Suddenly no spark

[lahrs37]

Hey folks,

So I have a real head scratcher here. Joee (forum handle) came over today to help me dial in the idle and get the car running right. We (more he) followed the procedures for setting ignition timing and then adjusting idle. We disconnected the battery and let the computer clear for a while. When we fired it back up it was really close to perfect. The idle was surging a little bit and there was a few little pops coming out of the passenger side pipe.

Then out of nowhere, as the car was running, it very abruptly died.

It appears to be spark related, as there was no spark coming from the wires where they connect to the spark plugs. There is 12v going into the ignition coil. I just ran another test and it looks like there is a little bit of spark jumping from the the end of the ignition coil wire - but it didn't seem consistant. I was by myself for that test so it was hard to tell for sure - and I am not sure exactly what I was looking for.

I have an extra brand-new ignition coil that I switched out which did nothing.

I also have a spare TFI which i swapped in and that did nothing.

I pulled the rotor cap and the rotor is NOT spinning when I am cranking.

When I key-on there is power that runs the fuel pump.

That is all I can think of right now. We are both stumped, and I am just learning how to diagnose electrical issues.

What do y'all think?

[Jeff Kleiner]

If the rotor is not turning when you crank the engine over you don't have an electrical issue, you have a mechanical issue. Start by pulling the distributor to see if the pin sheared, the gear got eaten or ??? If nothing is obvious upon removing the distributor pop a valve cover to see if the cam is actuating valves.

Jeff

[steno]

Jeff hit it on the head!

[Joee]

I pulled the rotor cap and the rotor is NOT spinning when I am cranking.


That is not good, didn't think to look at that. If it is not turning do as Jeff recommends. He is referring to the pin that holds the gear on the end of dist shaft.

[lahrs37]

Snuck into the garage and pulled the dizzy. The gear looks fine. The pin is still intact. Looking into the hole I can see the cam gear and that looks fine. I will pull a valve cover tomorrow to see if the lifters are being actuated.

[lahrs37]

If nothing is obvious upon removing the distributor pop a valve cover to see if the cam is actuating valves.

Jeff

If the cam is not actuating the valves, then the next step would be to pull the timing cover and see if the timing chain has come off or broken, right?

[lahrs37]

OK, so I got a light on the hole for the distributor and and cranked the engine over by hand. The cam gear did not move at all. So unless I am missing something, the problem is the connection between the crank and the cam i.e. the timing chain. I am pretty stoked that I figured out the problem, but pretty bummed that it looks like I will be tearing down the front of my engine. Fingers crossed that whatever happened in there was not too destructive. On a fox body forum a guy forgot to put the washer on the cam sprocket before tightening down the bolt. I can't quite tell if I would be happier knowing that I wasn't dumb enough to do the same thing, or if the fix ended up being really easy. Probably the latter.

[Jeff Kleiner]

Take the front off and let us know what you find. Sorry to have to break this to you but if the cam wasn't turning while the crankshaft was you're looking at the very likely possibility that you've had piston to valve contact resulting in bent valves and a complete teardown. Sorry dude...

Jeff

[lahrs37]

Take the front off and let us know what you find. Sorry to have to break this to you but if the cam wasn't turning while the crankshaft was you're looking at the very likely possibility that you've had piston to valve contact resulting in bent valves and a complete teardown. Sorry dude...

Jeff

Bummer. Major bummer. What will tell me whether I have to replace the pistons? Can they have little scrapes from the valves hitting them and still be OK? I am already assuming the valves are bent in this scenario and I am trying to prepare myself for how bad this could be.

[michael everson]

What's the story with the engine? Very strange that the timing chain would break. Especially at idle.
Mike You can remove the oil pan to check the timing chain. I can see any scenario that it isn't broken though. there was a dowel in the cam shaft right?
Mike

[lahrs37]

What's the story with the engine? Very strange that the timing chain would break. Especially at idle.
Mike You can remove the oil pan to check the timing chain. I can see any scenario that it isn't broken though. there was a dowel in the cam shaft right?
Mike

My working theory is that I forgot to put the washer (or maybe the bolt if I was a complete idiot) on the cam sprocket and the whole sprocket worked it's way off. I doubt the brand new timing chain broke. If I can get enough garage time today I should be able to confirm that.

[lahrs37]

And yes, there was a dowell in the camshaft.

