Fragmare

Hey, all. I've got a 1993 Civic DX with a D15B7. The car has 278,000 miles. I recently had the head resurfaced and changed out the head gasket (and all accompanying gaskets you'd normally change when doing so). Somewhere along the line the valves in cylinder #1 got stuck open or bent, so it's obviously reading a big fat goose egg when I do a compression test. I'm just going to replace all 4 valves in that cylinder. I did a compression test on the other cylinders as well. The readings for cylinders 2, 3 and 4 were all between 105-115 PSI with little or no drop off after 4 or 5 cranks. My question is: Are those acceptable results, considering the mileage of the engine?

kellogg6316

make sure you change the valve stem seals as well

ezone

You did an invalid test.

Keep cranking until the gauge stops climbing, probably 10 hits or more.

I'd expect over 180 PSI.

HTH

Fragmare

Interesting. The gauge seemed to stop climbing after 5 cranks or so on my car. Maybe the valve stem seals could use replacing, you think? I was planning on changing all 16 stem seals while I had the thing taken apart. I've got a full, unopened package of 16 stem seals that came with the head gasket set. Might as well use them all, since I'm going to be popping valves out and whatnot.

ezone

Valve stem seals only control oil. They have nothing to do with compression.

If your engine can only muster 105-115 PSI, I'd think your method is wrong, or your gauge is wrong, or the cam timing is off, or the rings are seriously worn.... Something is wrong...Good strong battery and good cranking speed?

Did you do the compression test with ALL of the plugs out at the same time?
Not doing so might explain low readings.

A wet compression test may tell more about the condition of the rings.

HTH

Fragmare

Yea, when I did the test I let the car idle for about 10-15 minutes, removed all 4 spark plugs, disconnected the distributor connections and had my gf crank the car with the throttle wide open until the gauge topped out while I monitored the results. I took 3 readings per cylinder to make sure they were consistent. That being said, the gauge was only screwed into the spark plug sockets "finger tight", as I couldn't get a socket down in there due to the hose leading out of the top of it. Also, there are currently 3 studs missing from the exhaust manifold (they got sheared off due to corrosion while disassembling to replace the head gasket). I'm waiting on the local dealership to get them in. The cranking power of the battery should be alright. Even with cylinder #1 getting no compression, the car pretty much starts right up within 2 or 3 cranks. If the cam timing is off, it's only off by a tooth on the timing belt, but I really don't think it is. It was off by 2 or 3 teeth after reassembly of the engine, but I adjusted it using the "bullseye" on the timing belt cover with the TDC mark on the crank pulley along with lining up the marks on the cam pulley so they were at 9 o'clock and 3 o'clock (relative to the top edges of the cylinder head). The ignition timing is probably off a little, as i just installed a new distributor and set it right about in the middle, but I wouldn't think that would affect compression readings. The piston rings being worn is a real possibility, I suppose. The car does have 278 ticks on the odometer, and I've taken it on numerous long trips. Should I try again with a "wet" compression test or do you think a leak down test would be even more informative? I've seen ways to construct your own FAA 1mm standard leak down test device using a vacuum gauge, some couplings from the hardware store and some J-B Weld. I'd really like to make sure things are right on all 4 cylinders while I've got the engine taken apart this time. Clearly, the valves are stuck and/or bent on cylinder #1, but if cylinders 2-4 are in need of attention too, I'd like to give them the love they deserve while the whole thing is disassembled, ya know?

ezone

Ignition timing has absolutely nothing to do with compression. Cam timing has everything to do with compression. You are measuring the pumping ability of the engine.

Adjust the valves and retry the compression test.

Wet test and leakdown tests both have their own purposes. Use each for its intended purpose.

At that mileage, I'd expect the rings to be significantly worn. If you tear the head off, that's the time to do the rings if you are going to.

HTH

Fragmare

Actually, I think I'm just going to remove the entire rocker arm assembly and camshaft and get a good birdseye look at the valves from above. Then I'm going to reseat the cam/rockers back down into the head and see if that helps anything. A friend of mine made a good point that the rocker arm and/or camshaft assembly might not be seated into the head quite right, which would cause problems similar to what I'm experiencing, and that I should at least try reseating the cam/rocker assembly before yanking the head off and replacing valves. As for cylinders 2-4 not getting the compression they should, I'll see if reseating the rockers/cam fixes that. If not, I'll just give all the cylinders new piston rings the next time I remove the cylinder head... whether that's sooner or later is the question now.

ezone

Not a good point.

Did it do this on its own, or has it run bad ever since someone last had their fingers in it?

None of that stuff should ever need to be messed with unless a human was in there and screwed it up. It wouldn't have "grown" to be screwed up without human intervention.

All you need to do is run the valve adjustment, make sure they have proper (or adequate) clearance. Tight valves not only burn, they cause low compression for a while before they burn.

