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Thread: '95 low rpm sputtering after head gasket replacement

  1. #1
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    '95 low rpm sputtering after head gasket replacement

    I just completed (my first ever) head gasket job on my 95 325is. It took a few cranks to get started but she finally got going. I've driven it about 30 miles and had several turn off/on cycles but it's still not running right. The engine is vibrating at idle (doesn't stall though) and lugging until about 3K rmp then she feels OK up from there. It almost sounds like a wrx turbo at low idle- a muffled sort of sound. Starts are a little difficult. No check engine light (yet). I used the cam block tools when reassembling so I feel good about getting the camshafts timed well. Putting the vanos on seemed to go OK, though it's possible I didn't get that lined up exactly as it should be.

    My question: are there other things to check before opening her up again and double checking the timing? Would the vanos timing being off cause the issues I'm describing?

    Head was pressure checked and planed.

    Thanks for any feedback.

    Sean

  2. #2
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    Did you buy the correct head gasket? Maybe you installed a thicker one and lowered the compression by doing so

  3. #3
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    Sounds like it could just be a vacuum leak. Are you sure that you have all the vacuum hoses, crankcase hoses, and air boot attached with no rips?

  4. #4
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    I installed the victor reinz set that includes the VCG and all other related gaskets so it was the standard gasket.

    I'll poke around and make sure all the hoses are attached and in good shape tonight.
    Last edited by FamilyForce6; 06-19-2017 at 10:56 AM.

  5. #5
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    Ive had to do several head jobs from botched 1st attempts from diyers. My walk-through process to determine all possible problems start with first a compression check to see if bent valves are the issue or cylinder wash accured. Happens on cylinder 6 intake a lot actually. I recheck the timing by popping the valve cover and setting tdc and retiming the camshafts and Vanos myself and assuring the camshaft gears are not overtightened and the Vanos seals are not completely worthless. Double check the intake tract and fuel rail and injector for being installed properly with the spray method. Check all sensors and connections. After that rely on codes for minor maintenance items like coils or sensors.

  6. #6
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    Had to Google fuel wash. Yikes, I hope it's not that.
    After installing camshaft I turned the engine 2 full rotations and verified timing, but I am a bit concerned I didn't get the vanos on correctly.
    Would it throw a CEL? Still don't have one... seems to be running a bit better today. Is there a learning process for the computer?

    I installed a rebuilt VANOS , had fuel injectors rebuilt (sonically cleaned, new o-rings and filters) and installed new fuel filter. I just checked the major vacuum hoses and didn't see anything.
    Last edited by FamilyForce6; 06-19-2017 at 10:48 PM.

  7. #7
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    If there are no codes then the tests preformed should still be 1st a compression check for bent valves and cylinder wash. It happens regularly from improperly drained head when the head is pulled off and coolant spills into the cylinder. When the coolant is cleaned it takes the oil film with it leaving an un oiled cylinder wall. This can lead to misfire or blatant no combustion. Leaving some oil in the cylinder over a couple days will restore the seal and fix the misfire. This will usually be around 50lbs or so of compression.

    If there is no compression you have bent valves in the installation process.

    Also for possible no code scenario. You can externally check crank and Cam sensors. I've had guys pinch the crank sensor wire on accident during head install. Cam sensor doesn't always throw a code and non factory Cam sensors tend to be junk from the box despite testing good.

    Fuel pressure test. Start with those.

  8. #8
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    Quote Originally Posted by spyderg0d View Post
    If there are no codes then the tests preformed should still be 1st a compression check for bent valves and cylinder wash. It happens regularly from improperly drained head when the head is pulled off and coolant spills into the cylinder. When the coolant is cleaned it takes the oil film with it leaving an un oiled cylinder wall. This can lead to misfire or blatant no combustion. Leaving some oil in the cylinder over a couple days will restore the seal and fix the misfire. This will usually be around 50lbs or so of compression.

    If there is no compression you have bent valves in the installation process.

    Also for possible no code scenario. You can externally check crank and Cam sensors. I've had guys pinch the crank sensor wire on accident during head install. Cam sensor doesn't always throw a code and non factory Cam sensors tend to be junk from the box despite testing good.

    Fuel pressure test. Start with those.
    spyderg0d, thank you. Your comments have been extremely helpful. Yes, I had coolant in cylinder 6 after I removed the head. That must have been part of the issue. I added a little oil to the combustion chamber and let it sit overnight and then started and it does seem to be running better. I did test compression last night. Ranged from 90 (cylinder 6, but the adapter I used for that cylinder only was a little funky that may have affected the reading of this loaner tool) to 125.

    Still getting just a bit of engine shake at idle through 2500 RPMs. I'll start driving it and see if it improves. It did finally throw a check engine light, but that was right after I tested the compression. It went away on the next start-up.

    Also, at the upper end of the engine speed, from 5-6K I hear a high-pitched whistle sound. I heard it before the head gasket job but it seems a bit louder now. Wondering if this is normal? I'll do a quick search of this forum and see what I come up with.
    Last edited by FamilyForce6; 06-23-2017 at 06:12 PM.

  9. #9
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    A whistle is probably an intake leak. ALOT of times the icv hose on the underside of the intake comes off.

