: Help! '84 Deville Timing Gear Alignment Dilemma

07-06-13, 01:24 PM

Has anyone done a timing component replacement on their early '80's Deville and found that their crank gears had no dot or only a faint dot? I'm starting to second guess the way I lined everything up.

I didn't really see a distinct dot on my crank gear, so I assumed that I should use the key as the marker and line up the key with the mark on the cam gear. It turns out that someone on youtube pointed out to me that I might actually have a faint dot on my crank gear.

I went back to all my videos and photos and analyzed them over a period of two days, and I'm still unsure about whether I did it right.

Here is a screenshot from my videos showing the possible faint dot. If that arrow is painting to a legitimate dot, then I need to pull the water pump and timing cover off and do it again:


And here's a video of the new crank sprocket with no discernable dot:

To try to find an answer, I spent two days googling the topic. I tried to find out what other people did, and in this picture (the only I could really find), it LOOKS like they lined the key up with the dot (the arrows are my estimations):


My friend whose driveway I'm borrowing has given me a deadline to finish everything by end of July, so I don't want to put everything back on the engine only to find out I have to tear it all apart again. Please, please help if you know how the timing gears should be aligned!

Thanks so much in advance!

07-06-13, 02:33 PM
Gonna have to pull it and line it up. The crank key that you lined it up with it not the correct way. I think you can also pull the number one spark plug and see if the piston is at the very top of the stroke...dont quote me on that.

07-06-13, 03:12 PM
Thanks for the reply! I just found a diagram online (after all this searching) that shows that the key is not the guide for lining up the sprockets. I went ahead and ordered another timing cover gasket and water pump gasket. Btw, this is the diagram:


This brings me to another question though!

This diagram shows the dot is located to the right of the keyway, whereas the faint "dot" on my old crank sprocket is located to the left of the keyway. Which do I go by?

I'm assuming that I go by the one that puts the #1 piston at TDC, right? Can anyone confirm this? Also, what's the best way to be sure the piston is at TDC? Can I stick the the depth gauge part of my calipers in the spark plug hole?

07-06-13, 04:35 PM
I think the diagram is a general idea, you will wanna go by the dot on your crank gear which will probably be to the left as most Cadillac engines are. To confirm TDC, you can just stick something long in the cylinder as you turn it and you will notice when it starts to go down. There are two strokes in a complete revolution so the dots will line up every two turns.

07-06-13, 11:28 PM
It turns out THERE WERE MARKS on the crank sprockets!! They were SO faint I had a hard time get a photograph of them!

Old sprocket with tiny triangle...

New sprocket with very soft, faint dot...

The sprockets lined up by their dots (sorry, I simply could not get a clear picture of the crank sprockets dot here..)

So if anyone finds themselves in the same situation wondering where the marks are, just put your crank sprocket in the sunlight and move it around until you find the marks. That's the only way they can really be seen.

So I ordered a new gasket set and picked it up from the auto parts store today, took the water pump and timing cover off, realigned the sprockets (I spent an hour doing this trying to make it as perfect as possible), and then I put the water pump, timing cover and their new gaskets back on and torqued the bolts down. I'm exhausted (lol). Tomorrow I start putting the rest of the engine back together!

Thanks again for your replies. :)

07-07-13, 12:45 AM
I see it was to the right of the crank key. Was the piston at TDC?

07-08-13, 06:11 PM
I see it was to the right of the crank key. Was the piston at TDC?

With the timing marks consistent on the old and new sprockets, as well as the agreement with the AllData diagram, I decided not to check it manually. If you're really curious, since the crankshaft is in the exact position as I installed the sprockets, I can do the test next time I go over to work on the Caddy and let you know what I find. :)

07-08-13, 06:19 PM
You dont have to, I was just wondering. I'll find out in my next build someday.

07-08-13, 06:26 PM
If for some reason I do check it at some point, I'll be sure to let you know what I find. :)