jonthejester

Hey there.

I have a 1992 Honda Civic DX with close to 200k miles on it, just recently got it a couple months ago and took it on a road-trip across the US, from CA to the east coast and back. On the east coast, I noticed the engine running really rough and lost some performance rather suddenly, so I got the car checked and got a compression check, found compression on cylinder #3 about 70 pounds instead of 120, the default, which was what the other cylinders had.

So since then, I did an air leak test on the bad cylinder with the exhaust and intake valves closed, and air leaked into the 4th cylinder. Naturally I assumed it was a head gasket break, so I got a head gasket set and opened up the cylinder head today--to find that the head gasket was alright and one of the exhaust valves had a small break in the metal. Basically a burned valve. I think this would definitely explain the compression loss and the occasional overheating the car's had when I've pushed the engine for a while, like going uphill.

As the situation stands, this is what I'm trying to figure out, whether to:
1. take the car into a professional, have him replace just the two exhaust valves in the bad cylinder,
2. have the pro replace all the valves, or
3. get a new cylinder head

I was talking with my mechanic cousin, who helped me out with this, and suggested I just take it to a pro and just have the two exhaust valves replaced. I'm just wondering, considering the age, should I do that, replace everything, or would it be cheaper, with labor + parts together for the pro jobs, to just get another cylinder head and do that myself? I'm still figuring out how much it'd be, taking it to a pro. Thanks.

-Jon

gsrhatch2356

rebuilt head would be the better way out just cause it would be cheaper and then you can save the money on the labor of having the work done by somebody else. just make sure that when you get ready to put it back together that you clean all the carbon out of the combustion area like on top of the pistons and whatever else. carbon can get red hot causing preignition and burning valves cause of it.

jonthejester

what about the valve seating? is this something a valve non-expert like me could do? and also would I have to buy all new valves or just new valves for the cylinder with the burned valve? I think the valve seating is what really concerns me, with rebuilding the head, gonna need a little help there I think.

gsrhatch2356

I mean buy one that is already rebuilt and you put it on. valve seating and grinding has to be done with a very precise machine that you cant just get anywhere.

TOO MUCH TORQUE

is the car back in cali? i would replace the entire engine. i heard some bad things about rebuilt heads on old blocks.

jonthejester

yup, in cali, hour from LA. hmm...replace the engine? how much is a replacement engine?

here's another idea I was thinking of: what if I were to do all the labor of taking out the head from the car, take the head to a specialist, tell him to replace the valve--or all the valves--and do the valve seating and stuff.

would it be more worth it to do this as opposed to a new head or even new engine?

gsrhatch2356

there is no reason to replace the engine unless it had been overheated and the deck is no longer square. a engine or head is no diffrent in cali then it is any where else. and when you get a head rebuilt they should do the seating. seating a valve means regrinding it and the head to a 45-60 degree cut and can only be done with a very VERY expensive machine. so doing the seating yourself is out of the question. you should be able to pick up a rebuilt head for uinder 300 bucks and if you add up the valves, the seals, the labor to recut the head you could very well end up over that and on top of that you might have to wait several days depending on how busy the shop is. GL

jonthejester

yeah, the deck's still square, everything else looked alright. I otherwise don't see why I'd want to replace the engine as it is.

but reality check, this is just one burned exhaust valve, I mean so far as it seemed the seating seemed alright otherwise, with that valve and the other valves. guess I wonder, would I still need to rebuild the head? is it still possible to just replace the valve without having to rebuild?

gsrhatch2356

you cant just look at the engine deck and tell if it is still square, you have to get a straightedge and use a feeler gauge to see if there is any warpage. and when I say straight edge I mean a long piece of metal that has been cut on one side to perfection meaning less than .001" of play down the face of it. and same thing for the valve, you cant see if it seals or not. Its obivious that you are better off leaving the rebuilding to proffesionals and stick to r&r. I am not trying to be blunt but I wrote this long explaintion earlier and the site went down for repair or something so. my best reconmendation for you is get a rebuilt head and use that.

jonthejester

yeah, makes sense perfectly there. there's a guy in town here who'll rebuild the head and replace all the exhaust valves for ~250, so I might do that instead, take out the head myself and have it rebuilt. feel a little easier doing that, slightly cheaper.

gsrhatch2356

well good luck to you