This is the first time I've ever posted anything in any forum ever, so please bear with me. It's been years since I've done anything to do with timing. I got overzealous when taking things apart and this is where I'm at. I have a 1991 Chrysler LeBaron GTC - V6 - 3.0L 2972cc 181ci GAS MFI 2 valve SOHC. I'm doing a water pump, oil pump, and replacing the oil pick up screen. Now the question is. I have the 2 camshaft at top dead center. Now what about the crankshaft one? The camshaft one did move then I readjusted it to make sure both camshafts were at TDC. I'm just not sure if the crankshaft moved or not. I forgot to mark it before I took off the belt. I know the gear has to come off to replace the oil pump. I think the biggest question is do the crankshaft and and the camshafts both be in the top dead center position to keep it in correct time. I'm also not sure which mark on the gear of the crankshaft is the timing mark. Is it the square, or is it the small circle on the gear? I have a picture of the crankshaft gear with the markings I'm talking about but I'm not sure how to upload it. Thanks if anyone can help me out it would be very much appreciated.
Timing trouble
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There is a mark on each camshaft sprocket that aligns with a mark on the generator bracket, inner timing cover. The crankshaft sprocket aligns with a mark on the oil pump cover. See attached image.
Be careful rotating one camshaft independently of the other. An open valve will not hit a piston but an open valve on one bank might hit an open valve on the opposite bank.
Thanks AllanC. I know I probably seem kind of ignorant and some may say I shouldn't be doing this. I have little money and haven't taken on a project quite this large for some time now, but I'm trying lol. I think I'm saying everything correctly. The one camshaft ended up moving on me. I honestly don't know how it happened. I got both camshafts lined up with the marks on the bracket and oil pump. I'm not sure what mark on the crankshaft gear is the correct timing mark. If it's the square(blue) or the small little circle(red) that's on the gear. I don't see any other markings on the gear. I'm pretty sure the arrow circled in green is the timing mark. When I put the belt on all three should be on there marks or TDC(?) and it will be in time correct? I'm doing my best to describe things, so I hope I'm doing ok. Here are the 2 pictures of the camshaft marks and the picture of the crankshaft gear.
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Quite often when aligning timing marks on the camshaft, one or more valves will be open. That means the cam lobe is exerting high pressure on the valve tappet or follower and compressing the valve spring. It does not take much vibration or other action around the camshaft sprocket to cause the shaft to turn and relieve pressure on the compressed valve spring(s).
I believe you mean camshafts aligned with the mark on the generator bracket and timing cover. Mark on the oil pump housing is for aligning the crankshaft sprocket.
See attached image. Align depressed circle highlighted in red with arrow on oil pump housing. Then you will have timing of crankshaft to camshafts set correctly. I am including a second image that details how to install belt and set tensioner. Instruction #6 is important. Once all timing marks aligned properly and timing belt installed and tensioned properly, slowly turn crankshaft TWO full turn turns clockwise. Listen for any strange noises or feel anything in the wrench when you turn the crankshaft. If everything done properly no jarring, or sudden lockup or strange noise will emanate. If you pass this test then you are ready to continue engine reassembly and engine startup.
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The dot circled in red is the crankshaft sprocket index mark. Line it up with the pointer circled in green.
I have used the soft clamping action of clothespins, etc to hold the belt from jumping in the sprocket teeth while reassembling.
I have used the soft clamping action of clothespins, etc to hold the belt from jumping in the sprocket teeth while reassembling.
I have the water pump, oil pump, and replaced the oil pick up screen. It also turned into new plugs, wires, valve cover gaskets, fuel injectors, cap and rotor, and a new oil sensor. I believe that's all. I checked the timing by doing the manual rotations with the marks lined up. As far as I know when I put things back together the marks were where they are supposed to be. The car seemed to take a little bit to start up. Was running a little rough and took it for a drive and it didn't seem to straighten out. There's like a pulse sound when the engine is running, so I went and moved the distributor cap and adjusted it as well as possible and it cleared up some. Used a timing light and it seems to show the mark appearing before the metal tube that's, as far as I know, the reference point to go by for seeing if things line up correctly. There's nothing other than that tube to shine the light through. There's no other guide like what I have observed in some pictures where there is a piece of metal that has numbers for showing how far above or below TDC. I'm guessing the timing is off. I took the one cover I could get to for the one cam shaft and used the light on it and it seems to hit pretty close to the timing mark on the engine when it is running. It may be a tooth off at most as far as I can tell. Do I need to take off the front plate and pulleys off so I can readjust things? I don't think there's any other way to check all the marks other than doing that. Stupid question probably, because that' was my plan to try and check things out. Everything else seems to be working great. Thanks for all the help so far it's been great help to me.
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Double-check the timing mark locations. After first setting them, it is a good idea to rotate the crankshaft 2x to see if the marks land in the same place, as Valiant says. The timing belt can settle into the sprockets and the belt length/mark positions may change.
The tube at the timing marks is for a magnetic probe used by the shop to read ignition timing. You can still use the timing angle numbers.
Is the 'pulsing' perhaps a single cylinder misfire?
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The tube at the timing marks is for a magnetic probe used by the shop to read ignition timing. You can still use the timing angle numbers.
Is the 'pulsing' perhaps a single cylinder misfire?
When checking the timing with appropriate pulse lamp, did you first disconnect the coolant temperature sensor at the thermostat housing? You must do this to put the engine in fixed, base timing mode. This will cause the radiator fan to start running, illuminate the CHECK ENGINE lamp, and set diagnostic code 22 in the engine control unit. After adjusting the timing accordingly and then reconnect the sensor wire. Disconnect battery momentarily to clear the diagnostic code. See attached image.
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I just skimmed over this thread as I don't know much about 3.0's
I typically don't post on topics I'm not familiar with but you've mentioned TDC.
TDC stands for Top Dead Center, referring to when the #1 piston is at this point.
Typically, this was the starting point for aligning camshafts with crankshafts.
With the advent of interference and OHC Engines the dots often are not aligned at TDC
They're often aligned at a point where piston to valve contact is minimized.
Again, I'm not familiar with 3.0's so they might be at TDC with the marks/dots aligned.
We have a foot of snow and I'm dreading doing snow clearing, still inside and warm.
Best of luck !!
Thanks
Randy
I typically don't post on topics I'm not familiar with but you've mentioned TDC.
TDC stands for Top Dead Center, referring to when the #1 piston is at this point.
Typically, this was the starting point for aligning camshafts with crankshafts.
With the advent of interference and OHC Engines the dots often are not aligned at TDC
They're often aligned at a point where piston to valve contact is minimized.
Again, I'm not familiar with 3.0's so they might be at TDC with the marks/dots aligned.
We have a foot of snow and I'm dreading doing snow clearing, still inside and warm.
Best of luck !!
Thanks
Randy
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