[lahrs37]

Yup, I forgot the bolt and washer for the cam sprocket. Oh the shame! The carnage included the cam sprocket and the timing cover. I will upload some pictures once Photobucket stops being wonky.

[Jeff Kleiner]

Yeah, well, that would explain things. Time to yank it.

Jeff

[lahrs37]

Yeah, well, that would explain things. Time to yank it.

Jeff

What is the best way to tell if I have bent valves? Do I just have to yank the heads and then pull each valve and inspect it? If I replace the timing set and valve cover, could I try it before going for a whole tear down? And if I go that route what is the telltale sign that I have bent valves or other damage cause by piston/valve contact?

[NAZ]

Before you pull the heads do some investigating to evaluate the situation. You may have gotten lucky and not have to pull both heads. Use your leak-down tester to check for leaky valves. This must be done on the compression stroke while both intake & exhaust valves are closed. If you do detect a leak you will be able to tell if it's an intake valve or exhaust valve. If you hear air escaping through the intake manifold you have a leaky intake valve. Air escaping though the headers is an exhaust valve leak. If you don't have a leak-down tester (everyone should) use your compression gauge to adapt an air hose and use the same procedure but instead of measuring actual leakage you are looking for gross air leaks through the valves. A bent valve from piston contact usually causes a big enough leak you can hear air blow by the valve. Use something to hold the crank from turning before applying air. If it's a stick simply put it in high gear with the parking brake on. An auto will require physically holding the crank.

[lahrs37]

Before you pull the heads do some investigating to evaluate the situation. You may have gotten lucky and not have to pull both heads. Use your leak-down tester to check for leaky valves. This must be done on the compression stroke while both intake & exhaust valves are closed. If you do detect a leak you will be able to tell if it's an intake valve or exhaust valve. If you hear air escaping through the intake manifold you have a leaky intake valve. Air escaping though the headers is an exhaust valve leak. If you don't have a leak-down tester (everyone should) use your compression gauge to adapt an air hose and use the same procedure but instead of measuring actual leakage you are looking for gross air leaks through the valves. A bent valve from piston contact usually causes a big enough leak you can hear air blow by the valve. Use something to hold the crank from turning before applying air. If it's a stick simply put it in high gear with the parking brake on. An auto will require physically holding the crank.

Thanks for the insight. I actually do not have a leak down tester but I guess now is the time to get one.

[lahrs37]

The forgotten bolt and washer:

http://i36.photobucket.com/albums/e18/laurenceharrington/Mobile%20Uploads/IMG_20170205_131956_zpsegb5fsnp.jpg

What it looked like when I pulled the timing cover:

http://i36.photobucket.com/albums/e18/laurenceharrington/Mobile%20Uploads/IMG_20170205_153654_zpsul3mwuao.jpg

Part broken off from the timing cover:

http://i36.photobucket.com/albums/e18/laurenceharrington/Mobile%20Uploads/IMG_20170205_154028_zpslun7ixmn.jpg

Damage to the teeth of the timing set:

http://i36.photobucket.com/albums/e18/laurenceharrington/Mobile%20Uploads/IMG_20170205_154049_zpsehu1fdie.jpg

[blitzkreig baja]

Bummer!! Just when you were getting the gremlins worked out. On the bright side, more wrench time.

[lahrs37]

Bummer!! Just when you were getting the gremlins worked out. On the bright side, more wrench time.

Totally! It is all a learning experience and I do love to wrench. :)

[DaleG]

Love the positive attitude!

[GSides9]

Lahrs,

Do you feel lucky? Do you have an air compressor? I'd pull the valve covers and remove or loosen the rocker arms. This way the cam won't have any valves open. Remove the spark plugs and thread in fitting used for replacing valve seals without pulling the heads. It hooks up to your air compressor and pressurizes the cylinder. You will hear air getting past the rings. Same as the leak-down tester, but cheaper, you will hear air coming out the exhaust or intake manifold if you have a bent valve. One cylinder at a time. If you have a bent valve, I'd pull the engine to get all the metal out that is missing from the timing gears and cover. None bent- pull the oil pan and wash the daylights out of everything to remove all the debris. Smartest way is probably listen to Jeff Kleiner. Building an engine is not easy.

