Exhaust concern after major rebuild

[jkenan]

I have just completed a major rebuild, and in testing the engine with no exhaust pipe attached, (besides being very loud) I noticed a very small amount of wetness spattering out of the exhaust port in the manifold with the exhaust. It did not really amount to any significant quantity, and was just enough to show up as a very light splatter on a boart held up just behind the exhaust port for a few minutes.

I later attached a 'shop' water muffler built of galvanized pipe from the exhaust port and into a trash can filled with water, which quited things down very nicely so I could hear how the engine sounded running (I built a wooden lid for the can with one hole just big enough for the pipe to pass thru and into the water, and another hole to which a 1.5" hose is attached, leading exhaust fumes well away from the shop). Timing sounded good, and generally the engine sounded like it was running well. RPMs were easily attained, and it would run smoothly at Idle as well as high throttle.

After running this way for a while, I let the engine cool and inspected the pipe. Sure enough, there was was slight bit of dampness inside the pipe (far enough away from the water to feel like that did not cause the dampness). I removed the pipe flange attaching it to the manifold and inspected the manifold itself. It seemed dry enough.

I had all housings magna fluxed and checked for cracks. Everthing came back fine. All my manifold studs are sealed with JB weld, and all my head studs dry-fit very snugly, and are permanantly fitted with Lock-tite Red. Compression is as expected with a non-broken in engine, about 90PSI.

What is going on?

[Don Moyer]

John,

Whenever we run engines in our shop, there are almost always some water droplets coming out with the exhaust as a result of the condensation process. The condensation process is at a maximum on cool damp days, when warm moist air (warmed by the engine) condenses as it passes through the relatively cooler exhaust pipe. This same condensation process occurs in automobiles on cool days.

Dry combustion chambers and exhaust manifold are the best indication of good cooling jackets in your block, head and manifold.

Don

[jkenan]

Thanks Don. That does put me at ease.

How would water (and antifreeze) reveal itself if it were getting into the combustion chamber? What would the plugs look like?

John

[jkenan]

I just pulled the spark plugs to inspect the combustion chamber, and #1, 3 & 4 chambers & plugs were dry and clean (you could see some slight sootiness in an area offset from directly beneath the plug, and the remainder of the block surface was clean in each of these chambers), but #2 had an oily residue in the chamber as well as on the spark plug.

What could this mean?

John

[jkenan]

Steps to resolve oily residue in combustion chamber & on plug

Don-

Based on our phone conversation on the subject, these will be the steps I undertake to troubleshoot the issue:


1. Check compression. If 30-40 psi less than other cylinders, then there is some structural concern as to why combustion chamber won't hold compression.

2. If compression is good, remove spark plug wire as engine is running from #1 - 4 separately (and reinstall before removing next one). Note whether sound changes as engine misfires with wire removed. If #2 produces no noticable change, it was never firing to begin with.

3. Change spark plug & repeat step 2. If engine runs more smoothly with all four firing correctly, then periodically check plug for oil to determine if oil is slowly getting into combustion chamber.

4. If oil continues to deposit in #2, there is great concern that a piston ring is allowing oil to get into combustion chamber, and disassembly will be necessary to resolve the issue.

Please let mek know if I am missing anything.

Thanks.

John