Help request: Crank pulley bolts sheared at speed. Now she won't start.
 

I just need a little bit of direction if you can help.

I have a turbo'ed NA w/ a 1.8L transplant purchased a couple of months ago. A week ago, the crank pulley bolts sheared off at highway speeds (80mph). After I extracted the bolts and reattached the pulley she wont start. Cranks and backfires out of the turbo.

My first thoughts are that the timing jumped when the pulley bolts sheared. Is there anything else that i should check before pulling the valve cover to check the timing belt position?

That sounds like an entirely reasonable assumption, and is the only explenation I can think of given the circumstances, which fits.

If you aren't using a trigger wheel (OEM or other), and you didn't play with the coil connectors, then the TB probably jumped.

I have a trigger wheel. I didn't even know what to call it before now. This is something that has to be set up again?

Make sure the sensor that detects the trigger wheel was not contacted and damaged or the air gap increased between it and the wheel teeth.

Make sure the trigger wheel isnt on backwards.

Thanks for the suggestions. I'll check and report back.

+1

Make sure the sensor is positioned correctly and not damaged from the pulley hitting it on the way out, the triger wheel should have a tooth under the sensor when you have the timing mark near the 10deg mark.
You may want to install biger bolts on the pulley if you keep the stosck balancer and track the car, i use them on my engines and it is cheap insurance since the bolts are known to break with sustained high rpm even in stock power levels
https://www.miataturbo.net/attachmen...ine=1450135787

All this talk of trigger wheels, in a car which has a "1.8L transplant."

Zoomy, what ECU is your car using? If it's the stock 1.6L ECU, or the ECU from a '94-'97 1.8 car, or an aftermarket ECU connected to a little distributor-like device plugged into the back of the head on the exhaust side, it'll run just fine without the trigger wheel.

Because

To cover all bases, when you put the pulley back on, you did verify #1 was at TDC? If the markings on the pulley indicate correct timing, but it's 90 or 180 degrees out of phase, car no work.

That is hard to do because there is a locating pin for the pulley and triger wheel the only thing that can go in wrong is the trigger wheel and that will cause the engine to back fire and not run

I have an Electromotive TEC2 ECU.

I did not verify that the trigger wheel position when i put it back on. Please forgive my ignorance here, I want to make sure that understand this correctly.

The timing mark (flat spot on the trigger wheel) should be at the 10 deg mark as identified in the picture when the timing is TDC?

EDIT: For reference this is my trigger wheel kit. https://electromotive.com/our-produc...a-trigger-kit/

The "tooth under 10 degree mark at TDC" rule is for the stock 1.8 trigger wheel, which has four teeth. Your 60-2 wheel may be completely different -- check the instructions that came with it.

--Ian

I adjusted the trigger wheel last night and she started right up!

Thank you everyone for your help. You guys fucking rock.