Rep Power: 0

Hello all! New to the forum and hoping to learn and get useful inputs.

First for me doing a head gasket. Seems to be going good so far. I did this for preventive maintenance only since my 03 Civic has 221k miles and I don't want to wait til the head gasket blows to do it. Car still runs great when I started the teardown.

My question is do I take the head to the machine shop and get it serviced since there were no issues prior to this maintenance? If so, what type of work should I get done on it? This is a daily commute car, everything stock, maintained very well, and I've driven every single mile on it so I wouldn't want any fancy work done to the head like a race engine would get. Just looking for basic service. Any recommendations, thanks in advance!

 
Rep Power: 512

take it in regardless to make sure it's flat. They can tell you if it needs to be machined or not. I think the tolerance for warping is something like .004" or something tiny like that.

 
Rep Power: 210

Since you have the head off and you are doing it as preventative maintenance you may want to consider spending extra on it such as:
1) Milled flat (shaved)
2) New valve stem seals (inexpensive)
3) Valves checked for sealing and have them lapped (honed) and polished if need be.
4) Get the head hot tanked (cleaned).

It would be a good time to change the thermostat (Honda genuine only) if it has 50k miles or more on it. Also, replace the coolant,

 
Rep Power: 0

Got it. Thanks. Now looking for reputable machine shops in the area.

 
Rep Power: 0

I understand reasons behind #1, 2, & 4. As for #3, I know sealing is good to get done. I’m actually replacing almost all seals and gaskets while I’m at this.

But what is the reason to get valves “lapped (honed) and polished”? I see you mentioned if needed.

Since I’ve drained the coolant it’s bound to be replaced. Thermostat actually looks fine when I cleaned the water passage unit and changed seals on it too. Seems easy to get to if I need it later. Also, the car had zero issues whatsoever when I decided to do all of this. I will keep that thermostat replacement in mind though. Thanks for the helpful tips.

 
Rep Power: 224

The machine shop I use does 3 and 4 every time I bring them a head, they only do 1 when needed.

 
Rep Power: 210

A good machinist will most likely check the valves seal using water. The better the valves seal the least amount of compression loss. Lapping and polishing helps reseat the valves for optimal seal. The valves develop carbon buildup over time and that's where the polishing comes in.

The best prevention of a breached head gasket is to prevent the engine from overheating. A new Honda genuine thermostat is worth the extra $30 and install time IMO.