Glen

[lahrs37]

Lahrs,

Do you feel lucky? Do you have an air compressor? I'd pull the valve covers and remove or loosen the rocker arms. This way the cam won't have any valves open. Remove the spark plugs and thread in fitting used for replacing valve seals without pulling the heads. It hooks up to your air compressor and pressurizes the cylinder. You will hear air getting past the rings. Same as the leak-down tester, but cheaper, you will hear air coming out the exhaust or intake manifold if you have a bent valve. One cylinder at a time. If you have a bent valve, I'd pull the engine to get all the metal out that is missing from the timing gears and cover. None bent- pull the oil pan and wash the daylights out of everything to remove all the debris. Smartest way is probably listen to Jeff Kleiner. Building an engine is not easy.

Glen

Hmmm. I am not sure I am feeling lucky. lol I ordered a compressor and leakdown testor so I will be doing that. I was planning on dropping the oil pan anyways. If there are no bent valves and I flush the bottom end, what is the worst that could happen? I might miss a piece of metal which means that it could cause more damage and force me to pull the engine anyways. Right? So at that point I might as well see if I am lucky first. That is my logic at this point.

[Norm B]

Lahrs, the only component that can get damaged from bits of metal in the oil is the oil pump and the pieces of metal have to be small enough to get through the screen on the pick up tube. All the other oil fed components are after the filter. I would take the valve covers off and remove the rockers and and push rods. I am a bit anal about putting things back together in the same place so I use a labelled egg carton for the rockers and a box with 16 holes punched in it for the push rods.

If you do this, roll the push rods on a clean flat surface to make sure they're straight. Any bent push rods may indicate valve damage. With these components removed, you should be able to put a straight edge along the top of the valves. They all should be close to the same height. Any valve that is lower by more than a couple thousands of an inch is bent. At this point, you can use the compressed air test mentioned above to check for leaking past the valves. Air flow noise will be heard out of the intake or exhaust if the valves are bent. Be careful if you do this. THE CRANKSHAFT MAY ROTATE. Make sure nothing is binding at the front end and the transmission is in neutral. At the most, the crankshaft will rotate 180 degrees.

You may have no damage to your valves at all. Camshaft lift, rocker arm ratio and the size of valve reliefs in your pistons are all factors.

I would get a magnetic oil pan plug as insurance.

Good Luck (you are do for some)

Norm

[AC Bill]

Perhaps you could beg-borrow-rent a bore scope, and have a little peak before tearing the heads off?

[RRussellTx]

Perhaps you could beg-borrow-rent a bore scope, and have a little peak before tearing the heads off?

I just bought a Wireless Endoscope off of Amazon that creates a Wifi signal that connects to my iPad for about $40 bucks - that would probably do the trick.
I'd offer to let you borrow it but the shipping costs would just about get you a new one.

Technology today is amazing!

[Boydster]

Since the 5.0 is a non-interference engine, at least in a stock build, there's a chance you did no other damage at all. I'm running the Trickflow S1 cam in my Mustang with the old skool (original) Edelbrock aluminum heads, and it is still a non-interference, or free-wheeling, engine. You may still come out lucky. The boroscope is a great idea.

edit: I've since been told that the 5.0 IS an interference engine, so due diligence is suggested...

[AC Bill]

He mentions SVE heads, and I wondered if they could make a difference with the non-interference aspects, or if it had new pistons without reliefs, etc..?

[lahrs37]

So I have several obviously bent pushrods. Looks like I will be pulling the heads and seeing how extensive the damage is.

[Norm B]

Bummer!

Did you put a straight edge along the top of the valves? With the pushrods removed the valves should all be very close to the same height. A bent valve will be lower.

Norm

[lahrs37]

Bummer!

Did you put a straight edge along the top of the valves? With the pushrods removed the valves should all be very close to the same height. A bent valve will be lower.

Norm

They were all over the place. :( I have my stock heads still, so I compared them.

I just finished tearing everything down and pulling the heads. The bottom end looks fine. The are no nicks or dents that I can see. Everything still rotates well. I guess I am going to go teach myself how to replace valves. Right? I shouldn't have to replace the heads...

[NAZ]

You may also be teaching yourself how to install pistons if they contacted valves. I know some folks that have repaired minor damage to forged pistons with success but if your motor has cast (including hypereutectic pistons) I wouldn't chance it as cast pistons are way less malleable than forged aluminum pistons and will crack where forged will simply yield. A broken piston does significant damage to the cylinder wall and head -- read that as significant $$$ to correct. Ain't hard knocks learning fun???

