bsconz

1999 Civic EX
148K miles all original

I bought this car for pretty cheap knowing it had this issue. The previous owner replaced a bunch of parts trying to solve it. IAC valve, distributor cap & rotor, spark plug wires, spark plugs, fuel injector on #3 cylinder, and fuel filter.

The CEL is on and codes are all for misfire of cylinder #3 and random misfire. Compression test on cylinder #3 doesn't even register on the gauge. All other cylinders are making good compression. I did not leak down test any of the cylinders.

Instead I removed the valve cover and all spark plugs, rolled the engine over to where cylinder #3 intake and exhaust rockers were both loose (meaning the valves were all in closed position), and then put compressed air into the cylinder while holding the camshaft in position. I got air coming out the tail pipe (alot) and also out of cylinder #1 spark plug hole (only cylinder that i could see had exhaust valves open by cam). No air came out either cylinder next to cylinder #3. No air bubbles at the radiator cap. No air seemed to come through the crankcase and out the oil dipstick tube or back through the oil galleys.

My theory is buildup on one or both of the exhaust valves on cylinder #3. The compressed air mainly shot out the tail pipe but also went a little back through cylinder #1 through the manifold (probably enough backpressure from the cat).

Any more experienced thoughts on this?

I am thinking about trying to fix the issue without removing the head (removed timing belt, cam/rocker assembly, valve springs on cylinder #3, and then spinning the valves with a drill while pulling up on them into the head). I could probably get some lapping compound on the valves through the exhaust ports?

em1type-r

From what you have described in your thread, I would agree and conclude that you have 1 or both burnt exhaust valves on cylinder 3. As far as putting lapping compound on the face of the valve through the exhaust port and spinning the valve with a drill would be quite difficult in my opinion. Also depends how bad the valves are and may require replacement regardless of how much lapping is done.

bsconz

Yeah, I figured it might be a waste of time. I decided to just pull the head off this weekend.

Just out of curiosity, is it possible to remove a piston and connecting rod assembly on this engine with it installed in the car still?

(i'm just preparing myself for the worst in case i take the head off and there's a huge effing hole in the piston or there's a lot of scuffing on the cylinder wall.)

bsconz

Does anybody know of good cylinder head removal DIY writeup? I have the full service manual for this car but was interested in the tricks others may know about for this job!

purgat0ry

iTrader: (3)

If there is a write up, it would be here => FAQs