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Previous owner put a ton of time and money into this car. Cylinder head was even replaced at some point due to burnt valve. Anyway, went and charged my A/C this summer…drove it about 10 miles with no problems. Started to lose power and make an odd tapping/knocking noise and kept trying to die on me all within about a mile…limped it home, it sat ever since. Here’s the sound it makes under throttle:
https://www.youtube.com/watch?v=4au-xVDaJnk
I used a screwdriver as a ghetto stethoscope and could “feel” the tapping all over the rocker cover. No problems with timing or timing components, no exhaust leak…car starts and idles fine for the most part…put it in drive/reverse and it dies. Any thoughts? I would love to get this thing rolling again.
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http://www.ericthecarguy.com/faq/diagnosing-noises-in-your-car
take a look in there…. im sure youll find something.
Sounds a lot like rod knock in the video. Have you tried doing a cylinder contribution test (aka power balance test or cylinder drop test)? If not, it could be a good next step. If you’re not familiar with that test, basically you just remove spark plug wires one at a time (be careful of getting shocked–use insulated pliers and keep one hand behind your back so you don’t ground yourself with it). If the knocking sound gets a lot better (or even goes away) when you pull a certain plug wire, you’ve located the problem.
Cylinder 4, closest to the timing end, upon removing the spark plug boot makes absolutely no change to the way the car runs. Pulling the other 3 either make it die or prevent it from starting. Dead cylinder?
Well cylinder 4 isn’t getting spark, fuel, or compression. You need those 3 (and air) to create combustion.
It’s definitely getting spark. Injectors are new, and that one is clicking away like normal. Shuffled plugs around just for fun and there was no change, 4 still “dead” — will get a compression tester tomorrow. None of that would explain the loud sound under load, though, AFAIK…which can’t really be anything else besides an internal problem which sucks unless I am completely missing something.
It definitely sounds like a mechanical problem from the video, and based on your cylinder contribution test, #4 isn’t doing its job. All cylinders are supposed to contribute evenly. On an engine with no problems, the engine would react the same way when each of the cylinders is dropped out. Since #4 causes no reaction, therein lies the fault. If it were just missing spark or fuel it wouldn’t make the knocking sound IMO. A compression test can’t hurt, but probably won’t reveal much. The sound you are hearing comes from parts contacting each other when they aren’t supposed to (which doesn’t necessarily mean a loss of the ability to build compression). The next thing I would do, if it were mine, would be to take off the valve cover and check out the valve train to make sure it is all intact and okay. The reason is, this symptom can happen when a piston hits a valve, which can occur if there is a defect in the valve train such as a broken spring, loose or broken rocker, broken rocker stud, broken valve stem, etc — Since it has had head work done in the past, the head and valve train should be looked at very carefully. If everything in the valve train checks out fine, the problem is going to have something to do with the bottom end rotating assembly (crank, rod, bearings, wrist pin, piston, etc). You can certainly still do the compression test, it may yield a clue, but it’s pretty even odds that it won’t . A cylinder leakdown test would probably be better than a compression test, but it’s harder to DIY and would be best done in a shop with a beefy air compressor.
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