What's the definitive answer about lining up timing marks on the crank pully?

I have an 88 acura that has overheated once again. This time it blue the h= ead gasket. I'm reassembling it now, and I come to discover that I may hav= e had the valve timing wrong from last time.

I don't have any manuals. The only documentation I can find says to line u= p the marks on the cam pulleys (obviously), and then attach the bottom half= of the timing cover and the crank (accessories) pulley. Then check the li= ttle "white mark" on the pulley. It should line up with the plastic pointe= r on the timing cover when at TDC. =20

Really? This seems kinda silly and a real pain in the neck.

Okay, there is no white mark on the rusty old crank pulley. However, there= are a few tiny notches "chiseled" into it. One of which looks like it mig= ht be painted red. The others could be construed as ignition timing marks = because they occur several degrees before the red notch (assuming the engin= e spins counter-clockwise when facing the timing belt, which I believe it d= oes). =20

Now, several degrees (maybe 10-20) clockwise from all the notches on the cr= ank pulley is the actual key-way. Furthermore, there is a single small dim= ple/notch on the crank timing belt pulley itself. This dimple is several d= egrees farther clockwise from the key-way.

Does anyone know for sure what all the this means? Does the key-way play n= o role whatsoever in setting TDC? What about that dimple/notch on the cran= k timing belt pulley?

It seems odd that the key-way is not used, since the cams, distributor, and= cam sensor all have some type of key-way that points up when at TDC. But = not the crankshaft?

Anyway, I intend to follow the only documentation I have, and line up that = red mark on the crank accessory pulley with the plastic pointer on the timi= ng cover. It is in the neighborhood of TDC when eye-balled with the piston= itself.

Any insights would be appreciated.

Reply to
rodwbrick
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snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:

The timing-belt's crank pulley ought to have a boss that intrudes into its center hole. This is what lines up with the keyway in the crank.

If you look closely, you'll find that there is a little triangular arrow stamped into the timing-belt's crank pulley, and a corresponding arrow cast into the oil pump. These both MUST be visible, and they MUST match.

If you cannot see the little arrow on the timing-belt's crank pulley, then you've got the pulley on backwards. If there is no protruding boss into the center hole, then you've got the wrong pulley on there.

The TDC mark will be the notch that's all by itself on the pulley. The middle one of the group of three is the one you're shooting for when you set the timing once the engine's running again. I like to file these notches and put some Wite-Out on them, so they are easier to see.

But the timing-belt depends on everything you do /before/ the lower timing belt cover goes on.

You need to be 100% dead-on when setting the timing belt. Even one tooth off (easy to do!!!) and you'll have all kinds of problems.

Reply to
Tegger

Thanks for the advice. After wiping away a bunch of sludge behind the cran= kshaft timing belt pulley, a little arrow on the block revealed itself. =20

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The arrow lined up with the little notch on the timing pulley when at TDC, = as measured by a dial indicator on the piston through the spark plug hole.

Ironically, the crank accessory pulley is really confused about what it's t= rying to tell. I did find a little dab of white paint, but it was easily a= few degrees off from TDC when checked against the timing cover tab.

Also, the notches in the pulley you mention were strange, too. I figured t= he three notch cluster was for ignition timing. But, there were actually t= wo other notches some ten degrees or so clockwise from the first three. On= e of the notches (the fainter one) lined up nearly perfectly with TDC. The= other one (the big one) was doing who knows what. I added some more white= paint to the accessory pulley where true TDC is.

It's all back together now and seems to be running well, except the timing = belt still seems a little loose. It jiggles when the engine is running. I= s there an easy way to tighten it once it's all back together? I can't see= how without pulling the cover off again. But why is there an access hole = for the idler pulley bolt in the timing belt cover?

Thanks again for the advice.

Reply to
rodwbrick

snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:

About that timing pulley... why is the crank keyway open? I'd swear the timing pulley you're showing is from a '96+ engine.

That hole is so you can tension the belt properly.

Two questions:

1) what method did you use to tension the belt? 2) how much slack is there in the belt?

To determine slack:

1) set crank to TDC compression for the #1 cylinder 2) remove the upper timing belt cover 3) use the crank pulley bolt to turn the crank exactly THREE TEETH counter- clockwise, then HOLD it there 4) use your finger to push in on the belt run that goes from the water pump pulley to the intake cam.

