3rz water loss issues

[T4Life]

Hey everyone, I recently bought a 96 4cyl standard 4runner with a coolant/water loss issue. The guy I bought it from said he was still using the truck to commute to work but was dumping a jug of water in the rad every two days.

Yesterday I did a compression test and found there was at least 150 psi across all cylinders. I did a cooling system pressure test and found that the system was holding pressure. The motor oil is old and has no signs of water in it.

When you start the truck, it runs rough for 10-15 seconds (like it's only running on 2-3 cylinders) but then it clears out and starts running smooth.
With these results, I'm stumped as to what it could be. I think that water is getting into the motor and sitting on top of the piston and that's why it starts rough.

Any help would or advice would be greatly appreciated as I am very new to this motor.

Thank you

 

[kball]

Any white smoke on startup?

 

[Srabai]

Did you run a block test yet and do you have any CEL lights on? Try parking it over some cardboard over night to make sure it's not just a regular radiator leak.

 

[T4Life]

Any white smoke on startup?

Yes! The water is definitely getting burned off in the cylinders

Did you run a block test yet and do you have any CEL lights on? Try parking it over some cardboard over night to make sure it's not just a regular radiator leak.

What is a block test? There are no codes, and no visible external leaks.

I'm positive that somehow the water is leaking into the cylinders, but with good compression and cooling system pressure I'm stumped.

It also sounds like there is an exhaust manifold leak. I will investigate tomorrow for a cracked manifold.

 

[kball]

Sounds like you have a head gasket or cracked head issue. When you did the coolant pressure test was the engine warm or cooled down? If it was warm things could have expanded and sealed up. Try it when the engine is cold.

 

[T4Life]

Sounds like you have a head gasket or cracked head issue. When you did the coolant pressure test was the engine warm or cooled down? If it was warm things could have expanded and sealed up. Try it when the engine is cold.

I ran the engine for a minute but it wasnt near fully heated. I did notice one wet plug and spray coming from one of the cylinders during the compression test (the source of my leaking water it appears).

I just don't understand how water could be getting in if I have 150 psi across all cylinders.. I will tear the motor apart tomorrow, hopefully it's not a cracked head.

 

[kball]

Compression tests are more for worn rings or burned valves. A cracked head or head gasket issue may or may not affect the readings of a compression test. If you've got coolant coming out of a cylinder you've answered your own questions.