Low Compression Test Results
 

I just finished doing a compression test and the results are relatively consistent but very low.
Cylinder #1: ~160psi
Cylinder #2: ~150psi
Cylinder #3: ~147psi
Cylinder #4: ~156psi

https://cimg1.ibsrv.net/gimg/www.s2k...2fc9c7d4d7.jpg
Cylinder #1
https://cimg4.ibsrv.net/gimg/www.s2k...132edc37e4.jpg
Cylinder #2
https://cimg9.ibsrv.net/gimg/www.s2k...4c432506aa.jpg
Cylinder #3
https://cimg9.ibsrv.net/gimg/www.s2k...41f832bf44.jpg
Cylinder #4

I read in a few posts here that you should expect the range to be around 200-240psi but that consistency was more important. Is there any kind of leak that would lower overall pressure? Should I be concerned? I have the tools to do a leak-down test as well and will likely be doing that this upcoming Tuesday if the weather permits.

Additionally, I bought this car used a few years ago and just recently decided to start fixing everything wrong with it. I've done regular maintenance to it, but there are some issues I've known about but was not in a position to either fix myself or have fixed professionally. With that said, I just recently noticed this:
https://cimg9.ibsrv.net/gimg/www.s2k...1ec12c0bb8.jpg
Engine
It looks like there is a leak coming from the bolt that holds the idle gear. I'm going to order the O-Ring to replace and tighten it to 36ft./lb., but in the meantime do you think that may be a cause for the low pressure? I also noticed that the oil drain valve is leaking (not sure when that started) so I'm going to tighten that as well (I assume to 29ft./lb. like the OEM drain bolt?). The MAP sensor likely needs to be replaced as well (whacking was not effective, but I'm going to clean the IAC valve first to make sure), would that cause issues with pressure?

Lastly, as I did the test I noticed that while the engine was cranking, there was a rather loud noise and smoke/vapor coming from the engine... is this normal? I would assume that it is not.

Thanks for the help.

You should have also read on here not to use a Harbor Freight compression tester. They just don't work. At least not for high compression engines like ours.

I like HF. I buy a lot of tools there. Most of their stuff is decent. Some of it is excellent. Some of it is total junk. Their compression tester is at or near the junk category.

Rent a gauge from a place like Autozone. Make sure motor is warm. All plugs out. Throttle wide open. Fuel pump fuse removed.

I see. I mostly followed Rob Robinette's guide that was linked on here as well as the faddis2k's guide. In Rob's guide he used a Harbour Freight tester. I'll go ahead and return it and try to see if the O'Reilly or Napa near my house has something better I can use. Thanks for the tip! Do you recommend the same thing for Harbour Freight's leak-down tester too?

The important thing if using a questionable gauge (or technique) is that all the readings are somewhat similar. If one stands out that is an indication of a problem.

Glad to hear, the engine pulls hard and feels really good so it seemed odd to see such low numbers. Because of the solid results, did you bother with the leak-down test?

Hard to tell from the one photo, but the accessory belt looks to have a sheen on the surface. When was the last time you changed it?

:)

I tested with the same tester as you and got similar results, it lead me down a paranoid path thinking I'd be shopping for a new motor soon. Long story short, everything is fine and the car tested at leakdown numbers below like 5% and tested normal compression numbers on a different gauge.

I'm going to be completely honest and say I have no idea when it was last changed. You're referring to the serpentine belt, right (are those the same thing?)? What exactly do you mean by a sheen? I can post some more photos tomorrow.

Well that's good to hear! :)
Did you use a Harbor Freight leak-down tester or did you opt to go with something a little nicer? I'm pretty sure I've got a leak(s) based on the oil on the exterior of the engine. More than anything, before I continue doing work on the car (needs a lot of body work and misc engine work) I just want to make sure the engine is healthy since that's priority #1.

BTW see you are using a K&N filter many people consider using an OEM filter on these to be a must. Dont want to start another engine oil or filter debate though.

No, that leak is not a source of any low compression.

Thank you. I've used a few different oil filters: OEM, Bosch, and K&N. They all seem to work fine, I haven't found any of them to be particularly better than the other for my uses. I change my oil and filter pretty frequently and check my oil levels frequently. I just use the car as a daily driver (no track use) so as long as it doesn't cause any damage I don't mind. I only recently moved near a Honda dealership so I may switch back to OEM if the price is reasonable. For oil I've just been using Castrol GTX 10W-30, it's been great. I sometimes use the High Mileage variant if I can find it, but they both seem to do the job. I have yet to try Mobil-1 but I hear great things (outside of burning a lot of oil). Oil burning hasn't really been that much of an issue, I don't use VTEC that often and mostly just drive regularly unless I'm impatient with people being stupid on the road :argh:. For the air filter, it's the K&N filter that a lot of people on here recommend. I installed it about a year ago and it's still really clean (looks almost brand new) but I'll probably clean it again soon to be safe. Now that the car is getting to some pretty high mileage (187k and counting), I'll probably double check all the fluids since I have no idea when the last time the Transmission or Differential fluid were replaced (Clutch and Brake fluid are fine).

FYI, a leakdown tester won't find external oil leaks. It only finds internal 'air' leaks. It only tells you where your loss of compression is coming from.

From all indications you don't really have any loss of compression (we'll know for sure once you test with a good gauge). So a leakdown test isn't going to have any worthwhile results to offer.

+1 with the other guys -- I've used the HF tester and get similarly [low-but-consistent] results.

I always make the argument that consistency is all that matters, as opposed to the raw high numbers that people are chasing, but people just don't care.

Be careful with that o-ring replacement -- follow Billman250's instructions to the dot (you do NOT want to remove the bolt too much or you'll be screwed):
https://www.s2ki.com/forums/s2000-un.../#post23054279

I see, I completely misunderstood it's purpose, thank you for the clarification. Sounds like everything should be fine with the engine so I'm going to skip the leakdown test :)

That's the same thread that I saw suggesting the replacement, I'll be sure to be careful. This is my daily driver so I can only have a few days of downtime at most so I will plan accordingly just in case.

Where I live is between 500-1000ft. above sea level. I don't have specifics unfortunately so I can only go off a rough estimate. I think it is just the Harbor Freight branded Compression Test that is at fault, everything appears to be good as far as the engine goes.