Timing belt - what moved

[urdrwho]

Continuing the saga and the search for my poor running subbie.

 

So on my post timing adjustment how hard special tools I posted pictures and how I accomplished the timing belt adjustment.

 

That was yesterday and I went for a 12 mile mostly expressway driving (55 > 60). No codes until I got off and went in a mall then I threw my 304 code.

 

So today I pulled off the cam sprocket covers to check out the lines on the belt and the lines on the sprockets. Well something has changed.

 

Yesterday I had everything perfect. The lines on the belt were matched to the notches and the double lines on the sprockets were lined up perfectly. I had a friend here that can attest to that fact.

 

Now when I match up the belt lines to the notches, the double lines on the sprockets do not match. When I match the double lines on the the sprockets, the belt lines do not line up to the notches.

 

It isn't as though the double lines on the sprocket never line up, they do. What could have moved? I am imagining that the crank line wouldn't match up to the crank belt line.

 

My neighbor the old guy mechanic type that sold me the car says if the timing were off I would get codes 301, 302,303, a combination or varying codes. I can agree that always getting the 304 is a sign of something wrong in that hole but if the timing goes off wouldn't it exacerbate the chance of throwing a code?

 

All I am trying to do is have the car stay run ready for inspection.

[johnegg]

belt lines mean absolutely nothing after one full rotation of the engine.

it takes a bunch of rotations, like hundreds, to get them to line up again.

 

so if the marks on the cam sprockets line up right, both sides, the timing is still good.

[jp71ss]

belt lines mean absolutely nothing after one full rotation of the engine.

it takes a bunch of rotations, like hundreds, to get them to line up again.

 

so if the marks on the cam sprockets line up right, both sides, the timing is still good.

 

 

What he said!

[urdrwho]

Ah I see. So my 4 or 5 rotations by hand didn't do a thing.

 

I'm trying to run the math through my head to get that one. In my hear I think one rotation equals one rotation and all the wheels move the same. But maybe it is that wheel pulley block and tackle calculation.

 

belt lines mean absolutely nothing after one full rotation of the engine.

it takes a bunch of rotations, like hundreds, to get them to line up again.

 

so if the marks on the cam sprockets line up right, both sides, the timing is still good.

[johnegg]

the cam sprockets are all the same size, same number of teeth, so they all turn together.

the crank sprocket has half as many teeth, it turns two rotations for every one rotation of the cam sprockets.

 

 

the belt on the other hand has over 250 teeth, it is going to take a long time for the belt and the cams to find a common denominator.

 

besides the belt marks are just an aid for installing the belt.

the real key is the cam and crank hash marks.

[urdrwho]

Yep after you said it I thought about it and the engineering worked out in my head.

 

I just keep grasping at things hoping that I don't need to replace this engine. Tomorrow I hope to get a chance to replace the injector another hope and prayer.

 

I just keep spending money on this car. New brakes to get prepared for inspection and then find out that I can't get it inspected because I can't get it run ready to pass the emissions test.

 

the cam sprockets are all the same size, same number of teeth, so they all turn together.

the crank sprocket has half as many teeth, it turns two rotations for every one rotation of the cam sprockets.

 

 

the belt on the other hand has over 250 teeth, it is going to take a long time for the belt and the cams to find a common denominator.

 

besides the belt marks are just an aid for installing the belt.

the real key is the cam and crank hash marks.

[johnegg]

there are several mis-fire threads going on at different sites so i forget what you have done already....

 

check the compression, if #4 is low it is probably a valve.

warm up the engine,

remove all plugs,

install compression tester,

use the key to turn over the engine

with the throttle wide open.

 

this is also a good time to replace the plugs if you have not already done that,

but i figure you already have.

 

#4 is the hard one to remove and the hard one to insert the tester.

and since it is the misfire cylinder,

i would start there.

the readings should be around 180 psi,

and all four with in 10% of each other.

all four a little low is not a big deal,

but one or two cylinders low is a bad sign.

 

the other thing to check is the valve clearance.

i forget the spec, but it could be off causing trouble.

 

but this advice assumes that the plugs and wires are good.

 

an after thought,

move the #4 injector to the another cylinder.

i'm not real clear on how much work this is,

but i just read a post where this fixed a mis-fire.

but injectors do not fail often,

i think valves are a more common problem.

[urdrwho]

I've been chasing hopes and I have known the problem for a while. Last summer I took a compression test on #4. Granted I didn't remove all plugs and it was a cold engine. Burning myself trying to get #4 out of a warm engine isn't in the cards.

 

Anyhow the compression was 70 something.

 

Not sure if I did it WOT but that wouldn't add enough PSI to matter or would it?

 

I really think it is a valve. Low compression in #4 a lumpy idle, when the RPM's are up you never notice it. It all points to a valve problem doesn't it?

 

there are several mis-fire threads going on at different sites so i forget what you have done already....

 

check the compression, if #4 is low it is probably a valve.

warm up the engine,

remove all plugs,

install compression tester,

use the key to turn over the engine

with the throttle wide open.

 

this is also a good time to replace the plugs if you have not already done that,

but i figure you already have.

 

#4 is the hard one to remove and the hard one to insert the tester.

and since it is the misfire cylinder,

i would start there.

the readings should be around 180 psi,

and all four with in 10% of each other.

all four a little low is not a big deal,

but one or two cylinders low is a bad sign.

 

the other thing to check is the valve clearance.

i forget the spec, but it could be off causing trouble.

 

but this advice assumes that the plugs and wires are good.

 

an after thought,

move the #4 injector to the another cylinder.

i'm not real clear on how much work this is,

but i just read a post where this fixed a mis-fire.

but injectors do not fail often,

i think valves are a more common problem.

[johnegg]

dollar bill test?

hold a dollar bill over the exhaust at idle,

if it sucks back in at any point you have a burnt valve.

[spooln30]

70 psi? Dude there's definitely an internal issue. The marks the the belt not lining up did give me a good chuckle.

[urdrwho]

Interesting. I've never heard of that test before and I like it.

 

 

 

dollar bill test?

hold a dollar bill over the exhaust at idle,

if it sucks back in at any point you have a burnt valve.

[urdrwho]

Rain stopped today and I did the dollar bill test. If I stuck it into the tail pipe a bit, I swear it would have gotten sucked into the pipe. If I held it outside the pipe, there really wasn't much of a suction and mostly blowing out.

 

I wasn't going to let go of the bill while inside the pipe, having it get sucked into the muffler. Why waste money?

 

dollar bill test?

hold a dollar bill over the exhaust at idle,

if it sucks back in at any point you have a burnt valve.