANT TEMPERATURE SENSOR FROM BEING SUBMERGE IN HOT COOLANT WHICH TURN ON THE COOLANT FANS.WHEN ENGINE COOLANT TEMPERATURE GET CERTAIN SET TEMPERATURE LIKE 190 DEGREES THE PCM AND COOLANT SENSOR WILL TURN ON COOLANT FANS, IF VECHICLE OVERHEATING COOLANT FANS NOT WORKING EITHER YOU HAVE FAULTY ENGINE COOLANT TEMPERATURE SENSOR CHECK COOLANT FANS FUSE AND RELAYS. YOU CAN CODE SCAN CAR TO SEE IF YOU HAVE FAULTY PCM, FAULTY ENGINE COOLANT TEMPERATURE SENSOR OR FAULTY COOLANT FAN RELAY.IF COOLANT FAN AND ENGINE COOLANT TEMPERATURE SENSOR OKAY,YOU HAVE CORRECT COOLANT LEVEL IN COOLANT SYSTEM, THERMOSTAT AND RADIATOR PRESSURE CAP BEEN REPLACED, YOU COULD HAVE BLOWN HEAD GASKET CHECK ENGINE OIL LOOKS LIKE MILK SHAKE HEAD GASKET BLOWED ALSO WHEN HEAD GASKET BLOWED YOU CAN DRIVE CAR SHORT DISTANCE START OVERHEATING AND YOU LOOSE ENGINE POWER SUSPECT BLOWED HEAD GASKET.

I would strongly suspect that you have a blown head gasket and or a warped cylinder head, or both. It sounds like compression from the combustion chambers is leaking through the breached head gasket, causing back pressure in the lubrication system. There is a tiny tiny possibility that there is a hole in a piston doing this, but I would think that pretty rare.

This is quite uncommon, but by no means unheard of. Other symptoms you may be experiencing which might strengthen the hypothesis are:

Oil seepage into your radiator (Take off the rad cap, is there oil floating on top of the water). Though this will ony happen if the oilway AND waterways have breached at the point of the defective gasket
Similarly, Water in the oil (Take off the oil filler cap and examine for grey/white emulsified sludge
Difficulty starting due to low compression (This will be particularly noticeable when the engine is warm
Lack of engine power and pull due to low compression
Misfires and or oily plugs
Blue smoke when you start the engine in the morning.

Any or none of these symptoms might be present. An absence doesn't necessarily mean no problem, though a symptom being there will pretty much confirm it.

This looks like it's going to lead to the cylinder head needing to be taken off very soon

Sounds to me like the shaft seal has failed on your water pump and you need to replace the pump, theres usually a tiny hole either at the bottom of the water pump or at the top of the pump its called the weep hole, when coolant comes out of this hole it means the internal shaft seals of the pump have failed and it requires replacement of the pump, now if the coolant is coming out of where the pump bolts onto the engine block you propbably only need the waterpump to block gasket to fix the leak, check and see exactly where the coolant is coming out from so you can be sure exactly what you need to replace....

It sounds like you have either a leaking water pump or hose near the water pump. Sometimes you can take a small mirror and a light and follow the trail of coolant back up to the source [worth a try anyway] Most water pumps will leak from a small weep hole that is located behind the pulley and it can be hard to see this. Be careful not to overheat the engine as that can cause cylinder head damage, or worse, if it gets hot enough and can make a small problem much bigger and more expensive. Hope this helps!

I'm sorry to hear that!
When you get it fixed get your injectors serviced as holes in pistons are usually caused by pre-ignition ( pinking ) or running too lean.
If the injectors were left wet ( can happen if a blown head gasket was the cause of the first rebuild ie water in the bore ) , or dirty , they may not be delivering enough fuel causing the top of the piston to get too hot and melting a hole in it.
Option 2 , the timing was set wrong, ( too far advanced ) causing pre-ignition and ending in the same way.
Good luck with the rebuild.

SOUND LIKE BLOWED HEAD GASKET.BUT WAIT TO SEE IF ENGINE WILL CRANK WHEN ENGINE COOL DOWN.MOST CARS PCM WILL SHUT CAR DOWN TO KEEP FROM DAMAGING THE ENGINE.CHECK FOR LOW COOLANT.YOUR OVERHEATING PROBLEM COULD BE CAUSED BY BAD THERMOSTAT OR WATER PUMP.CHECK PUMP WEEP HOLE TO SEE IF LEAKING.IF YES REPLACE WATER PUMP.

Yes, I am sorry to say this could be a blown head gasket. It could also be a bad water pump. Lets hope that it is the pump. You can get a pump replace for under $200.00 as opposed to the head gasket which runs over a thousand. It really sounds like water pump problem because you are not getting heated water to you heater core, where This would also cause the non mixing of fluids. Take the radiator cap off and see if you get bubbles rising to the to cover. Also if you rev the engine up and water comes shooting out the radiator cover hole the you definetely have a head gasket problem. Be very careful not to burn yourself. I bet anything it is just a pump. Gaskets ususally only go bad if you drive the car while overheating. Lets get this solved for you. Send me your qustions and we will get you taken care of. Please leave me good feedback, it means a lot to me....

This is the water pump weep hole, so yes you need a water pump.