Small Imperfection In Pushrods

Discussion in 'General Automotive Tech' started by AshTray900, Mar 3, 2020.

  1. AshTray900

    AshTray900 Well-Known Member

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    So I've got the good old 3100 in my midsize wagon, It ran well and blew the intake gasket, I replaced it, however the stupid parts store sold me the wrong one like always... anyway this gasket had retaining plastic guides for the rods but mine was the earlier model with metal ones included on the engine, i did not notice this, mounted the gasket, put the car back together, it ran horribly, then sometimes great then sometimes horribly, off and on, no rhyme or reason. i pulled the LIM again, noticed the issue, replaced with the felpro metal one (i should have done this initially but again the idiot at the parts store didnt know anything and didnt bother to even suggest it until i yelled on the second trip to them.

    I checked the pushrods as i noticed (i think it was the intake ones) had been rubbing against the plastic guides, the rods looked fine, i even rolled them on the concrete and barely noticed a difference in how smoothly they rolled, but i never thought of these as bent or even an issue, but the set that was in a bind on the old gasket didnt roll as easily, however even looking at them as i rolled them around i really couldnt tell a gap popping up that i noticed. so (when i should of course just got new ones) i reinstalled the originals, the car then ran and drove ok, but idled a little crappy but never threw any codes at all, just shakey idle, and the temperature gauge doesnt appear to be stable it moves up and down based on the fans, before it would lock dead on (the thermostat and sender are fine) and it doesnt overheat it just kicks the fans on and brings it down, heavier driving brings it on more, not sitting at a light, outside temp does not make a lick of a difference on its behavior

    no cross contamination of oil and water, no noticeable compression entering the cooling system no blubbles in coolant, no loss of coolant.

    so pushrods causing shakey idle or does it just need head work, what do you guys think, ive heard horror stories of stripping the rocker studs and they are all currently fine, while easy to get to id rather not change these rods if there is little to no change such a small imperfection would make it idle crappy (it never dies or tries to, just shakes at idle and feels like a car missing but thats been ruled out all the way to the plugs) and before this fiasco it did not do this

    best course to move forward, id like to turn it into a daily driver i can trust as i need it for a long road trip to haul something, driving it around town is no issue.

    thoughts here would be welcome, thanks!
     
  2. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    I've done several head gasket jobs on this line of engines, and I have found that the engine won't smooth out until the lifters have finished filling up. I also found that when filling the cooling system, if you take the small hose off the pipe that runs under the upper intake above the bleeder, it allows more air to escape that piping before you fire it up.
     
  3. AshTray900

    AshTray900 Well-Known Member

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    The head gaskets we’re not changed, the LIM gasket was, been driving it 20 k miles since, but not long long trips, I assume the tiny difference is irrelevant since like you say it’s not an adjustable system to my knowledge, it relies on the lifters, I notice the stupid air vent is not the highest point which is ridiculous, but after all this time I would hope it would have “burped” any little air that might be trapped.

    symptoms, fires up like a champ, like a new car, runs a little rich as expected on startup, idles a tiny bit high which I also assume is normal, and it idles perfectly for a minute at tops, then notice it start to shake and I can hear the unsteady rpms, and can also see them on the scantool, say 650-800 which would be ok but it bounces around and this is before the gauge even registers any temp and the motor is still basically cool, once driving under acceleration I don’t notice any issues, but stop at a light and it’s shaking like a misfire, no codes at all, passed scottys cigar vacuum leak test lol. It won’t die it just shakes.

    mechanic said “no signs of head gasket failure” but I have no idea if he did the compression check or not. By the absence of codes and no actual signs of an issue I can pinpoint and several sensors changed I’m not sure what I’m dealing with, feels like maybe the computer keeps trying to rectify an issue and can’t balance it out.

    I actually took it to a mechanic to figure this out and do some other stuff, he said the injectors were bad and changed them but 0 difference, he replaced a lot of mounts and seals requiring the subframe lowered and didn’t charge me much so they basically did the labor for free on the injectors but they seem to act like it was fixed, cranked up great in their shop and drove off, after 3 lights it was doing it again, and I also noticed I lost a couple quarts of tranny fluid bc they did not tighten the freaking pan so I finished that off and never took it back there for further diagnosis, but I think it stumped them too

    it also seems to be putting out a lot of exhaust fumes, not fuel, not coolant but just like 3 times as much as my 6cyl accord, just regular exhaust, it will have me running out of the garage even with the door wide open
     
