Setting timing on Mazda 626

I just replaced the water pump and the timing belts on this Mazda 626

2.5L V6. Definitely not a novice job, took me two days.

Now that I got everything together through a miracle, the engine will turn over but not run. The timing needs to be set. The worthless Haynes manual talks about Top Dead Center (TDC). I don't get it. What is it I need to do to set timing on this V6 after the timing belt change? Thanks in advance.

Reply to
SQ
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Did you get the cam timing set? I would not even attempt to run it if you did not. ...Don't even try to crank it.

Reply to
« Paul »

I don't know what you mean, cam timing set.

Reply to
SQ

Did the Haynes manual mention either not disturbing the position of the camshaft(s) and the crankshaft when replacing the belts, or to line up the timing indicators on the camshaft(s) and crankshaft if you do? If the shafts get out of sync when the belt is taken off or put on they need to be put back in sync before the parts are all put back together and the engine started.

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Reply to
William R. Watt

2.5L 4 cam w/VRIS is a great engine... except for the oil leaking into the spark plug holes. Unfortunately I don't remember the cam positions any more. IIRC, the dots on each set of cams must be facing each other. You will have to make really, really sure that neither the cams or crank is 180, or 360 out, and with #1 TDC on compression stoke. I remember it took awhile to line everything up. If you don't know what I am talking about, then I sincerely suggest having it towed to a shop and have it worked on by a tech. That same engine is in a Ford Probe.
Reply to
« Paul »

OK, I got the timing belt set up correctly, except it's one tooth off on the camshaft. It's the best I could do.

But I cannot start the car, it is not getting the spark. I haven't yet put the water pump and the alternator belts back on. Is that the reason why it doesn't start? Or is it because it's one tooth off?

Reply to
SQ

Valve-timing must be *EXACTLY* right for things to work. "One tooth off" is nowhere near "close enough" - there is *ABSOLUTELY NO ROOM* for any error - It's either set correctly, and the engine runs (although it may run poorly due to other factors) or it's not, and short of going back in and redoing the job (PROPERLY this time), nothing you try will get the engine to run AT ALL. Depending on the engine, one tooth worth of valve timing error can be enough to punch valves through pistons.

If the timing is screwed up, potential problems range from the quite mild ("darn, won't start") to the substantially worse ("It tried to turn over, but went "CLANK!", and now I can't even rotate the crankshaft"), to absolute disaster in the form of destruction of the engine. ("Wow... Look at all these valve-shaped holes in the tops of the pistons", or "Are you *SURE* valve stems are supposed to look like the warning sign for a curvy road?", or "I don't recall installing a two piece camshaft...")

Sounds like you've encountered the "best case" (Won't start) scenario. Count your blessings (First one being that you didn't punch a valve through a piston in the process of trying to start a mis-timed engine), and get back inside to put things back together CORRECTLY.

Reply to
Don Bruder

You are dealing with two different kinds of timing.

First there's valve timing which makes the valves open and close when the piston reaches certain points in its up-and-down motion. Valve timing is controlled by the timing belt. For it to work the camshaft and the crankshaft have to be positioned correctly when the timing belt is installed.

Second there's ignition timing which makes the spark plugs fire when the piston reaches a certain point in its up-and-down motion. Ignition timing is controlled by the position of the distributor until the engine warms up when its finely adjusted on modern computer-controlled engines by the computer.

When you change a timing belt the ignition timing shouldn't be affected. At least mine wasn't when I changed the timing belt on my car. I did check the ignition timing after changing the timing belt and it was fine.

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Reply to
William R. Watt

If there is no spark, then there is something else wrong. Something may be unplugged. Ign.mod? Crank sensor? etc. Even if the cams were way off, there should still be spark. The engine probably won't start though. As you know, the distrib runs off of the left (front) bank. Check the wires. Put ford probe engine into Google. There is a lot of info on the 2.5 available.

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running with one cam tooth off will eventually destroy the engine.

Reply to
« Paul »

quote ====================== If there is no spark, then there is something else wrong. Something may be unplugged. Ign.mod? Crank sensor? etc. ===========================

I redid the timing belts. The second time it was much easier. I wanted to test everything and did not put the plastic timing belt cover back on and the alternator/water pump belt. Well, it wouldn't start. I put the belts and everything back on - and it started and ran wonderfully. I think I might have left out the camshaft position sensor.

Anyway, thanks - that's a lot of new info. I've never done the timing belts before but it's an interesting (and very frustrating at times) learning experience. One thing I learned, I don't want a car where you need to remove the timing belt to change the water pump, such as this

626!
Reply to
SQ

Great! Good that you got it running right. I used start that engine without the plastic covers also to see if it ran ok before buttoning up. There are more than a few engines with water pumps like that from most mfgs. You did one of the more easy ones! Still a great engine though - the 2.5.

Reply to
« Paul »

As a corollary, if you are finding it exceedingly difficult to correctly set the ignition timing (if the mark will not stay steady under the light), that is a pretty good indication of a worn or slack timing belt. Usually the two aren't related but that is one specific instance where they can be.

Reply to
Ryan Underwood

I have another issue... The vehicle vibrates rather badly in "D" (and not any other gear)

Could it have something to do with what I did? The engine mount maybe? I torqued it well enough, I thought.

Reply to
SQ

Bad plug wire. Check 'em while they're hot! Not more than 5k on the shortest one and not more than 12k on the longest.

Reply to
« Paul »

Thank you. I will check it promptly with the voltmeter. I should probalby replace them as I don't know how many miles/years they got on them.

Reply to
SQ

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