Good news on broken timing belt and a couple questions

[ck1938]

My timing belt broke Thursday night, two days before I was going to have it replaced. It's a good reminder for the future, 60,000 miles and 64,000 miles aren't the same, get it replaced before 60,000, not after.

The good news is that I was going about 10mph and my foot was on the brake, not the gas, when it snapped. I took the covers off today and the belt didn't cause any damage that I could find. It was still in place around the sprocket, just slack. It looks like all I'll need to do now is put the new belt on. My repair guide has some diagrams for the 2.4 L engine but no pictures.

My first question is about something my manual says:

Before installing the timing belt, ensure that the left side (rear) silent shaft (oil pump sprocket) is in the correct position as follows:

1. Remove the plug from the rear side of the block and insert a tool with shaft diameter of 0.31 inches. (8mm) into the hole.

I was unable to locate any plug besides the oil pan one. Where is the plug located? And what block are they referring to?

My second question:

Does anyone have pictures of the 2.4 L timing belt as it should be. The tech article I found shows the 2.0 engine, which has more sprockets than my 2.4.

This is the 98 Spyder with a 2.4 liter engine and an automatic tranny. Thanks in advance for any help you can offer me.

 

[luv2rallye]

...The good news is that I was going about 10mph and my foot was on the brake, not the gas, when it snapped. I took the covers off today and the belt didn't cause any damage that I could find. It was still in place around the sprocket, just slack. It looks like all I'll need to do now is put the new belt on.

Before installing the timing belt, ensure that the left side (rear) silent shaft (oil pump sprocket) is in the correct position as follows:
1. Remove the plug from the rear side of the block and insert a tool with shaft diameter of 0.31 inches. (8mm) into the hole.
I was unable to locate any plug besides the oil pan one. Where is the plug located? And what block are they referring to?

My second question:
Does anyone have pictures of the 2.4 L timing belt as it should be. The tech article I found shows the 2.0 engine, which has more sprockets than my 2.4.

The bad news is when the TB snaps you almost certainly bent some valves since it happens instantly. Unfortunately the only way to tell is to pull the head or put a new TB on and measure compressions. You could remove the valve cover and see if any valve stems aren't reaching the rockers which is a sure indication (but if they all are it doesn't mean some aren't bent).

The rear balancer shaft is run off the oil pump shaft but it is half the speed. That is why you can have the oil pump shaft off by 360 degrees and not know it unless you do the screwdriver in the hole trick (there's also another easier way if you look at the VFAQ for TB install step 24). See pics below for 2.4L location.

See pic below for 2.4L TB.

 

[ck1938]

Thanks for the info. I've been sick a few days and haven't been able to work on the car. On Sunday I found the place where I thought the screwdriver head should go but it will only go in 1.25 inches. It presses against the oil pump shaft, you can feel the movement through the screwdriver handle as it turns, but I can't find any depression for the screwdriver, 6 mm diameter, no matter how many times I revolve the shaft. I'm guessing there is a second plug I need to search for this weekend.

After reading several articles on here I'm a little concerned about causing more damage if I start the car and something is in the wrong place. I see the timing mark for the oil pump sprocket, two arrows each come to a point and I'm assuming that is where the sprocket should be stopped, where the two arrows meet. On the camshaft sprocket I see what looks like a timing mark, a machined indentation, on the sprocket and a vertical line/timing mark that I think it should like up with on top of the engine. On the crankshaft sprocket I see the machined indentation on the sprocket but I can't find a mark for it to line up with. I'll clean it this weekend and hopefully see something. Am I correct in assuming it should be close to the 11 o'clock position like in this diagram from the manual? If the sprockets aren't in the correct position how much damage would trying to start it cause? I'm guessing more bent valves would result. What other damage might be possible?

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[luv2rallye]

On the crankshaft sprocket I see the machined indentation on the sprocket but I can't find a mark for it to line up with. I'll clean it this weekend and hopefully see something. Am I correct in assuming it should be close to the 11 o'clock position like in this diagram from the manual? If the sprockets aren't in the correct position how much damage would trying to start it cause? I'm guessing more bent valves would result. What other damage might be possible?

It lines up with a tang under the bolt - see attached picture. Yes 11 o'clock. Sprockets not in correct position (except balance shaft) results in bent valves. Turn crank sprocket (in forward direction) slowly with racket to see if valves are going to be smashed before starting. For the oil pump sprocket orientation see the red in step 24 of http://www.vfaq.com/mods/timingbelt-2G.html. I know this is for the 2.0 turbo but the 2.4 may have the same trick.

 

[ck1938]

Thanks, that helps a ton. It got me thinking though. When the car died I wasn't sure what happened and tried to start it a few times. Would those attempts to start the car have caused any additional damage? When I got the belt cover off the timing belt was slack so I'm guessing neither of the other two sprockets did any more turning.

 

[luv2rallye]

If the camshaft is ever off more than 3-4 teeth with the crankshaft you run the risk of bent valves. If you already turned it over and want to know, just do a compression check. Bent valves will show 0 compression. There shouldn't be any other damage unless the valves punched the pistons.

 

[ck1938]

Thanks for your help. I get the car from the shop tomorrow. It came to $1349. So much for being out of debt by X-mas.