Fourteenrbagger

Hi. I replaced the head on my 2001 CRV with 184K miles with a re manufactured head assembly (the car had low compression on cylinders 3 and 4, and the tappet adjustments were maxed out on one exhaust valve on each of those cylinders. The CEL showed misfire codes P300, P301, P302, P304.)
After changing the head, the compression got worse- from 163-158-138-133 psi with the old head to 120-120-120-120 with the new head. A leak-down test showed losses in the range of 3% to 10%, with the only hissing sounds at the dipstick tube and/or the oil filler opening.
I put the old head back on and compression was still at 120-120-120-120. Since the cylinders were glazed badly and the combustion chamber was black with carbon and the intake ports and manifold were covered in gooey carbon, I de-glazed the cylinders using a drill/hone and replaced the pistons and rings.
So now, with the newly re-manufactured head in place (with another new head gasket) and the cylinders overhauled, the compression was STILL 120-120-120-120. I hoped against hope that breaking in the rings with a few miles would help. Nope. After 200 break-in miles around town, the compression is still 120-120-120-120. The CEL has not come on again since the rebuild and there are no OBD codes. I double-checked the cam timing and the valve clearances

F22Master

Get another compression guage.

How does the car drive? Lacking power? Bad gas milage?

Fourteenrbagger

Thanks F22... I'm thinking about that gauge... maybe test it on the wife's car...

The power is sadly lacking... i had to move the distributor to fully advanced so there's at least enough power to be able to get back up the driveway and up the many hills getting to and from anywhere here. Prior to the overhaul i dragged quite a few trailerloads of bad dirt across town up and down hills maybe 15 miles to exchange for good soil, then back home... at least 500 ft net elevation difference too so the CRV was really putting out. Now that would not be possible. It's embarassing when the stoplight turns green and i can't keep up with the slowest 18 wheelers for the first 30 feet/first 5 seconds.

TravisBiggie

What is your piston to wall clearance? What are you piston ring end gaps for the 1st and second? and thirdly, how much did you hone? At 184k miles, I bet you your cylinders are pretty tapered. This is why its always safe to bore it, deck it, so you KNOW its good to go. just bored, decked, and put new pistons in my b20 a year ago. I beat the **** out of it and only has ~300 miles on it. Burns no oil. I don't believe in break in periods.

I concur, make sure that gauge is working properly.. I think auto stores rent them out for free with a deposit?

PSI GUY

iTrader: (2)

Make sure the belt timing is correct, if you have to move the distributor all the way advance it's a good chance the timing is off. If the cam timing is not correct you could have compression bleeding off as well. As well the valve adjustment should be 0.005" intake and 0.007" exhaust.

F22Master

^That was my next thought. Sounds like mechanical timing is off.

Fourteenrbagger

Thanks PSI, F22, TB for your questions and ideas!
I bought another compression tester gauge (couldn't find a loaner, although I had been able to borrow a piston ring compressor, ridge reamer, and hone/deglazer from the store earlier).
Now psi =
TB- I followed Haynes, and used a "T" gauge, difference between piston and bore/clearance was 0.001 inch. But as Haynes says, the ability to do these measurements comes with time (experience!) I'm still a novice but I did my best and believe that we should be good enough for family car street driving.

• What is your piston to wall clearance?
  I used a "T" gauge, difference between piston and bore/clearance was 0.001 inch
• What are you piston ring end gaps for the 1st and second?
  We checked these as well, following Haynes. I didn't write these down but they met spec. About this time the FSM on CD arrived and we cross-checked Haynes specs to the FSM and referred to the FSM when we weren't clear on directions from Haynes.
• how much did you hone?
  tried to just deglaze and stop. I ran the drill as slow as I could to get some angle between the lines, it looked about like your picture. Just not possible to get those factory angles! When cleaning up, it seemed all the gray stuff seemed like just stone residue so we didn't believe we had taken off any metal.
• At 184k miles, I bet you your cylinders are pretty tapered.
  I did my best with the "T" gauge and am confident there is no gross taper based on the "T" gauge, the ring gap measurements at the bottom of the cylinder, and also the factory hone marks seemed uniform.
  its always safe to bore it, deck it, so you KNOW its good to go.
  Having the machine shop bore, deck and get things to a known baseline condition does make sense! But- I hadn't planned on going that far, just wanted to improve performance to near-factory and to get another 180K or better. Originally when I bought the car new I was hoping to get 350K or 400K on just routine maintenance, then a few years back our shop mechanic found low compression for low power and adjusted the valves, then when I adjusted 'em a year or so ago for low power I learned from this website about the well-known secret about the B20Z2 valve clearance/seating/burnt valves issue, and found there was not enough adjustment left on two valves to get to spec on clearance and compression. So I ordered a re-manufactured head assembly, hoping to get by without working the cylinders/pistons.
  

