Hey everyone, I'm new here and found the site trying to figure out why my 3800 completely died driving home from the bar 3 weeks ago @ 2:30 in the morning!
Background: Bought the car Oct 09 from a lady I knew with blown engine (had a nice solid knock at higher RPM'* but car still ran and i drove it across town to my house). Pulled motor and bought a new one from Schram'* in Mason tagged with 6,800 miles for $650. Dropped it in and have never had a problem with it until 3 weeks ago.

The night of:Driving home I had no signs that I had troubles, I drove the car that day probably 70 miles or so. Coming home from the bar went through an *-curve after the first curve it felt like the car didnt have any go (I thought transmission since it shutters upon hard acceleration.. figured it decided to go out) and when i got out of the second curve i realized the engine was off. Coasted off the road and tried to re-start it. I had full power but motor was just turning over and no firing. Pulled it home the next morning and started diagnosing.

Progress so far: First off, I can't thank the ADMIN guy on here enough, he was the only one I could get fast information from since I was not able to PM anyone because I was new and didnt have 20 posts. The posts that had very similar symptoms NEVER ended with a resolution, I will make sure I complete this. He gave me some starting points and along with what I read I got to work. When I tried starting it the first couple times it almost seemed like it was locked up for some reason, the started was turning the engine at all. Checked battery and starter and found out the entire nose (part sticking into bell housing) on the starter had cracked, thankfully it was still sitting in same position and hadn't fallen down into flywheel. Bought new one and threw it in and still no turning over. I was able to turn it over by hand, which was strange and then it started turning over from that point on.
I scanned the car and got P0300 Random Misfire which many of you probably know is one of many things. First thing to check was fuel pressure, I had 40psi which is below recommended pressure so maybe the injectors weren't opening to let gas in (I am not aware of min pressure to open injectors but it seemed like I couild smell gas). I sprayed starter fluid into intake trying to bypass injectors to prove a fuel issue, but this resulted in no firing either.
Second check was spark, pulled all plug wires and tested them, they were fine. i went ahead and switched all coil packs just to be sure they weren't the problem (even though i had spark) and they were all fine too, engine still just turned over with no fire. Swapped out the Ignition Control Module (under coils) and that also had no affect.
Now, with spark and fuel I assumed timing next. Third I changed the Cam Position sensor and this also didn't change anything. Next up was the Crank Position sensor, pain in the *** BUT car pretty much fired right up instantly!

I have more to the story, this got the car running but now an even worse issue came up..... I will add more to it later, I am done with lunch at work and need to get back

Okay well im glad you got it figured out i shall await the rest of the story and standby to help with the bigger issue

His name is Danthurs... I can tell based on your steps of diagnosis.

Yep that would be Dan the man lol

Off topic but why can't I edit my first post to change a few typos?
1/8/2010 Continuing from yesteday

Once the car fired up I let it run for a minute tops and shut it off to check belt and area. I started it back up and it idled a bit rough and I let it run for maybe 2-3 minutes and was so happy and realized the garage started to fill up with a white hazy cloud..... killed engine and coolant came to mind.

I checked reservoir and it was empty, looked into radiator and couldn't see the level of coolant, and I added 1/2 gallon to top off radiator. Before I got the car running I checked the dipstick and oil looked good since I had just had it changed the week of/before car died. After I topped off coolant and tried to start it, she turned over twice and completely locked up! Checked dipstick and from car running it must have sucked coolant into cylinder or something because dipstick was already noticeably different....thicker milky looking.
Todays Progress Pulled all spark plugs and when I came around to cylinder 6 coolant immediately came out when I got plug out. After reading technical service bulletin http://www.tomorrowstechnician.com/A...II_Engine.aspx on upper intake plenum problems I pulled everything to get it off and look around EGR stove pipe. Once plenum was off we could see there was coolant leaking from somewhere, the entire lower intake areas around the ports leading to the valves was full of coolant. Gasket didn't appear to be sealing around the ports BUT this may have been due to trying to turn car over numerous times with throttle body closed and backfire pressure having nowhere easy to escape other than out through the gasket (who knows at this stage now, there could be a couple reasons why it appeared this way).
Heres what it looked like

Compression test showed cylinder 6 at 195 and the rest of the cylinders between 200-210psi. Lower intake/gasket didn't appear to be bad but since we were there and I don't want to do this again 6 months later I decided to pull that too to replace gaskets.

