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Crankshaft Timing Mark TDC

9K views 25 replies 5 participants last post by  dmdicks 
#1 · (Edited)
I'm up a creek without a paddle...

2008 G6BA

Following 'DIY Timing Belt Replacement', I lined everything up, took the crank pulley, belt etc off with no worries. It is in neutral

Putting it back on, I had many worries.
When putting the belt on and turning it over for two rotations, I had the crank pulley overshoot the timing mark, but the cam sprockets were both on TDC. I got mixed up with the instructions while having the belt on and having it off and I rotated the crank pulley two full revolutions and tried again. Same thing happened, so I repeated. On the third time, while rotating the crank, at just short of half a turn it has become stuck, it will not move either way. I took the spark plugs out and it made no difference.

I can't wrap my head around why it's stuck - it makes sense that if it was colliding with valves that it would stop, but would turn back the other way. I'm clutching at straws, but I'm honestly praying that turning it over by hand means that the cylinders weren't lubricated.

Other than 'you've messed it up' or 'call a mechanic', does anyone know what is happening in the engine, and possibly what to do about it?

Thank you
 
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#2 · (Edited)
Welcome to NT.

Is this an I4?

How far off was the timing when you started this? If a tooth or two, doubt you did anything to the engine while turning it by hand.
You were turning it clockwise, yes?
You let the tensioner go before turning the crank, yes?
Is it still in neutral?

PS, please put in a location and fill in your signature with car year, model, engine, trans and any mods.
Thanks.
 
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#3 ·
G6BA = Delta 2.7 V6 ;)

Trying to understand what the poster did. Did you rotate the crank two full revolutions without the timing belt attached? How far off is the crank from TDC when the cams are lined up?

If the valves were somehow open as #1 cylinder approached TDC then its possible they contacted the pistons and jammed the engine. Did you remove all the plugs from the engine or just the from bank?
 
#4 ·
I thought it was a V6, but didn't want to assume.:wink2:
 
#5 ·
Hi Guys, thanks for your replies

Yep it's the V6

I lined the three marks up when I took the belt off, however when I put it back on it and hand rotated, the sprockets were aligned, but the crank was off by half a tooth (in the clockwise direction) the first time. I took the belt off and then rotated the crank two full revolutions clockwise (I'm a bloody genius I know). Then I put the belt back on and turned the crank through two revolutions and it was off by about a tooth and a half. I took the belt back off and tried to rotate the crank again. At about half a revolution it has seized, and won't move either way.

I took all six spark plugs out and there has been no change. Looking through the holes, there is wet, black, sooty sludge on each cylinder, I'm unsure how deep this is.

I've read a few different things about valve position when at the alignment marks, I'm still trying to find a drawing for this engine which shows whether or not the cylinders will hit the valves when the sprockets are aligned with timing marks.

Hindsight being the beautiful feel-good thing it is, has shown me I should have just rotated the crank counterclockwise
 
#6 · (Edited)
(cylinders wont hit the valves, the pistons will) it sounds like you have a set of intake valves on one bank that are open and a set of exhaust valves open on the opposite bank so you have 2 pistons jammed against them. you should be able to look at the valve train and see if this is the case. if it is, (maybe @Charlie-III or @dmdicks has another way that is easier) you will need to release your cams so all the valves will close up. then set the crank timing marks at TDC #1 cylinder, then align the cam timing marks and reinstall the cams. wedge some rubber under the cam gears and cyl. head so they dont move on you. reinstall timing belt. doubtful you have bent anything at this point. :wink2::wink2:
 
#10 · (Edited)
youre welcome. i see your question has already been answered but ill try and "re-phrase" it. you have an "interference fit" engine. that means if you move the crankshaft, you must move the camshafts together in unison with the crank lest you have an internal collision since there is no clearance between valve and piston deck when a valve is open and its corresponding piston is at TDC. were it not an interference engine, this would not be a problem and you could just simply "line everything up" and be done with it. good luck, let us know how it works out.:wink2::wink2:
 
#8 ·
The problem is once you disconnected the crank from the cams by removing the belt you completed messed up the engine timing. Your cams may have been set to cylinder #1 TDC on the ignition stroke but now the crank is on TDC on the exhaust stroke.

You most certainly have valves in contact with pistons and the only real way to fix it is by removing all the cams like oni888 said. This will let you know if you've bent or broken anything and allow you to reset all the timing marks to where they should be.

Make sure you have a copy of the repair manual and follow everything it says.
 
#9 ·
@oni888 is correct.
Now, if I was in your position, there are a couple things I would try, but I also take my own responsibility and the method is more feel and would not translate well to a post.

This, I would go along with @dmdicks and follow the manual for installing heads. I will hazard a guess you don't have to pull the heads but you will likely need to pull the UIM and valve covers.

As an aside, and just for info, with the TB off, turning the crank 1 full turn (360*) is a full cycle.
With the TB on, turning the crank 2 full turns (720*) is a full cycle since the cams are now involved.
 
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#11 ·
Oni, Charlie and Dmdicks, you guys are absolute legends! Lifted the cams, valves closed and crankshaft was free to turn, thank you so much!

Also I now know that at the timing mark for the rear cams, cyl 3 is open for intake and 5 is open for exhaust. I could have rotated the cam a quarter turn clockwise to close all valves, good to know for the future!
 