  4. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    Have you watched the oxygen sensors, to see what they're doing? Have you noted the ECT (Engine Coolant Temp) sensor reading at start-up versus operating temperature? Have you watched the MAP sensor? And verified, with a vacuum gauge, that the MAP plus vacuum equals the MAP when the key is on but the engine isn't running? Those all affect the fuel control side of the air-fuel mixture. My example yesterday was based on not fully pumped up lifters. Today's example is what's affecting the computer's control of the injectors. At idle, the upstream sensor (only one upstream sensor on the 3100/3400) should be rapidly switching from 100 to 900 millivolts, generally at a 40 millisecond rate, but pretty fast on a scan tool screen, and should not be stuck at any one voltage. On the ECT, the reading at ambient temperature should be somewhere in the 3.5 to 4 volt range, and at operating temperature, around .8 to 1 volt. Disconnected, there should be five volts on one of the wires (reference voltage). The MAP should read approximate barometric pressure with the key on, engine off, but once started, should read about 10" of absolute pressure. Start with those, and verify you don't have vacuum leaks anywhere.
     
  5. AshTray900

    AshTray900 Well-Known Member

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    I’ve changed so many sensors out, all of those you mentioned, the upstream sensor reads like you say fluctuations as a I can remember, I probably should get a vacuum gauge and test that way. I’ll try to break out the scantool again, or convince my friend to bring out the 5 grand one lol. Thanks for the info, I wish I had another 3100 sitting right by it running perfectly to compare readings to, even my friend who is a real good mechanic kinda is guessing in the dark on this one, got tired of it a couple years ago and have just been driving it on the side for awhile like it is, maybe I should just put it into daily use when all the nasty weather is gone, hell it might work itself out, who knows. Thanks for the sensor info that’s a big help
     
  6. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    You're welcome. I kinda wish I could be there to do the diagnosis; it is difficult to do it this way. My magic crystal ball's funny in that way.
     
  7. AshTray900

    AshTray900 Well-Known Member

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    yeah, im kind of thinking its some kind of sensor related issue, but ive just been around the block with it and had 0 success i might replace the first 02 sensor, its stock, IAC was stock but i threw a bunch of cleaner in it when doing LIM and even removed it later and verified it would move fine, cleaned throttle body, adjusted butterfly as it would barely bind at closed throttle.

    i think it has to be sensors, as far as i know upon start the car runs with little to no computer correction and then it kicks in after a little bit, so initial fire up and perfect run seems to rule out the following below

    plugs/wires (recently changed)
    fuel system (injectors replaced)
    complete spark and fuel system all together
    internal engine issues
    cam and both crank sensors (or at least one) due to needing them immediately and getting no misfire code or any code at all
    just about anything required to run the vehicle at the basic level with default PCM/ECU settings in place

    dont think so because already replaced:

    downstream 02
    MAF
    MAP
    TPS
    CAM and side CRANK sensors (flywheel one is original)
    ignition coil packs and ignition module wires and plugs
    injectors and o rings
    catalytic converter (it was checked by exhaust shop)
    LIM gasket

    possible but i dunno
    vacuum leak (only hissing i hear is by the power steering pump and ive tried to narrow it down and it appears to be the pump which is a reman) i also replaced every hose, grommet and PCV valve
    charcoal can (who knows here?)
    upstream 02

    id really like to know the actual source code for the computer so i could read through it and see what happens at different intervals after cranking (pulling a sensor wire either results in stalling or same condition with a code thrown for the sensor) i wish you were here too! im tired of chasing my tail, might have to just break down and find a better mechanic to smoke test for vacuum leaks and to hook an expensive computer to it and read the data and just not mention any of the things i did so they dont start assuming i screwed it up or try to rule anything out.
     
  8. AshTray900

    AshTray900 Well-Known Member

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    or just plain out compression issues in heads that only surface a minute after the cylinder warms up before the entire engine. seems to have good pickup and go for the size of the car vs the motor, it will buck forward easily but not screech tires of course lol
     
  9. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    I didn't see one important maintenance item in your lists: a fuel filter. They should be replaced every year, without fail. Keeping the one in your car for a loooong time not only eventually makes the engine run rough, but puts too much stress on the fuel pump by causing it to overheat, which kills the magnets eventually. And BTW, changing the downstream does not affect driveability. It only informs the computer whether the catalyst is in its efficiency range, or not.
     
  10. AshTray900

    AshTray900 Well-Known Member

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    Yeah I replaced that 02 due to fault code, took her out on the highway for a few hours today ran pretty decent, she has better days than others, like the old ones that prefer certain climate conditions lol
     

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