Cylinder Head Pressure Test DIY

[Jonny]

Background....

Rough running for about 10 seconds upon start-up.
Coolant dripping out of exhaust system overnight.
Obviously coolant getting into cylinder(s) somehow.

Engine out, head off, coolant sitting in cylinder #2. Everything else about the engine looked great to me.

Head gasket and head gasket seal surfaces looked great.
After borrowing a 20x magnifying loupe I saw what might have been a tiny crack between the rearward pair of intake/exhaust valves.

Since I'm a first timer deep into an engine I took the head to a shop (with experts, right?) and asked them to confirm coolant system leak (or not) with pressure test, so that I knew with certainty which component to blame.
They called a few days later and said job was done, but when I went to pick it up all they had done was inspect for cracks, not confirm with pressure test.
They found one crack on cylinder 2, and three cracks on cylinder 3. Cylinder 3 was not leaking, even though there were visible cracks, so simply finding cracks obviously did not confirm leaks. The problem might still be with the head gasket or the engine block.
Instead of taking a deep breath and saying "you didn't do what I asked you to do. Would you please pressure test the head to confirm any leaks" I stomped out of there with the thought "if you want something done right why do you always have to do it yourself?"

So here we are with the DIY pressure test thread. TBC...

[Jonny]

The principle of pressure testing the head coolant system didn't seem very complicated. Seal off the coolant holes, pressurize system, immerse in water and check for bubbles. I can do that. Maybe I can rig it up with easily fabricated stuff, like pieces of wood I have lying around.

Here's my set up...

3/8 x 4-1/2 bolts with nylon washer on one end (inside the head) and fender washer on the other (against the wood).

13406

valve and plate for pressurizing

13407

4 pieces of 1x lumber to seal all the water ports

13408

This first attempt ended in spectacular failure because I had not identified all the water holes. I thought that the three small holes between the cylinders were oil holes. Nope. Pic of water hole not covered by first attempt (hard to see - in shadow next to the wood).

13409

So here are pics of all the water holes which need to be sealed (arrowed)...

Cylinder 1.... two top, two right, two bottom.

13410

Cylinder 2, 3... four top, four bottom, three small holes between the cylinders.

13411

Cylinder 4... two top, two left, two bottom.

13412

Total number of ports on gasket surface = 23.

Second time around, instead of using silicone and waiting for it to dry, I used some butyl rubber strip I happened to have. It flows under pressure, so isn't ideal because your sealing quality is limited, but it did work. Some strips of resilient rubber would be much better. All holes covered this time

13413

I could hear a leak somewhere from one of my (not sealing) seals, but was able to get enough pressure (didn't take much.... less than 5 psi on my bike pump gauge) to verify a leak at the crack between the intake/exhaust valve in cylinder 2. I dabbed soapy water on the suspected area rather than submerging the whole thing (easier for my purpose). That is a soapy bubble blowing up at the crack.

13414

Cracks on cylinder 3 did not leak (but no doubt would continue to get bigger and cause problems down the road)

13415

This is the butyl after removing the wood blocks. Worked, but rubber which does not creep like this stuff did would be much preferable.

13416

Remanufactured head ordered from Cylinder Heads International today. Yay. Progress.

[Previologist]

Instead of taking a deep breath and saying "you didn't do what I asked you to do. Would you please pressure test the head to confirm any leaks" I stomped out of there with the thought "if you want something done right why do you always have to do it yourself?"


You didn't take the head to Les Schwab did you? :roflmao: Sounds like my experience with all the front end opinions I got, and I arrived at the same conclusion: you gotta do it yourself. However your ingenious redneck pressure test is something I hope I never have to do myself. But it worked! I don't think I would have used that head even if it didn't leak...