With all slack removed, but no additional pressure applied to the belt, what is the observed deflection at the middle of the run?

Reply to
Tegger

I seem to recall we just applied what pressure we could on the tensioner an= d tightened down its bolt. It seems as though the tensioner's spring is su= pposed to take up the slack, but it did not seem to. It seems as though I = should be able to make the belt as tight as I can between exhaust cam and c= ranshaft, then let the tensioner's spring take up the slack on the water pu= mp side.

One other issue is that the tensioner is attached to a little bracket with = a hole. The hole must fit into a little dowel sticking out of the block. = It wants very badly not to stay in that hole when being tightened. It took= two people to get the tensioner bolt tight. One to ensure the bracket sta= yed in the dowel, and the other to tighten the bolt.

Here's the expanded pic from before, showing the bracket hole in the backgr= ound, and the dowel I mentioned.

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As for the key, there are thin anodized flange spacer things that go on eit= her side of the crankshaft timing belt gear. The one on the outside of the= gear is not shown here. Then there's the little key that goes into the ke= y-way on the outside of that flange. It loves to fall out, so it's not sho= wn here either. Only when the pulley is ready to install do I insert the f= lange and the key.

It's too difficult to measure the play in the belt at the center with every= thing together. I'd estimate it's a good inch though. It certainly seems = to jiggle about an inch when the engine is revved.

I don't see how it can be tightened without pulling off the bottom half of = the timing cover again. I'm not sure if it's doable just by pulling off th= e tire and accessing the crank and tensioner bolt though. I'm afraid that = tensioner bracket will fall off the dowel if I loosen the tensioner bolt en= ough to allow it to be adjusted. It was very precarious on that dowel unti= l the bolt was fully tightened.

I'll probably be pulling off the bottom timing cover this weekend to see if= I can get that belt tighter. The way it jiggles now makes me nervous to t= ake it much beyond 2500 rpm.

Thanks.

Rod

Reply to
rodwbrick

and tightened down its bolt. It seems as though the tensioner's spring= is supposed to take up the slack, but it did not seem to. It seems as tho= ugh I should be able to make the belt as tight as I can between exhaust cam= and cranshaft, then let the tensioner's spring take up the slack on th= e water pump side.

h a hole. The hole must fit into a little dowel sticking out of the block.= It wants very badly not to stay in that hole when being tightened. It to= ok two people to get the tensioner bolt tight. One to ensure the bracket s= tayed in the dowel, and the other to tighten the bolt.

background, and the dowel I mentioned.

ither side of the crankshaft timing belt gear. The one on the outside of t= he gear is not shown here. Then there's the little key that goes into = the key-way on the outside of that flange. It loves to fall out, so it&#39= ;s not shown here either. Only when the pulley is ready to install do I in= sert the flange and the key.

everything together. I'd estimate it's a good inch though. It ce= rtainly seems to jiggle about an inch when the engine is revved.

lf of the timing cover again. I'm not sure if it's doable just by = pulling off the tire and accessing the crank and tensioner bolt though. I&= #39;m afraid that tensioner bracket will fall off the dowel if I loosen the= tensioner bolt enough to allow it to be adjusted. It was very precarious = on that dowel until the bolt was fully tightened.

see if I can get that belt tighter. The way it jiggles now makes me nervou= s to take it much beyond 2500 rpm.

Follow up.

I was able to tighten the timing belt by just removing the tire and removin= g the power steering pump and bracket out of the way.

I loosened the tensioner bolt about 180 degrees. Just enough that it seeme= d sufficiently loose, and hopefully not enough to permit the tensioner brac= ket from slipping off that dowel. I turned the cranshaft counter-clockwise= while holding the exhaust cam in place with a wrench. I held pressure on = the crank to keep the belt tight between the crank and exhaust cam. Then, = while holding the belt tight between crank and exhaust cam, I tightened up = the tensioner bolt.

After removing the cam wrench I turned the crank a few revolutions, and the= belt is definitely tighter now. I'd estimate it now has about a half inch= of play at the center of the run between crank and exhaust cam. With the = engine revving, the belt hardly jiggles now. Maybe just a slight vibration= it noticeable near the center of the run at higher rpms. I'm much happier= with it.

Thanks again for the tips.

Rod

Reply to
rodwbrick

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