Leak test with water

[x Spades x]

Hey Everyone,

So I have the head off and im doing a leak test with water over the valves. If there is no leak, does this equal 0% leak? Assuming not, what is the minimum percent before water starts to leak through?

[sapote]

Use gasoline and not water. If no leak after 5 minutes then it's good.

[x Spades x]

Gotcha, ill do that now.
Is there a general rule on the %, if no leak?
For example... if there us no leak with gasoline this mean its >5%, >3%, etc?

[sapote]

If no leak I say perfect.

[sapote]

How did you remove the bent valves?

[digger]

Best way to check leak is vacuum check port with no valve springs

[x Spades x]

How did you remove the bent valves?

Machine shop. Didn't want to risk death. 😆

Now the last question is... how do I clean the piston heads? Brake clean in not doing the job AT ALL. :-(
I've read half Acetone and tranny fluid... but just want some input

[sapote]

Best way to check leak is vacuum check port with no valve springs

How? And why no spring install is a requirement?
I had installed 3 ductless heat pump for my house, and evacuated the pipes using vacuum pump down to very low level, and it was not easy to tell if the system had slow leak or not, especially for a small volume like the combustion chamber of the engine.

[bigjae46]

Machine shop. Didn't want to risk death. 😆

Now the last question is... how do I clean the piston heads? Brake clean in not doing the job AT ALL. :-(
I've read half Acetone and tranny fluid... but just want some input

I'm assuming the pistons are still in the block? Plastic scraper since it won't mar the surface. Try to minimize the schmeg that gets between the piston and cylinder wall. Or blow it out really well.

[x Spades x]

I'm assuming the pistons are still in the block? Plastic scraper since it won't mar the surface. Try to minimize the schmeg that gets between the piston and cylinder wall. Or blow it out really well.

Yeah, Pistons are still in the block.

Saw this video and didn't know if this is bad for our engine.

https://youtu.be/0vSNoB7M4iw

[sapote]

Yeah, Pistons are still in the block.

Saw this video and didn't know if this is bad for our engine.

https://youtu.be/0vSNoB7M4iw

But you need to turn the car 90* on its side. Even with 90* turn, I bet the dissolved mud got to the top ring and lodged in the ring lands.
When I did this on my 323iT engine, turned the piston to TDC, then seal the gap between piston and cyclinder using grease, then just scrapping the carbon with non-metal tool, then vac the debris off, then turn the piston down and clean off the grease that trapped the debris.

[digger]

How? And why no spring install is a requirement?
I had installed 3 ductless heat pump for my house, and evacuated the pipes using vacuum pump down to very low level, and it was not easy to tell if the system had slow leak or not, especially for a small volume like the combustion chamber of the engine.

i have a hand operated vacuum pump from Goodson you add the stem seal sit the valve on its seat with head inverted and apply the oiled suction pad over the port entry. There is a criteria for how much vacuum should be achieved and rate of leak when pumping stops

A very small electric vac pump also works (Jafromobile has a video its one of his only decent videos)

the spring masks issues with the VJ. Later i will link a video about the proper way to ensure the valves and seats are sealing , not bent, and associated info.

[digger]

How much deposit are on pistons? Got any pics? It’s pointless getting them 100% clean though

[sapote]

i have a hand operated vacuum pump from Goodson you add the stem seal sit the valve on its seat with head inverted and apply the oiled suction pad over the port entry. There is a criteria for how much vacuum should be achieved and rate of leak when pumping stops

So apply the suction pad on intake port for checking intake vavle, and exhaust port for exhaust valve?
But how to tell if the valve leaking or the valve guide leaking? And which of the 2 intake valves is leaking as there are 2 in each port?
I don't see this is better than fill the combustion with gasoline to test 4 valves at once.
Maybe the vac test is more convenience for checking with the head still bolted on the engine. With head removed, I choose the gasoline check method.

[digger]

So apply the suction pad on intake port for checking intake vavle, and exhaust port for exhaust valve?
But how to tell if the valve leaking or the valve guide leaking? And which of the 2 intake valves is leaking as there are 2 in each port?
I don't see this is better than fill the combustion with gasoline to test 4 valves at once.
Maybe the vac test is more convenience for checking with the head still bolted on the engine. With head removed, I choose the gasoline check method.

yes, intake and exhaust seperately. you apply stem seal to seal the guide. if there is leakage use a bright light in port inside a dark room or apply grease to one of the seats and retest.

the problem with liquid is not so much the liquid but the valve spring will force a slightly bent valve or seat/valve with poor runout to seal, giving you a false indication of the quality of the valve seat . This can manifest as premature wear of seat and or guide and also valve failure in extreme cases as the cyclic bending of the valve causes fatigue and this is probably the most common cause for valve head to break off the piston was tagged and slightly bent.

not sure if the OP has new valves or is worried they are bent. if so there is only one way to see if a valve is bent and that is to measure the runout. leakage can not 100% tell you a valve is bent as a slightly bent valve can still seal especially if springs are installed and the valve is flexible enough to conform under the force of the spring.