    However, your readings are not acceptable. To maybe try again and make sure the fuel pump relay is pulled out so that fuel doesn't continue to wash the cylinders. Also when cranking the car, hold the gas pedal down all the way. Then your compression numbers will be more accurate and able to be diagnosed.

  10. #10
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    What he said.. Ha. But sometimes it takes a few times of wetting the cylinder with oil before it gets back to healthy state.

    If it doesn't take care of it then it's either off time or the rings are bad.

  11. #11
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    After weekend update.

    A follow up compression test showed cylinder 6 at 130 psi. The rest of the cylinders were in the 130-150 range. I decided that timing must be the issue. Cracked open the valve cover and reset timing. While the main exhaust timing sprocket was biased to the left, there was room (barely) to move it more tooth and thread the bolts. When I did this and re-started the car it ran terrible and immediately threw a check engine light. Ughh! Crack it open again and put the main sprocket back to where it was (yes, using the cam block tools and engine locked at TDC) Verify max amount of travel with intake and exhaust sprockets and reinstall Vanos. I triple checked that the Vanos "hooked up" immediately when installing. Started it up and it's now running the same as before. Mildly rough idle and sputtering from idle to about 3500 RPMs. It's drive-able but obviously not running right.
    I did notice that the high-pitched whistle is a little more noticeable so I'm going to try a smoke test on the intake side and see if I can detect any vacuum leaks.

    Curious, is this engine behavior consistent with a vacuum leak?

    Starting to get frustrated now. May just take it in to a indy BMW shop and have them poke around. Too many hours spent on this project!

  12. #12
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    Ok. So your compression came back OK. That would have left out the timing being off and rings being worn. That does narrow it down to a severe intake leak.

    I've seen cheap intake gaskets that expand and blow out of the slots of the intake port guides. Leaving 1 cylinder open to atmosphere and creating a horrible idle and a engine that shook like an overloaded cloths washer being kicked down a flight of stairs.. A vacuum leak absolutely can cause it.

  13. #13
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    You either timed it right or you didn't!?
    Attn. NEWBIES: Use the search feature, 98% has already been discussed.
    Click the search button, select "search single content type", select the "e36 sub forum" specifically, try the "search titles" then try the "search entire posts".

  14. #14
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    You had the vanos off and followed the besian systems guide to do the job? Properly advanced the gear when installing the vanos?
    Attn. NEWBIES: Use the search feature, 98% has already been discussed.
    Click the search button, select "search single content type", select the "e36 sub forum" specifically, try the "search titles" then try the "search entire posts".

  15. #15
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    If the intake or the exhaust camshaft where off by a tooth The compression would be obvious signs and would drop about 30lbs or more. Even if the Vanos was off a tooth, the engine would run OK minus an idle bounce and the Vanos actuator code or the alike in camshaft CEl code.

    The thing that concerns me is the lack of cel. Usually with misfires lean codes or something similar will show up atleast. The only time a lack of code has ever bothered me was crank or Cam sensors on the way out.

  16. #16
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    Yes, I'm confident that I installed the vanos properly.

    Last night I performed a smoke test on the intake and no leaks detected. Grrr. I'm still not throwing a CEL.
    The idle does bounce around a little, especially when cold but it's not terrible (I did clean the ICV when I had the head out). I believe it's running rich. There is just a little black smoke at WOT before it totally warmed up (only taking it up to 3-3500 RPMs)

    What would be next on the troubleshooting list? Coils?

    One other note... After the last re-assembly when I was test driving coming on a cloverleaf on-ramp and was moving fairly good then running it up to redline when it stalled out on me. I was able to re-start it before coming to a stop and that hasn't happened again.

  17. #17
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    If it runs better with a Vanos reinstall then it probably did indeed correct an issue. Sometimes even over tightening the Cam gears can cause serious issues.
    A puff of smoke at any piont would consider a rich condition.
    I think the next step would be to start checking Cam and crank sensors. You can also check coils with a meter while your at it. If none of that shows an fault, I would then take the car to get diagnostic tests done after you've double checked injectors are connected and fuel pressure is good. Unless you can find a way to read the live data and see obvious err.

  18. #18
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    Well, it's definitely running rich. I've just ordered a single ignition coil and will swap out 1 at a time to see if that might be my issue. I contemplated replacing the cam and crank sensors while I was in there but quite frankly I was sick of dropping dough on all the "while I'm in there" parts. I'm hoping that the coil is the issue. From my research it appears that the simple voltage check on the coils isn't a very effective diagnostic tool so I'm just going to start with the swap out method.

    Will driving it in this condition for a week or two ruin the cats? I have a diagnostic scheduled at a local bmw indy shop but they can't get me in for a week and 1/2.

    On an unrelated note my (brand new) low coolant sensor is not working- I have plenty of coolant but get the low warning every time I get out of the car. Oh the joy of keeping a 22 year old vehicle as my daily driver!

  19. #19
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    Solved!
    Took my car to a local place (shout out to Yanzito Imports in Parker, CO and Nick- awesome guy!) who diagnosed a misfire in cylinder 3. Found out that the fuel injector was dead. Kind of weird since it was working prior to HG job and I had the injectors rebuilt. Oh well.

    The important thing is that she is purring like a kitten. I'm thrilled to be FINALLY driving her after 7 months of various stages of disrepair. Woot!
    Last edited by FamilyForce6; 07-20-2017 at 10:09 PM.

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