'87 Accord Engine Mystery
#1
05-20-2014, 04:41 PM
'87 Accord Engine Mystery
Several years ago I took pity on this old Accord that was awaiting its fate at a local junkyard, and purchased it to restore. I got a lot done on it (mostly bodywork) but never quite had the time or money to complete it, although I still hope to. I do start it up every few weeks though and move it around the yard, but now there seems to be some serious engine issues and I'm debating if it's even worth finishing now.
When I first got it the engine seemed to run OK, not 100% but didn't seem to be burning oil or anything like that. Last fall when I moved it into place for winter, it seemed to be burning water (lots of steam) and the engine was running roughly, but with winter coming I just covered it and left it until now.
So now, it still starts but the engine runs as rough as ever, but no visible steam or smoke in the exhaust. The distributor and plug wires are good. All spark plugs were dry with no signs of damage or fouling. A compression check showed two cylinders within spec, one just under, and the #2 at just over half (around 80 psi). With the engine running, I tried unhooking one plug at a time, some made more difference than others but the #3 plug made no difference at all. Tried swapping the spark plug and wire but no change. Popped the valve cover (for the first time) and found nothing broken or even visibly worn. So I then tried injecting compressed air directly
into each cylinder, hoping to hear the source of any leak. The engine was cranked so as to close the corresponding valves for each cylinder under test. This test revealed that all four were leaking severely through the exhaust - enough that I could feel the air blowing out the tailpipe. I didn't think to measure the air consumption to see if one was worse than the other, but at this point I don't think it really matters as something is clearly very wrong.
I only entered the hobby of rebuilding old cars a few years ago, and this is only the second engine I've ever tackled, so I have to wonder if I might be missing something. But at the same time, while I'm no expert mechanic, I am quite sure that a cylinder should not be leaking air (especially at this rate) while all the valves are closed. BTW I was using around 120 PSI if this is of any relevance. I also ruled out any leakage between cylinders or back into the oil or water channels.
At this point I guess I'm more eager to just learn something than actually restore the vehicle, although that would still be nice. I'd rather not have to remove the head unless absolutely necessary, but I don't see any other alternative as it must be severely damaged.
What puzzles me is how a compression reading could be obtained with such severe leakage. I guess that must be something else I have yet to learn.
Thanks for any advice you can offer.
When I first got it the engine seemed to run OK, not 100% but didn't seem to be burning oil or anything like that. Last fall when I moved it into place for winter, it seemed to be burning water (lots of steam) and the engine was running roughly, but with winter coming I just covered it and left it until now.
So now, it still starts but the engine runs as rough as ever, but no visible steam or smoke in the exhaust. The distributor and plug wires are good. All spark plugs were dry with no signs of damage or fouling. A compression check showed two cylinders within spec, one just under, and the #2 at just over half (around 80 psi). With the engine running, I tried unhooking one plug at a time, some made more difference than others but the #3 plug made no difference at all. Tried swapping the spark plug and wire but no change. Popped the valve cover (for the first time) and found nothing broken or even visibly worn. So I then tried injecting compressed air directly
into each cylinder, hoping to hear the source of any leak. The engine was cranked so as to close the corresponding valves for each cylinder under test. This test revealed that all four were leaking severely through the exhaust - enough that I could feel the air blowing out the tailpipe. I didn't think to measure the air consumption to see if one was worse than the other, but at this point I don't think it really matters as something is clearly very wrong.
I only entered the hobby of rebuilding old cars a few years ago, and this is only the second engine I've ever tackled, so I have to wonder if I might be missing something. But at the same time, while I'm no expert mechanic, I am quite sure that a cylinder should not be leaking air (especially at this rate) while all the valves are closed. BTW I was using around 120 PSI if this is of any relevance. I also ruled out any leakage between cylinders or back into the oil or water channels.
At this point I guess I'm more eager to just learn something than actually restore the vehicle, although that would still be nice. I'd rather not have to remove the head unless absolutely necessary, but I don't see any other alternative as it must be severely damaged.
What puzzles me is how a compression reading could be obtained with such severe leakage. I guess that must be something else I have yet to learn.
Thanks for any advice you can offer.
#2
05-20-2014, 06:12 PM
Leaking through exhaust valves suggest valves are sticking badly causing the leakage. It could be a buildup of dried oil causing them to stick.
You could try a round of "top end cleaner" to see if valves can be loosened. Many folks like GM top end cleaner, but I've never used it.
It is likely the head must come off to repair the valves. You should rebuild head w/ new stem seals, reseat valves, and leak test. New head gasket should restore engine.
good luck
You could try a round of "top end cleaner" to see if valves can be loosened. Many folks like GM top end cleaner, but I've never used it.
It is likely the head must come off to repair the valves. You should rebuild head w/ new stem seals, reseat valves, and leak test. New head gasket should restore engine.
good luck
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