cannot start after head rebuild

[jdamron]

I very carefully got everything put back together after having the head rebuilt by a local machine shop. (I had some ongoing problems after replacing several parts -- see other thread for things I did before the head rebuild in case you are interested: http://www.gaownersclub.com/forum/showthread.php?t=85262).

I used all brand new gaskets and I was extremely careful with the timing. I have attached below some images of what the timing looked like before I closed the cover. However, now I cannot start the car. The engine turns over for a second or two, sputters a bit, and sometimes backfires, and then dies without every starting. I can smell fuel vapors and if I remove the throttle body cover I can see fuel vapors puff out of the throttle body when trying to start. I know timing is suspect but according to the images below my timing was right.

I was wondering if anyone has any ideas of anything else I should look at. Are there any special procedures for starting up this engine after a head rebuild? Also here is a link to more detailed pictures of the whole job if anyone is interested: http://damronplanet.com/grandam/headinstallation/index.html

Thanks,

Jonathan

[Ralph]

I suggest looking into your ignition setup. Plugs, Coilpack, make sure you plugged in ICM

[jdamron]

I suggest looking into your ignition setup. Plugs, Coilpack, make sure you plugged in ICM

Thanks Ralph for the ideas. I did double-check that the ICM is plugged in. And I also took out a couple of spark plugs and noticed they were wet with gasoline but otherwise looked okay. I will look more closely at the rest of the ignition setup.

Thanks,

Jonathan

[xGibbyx]

Are you sure you put the push-rods back in the places they came from? The pushrods for the 3.4 LOOK the same length, but they aren't. And I know the 3.1 doesn't look anything alike...and for that matter, we re-built his 3.1 AGAIN because he put the push rods back in the wrong way. This MAY be a factor, because it sounds like you aren't sucking or spitting when you're supposed to be.

[jdamron]

Thanks xGibbyx for the ideas. I agree with your description of my problem: it sounds like you aren't sucking or spitting when you're supposed to be.

However, in my particular engine I do not have push rods. My engine is the overhead cam type that does not use push rods.

Thanks,

Jonathan

[spy]

clean your plugs, make sure they're dry and not soaked, make sure all of your engine harness is hooked up properly. your assembly seems to be as it should be. Make sure your grounds are all hooked up correctly and properly. make sure your battery is hooked up.

you're going to have to just keep on looking around for some loose harness or ignition issue or something.





for the record this is the 2.4L section and there are no pushrods.

[Jchiasson]

Remember to that even though the connectors physically feel like they are connected it doesn't mean the wires are necessarily connected. Sometimes in the act of putting them together a wire may back out of the connector and not actually connect.

[xGibbyx]

LOL, i have no idea about the 2.4...I should have known though, since I did know it was a DOHC...anyway, good luck.

[jdamron]

Well, I just finished testing the compression on all four cylinders using the instructions in my manual. Everything seems to check out good. The compression maxes out the same for all four cylinders at round 210. And it does rapidly increase with each engine turnover as the book says it should -- basically it goes from 60 to 120 to 180 to 210 very quickly and then stays there. This seems to indicate healthy piston rings and valves.

So, the big question is if it is possible to get these good compression results and still have the timing be off? What do you guys think? I was thinking about checking spark before I tear off the front of the engine.

Thanks,

Jonathan

[Ralph]

get to checking the spark and inspect the coilpack for cracks these notoriously go bad on the 2.4

[jdamron]

Since my last post I have completed a spark test. And I have good spark on all four spark plug boots. I also put in new AC Delco plugs at the right gap. And I replaced the camshaft position sensor. But it will still not start.

My latest theory is that someway (even though I was very careful) perhaps I swapped my camshafts when I put everything back together. I went by the GM parts dealer today during lunch and confirmed that there are indeed two separate part numbers for the two camshafts for my vehicle. However, the person I spoke with was not able to find any identifiable markings to determine which one is which. And even though I took tons of pictures I do not have any pictures of the camshafts themselves when I was taking them apart. I do however, have pictures of the two camshafts when I was putting them together. So, my big question is if there is anyway of telling by looking at these pictures if I have indeed swapped my camshafts. My concern is that even if I take everything apart so that I can look at them that I will still not be able to tell which one is which.

Here is the best picture of the camshaft that I put in my exhaust camshaft housing:
http://damronplanet.com/grandam/headinstallation/full/HeadInstallation%20018.jpg

And here is the best picture I have of the camshaft I put in my intake camshaft housing:
http://damronplanet.com/grandam/headinstallation/full/HeadInstallation%20027.jpg

What do you think?

Here is my theory. I think the sixth round lobe down on the camshaft I installed in my exhaust camshaft housing looks to be a different color and width from all the other ones. And the position of it seems to line up where the camshaft position sensor is installed in the intake camshaft housing. My guess is that I have swapped them. Here is a picture of the identified special lobe highlighted:
http://damronplanet.com/grandam/speciallobe.jpg

And here is a picture of the camshaft position sensor highlighted:
http://damronplanet.com/grandam/camshaftsensorlocation.jpg

Thanks,

Jonathan

[spy]

on the intake camshaft there is a "half lobe" that the cam position sensor uses to determine cam position. if you have these cams switched that may be an issue. Then again you shouldn't need the cam position sensor to start the car as the car will simply go into a default batch fire mode.

However, if the cams are swapped in the wrong housings, disassemble and swap them around to the proper housings. Just to be sure and safe and of proper order. As having the intake cam in the exhaust cam housing and vice versa you're going to be throwing codes.

[biggnome]

Quick check to see if the cams are swapped, pull the P/S pump and check to make sure it has a receptacle in the end of the camshaft.

Tim