HTH

Fragmare

Yea, in the opening post I stated that I recently changed out the head gasket (along with the intake manifold gasket, exhaust manifold gasket, cam holder o-rings, thermostat gasket, distributor o-ring, cam pulley gasket, spark plug seals and valve cover gasket/grommets). After getting the newly resurfaced head back from the machine shop and reassembling everything, i tried to start the car but it seemed to only sputter after 2 or 3 cranks. I rechecked the cam timing and discovered it was off by a little bit (2 or 3 teeth). I adjusted it so it was correct, got back in and tried to start to the car again, but it basically did the same thing. I then gave it a little gas when cranking and then it finally started up, but it sounded like a Harley retrofitted with a washing machine motor. That's when I started to suspect the valves on at least one cylinder were stuck open and/or bent. I'm not really sure how they would've gotten that way, since the timing was only off by a little bit after my initial reassembly. I gave the underside of the head where the valve wells are a good cleaning with carb cleaner, an old toothbrush and a rag before I took it in to have it resurfaced. Maybe that loosened up some carbon deposits near the valve faces that are causing them to stick? The only other thing I can think of is that the machine shop got kind of rough with the cylinder head when they were resurfacing it. I just got done removing the rocker arm assembly so I could get a better look at the valve stems. When I manually compress the valve springs, the stems seem to move up and down as they should. After checking that, I put the rocker assembly back in and took extra care in seating the thing and torquing it down to spec. I double checked the timing marks on the crank and cam pulleys and slipped the timing belt back on. Then I started it up and it still sounds the same. To be quite honest with you, I'm not as concerned with the low compression readings on cylinders 2-4 as I am about cylinder #1 having ZERO compression... that's worrying to me. I don't think a simple valve adjustment is going to fix that. The new valves for cylinder #1 should be in at the autoparts store this Thursday. When they arrive I'll take the whole head off again and be able to get a good look at the valves from underneath. I'll probably also go ahead and replace the piston rings while I'm at it, as you suggested. Hopefully that'll solve the problem.

ezone

My reading comprehension problem is showing again, huh?

Here's a story for you:
I have seen the guy that works next to me bend several valves while trying to reinstall the rocker shafts and stands on an engine similar to this. Didn't have the rockers all in the right places and tried to go ahead and run the bolts in, that forced the ends of the valves to bend outward as the rockers got mashed into place. Needless to say, it got the head pulled off and a pile of valves installed.

Something else that is possible is setting the head down on something solid (workbench or floor) and bending whatever valves were open when the head came off.



A leakdown check should tell where the leakage is going on that cylinder. Put it at TDC (all valves closed) and apply air pressure, see where the air is going: intake, exhaust, cooling system, or crankcase.

Fragmare

Wow, that easy to bend the valves, huh? If that's the case, then the valves in cylinder 2-4 could be slightly bent while the #1 valves probably look like a damn curly straw. I never sat the head directly on the floor. I did, however, set it down on a block of wood with some cardboard in between. I also removed and reinstalled the rockers/cam while it was on this block of wood. I was pretty careful installing the rocker assembly, but from what you're saying it still sounds like there was ample opportunity for some valves to get dinged up. I kind of figured it would all come down to a leakdown test sooner or later. I need to actually get around to constructing my own leakdown tester (it's only like $30 worth of parts and some J-B Weld). I called a local shop to ask what they charged for a leakdown test and they quoted me $200. I told them to get bent (ironic, considering that's likely the state of some of my valves lol). I guess when I yank the head off again here in a couple of days I could always do the "budget" version of a leakdown test. That is, set the head on it's side and spray the manifold holes full of brake cleaner then see which valves leak fluid. Either way, I should start looking around for leakdown tester components and, more importantly, a valve spring compressor that'll fit my D15B7. If you know of any good spring compressors for my flavor of Civic engine, I'm all ears.

ezone

Dude, you don't need a leakdown tester. That's way too complicated for what you need at this point.
All you need is to connect compressed air to the sparkplug hole.
I use full line pressure, 170+ PSI.
A real leakdown tester usually doesn't allow enough airflow to even locate a leak reliably. You know the reading is low, but you can't hear where it is going.
This is why I use full pressure for this check.


Many compression tester hoses will connect directly to a shop air line quick coupler (Milton brand "M" type coupler IIRC).

Cylinder at TDC:
Remove the Schrader (check valve) from the compression tester hose first, then screw the hose into the cylinder, connect the hose to an air line from a compressor.

Fragmare

Ahh, I see what you mean. Just pump a bunch of air in there and listen for the "whistle", so to speak.

ezone

Well, I've never heard one whistle, but I guess you never know....

With sufficient air pressure and flow you will be able to feel the air flowing out of the intake (throttle body or a vacuum hose), or the exhaust at the tailpipe---- if it is valves.




BTW those valve stems are THIN. They do bend somewhat easily with enough pressure in the wrong direction.


HTH

Fragmare

You'll actually be able to FEEL it with your hand? Nice! Certainly makes testing easier! If the air is getting into the cooling system, I'm guessing you'll be able to see bubbles when you remove the bleeder and/or radiator cap? The water jacket should be sealed tight with a brand new Felpro head gasket, but it's worth checking I guess. Better to err on the side of caution. How about the crankcase? Drain the oil and check for air coming from the oil drain or oil filter hole?

And, yea, I was noticing just how thin those stems really are when I was examining them with the rocker assembly out yesterday. No wonder they're so touchy.

Thanks for all these tips, btw. Very useful info here!

ezone

That would make zero sense.
Pop the breather vent hose off of the valve cover and use it. You would feel air movement from a small port or hose far more easily than a large gaping hole.

Your nose hairs should be far more sensitive to air movement than your hand. (I know it sounds like a LOL, but I'm serious. Use it.)


Note:
There will always be leakage past the rings.
There will always be air movement into the crankcase.
Some is normal, you just have to do comparisons between the 4 cylinders to see if the bad one is excessive or significantly worse than the others.


HTH

Fragmare

Alright, I'll check that out on my next day off. BTW, do you recommend any particular kind of valve spring compressor? I'd imagine some fit better than others and some won't fit at all.

ezone

No.

Obviously, you would need one that fits.

No opinion, I don't do that sort of work.
It isn't worth my time and effort, and I don't have the tooling for it.
I send that out to a reputable machine shop.
They have all the necessary equipment to do valve work.


HTH