s2k_suzuka

I have a 2005 S2000 with 66K miles. A few months back I started getting misfire codes for cylinder 1 (most often), but also sometimes for cylinders 2 and 4. I did a compression test and here is what I found:

Cylinder 1: 165 psi
Cylinder 2: 238 psi
Cylinder 3: 240 psi
Cylinder 4: 242 psi

And these are the results of the leakdown test:

Cylinder 1: 64%
Cylinder 2: 3%
Cylinder 3: 1%
Cylinder 4: 3%

I also identified that the cylinder 1 leakage is through the exhaust valve. Maybe there is a small chance that the exhaust valve is tight and valve adjustment will fix it but otherwise it looks like the cause is a bent or burnt valve or worn valve guide necessitating removing the head. So here are my questions:

1. Is there a shop you can recommend in the Los Angeles area?

2. What should typically be replaced and machined in this type of repair? Does it make sense to fix just the damaged valve and valve guide or replace all 16 valves and valve guides? Should I use factory valve guides? What about replacing the valve springs and retainers?

3. What could be the likely cause of this failure? I am the second owner and haven't had any overrev incident in the 15K miles since I bought the car. When I bought the car I had the valves adjusted and the mechanic said some were very tight. Perhaps poor valve adjustment had led to overheating and damage to cylinder #1 exhaust valve?

Soviet

1. Evasive, Ballade, Laskey. The list goes on, check out the regional section for suggestions or do some googling.
2. It depends on the damage and will likely be up to the builder. Definitely go OEM for the best durability unless you are boosting/racing.
3. Tight exhaust valves cause burnt valves, which is right in line with what your mechanic said.

V6 Donut

I use InlinePRO and ship them all my stuff. its a little bit more due to freight but I know its done right the first time. From reading previous threads here I wouldn't go with Laskey.

Id talk to RSG, Ballade, Evasive, RS Machine, Eric's Racing. in your area. Ive used RS machine before with my B series and have nothing but positive things to say about them from Service to work done.

Good luck!

s2k_suzuka

Thank you. The only "racing" I do is once a month autocross (basically 4 runs). Would that justify not using OEM parts?

I have been going to Tony from Mid Valley Auto. I have had positive experience with a clutch change, but I haven't had any engine work done by him so far. Maybe others have.

s2000Junky

Just have all the valves and seats inspected, assuming all else is good, replace the valve/s on cylinder 1 that are burnt or bent, the valve guides and seals for those valves and that should be all that's needed. If there was damage to the seat on those valves in question, then obviously those will need to be replaced as well and the valve lapped in, which is all common practice with new valves and seats for proper sealing.

Soviet

IMHO it doesn't justify using OEM parts. Unless you plan to overrev a lot

Slowcrash_101

Any time you remove the head it's always good practice to lap all the valves. Usually if the seats need a re-cutting you would use an oversize valve. Worst case scenario you'd bore out the valve seats and have new ones pressed in and cut along with new exhaust valves. The reason the exhaust valves tend to burn over the intake valves is that the intake charge and fuel cools the valve. The exhaust valves depend on the face contacting the seat to radiate the heat towards the cylinder head. If your valve clearance is too tight the exhaust valves will fail to seat and get toasty.

With today's machine tools the guides need to be perfect, as the seat cutter goes into the valve guide. So chances are you may need new guides at least in cylinder one.

s2k_suzuka

I just wanted to provide an update for anyone who may read this thread in the future. The mechanic pulled the head out and saw that one of the exhaust valves on cylinder #1 doesn't fully close. Later on, the machine shop he works with replaced both exhaust valves, valve guides and valve seats on cylinder #1. I was told that two more valve guides on a different cylinder were replaced as they were going bad even though there was no compression drop for any of the other cylinders. It was never too clear to me what had caused the damage on a relatively low-mileage (66K) engine. But then I have had the car only for the last 15K miles so I have no idea what the engine had seen before that. By the way, I was advised not to use Mobil 1 engine oil but Royal Purple or Motul instead as they provide better lubrication.

Slowcrash_101

Any synthetic oil with the correct weight is golden. Is the problem resolved?

Slowcrash_101

Golden in the metaphorical sense, royal purple is...purple.