Well we had a customer come in with a 2006 Honda S2000, only 65K miles, and a consistent #3 cylinder miss fire code. The compression numbers came back as #1-250, #2-250, #3-150, #4-250. In addition, we performed a leak down test and were able to see a %40 loss, and hear the exhaust valve leaking. It was clear that the head needed to be pulled. Here is a video of what the #3 exhaust valve looked like after it was pulled.
The side to side movement is due to excessive wear on the valve guide. This is an all too common issue with the S2000. This side to side movement leads to wear on the valve seat, eventually leading to a leak, compression loss, loss of power, and poor gas mileage!
The head was treated to a Bronze Valve Guide upgrade along with a full valve job. Because this head come out of a 2006 S2000, it was already equipped with the later model AP2 retainers.
Once the machined head was installed, the compression was back to 250 psi across the board! After only a few miles of driving, the owner said that the car was completely different. It was running perfectly smooth, and the power increase was dramatic!
Like what we posted, want to know more? Shoot us an e-mail at BAWSSfab@gmail.comor check out our Facebook at https://www.facebook.com/BAWSSfabrication
For my 2006 s2000, I keep having to do valve adjustments every 4-5 months. After every valve adjustment, the engine feels strong and brand new, but as the miles go by, the engine starts to have a delay and loss of power and keeps getting worse as the weeks go by. What could be the problem?
ReplyDeleteHey Jared, Thanks for your question! That's a very common sign that the valve guides are worn. Doing frequent valve adjustments is a great idea, and usually customers wait unit those adjustments become less effective before rebuilding the head. AP2 heads seem to wear a bit sooner than AP1, I've seen an AP2 need to have a head rebuilt as early as 35-40k miles. What's actually happening is that because the valve guide is worn, the valve itself can rock back and forth. Imagine looking up at the valve from inside the combustion chamber. The valve would look to be moving in a circular, or egg shaped pattern. This causes the valve to not close perfectly flat on the valve seat. Repeat that issue millions of times and the surface of the valve and valve seat degrade, you loose compression, which causes all the power and idle issues. This process can destroy the valve seat beyond repair, but that is very rare. I would suggest rebuilding or replacing the head soon as you can to avoid unrepairable seat damage. If the issue is allowed to go on for long enough, or if the car spends alot of time at the track, low compression in one cylinder can cause an imbalance in the bottom end of the engine, leading to bearing issues. This is again rare but it can happen in severe cases.
DeleteLet us know if you have any more questions!
The reason there is valve wear is because 2006+ S2k's have drive by wire, they run hotter at idle than non DBW cars, which rely on an IAC valve. Because the non DBW have secondary air injection the heads are better cooled, on top they run richer. That is why they need less valve adjustments, as long as the exhaust valves are kept at the proper clearance there will be no guide wear.
DeleteThe guides wear because they warp as the valve is so tight that it does not radiate it's heat to the valve seat like it's supposed to, instead relying solely on the guides. This is worse on the exhaust guides because the exhaust valves don't have intake and fuel mixture to cool them.
Wow, yes I am noticing that i am having to do more frequent valve adjustments. Do I have to do an entire top head rebuild or can i just replace the valve guides? Thank you so much for this.., you guys are the first to give me such a detailed answer.
ReplyDeleteYour very welcome Jared, it's our pleasure to help every S2000 owner out there! The cylinder head will need a complete rebuild, replacing only the guides will not solve the issue. Because the surfaces of the valve and valve seat have been abnormally worn and degraded, they must be remachined back to being flat, within the correct tolerance. This is commonly known as a "Valve Job". With new guides in place, the valve will have a nice straight run back into the valve seat, and with both of those parts having freshly machined surfaces, they will mate together perfectly. With a perfect valve seal, an engine with a healthy bottom end will have the best compression possible, resulting in the best performance. We rebuild our cylinder heads using Ferrea Bronze Valve Guides. The Bronze material has a lower friction coefficient compared to the OEM iron valve guides. Less friction leads to less wear, and greater performance. There are lots of little details that must be accurately executed in every step of a head rebuild to avoid issues. We've built dozens of heads, and we've also had to fix screw ups! Whomever may rebuild your head, try and find an experienced machined shop, preferably with experience with sensitive, high output, NA engines.
DeleteThanks again for your questions. We'll post up more detailed info as our new website is being built. You can pop over to our Facebook so see a few photos of cylinder head builds we have done in the past.
https://www.facebook.com/BAWSSfabrication
you guys are located in AZ. I'm in CA, just realized this haha. But how much do you guys charge for a head rebuild?
ReplyDeleteThis comment has been removed by the author.
DeleteOur typical stage 1 head build currently runs $1950 parts and labor. That's to hot tank the head, have it vacuum checked, and machined flat. It also comes with new bronze guides, OEM stem seals, full valve job ect. Typical turn around time is 2-4 weeks if we don't have a ready to go core head in stock, and 2-3 days when we have a head in stock ready to go.
DeletePlease keep an eye out for our website launch, we will be posting up detailed info on our head builds. Thanks again for your question! E-mail us directly if you wish, BAWSSfab@gmail.com
I have the same issue with my 07 s2000. The valve seat is not properly closing the valve with leaking all around considering the compression test on that cylinder was 80 psi. Do i need i new head or it can be machined
ReplyDeleteThe seats in the head and valves can be machined back into spec. These newly machined surfaces will restore your compression and engine performance.
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