PSI-

• Make sure the belt timing is correct, if you have to move the distributor all the way advance it's a good chance the timing is off. If the cam timing is not correct you could have compression bleeding off as well.
• makes sense! If a pressure leak-down is good I will look at that again. I anticipate it's good, however, as timing belt is one part I can almost do in my sleep, so may try advancing by a tooth.
• As well the valve adjustment should be 0.005" intake and 0.007" exhaust.
• We put intake at 0.005, exhaust at 0.008, the upper spec limit. (In my mind, looser tappet = earlier/fuller valve seating)

wunfstgsr

I would #1 confirm mech. timing!!!! set the engine to TDC and confirm the cam gears and oil pump are at TDC.

double check your valve lash! im willing to bet your valve lash is off and your valves are tight, its easy to set the valve lash then when you torque the nut it can tighten the valve and you wouldnt kmow unless you double check.

Also the comp test is low but remember its consistancy you want to look for, 120 across is low but consistant, also if the engine is cold or warm it will make a diffrence in how high the compression shows.. Did you drop a cap of oil in the cylinders to see if the numbers would jump?

Best bet would of been to just buy a long block used there a few hundred bucks these days.

Fourteenrbagger

thanks wun- yeah in hindsight I sure wish I had opted for the long block, I did consider it! I will check lash as you say and definitely belt timing.

wunfstgsr

Yea to me it sounds like Timing and also the valve lash is off spec!

Fourteenrbagger

--The RINGS are leaking! I did a pressure leak-down test on two cylinders, losing over 10%, and could hear it coming out the dipstick tube, even at only 10 psi! This not right for new rings, pistons and cylinder deglaze. So I ran another compression check, this time on a cold engine, then added some oil in the spark plug holes and rechecked the compression. Adding oil raised the pressure about 35 psi on each cylinder.
-- After putting the plugs back in, i started it up and drove immediately to the steep hill right around the corner. The power was much improved - for a minute or so . Instead of taking it to 4700 rpm in first so it could manage to struggle the rest of the way up the hill in 2nd gear (bleeding off speed), i let the AT slide into 2nd much sooner, yet it ACCELERATED up that hill in 2nd! Haven't had that much power in 10 or so years.
--So then. How much do i need to plan for spending at a machine shop for a bore and hone? I guess the new standard pistons i bought must be replaced with oversized ones...

wunfstgsr

If you can go to a local auto shop they sell this product called engine restore in a silver can use it with a fresh oil change and it should help you regain some power untill you get it rebuilt the stuff works and iv used it when i had broken ring lands and very little power, i used the can and it restored lots of power and was a cheap way to get the engine to run better. Its worth a try.

Usually to rebuild the bottom block its anywhere from $850- $1700 depending on who does the work.
I think it would be much better and cheaper to get a used high comp B20 swap and swap on the rest of your engine to it and call it a day.

Fourteenrbagger

thanks wunfstgsr! As it turns out I had picked out Engine Restore at Advance Auto before reading your post! I wanted to buy some oil to replace the break-in oil with 300 miles on it now, but I wasn't sure what weight to use (10-40? 10-50?) since the power is MUCH better while the engine/oil is cold. So I decided to try the Engine Restore with the current oil just to see how it works...

Fourteenrbagger

Timing belt was off one tooth on both cams (retarded). Now with timing corrected, compression tests around 12 lbs higher, in the 140-150 range. More importantly, there is LOTS of power! Easily more power than two months ago before starting work, more power than in years! Thanks to all of you for your help!

Fourteenrbagger

All the grief was caused by my getting the timing belt off by one tooth. I thought sure I had that procedure down because I replaced that belt and adjusted the valves about a year ago and it ran great. One factor throwing me off was how much slop there was "pinning" the cams in place using an allen wrench, drill bit or pin punch. I recall reading a blog at "old guys" or something like that about building a 400bhp+ NA using experimental ceramic coated pistons they were developing. They have a "jig" their machinist made with two pins secured together at the proper spacing so it holds both cams in place spot-on. That would have helped. A second factor skewing my perception of TDC cam sprocket position is that the engine is tilted forward slightly from vertical when mounted in the CRV, and I didn't even notice that. C'este la vie!

wunfstgsr

Good to hear it was the belt! For vtec B series heads they sell a cam gear locking tool to help put on the belt and adjust the cam gears. But they dont sell one for B20 heads but wonder if theres one made for B20 heads i havent seen.

Streetrays B16A B18C Cam Gear Lock Timing Belt Installation Tool Civic Integra | eBay

GhostAccord

After reading this thread I was going to say. There is nothing wrong with your compression readings as all 4 cylinders are within 1-5 psi of each other. And your 10% leakdown results are also good to go. When your results are this tight you move on to checking physical timing.

Glad to see that you found the timing error and were able to fix the issue.