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EA82 Engine Knock at Low RPM


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Okay guys. Same old DL Wagon: 1985 EA82 2WD five-speed, with a BRAND NEW carburetor I just installed.

 

Before I couldn't get my wagon to idle under 1100 RPM (sound familiar?). I had the carb idle speed set way up, so the thing wouldn't die on me. This caused the engine to Diesel after turning the key, making a nasty knocking sound. The old carburetor was VERY worn, with noticable throttle shaft play, so I replaced it. This allowed me to bring the idle all the way down to 700, where it is supposed to be.

 

BUT after running the engine a while, it developed the knock sound again at idle speed. This had caused the engine to stall before, and is continuing to cause the engine to stall at erratic times right now. The knock seems more pronounced when the engine is WARM, possibly because the carb choke plate is opening? The knock is still definitely most pronounced whenever the engine dies, creating that Dieseling sound.

 

I don't believe this is preignition; that is only supposed to happen during acceleration, correct? Could this have to do with the idle adjustment? I only use the top screw to set idle adjustment, never bothered much with the bottom one; never seemed to do anything anyhow. The carb is the Hitachi DCZ-328.

 

Any guesses?

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TOD

 

hydraulic lifters

 

with the higher engine "idle" speed, the oil pump kept the lifters quiet and full

chech your oil quantity and quality

 

TOD? Tip Of the Day? =]

 

I check and top off my oil level regularly because my engine has internal oil consumption. I'm pretty sure its full right now but I will fill it up a little more and take it around the block to see if there is a difference.

 

By hydraulic lifters you mean the lash adjusters on the EA82, correct? I did head-gaskets on this car before and noticed that one of the lash adjusters WAS a lot easier to depress than all the others? Could just one or two of this soft lash adjusters cause the knock?

 

And hey where would I get a cheap set of new ones? Mitzpah? I've heard their name mentioned before on this board.

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Okay I put in about half a quart and warmed it up real good. Didn't detect the knock, but as I said it is erratic. What I DID notice was the damn idle was REALLY erratic. For some reason the idle changes during driving, perhaps in correlation with temperature...I reset the timing to around 800 after I put in the half quart (had to raise it up earler today because of the knock). Not sure if the knock is just because the idle gets really low or what...I'm going to be carrying my laser tachometer around with me a lot more so I can figure that out.

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So does the knocking cause the engine to die at idle? If it does then I would'nt think it was lifters. The erratic idle could be caused from a malfuntioning distributer. Make sure the vacume advance on the disty holds vacume. They have a tendency to go bad over time. Pull the cap off and stick a hose on the nipple and suck. You should see the rotor advance and hold. If you replaced the carb with a new one, I would'nt mess with the idle or air screw yet as it should be set from the factory.

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hey there add this to your subaru dictonary :) TOD means tick of death :grin: . and that's your subaru grammer lesson for today :lol:

 

Har har! Well I guess that means I'm not the only one who'se experienced the "TOD" then. I just read in the haynes that the HVLAs aren't supposed to depress more than 0.5mm, and I REMEMBER that one of them depressed nearly a centimeter when I took the engine apart for that head gasket job. If everyone seems to think that's what's up then I will DEFINITELY replace them...

 

Where is the best place to get a new set? I could just replace the faulty one (or however many are bad now) with a good one from the junk yard I suppose, but would brand new ones be a better investment choice?

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Brand new lifters are way expensive. It's pretty easy to check them. Take them out, put them in a bowl of oil making sure that the small oil hole on the side is submerged and pump them a couple times. If they still depress after pumping on them then they are bad. I don't think that good lifters would solve your idle problem though. I think that is something else.

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Hmmm. Well what could it be then? I just checked the distributor timing and vacuum advance system. The two vacuum advance hoses were on snugly (I had even put hose clamps on both of them on the distributor side previously). The hose on the end of the vacuum advance unit was the vacuum hose (apparently) and the other once was a pressure relief/regulator hose or something I guess. Checked vacuum from the intake manifold while the engine was running. Good there. Tested the vacuum advance hose on the end of the unit while the engine was off, and it moved the breaker plate under the dust-proof cover by at least a couple of degrees. The breaker plate is what is supposed to move, not the rotor, correct?

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Your right, plate moves, not rotor. Back to the TOD first. From my reading here most people suggest first trying MMO, Marval Mystry Oil or something like that in the oil to try to clean the oil passages. This can work sometimes. If it does'nt solve the ticking then pull the oil pump and check the Micky Mouse seal. If its deformed reseal the oil pump and put it back in. If that does'nt solve it, replace the oil pump. And finally lastly, pull the lifters and clean, replace the bad ones or one. Ive done this on three subs and have had the best luck with replacing the pump. Timing belt covers can be left off to make all this easier. Lots of people on here leave them off. But then there is the chance that the knock isn't the lifters. Lifter knock as far as I know won't make a car stall. I'm not very familiar with the 2 hose disty. Mine has just one. I have read on here about distys that have worn out. Can you bring it back to idle buy pumping the throttle? Could the throttle cable be sticking?

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Hey there. YES the idle is erratic. And I've noticed that by pushing the gas pedal to the floor and letting off quickly the car will go back to its proper idle speed. BUT if I slowly rev the engine to about 2000 RPM and then carefully let off the gas, the engine will 'float' at a higher RPM for some reason, until i pound the gas to the floor again. I don't know why the hell the car is doing this; both the old and new carburetor did this for som reason.

 

I've heard the HVLA tick of death that some people are describing. This is nothing like that. The knock sound is muffled, not obnoxious, and is always precedes the engine dying. When it does happen, the whole engine shakes on its mounts and then the engine dies. PERHAPS this is simply because something like the distributor is allowing the engine to idle LOWER than 700, causing the engine to naturally die. I don't know. Like I said I'm going to be carrying my tachometer around with me and see if I can't recreate the knocking at a HIGH RPM to eliminate this possibility.

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