My toyota duet engine overheated then I had the cylinder head pressure tested and skimmed but after assembling but water is getting into the cylinders though I put a new gasket and torqued down. What's the problem

Was the oil drained after the overheating occurred? You may have contamination from just before overheating. Did you find the root cause for it? Low coolant / no coolant, stuck thermostat, failed water pump, etc.

Or

The cylinder head job was done badly, did they use a new gasket, did they torque the nuts correctly?

Or

The cylinder head is fine, but the block is cracked.

You could try Holts Wondarweld

https://www.google.com/search?q=holts+wondarweld

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You didn't say what your compression readings were. If you do another 2 compression tests and note down the figures..

The first test is a dry test as per normal. Prior to the second test - the 'wet test', spray some some penetrating oil into the cylinder, spin it on the starter to get rid of the excess oil.

The second, wet test, allows oil to get in between the piston and cylinder wall.

If, on the wet test, your compression readings go up significantly this points towards ring/piston damage or excess wear .. a worn engine. This will give you a good indication as to whether it is easier just to fit a second hand engine instead of doing the cylinder head.

If, after doing the wet test your compression readings don't increase by more than 10% compared to the dry test, this suggests that the pistons/cylinders are okay.

Remember that an alloy cylinder head must be skimmed before refitting. Cylinder heads warp because of heat and become 'banana shaped' - raised in the centre. Failure to have the head skimmed is likely to cause head gasket failure very quickly.

If you're going to repair the cylinder head you should change the thermostat as a matter of course. It's good practise, that's all.

Well did you replaced the thermostat?

Pretty much same answer as I gave for 87 Reliant see below. Shops have equipment to do cylinder leakage test. Do basic stuff below before doing last test ...cylinder leakage...which costs $$$.

Main point you are losing antifreeze/water. Check to see if you have water on the dipstick mixed in with oil. If so...probably a head gasket. If oil looks normal..... Before you do any test, tighten every hose connection. Check for loose connection into antifreeze reservoir. Sometimes there are small cracks on top which lets out pressure from cooling system. Look for leaks on water pump and radiator. Look at spot where you park the car...any liquid on floor? Not sure?..Put piece of cardboard under car to see if liquid is dripping from car. No leaks?...Start with a pressure test of the system. The pressure test is simply equipment that replace the radiator cap, a hand pump connected to it then air is pumped into cooling system. You watch the gauge to see if pressure is dropping. If pressure does not drop ..problem is most like a worn radiator pressure cap or stuck thermostat.. Do not buy the kind with button on cap to push down and release pressure. get original type and correct pressure. If overheating still, thermostat could be stuck, replace. Overheating of engine causes vapor lock, bubbles in fuel, which causes car to stall and kill. When cools off, fuel cools down and fuel will flow through fuel system again. Large amount of oil disappearing with overheating also sounds like head gasket or cracked head....Tighten up all bolts to gaskets, look for oil leaks on garage floor or driveway. If engine has developed a miss when running, pull plugs out and look for wet fouled plug. If antifreeze leaking into cylinder...plug tip will be whitish, if oil leaking into cylinder, grimey oil fouled. Do compression test on cylinder that is fouled and that will pinpoint if bad head gasket or cracked head. When doing compression test, radiator cap is removed and you listen to hear bubbles in radiator from the cylinder leaking into cooling system. 87 Reliant not worth pulling engine apart if head gasket or cracked head. Best oil treatment to reduce oil consumption is "Engine Restore" Used on my 58 Impala 348 tri power for 28 years. If I did not add it after oil changes it used oil and smoked....I swear by it for ANY engine after 100,000 miles.

Check what head gasket was used . I suspect that an after market gasket was used. If that is the case there will be holes in the block and head thet have no matching holes in the gasket thereby causing the problem

I agree with Mike, but suspect you already have a measuring device to know the pressure is excessive. You should get the cap checked first.

But additional pressure that keeps coming out of the radiator above the release limit of 14-18 lbs is probably due to escaped compression from the engine cylinders. You will see bubbles inside the radiator while the engine runs.

Sometimes you will get water in the cylinder after the engine sets under pressure, but not always. Your engine works at about 140psi in the cylinder more or less. The radiator at 14-18 psi. A leak in a head gasket may take more than 14-18 psi to leak. So the leak acts like a one-way valve shoving air into the cooling system. Since the cooling system loses pressure as it cools, the water may not flow back into the cylinders when the engine is not running.

This is sometimes indicated in a cylinder bleeddown test where high pressure is shoved into the cylinder. Bubbles may be observed in the radiator from escaping air. Otherwise a compression drop in a cylinder may as easily be due to bad rings.

I hope my solution is helpful.

It is most likely pressure from the cylinder that is leaking into your expansion tank, and with all the misdiagnosis, you have probably overheated the engine and severely damaged the gasket. I am afraid that you expenses are not at an end yet. You are looking at at least a cylinder head gasket replacement and a head skim. Plus a lot of flushing and cleaning out of the engine. I wish fir your sake the news could have been better.

have you replaced the thermostat? This controls the engine temp

Your thermostat may be staying closed, if the top coolant hose becomes hot after the engine running for a while, then thermostat is opening ok. Next check to see if the bottom hose going to the rad is getting warm. If its staying cold then you may have a problem with the water pump not circulating the water around the cooling system. If thats ok check the rad cap is sealing ok. when the engine gets up to normal engine temperture remove the reservoir top filling cap which has a rubber pipe going to the thermostat housing. with the engine running there should be no water coming down the pipe and exiting the filler cap. If there is it could be the rad cap not holding pressure which it would need to be replaced or the head gasket is leaking and pressurising the coolant system.. hope this helps you..

Aerosmith, this sounds like a "blown" head gasket scenario. Does the vehicle idle roughly and if so it could be a compression factor where a blown head gasket is present. Have a look at the oil dipstick - is the oil level correct? - there could be signs of water leaking into the oil system, thus meaning the head gasket is at fault. Overheating - chances are there is damage to the cylinder head - addressed to an engineering shop for skimming & pressure testing.

Good luck