After inspecting upper plenum I can now see what the service bulletin was talking about and others who have experience with this degradation issue of the plenum. The gasket itself has some degradation on it also but it'* really interesting to see the problem. The coolant passages (1 on each side of EGR stove pipe passage) are so close that the heat melts the EGR passage and mine actually had a hole through the wall and the second picture shows what the wall of the passage all pitted and degraded.

This is where I am at this point, the replacement plenum everyone I have talked to said to get was a Dorman one. I will be getting one tomorrow for $120 and start to put everything back together.
If you have any suggestions or want info/pictures while I have it torn down let me know.

yours must have been way worse than mine, when it went i just got misfire code from that cyl. and a mysterious loss of coolant i couldnt find.

mine did the same thing.

crank sensor - except i had some brilliant mechanics changing parts....

-fuel pump, strainer, filter, relay

odd that they don't throw codes for a bad sensor.. nearly every other vehicle on the road would tell you via OBD.

my last LSS (1995) is rusting in peace now, due to intake manifold gaskets.

new LSS (1997) had them done already, and it seems to hold coolant and oil just fine. (i said that quietly, so the car wouldn't hear me)

Everything happened strange, the crank sensor going out and then getting it switched and having the car fire, start sucking coolant in all of a sudden to hydraulic 6th cylinder, and locking up to tear apart upper intake and find what the pictures showed above. There is no way I was driving for any period of time with the lower intake recessed areas full of coolant. My guess is from all the backfiring when trying to turn it over and get it to fire before having the crank sensor switched and the butterfly valve being closed on the intake forcing all the compressed air to blow out the upper plenum gasket. There was a few good backfires that actually blew smoke out from around the entire outer edge of upper plenum. I had the mysterious slow loss of coolant over time also, I just didn't realize I had the pin hole in the upper plenum causing coolant in. It was just burning off over time and due to coolant level sensor going on and off for so long (gunked up is my guess) I quit checking system.

Yea mine didn't throw code until 5-10 seconds before dying. I did upper and lower intake gaskets since I was there and flushed system of Dex-Cool and replaced with regular coolant. Car has been running good since having it back last Monday

Here are some additional pictures, I had issues with finding the same LIM gaskets that were originally on. When I tore them off and went to NAPA to get new ones they gave me the fel-pro ones (which normally I would have used BUT the ones I took off were so much nicer looking and heavy duty. NAPA wasn't seeing what I had online or in their catalog. They had the version 1 and version 2 (shown in first pic) but the fel-pro kit was showing as version 3 to replace V1 and V2.

This is the fel-pro kit

Here is the comparison of the two different gaskets, and why I wanted to get the OEM style that was originally on the car.

The contact surface is pretty much 100% of the surface of the head verse the contact surface of the fel-pro kit being only where the black rubber is. Andrews Chevrolet (our dealership in town) did some research and found them I believe on the 2005 year (I can double check this for anyone if you need, I have the part number too).
And one of them installed before UIM went on.


Car has run beautiful since, I just have a squeak coming from the belt now which is a bit annoying but you don't hear it once inside car and driving. Temp is good now and the oil even looks really good so far with not having done 200 or so miles and changing it due to small amount of coolant being in oil.

Maybe this will help someone else with the diagnosing process if your car does the same and some of the problems that could exist. All in all, all the mechanics of this was simple, just time consuming with the diagnosing and working on it in my small garage in the winter.

Phew..for a minute I thought that maybe you didn't use the latest and greatest aluminum framed gaskets.