Jfrahm

You might be on to something, particularly as a very proud starter ring bolt is pictured above.

500

Well-spotted! I see that now, that bottom picture does show unusual bolt stickout.

944M3

Apologize if this has already been covered. Have you checked the part number of the bell housing to ensure it’s a turbo one?

I installed a non turbo one and experienced something similar. They are identical but the starter location is different by a few millimeters.

944tger

Guys, I think I found the culprit today. It was the speed reverence sensor. It seems like it was incorrectly installed and dragging on the teeth. I spotted some drag marks on them which led me to the sensor. My engine builder said he had gapped it properly but admitted that he must have messed it up. Well mistakes happen…

I have no idea why it would not turn at all at first and then started to be turntable after removing the clutch fork… That totally led us in the wrong direction and I have wasted a lot of hours on this but at least now it is found and there is no need to remove the clutch which I am really happy about.

Thanks for all the replies and suggestions, I appreciate it!

944M3

Awesome, good to hear it was something simple. We’ve all been there, keep plugging along

MikePellegrini

I had a bolt back out of the ring gear one time. I hadn't torqued it properly. Just came out one morning and when I tried to start the car, it made this nasty banging sound. Pulled the starter, rotated the engine and found the bolt - a little farther out than the the one in the picture above, with the head damaged. Replaced it with a new one, then re-torqued all the other bolts (which doing it one at a time through the starter access is a real PITA) and then started the car - voila - no banging. I've paid more attention to torquing stuff since then. A good, cheap lesson.

jeyjey

I read all of Carroll Smith's books back when I raced. He prepped the GT40s for their successive LeMans wins. One of his maxims was "There's no such thing as an un-torqued bolt. Either torque it to spec, or don't install it at all."

Great books.

944tger

Hi everyone,

small update from my side again. I think the issue was that the eight-shaped washer was missing from under the sensor. I tried building a 2mm think washer from to plastic washers I had lying around. I reinstalled the sensor and readjusted the gap.

The car cranked over under its own power for the first time today which was pretty nerve racking.
Sadly no start! Guess I am back where I was before the engine blew up

this time there is no tach bounce which I think I had before… the sensor didn’t look to badly damaged and it was brand new so I don’t think it is broken (ohm reading is fine) but I will order a new one just in case. And I will try to get the washer at Porsche.

Any other ideas what I could check for the no start/no tach bounce issue in the mean time? (DME Relais is brand new as well)

944M3

Did you try jumping the DME relay? This will allow you to rule out several things. Many how-to’s on the board.

944tger

I did not jump the DME Relais. Does it make a difference if the Relais is fine? (Which I am assuming for now since it is new)

As a small recap, before this engine debacle happened, I was in the process of diagnosing a consistent no start issue with the car. I had pretty much tested everything that can be found on clarks garage and on the forum. It was during a repeated test of measuring some voltage the engine got stuck while cranking. I am slightly nervous to go back to constant cranking and trying to diagnose the issue... Is there anything I can do to protect the cylinders if that becomes necessary? I feel like fuel washing off the oil from the cylinders was a contributing factor to the engine damage.

Like I said, last time I was in this situation I had a bouncing tachometer, which I don't have now, so I have some hope that it's an unrelated issue.

peanut

as 944m3 says , DME relay bypass is the next step for a no start scenario.

First remove the DME relay and test that you have 12v+ on terminal 30 of the DME relay socket .
This is a constant live feed from the battery via the ignition switch even with the ignition switch turned off .

If there is No 12v+ on terminal 30 then you need to check why as neither the DME or a DME bypass will work without that 12v+
Next check that you have a ground at terminal 85 on the DME relay Socket by doing a continuity check between 85 and any convenient ground point under the bonnet ...hood

If both of these tests check out then fit the bypass... between terminals 30, 87b, & 87....making sure that you do not connect to either 85 or 85b These terminals are used to activate the relays and the wires are too thin to carry heavy current like the fuel pump.

With the bypass in place you should now hear the fuel pump pumping fuel continuously even with the ignition in the off position.
Now crank the engine and see if it will start . If it still won't fire check for an ignition spark at the spark plugs and fuel at the fuel rail /spark plugs.

Oh and check for a very tiny movement of the rev counter hand when you crank the engine .

944M3

What helps me is to keep it simple in my mind….the car needs air, spark, and fuel to start.

If jumping the DME relay doesn’t work, you might have a bad DME (ECU computer). I’ve had 3 fail.

peanut

Not really .... What this engine needs primarily is a fully working Bosch Motronic Fuel Injection & Engine Management system .
Without that ........the presence, or not ,of air ,fuel and compression are academic .

peanut

My guess for the non bounce of the Tachometer is that you have gapped the speed reference sensor too far off of the flywheel with the plastic washers.
Have you got a Workshop Manual ? there are plenty of sources for setting the correct gap. I believe the gap should be 0.8mm . I have read that some owners glue a small piece of feeler gauge to the sensor tip but I would use Engineers blue smeared around part of the flywheel and decrease the Sensor gap until you see the blue dye on the tip of the sensor then space the sensor 0.8mm to 1mm gap

MN

Getting more and more appreciative of my car mech (hi, James) who eventually always figures out (but often at eye-watering expense!) the issues of my aging, retromodded, 968 motored, and supercharged 944!