Reasons a Miata camshaft doesn't spin?

In reply to Streetwiseguy :

I've done a redblock 6 or 8 times and did the NA cam swap on my 850 turbo, then tuned the overlap out of them at the drag strip.  Make a run, wait 30 min, adjust them away from each other, make another run until the times stopped getting faster, lol.  I was a newbie but it worked and that's an interference engine

I can't stand the waiting! Get that valvecover off already!

In reply to Robbie :

I repair medical equipment with tons of deadlines by the end of each month, plus "putting out fires" for the boss since I'm the only one of 7 biomeds that's been here longer than a year.  I've been too busy and I have my 03 Matrix XRS 6 sp manual as a "backup" so it's not critical.  Tomorrow I'll have over 50 hours so I can knock off early and work on the Miata

Bit o' duct tape will fix that .

That's honestly about the best kind of broken you're going to get. New belt and tensioner, retime it all, hit the road.

Woo! Called it!

Surprised that it's broken at 20k, that is really unusual. Worst case without FOD is usually 80-90k.

Even the tensioner should be okay. Just check to make sure the idler pulley has a little bit of drag instead of feeling really loose.

Retiming is easy. You'll have to tear down the front of the engine, but just set the crank to TDC using the marks on the block. The intake cam is going to try to hop over a tooth because there's a bit of valve spring tension on it, that's what the Ninja tool is for.

Keith Tanner said:

Retiming is easy. You'll have to tear down the front of the engine, but just set the crank to TDC using the marks on the block. 

Or just stick a screwdriver down the #1 spark plug hole? :)

Did it break at low mileage because its was a cheap piece of E36 M3 belt, or because something seized up?

Streetwiseguy said:

Did it break at low mileage because its was a cheap piece of E36 M3 belt, or because something seized up?

Or because something was accidently dropped into the timing cover.  I'm guilty of that one.  Ruined a belt with exactly zero miles on it....

When I bought the belt kit I was told it was a Gates belt. However it was not written on the Belt so there is no guarantee I didn't get screwed

Streetwiseguy UltimaDork 8/31/18 8:03 a.m.

Did it break at low mileage because its was a cheap piece of E36 M3 belt, or because something seized up?

That's a good question!

Clearly you'd want to spin the cams (yay non interference!) and crank to make sure everything spins freely. 

codrus said:

Keith Tanner said:

Retiming is easy. You'll have to tear down the front of the engine, but just set the crank to TDC using the marks on the block. 

Or just stick a screwdriver down the #1 spark plug hole? :)

 

I mean, if you want. But the mark is right there and pretty darn hard to miss. Why bother pulling a spark plug?

Keith Tanner said:

codrus said:

Keith Tanner said:

Retiming is easy. You'll have to tear down the front of the engine, but just set the crank to TDC using the marks on the block. 

Or just stick a screwdriver down the #1 spark plug hole? :)

 

I mean, if you want. But the mark is right there and pretty darn hard to miss. Why bother pulling a spark plug?

I was thinking it was easier to pull a plug than to pull the crank pulley (doubly so if the car has an ATI damper).  Thinking about it some more though, you have to pull that to replace the belt anyway, so never mind. :)

Yeah, my reasoning would be different if the belt was in place and he just had to retime the cams. In that case, I'd use the ignition timing mark on the damper but might back that up with a TDC check via the plug hole if the damper was of unknown age.

wae said:

Streetwiseguy said:

Did it break at low mileage because its was a cheap piece of E36 M3 belt, or because something seized up?

Or because something was accidently dropped into the timing cover.  I'm guilty of that one.  Ruined a belt with exactly zero miles on it....

Also guilty of that, had a timing belt cover bolt back out and shred half the belt, somehow I didn't bend a valve on my gsr 

We had a car with an exposed belt on the dyno once. It lost a decorative acorn nut during the run that went straight through the belt. We did the new belt right there on the dyno

This doesn't look like FOD to me. That looks more like a shear - either something jammed or it was just a bad belt.

Statement 1: I rotated the cams by the timing gear bolts and they move together with the gears freely.

2: there is powdered rubber on a spring right behind the water pump pulley mount indicating there was a rub somewhere but it's not so much that it couldn't be from me turning the car over during troubleshooting after the belt broke

3: I bought the kit that includes idler and tensioner just in case.

Question: what is FOD?

In reply to Justjim75 :

FOD = Foreign Object Damage.  Make sure you look for anything in the area that shouldn't be there.

In reply to Hal :

Thanks, will do.  Anybody know off the top what size the crank bolt is? Work and then rain stopped progress today but hopefully I'll have it buttoned up by lunch tomorrow 

21mm is what I remember. For the head. 

Thanks!

All buttoned up, runs like a sewing machine, took the opportunity to install the fat aluminum rad that came with trade and dress up the valve cover.  Thanks to all for your advice and pics, special thank you to Keith and FM for the special tools too.  Just in time for ALABAMA FOOTBALL, ROOOOOLLLLLLL TIIIIIIDE!!!!!