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Justjim75
Justjim75 Reader
8/28/18 6:43 p.m.

Car just quit, pushed to parking lot, walked back to work, searched net.  No movement from tach needle, check engine light on, fuel pump questionable, look in oil filler cam doesn't move.  Sounds like the other cam is moving but no confirmation. Obviously it could be the belt, but it was done by Dusterbd 20k ago sp is there anything else? 2000 NB 1.8 stock afaik.

Stefan
Stefan GRM+ Memberand MegaDork
8/28/18 6:55 p.m.

broken camshaft, cam gear came loose due to a sheered drive pin/loose bolt, belt tension came came loose.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
8/28/18 7:01 p.m.

It' s most likely to be a broken belt. Low tension wouldn't stop it from moving. Could also be a problem at the crankshaft.

Not that it matters, you're going to be taking it apart regardless and it will be painfully obvious at that point.

mazdeuce - Seth
mazdeuce - Seth Mod Squad
8/28/18 7:11 p.m.

As Keith said, you'll know when you take it apart. In all honesty it will probably become apparent when you pull the timing belt cover which you can do without removing too much. Bunch of 10mm bolts, belts, that sort of thing. 

If the car cranks over and you can't see the cam spin, it's time to learn about Miatas. 

Justjim75
Justjim75 Reader
8/28/18 7:31 p.m.

Ugh, thanks yall

mazdeuce - Seth
mazdeuce - Seth Mod Squad
8/28/18 7:39 p.m.

Depending on what you see, you can probably ping Duster for the FM cam tools. I borrowed them from him to fix a friends Miata and mailed them back not too long ago. They're probably not necessary, but they do make things easier. Take a bunch of pictures, ask a bunch of questions, there's about 1000 of us here that have been up to our elbows in these cars. 

Justjim75
Justjim75 Reader
8/28/18 7:46 p.m.

In reply to mazdeuce - Seth :

That wont be necessary, he gave them to me with the car since his Miata isnt Mazda powered!  Thanks tho

mazdeuce - Seth
mazdeuce - Seth Mod Squad
8/28/18 8:48 p.m.

When I borrowed them he said to keep them until he needed them back. Now I know why he needed them back. laugh 

Justjim75
Justjim75 Reader
8/28/18 11:13 p.m.

In reply to Stefan :

It was at very low rpm and low load, bumper to bumper traffic making a left hand turn at a green arrow, 3rd car back.  I'm hoping it's the loose bolt or bad belt instead of broken things

Dusterbd13
Dusterbd13 MegaDork
8/29/18 4:28 a.m.

My bet is tensioner. No reason why, just what my magic 8 ball says.

 

And miata engines are not interference. 

Service manual available via a link at miata.net

AWSX1686
AWSX1686 GRM+ Memberand Dork
8/29/18 8:53 a.m.

Even if you have to replace the timing belt, it's not too bad of a job. And yeah, fortunately you have a non-interference engine, so unless the cam is actually broken it shouldn't be too hard or expensive to fix. 

Justjim75
Justjim75 Reader
8/29/18 9:25 a.m.

My only concern about doing it myself is getting the cams properly aligned before installing the belt and applying tension.  I've done turbo FWD Volvos and I've done the tensioner on my Yamaha tuned VVTLI Matrix XRS so I'm at least gonna pull the valve and timing covers.

AWSX1686
AWSX1686 GRM+ Memberand Dork
8/29/18 9:38 a.m.

In reply to Justjim75 :

There are some pretty clear markings, so you shouldn't have too much trouble. Lookup a full timing belt process guide to be sure. 

wae
wae SuperDork
8/29/18 9:44 a.m.

In reply to Justjim75 :

It's not that difficult to get things lined up.  It's a bit tedious and takes some time, but it isn't "hard", if that makes any sense.  If you could borrow a second set of hands, it would probably be slightly easier, but I found with a ratchet on each of the cam gear bolts, I could hold intake in place with my hand, exhaust with my elbow, and thread the belt on without a tremendous amount of drama.  Get one of those Milwaukee paint pens from your local hardware store to make yourself a good, super-visible set of marks and then just check, double-check, and triple-check.  There are marks on everything that you can rely on and the FSM procedure is really straightforward.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
8/29/18 10:05 a.m.

Miata guys have been making timing belt alignment sound hard for a couple of decades. It's not. The trick is to remember that until the tension is set, the marks will be a little bit off. Once it's set, they'll be bang on. Not "I think that might be it", but dead nuts. If it's going to be off, it's going to be off by a full tooth and that's really obvious. More time is spent making it "easy" than it actually takes to do the job. I have never counted teeth or marked up the gears - I just look to see if the upper marks are vertical. That's all it takes. As I said, if they're off they'll be off by a full tooth.

A loose tensioner is not going to let one cam spin. A loose bolt isn't going to either unless it's allowed a cam gear to fall right off, as they have pins in the end. I suspect something is broken - but it still doesn't matter what we think. Dig in there and find it. It'll be faster than theorizing, and coming up with the perfect diagnosis ahead of time won't make any difference.

rustybugkiller
rustybugkiller HalfDork
8/29/18 10:21 a.m.

In reply to Keith Tanner :

Agree. Internet makes you think it’s rocket science. Miata TM is  actually one of the easiest dual cams to work on.

Justjim75
Justjim75 Reader
8/29/18 10:32 a.m.

In reply to AWSX1686 :

That's great news!

Justjim75
Justjim75 Reader
8/29/18 10:38 a.m.

Thanks Keith, I have 2 tools from FM, the bottle opener and a longer tool, about 16 to 18 inches maybe that came with the car.  I've seen that the bottle opener goes between the 2 gears to hold them in place.  Is there a procedure on the FM site for the rest?

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
8/29/18 12:50 p.m.

The longer tool is the crank bolt tool - it'll let you hold the crank as you undo the bolt. Shouldn't be necessary in your case unless that's where the problem lies. I'll bet pulling the valve cover will tell you everything you need to know.

Dusterbd13
Dusterbd13 MegaDork
8/29/18 1:13 p.m.

Jim, you alsohave the aluminum cups for cam and crank seals.

Unless i forgot to pack them. In which case i lost them and apologize. 

codrus
codrus GRM+ Memberand UltraDork
8/29/18 2:46 p.m.

I think the thing that screws people up when doing Miata timing belts is that the tensioner is on the intake side of the belt, and if you put it together with slack on the exhaust side then when you release the tensioner it will turn the cams as it takes up that slack.

Justjim75
Justjim75 Reader
8/29/18 3:53 p.m.

I have the seal tools Mike, thank you Keith and Codrus.  Btw, after I'm done I have no probs loaning the special tools

Dusterbd13
Dusterbd13 MegaDork
8/29/18 4:03 p.m.

In reply to Justjim75 :

Just make sure you charge a rental fee payable in homemade cookies

Justjim75
Justjim75 Reader
8/29/18 6:54 p.m.

Ice cold Dews at the Challenge?

Streetwiseguy
Streetwiseguy UltimaDork
8/29/18 8:53 p.m.

If you have done a 5 cylinder Volvo, you can handle a Mee-otter.

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