I was the first to mention valve guides early in this thread.
As a novice DIY guy, I learned a lot listening to you guys troubleshoot this thing. What a great question and great answers!
Just ran across this old thread. Very informative. I just rebuilt my first engine (ā86 Honda CRX EW4). Lots of smoke from the get go. Still really bad at maybe 100 miles in. Rings are 0.03 overbore because standard ring gap was too big. I gapped and clocked the rings myself, have tried 2 sets of valve seals. I honed the cylinders with a ball hone, and the crosshatch looked just like the videos on YouTube. Cleaned cylinders thoroughly after honing. Iāll do a wet/dry compression test ASAP, but hoping for bad valve guides. Thanks for all the info!
Man, youāre brave. I have a hard enough time finding parts for my 2nd gen CRX. I bet sourcing stuff for a 1st gen is a nightmare these days.
Was a machine shop involved in your rebuild @86crx ? If so, what did they do?
No machine shop. Head looked good and flat, didnāt need to bore anything. So far no evidence of head gasket leak, so thatās good. All I did was hone the cylinders, gap the rings and lap in the valves. Thereās some possibility I goofed up a ring or two but Iām getting oil in all 4 cylinders, so I doubt thatās the case.
I had 2 of them. The engine and tranny are out of a parts car that sat in a yard for 20 years. Amazing how many parts were still good. Radio still works. Wiring harness untouched by rodents. Sunroof still functional. Throttle body flawless. I even salvaged the starter, distributor and injectors. Had to Zn coat a lot of brackets and stuff, but it was all pretty solid. Actually, I had very little trouble finding the parts I did have to buy. Even got a FITV for it off eBay.
How many miles on the engine? If itās high miles then odds are high that the cylinder bores are tapered and egged.
This means that in spite of honing, a circular piston ring will not work too well in an oblong cylinder bore.
Are you certain the oil control rings are free to move in the piston grooves? Theyāre designed to constantly expand and contract in the cylinder bore to keep the oil wiped off of the bore.
This also goes back to the tapered and egged cylinder bores.
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The engine had 180k on it before the rebuild. The previous owner says it was running great when he parked it. Apparently the suspension was nickel-and-diming him to death. Pretty hard to verify any of that though, since he hadnāt driven it for 20 years.
Some reasons to be hopeful about the cylinders though: I could still see some light cross-hatch in the cylinders before I honed them, and other areas of the car indicated that he really babied it. The transmission looked practically new inside, and virtually every internal engine component was in flawless condition. There was still oil in it when I took it apart, too. I think the wet/dry compression test is definitely the next thing to be done. That should rule out/in ring issues.
As for the oil control rings, I canāt be 100% certain, obviously. This was my first ring job, so itās entirely possible I goofed something up. But I was really, really careful about gapping/installing/clocking them correctly (just like Eric the Car Guy), because I knew that was the one thing I couldnāt afford to get wrong. Hereās hoping.
I changed the oil yesterday and it didnāt look bad. No smell of gas in it either. I havenāt yet pulled the filter apart to check for fragments. While I havenāt done a compression test yet, the car is super peppy on the road, so major loss of compression doesnāt seem to be an issueā¦the numbers will tell all, though.
Note to self: just replace the damn valve guides next time. I think that is probably a good habit to get into, as itās not too expensive and can save the DIYer a lot of head-scratching.
I rebuilt engines on a '75 Civic CVCC and an '81 Accord (with assistance of friend who was a Honda tech).
In both cases we just handed the head over to a machine shop.
They checked for flatness (the '81 needed a bit of milling), cut the valve seats, replaced the valve guides for the '75.
Didnāt cost much to make sure the heads were tip-top.
@86crx:
Did you verify that all the rings, including the oil control rings, were installed right side up (e.g. none were upside down)?
Yes, they all had little indicator dots on them, so pretty hard to screw that up.
Does anyone here have experience honing & re-ringing an aluminum block? I would think that a different technique would be used on aluminum compared to cast iron and a dingleberry hone wouldnāt seem appropriate.
Yes, replacing the valve guides is cheap money while already in there. Since you did not, did you at least make sure the valves went back into the same positions or did you mix them up? The one time I saw the result of this, the car was a mosquito foggerā¦
I lapped each valve in individually and made sure they all went back in the holes they came out of. The block is aluminum, but the sleeves are steel.
If you remove the head again to figure out what the problem is or to replace the valve guides, pay a machine shop at least measure the inside diameter and the circular-true-ness of the cylinders vs depth. Theyāll have a gauge that makes such a thing easy and relatively inexpensive to do. It also possible some of the rings are bound to the piston grooves for some reason, or there isnāt enough space in the gap between the two ends of the rings. Or the gaps from adjacent rings ā which should be staggered ā have moved for some reason and now are aligning. As I recall one of the major auto manufacturers had the latter problem on one of their fairly recent engine designs.
A ball end cylinder hone will not straighten out the bore in tapered or egged cylinders. That can be done with a rigid hone if time is not an issue and one is very, very patient. Very.
What would I recommend? Remove the spark plugs, prop the throttle plate open, and run both a dry and wet compression test.
A Honda engine in great shape should have 190 PSI of compression. If itās way lower than that or the wet test drives the numbers up then thereās a ring issue.
Good input. Especially wrt to the bore and the rings ability to follow it (if tapered or egged).
But given the burning of oil, if there is something wrong with the oil rings, would this show it?
Not likely. The compression rings can be fine and the oil wiper rings suffer a problem. The only thing it will reveal is that if the compression shows a problem then one knows the engine will have to be gone back into.
Example. Many years ago I built a Subaru engine. It was done right with block bored, oversize pistons, reground crank, etc. When started it ran fine BUT, it smoked and would not quit smoking and going through oil like a grounded tanker.
A compression test showed 185 on all cylinders but No. 2 showed oil on the plug.
Not happy at all I tore back into it and could find absolutely nothing wrong with that cylinder. Piston, rings, etc all good. The crosshatch in the cylinder looked great. Putting it on hold for a few days and after some thought I figured I would run the hone through the cylinder just in case there was something wrong with the hone job from the machine shop. The machine shop hone job looked fine to me butā¦
Put it back together with the existing piston rings and everything was well after that. Go figure.
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