The difference between 2 and 4 is 35? Yeah, rebuild time.
Decide whether you are Arite or Paul! lol

For least ammount of downtime, get used low mileage 99/00 motor and swap, then sell of your motor to make some money back, and give your current 99/00 head to me for free for helping you out :eek:

Ok, here it is for the last time. I got home from work this morning, started the car up and left it idle for 10 minutes. Then I pulled the plugs and did the compression test:
Cyl 1: 160
Cyl 2: 140
Cyl 3: 160
Cyl 4: 160

Then I added 3 pumps of 10w30 from my little oil squirter can, and did the test again.
Cyl 1: 175
Cyl 2: 140
Cyl 3: 170
Cyl 4: 180

What is it guys? Am I ripping the head off, changing valve seals, or just pulling the whole damn engine out?

its not your rings.

For real? It's funny...cause all my motor head friends told me the same thing, they all said valve seals or guides. It just doesn't seem right how low my numbers are, when paul gets 195 and that other guy was at like 205, and I'm like 160's. So you think it's in the head? I noticed, if I drive the car nice and stay out of boost as much as possible, it doesn't take near as much oil. When i boost it a lot, it does. As I mentioned before, I tested my PCV and it tests good. I could have f'd up turbo seals due to too small of a drain line diameter. I asked my uncle when I first bought the car, why it takes 1/2 a quart between oil changes. He said that when an engine is manufactured, the tooling wears out just like anything else. Depending on how many times on that particular set of tooling, the tolerances will differ between blocks, thus meaning slight oil consumption pretty much straight from the factory.

If you really want to know for sure where you're compression is going, do a cylinder leakage test. They're a PITA, but it'll tell you what you need to know. You've got a compressor, right?
--Alex

If you have the means to do a leakdown test, you would have more of an idea of what exactly is the problem when you go to pull the motor apart.

Edit: Too slow

the wet test is to better seal the rings. Since #2 didn't increase pressure, the loss of compression is through the head.


CAS disconnected, throttle wide open, crank until no more compression can be made.


what you need now is a leakdown test to confirm it's the valve seals.

That's how I did it (CAS disconnected, throttle wide open, crank until no more compression can be made.)

So someone is going to flame me for asking before searching, but how do I perform a leak down test? I have a tool that I used to use on prior applications... It's an air chuck with a spark plug thread on the end of a pipe nipple, I used it to hold valves open when changing springs. Do I use this for a leak down test?

The leakage tester is a bit different. You have regulator gauge and a "pressure loss" gauge. Setup is the same, cylinder at TDC and fit the rig in the plug hole. Apply pressure and it tells you how much is leaking. But if you have the spring change setup, you could use that. You don't *really* need to know how much is leaking, just where it's going. Once the cylinder is pressurized, you listen for the air leaks in various places. i.e. leakage in the radiator = head gasket. From the TB = leaking intake valves, from the exhaust = leaking exhaust valve, and from the crank case = rings.
--Alex

So last night at work I brought an old spark plug in. I broke the porcelin out of it and welded a 1/4NPT piece of pipe to it. When I came home I threaded the pipe nipple end to a regulator with an air fitting on it. I took all my plugs out. I took my intercooler pipe off my throtte body, my oil dipstick out, my breather line off, and my PCV valve off. I started with cylinder 1. I took a metal rod and put it down the plug hole and then I turned the balancer until the rod was up all the way (piston at TDC.) Then I screwed the shady tree mechanic leakdown tester in there. I ran about 100psi to it? I did all 4 cylinders the same way, (piston at TDC.) There was absolutely no leakage at the oil dipstick, breather, or PCV. If I went to the back of the car, air would blow out the exhaust, and I had my throttle body blocked open, and air came out of that. So those of you who said "it's not your rings" you were right, looks like I'm ripping the head off. I might hold off a while yet, cause if I take it off, with my busy schedule I might not have it back on by the DE Dyno Party.

Valve guides!
Miatas valve seals are stout, I doubt this is your problem, but may as well change them out if you refresh your head. Why not?

I decided what I'm going to do, but like I said, I am probably going to hold off until after the NE Dyno Meet. I'm gonna pull the engine out, bolt it to my stand, and then rip the head off. Get new guides (hopefully the valves are ok), new seals, and get a new clutch (I still have the stock one in there). I'm gonna say, after the dyno meet, it's engine removal time. I gotta have the car back on the road a.s.a.p. So if there's anybody who's interested in a saturday afternoon engine pull in May, maybe this should be planned and we'll make a party out of it...I'll buy the beer.
Does anyone know the average cost of having a shop do seals and guides? (If that's all it needs)

Funny. cause the same time you started this tread I've had the same problems. Paul and I did a leakdown test yesterday. Turns out my head is warped and my head gasket shot. Im going to be taking off my head either today or tomorrow. There's a couple people looking into how much its gonna cost me to get a head redone. Disturbedfan knows a guy who had his 240 head redone for 285. Not sure what work that actually included.

How hard is it to do the valves? Is this something i dont wanna mess with and just have a shop do it right?

Here's a vid that Paul took. About 100Psi going into cylinder 1. Spark plug put back in to cylinder 2 because we felt all the air coming back up it.

Air into cylinder 2 made it come out of 3. Air into cylinder 3 made it come out of 2 and 4. Air into cylinder 4 made it come out of 2 and 3.

I didn't have that problem, my air just came out of my exhaust or my throttle body. Therefore, my compression loss was through the valves.