#12 ·
So, is it running yet!?!?>:D

We're glad to help, hope it works out. Post back here if something else comes up related to this task, I hate merging threads to keep all relevant info together.

If you have something else come up, it's fine to start a new thread.:wink2:
 
#13 ·
Okay Charlie, it's not running...

So the car hasn't been running in a month, and has spent most of that on two stands at the front. When turning the ignition, the starter motor is engaging and the crank is turning over, the spark plug cables are getting electricity, but there's no combustion in the cylinders. I've gone right over a few times, all the cables are plugged in, all of the hoses are connected. The battery had 13.5V when I started. I'm thinking something along the lines of fuel has drained from the lines. Can you guys think of possible causes and possible solutions?

Thank you!
 
#14 ·
Also, I should add - I changed the spark plugs with new plugs (same type), connected the correct cables to the correct cylinders and pushed the boots on so they clicked

Turning the engine over the first time, it sounded like it was about to go, but then didn't

Thanks
 
#15 ·
Thanks for replying.

When you turn the key "on", do you hear the fuel pump come on? You should. If you don't then you need to check fuses.

Are you saying you're getting spark? I assume yes.

There are 2 plugs by the throttle body, same design but,slightly different colors, double,check them. If that looks good, try unplugging the MAF and cranking the engine, see if it starts.
 
#16 ·
Prime the fuel injectors a few few times by turning the key on until you here the fuel pump kick back off and turn the key off for a couple seconds and repeat, I would recommend 3 or 4 times as that should refill your lines. Your fuel lines may be out of fuel and they just need refueled. If it still cranks it but no start... . Pull one of your spark plugs and smell for gas on it. If there is no gas on the plugs, You can pull the front two bolts holding your injectors rail and wiggle the front injectors out of the head. Careful not to bend or crimp the fuel rail when doing this. Go back and turn the key to see if any fuel sprays out of any of the injectors. If that fails, remove a clip holding the injector on and wiggle a injector off.. hopefully fuel will come gushing out. If it does.. it is probably your crankshaft position sensor that needs replaced. As for those two sensors Charlie was talking about connected to the throttle body.. one has a grayish stripe on it.. that one goes to the TPS as the full black one goes to the IAC. They easily get switched up.
 
#19 ·
Great news, she's running!

I charged the battery and turned between 'on' and 'acc' many times to keep the fuel pump going. After lots of coughing and spluttering, we finally got there! Thanks for your help!

Stay tuned, I'm sure I'll have more questions before she's 100%
 
#20 ·
Okay, so we were running well... until today. I hadn't driven the car in 36 hours.

Had trouble starting, tried two or three times where the engine would crank, but it would just die. I ran the fuel pump a few times, put my foot on the accelerator and tried, and she started. Starting the car after work was no issue. I should also add it was a bit colder this morning, 8 degrees celsius, and in the afternoon it was about 20 degrees celsius.

Today I also lost acceleration, this past week it has been better than ever, but today it had lost so much. The idle is also rough, not high, but rough.

What's been happening over the past week, is there's been a delay between starting and the tachy kicking in. When it does, it usually shows about 750rpm. Then it would pick up to about 950rpm. Idling after driving is about 950rpm. This has not changed. When stopping on hills and trying to pull off, it has been a bit of work to prevent the revs from dropping low enough for it to stall, which seems to happen less than 500rpm. The throttle was also sticky, I did notice a bit of a build up in the throttle body, but didn't get around to cleaning it yesterday. The throttle was not sticky today.

Since I got the car almost three years ago, a full tank would always give a range of 389km. Now it's showing me 530km and this seems to be accurate.

I'm hoping that the issue is fuel - maybe a clogged fuel filter. I'm thinking that if it's running lean, opening the throttle without much more fuel being added, would cause the reduced acceleration.
I'm thinking that if it was a vacuum leak that the revs would be higher. Air filter was changed three months ago.
I'm thinking that if it was a compression issue I'd have trouble starting all the time, and also if it was the valves, the issue would be consistent.
I did change the spark plugs when I did the belt, and torqued them to manual spec.
So far, there are no apparent leaks. The engine bay does smell like coolant, but to be fair I spilled a fair bit trying to bleed the lines

The other thing I'm thinking is the crank position sensor. I'm honestly not too sure how this works though.

Would anyone please be able to shed some light?

Thank you
 
#21 ·
Crankshaft position sensor reads the orientation of the crankshaft in the block. I believe I read somewhere by a magnet? This corresponds and send info to the ECU along with info from the camshaft position sensor to to send fuel and spark to ignite whatever piston is suppose to be firing for the engine at that stroke. On the tib the crankshaft position sensor is a common problem. Located below the front exhaust manifold. Mine was terrible when I replaced it. No insulation left on the wires and they were horribly corroded coming off the sensor. I had issues like yours stated earlier after a timing belt change. Wouldn't start, and when months before I could start it and it would immediately die. Replaced the crankshaft position sensor a few weeks back and no more problems
 
#24 ·
Hey Guys,
Before I drop $150 on a crankshaft position sensor, I noticed that when my headlights are on, the air recirculation button and the A with the circle (don't know what this does) button lights aren't on when they should be blue.

Is there a chance a fuse has blown and this is related?

Thanks
 
#25 ·
I highly doubt it.
 
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