[Norm B]

The heads could be fine but the valve seats and guides should be inspected.

Norm

[lahrs37]

You may also be teaching yourself how to install pistons if they contacted valves. I know some folks that have repaired minor damage to forged pistons with success but if your motor has cast (including hypereutectic pistons) I wouldn't chance it as cast pistons are way less malleable than forged aluminum pistons and will crack where forged will simply yield. A broken piston does significant damage to the cylinder wall and head -- read that as significant $$$ to correct. Ain't hard knocks learning fun???

Well crap.

[Jeff Kleiner]

...A broken piston does significant damage to the cylinder wall and head.....

I concur:

http://i269.photobucket.com/albums/jj43/jkleiner/100_3717.jpg

:(

Boydster, whoever told you a 5.0 was a non interference engine was mistaken.

Jeff

[Boydster]

Boydster, whoever told you a 5.0 was a non interference engine was mistaken.

Jeff

Really?!?! I have been playing with these roller motors for 25 years, and I have always believed they were non-interference. I could be wrong, I have no reference, but I really thought they were free-wheeling engines.

If not, my bad to the OP...

[Jeff Kleiner]

I'd say that the OP's comments about his "obviously bent pushrods" and valves "that were all over the place" pretty much answers the interference/non-interference question.

Jeff

[lahrs37]

Ok, so my current plan is to take the heads to my machine shop and have them inspect/fix them. I don't trust myself enough for that, especially because they are aftermarket heads. I am ordering up new pistons/rings and will pull the engine to install them. Has anyone pulled just the engine without the trans? Or is easier to pull both?

It's funny how this started as a no-spark problem and has ended up with me rebuilding the dang engine.

[Norm B]

I saw a video of a dyno run gone wrong. There was a valve problem, that broke a piston and the whole thing grenaded. Looked like someone set off a stick of dynamite in the valley under the intake manifold. Much safer to replace parts now and have professionals inspect the ones you're keeping.

Your plan for rebuilding seems like a good one.

Norm

[CraigS]

I almost always pull just the engine. Seems a lot easier to me. I leave two bolts in the bellhousing holding it to the engine as I lift the engine enough that the mounts clear the frame. Then I rig a stick to hold the trans up as I separate the engine.
http://i3.photobucket.com/albums/y91/craig-s/Trans%20support_zps7jrldguu.jpg
Once the trans is supported remove the last two bellhousing bolts, move the engine forward 3 inches and pull it straight up.

[lahrs37]

I almost always pull just the engine. Seems a lot easier to me. I leave two bolts in the bellhousing holding it to the engine as I lift the engine enough that the mounts clear the frame. Then I rig a stick to hold the trans up as I separate the engine.
http://i3.photobucket.com/albums/y91/craig-s/Trans%20support_zps7jrldguu.jpg
Once the trans is supported remove the last two bellhousing bolts, move the engine forward 3 inches and pull it straight up.

That is great info! Thanks! One last question: what is a good lifting point on the engine. I was attaching my chain to the heads using exhaust manifold bolts. I suppose I could temporarily reattach the heads, but there seems like there should be a better way.

[Boydster]

I'd say that the OP's comments about his "obviously bent pushrods" and valves "that were all over the place" pretty much answers the interference/non-interference question.

Jeff

Absolutely. I searched the net, just to learn, and of course, answers are all over the place. Obviously, it is not a free-wheeler.

Ya learn every day... :)

[Joee]

That is great info! Thanks! One last question: what is a good lifting point on the engine. I was attaching my chain to the heads using exhaust manifold bolts. I suppose I could temporarily reattach the heads, but there seems like there should be a better way.

Attach chains to the accessory bolt holes in heads. Get yourself some shorter bolts for the Alt mount holes or PS mount and there are also one or two holes in back of heads facing firewall. Sorry dont remember bolt sizes.

[CraigS]

Your heads are off the block. Get some shorter bolts the same size as the head bolts and bolt your chains to the block itself at the outer corners. Do you have an engine leveler? They really help especially going back together.
http://www.autozone.com/engine-and-vehicle-lift/engine-leveler/duralast-3-4-ton-engine-leveler/155794_0_0/?cmpid=PS:3:1:90

[frankb]

As Craig said above, use the corner head bolts in the block. However, don't tighten the chain link against the deck surface. Use a large flat washer to protect the block's surface so there is no impression of the link left behind.

Frank B