1992 Fod Explorer XLT: When I attempt to turn over the engine, the flywheel spins, but the engine doesn’t. This is a very gently driven vehicle. I drove home hone day, backed into the driveway and unloaded the groceries. The next morning, when I tried to start it, the engine will not turn over. I dropped the starter and tested it–all good. While I had the starter off, I found I could spin the flywheel freely–appears to not be attached to the engine. It’s tight with no play whatsoever. Last year I had a new flywheel installed–something I would do myself, but decided I’m at the age, I’m just not up for it. It’s been running great for 18 months with no problems. There was never a noise. Thi just happened one morning. I thought the crank may be broken, but that seems unlikely since it was driving great until the next morning.
@william969
I’m going to assume your truck has an automatic transmission, unless I hear otherwise
If you do have an automatic transmission, you don’t have a flywheel, you have a flexplate
A flexplate can crack, such that the starter will spin the ringgear portion of the flexplate, but the engine won’t turn over
Since the starter is already out, I suggest crawling under the truck with a small telescoping mirror and a small LED flashlight. Carefully look at the flexplate, turn it if you must, I think you’ll find it’s cracked
If I’m wrong, and you have a stick shift, then you do have a flywheel
Anyways, it’s possible the ringgear separated from the flywheel itself. I believe the ringgear is supposed to be welded onto the flywheel in a few locations. In any case, the mirror will still help locate where the separation occurred
If you do find a crack or separation, it wouldn’t hurt to call the shop that installed the part, and explain the situation. Perhaps they will do the job for free, or for a greatly discounted price, as you undoubtedly spent a lot of money for the repair
It sounds like the crankshaft is broken.
Try turning the engine over by hand at the crankshaft bolt while watching the flywheel. If the flywheel doesn’t rotate the crankshaft is broken.
Tester
Thanks, Tester. I knew that was going to be it. Just didn’t want to drop the transmission. I’ve already talked to the garage and they said “if it’s the fllexplate, it’s equipment failure, it’s not our problem.” Another $650.00. I’m selling it to the neighbor who can do the repiars himself. Incidently, I knew the flexplate difference, but so many use it interchangable with fly-wheel, I tend to use both to cover all the bases. I’ve changed the flexplate 3 times and the transmission 4 time in my 78 4X4 van conversion (and I’'ve had it for all of it’s 36 years). It’s not that tough on the van–a half-day job. The ford is nothing short of a pain and I’m getting too old and decrepit.
Thanks Again!
I sure have to wonder about the multiple replacements of the flexplates and transmissions. There has to be reasons for replacing both of those so many times.
A flexplate seldom fails on its own; something causes it to fail.
The flexplates wern’t broken, but cracked on one occassion and the others were from starters coming unaligned causing some damage to the teeth. The suspension is so tight on this beast, I have to tighted bolts from time to time. I didn’t like having a single dead spot, so it was easier to change them. The van has about half-a million miles on it. Second engine and running great. Old school–change the oil and tune it up, old 400’s run forever.
I would not be too quick to condemn the crankshaft, although with NO PLAY that may well be right. I have seen flexplates separate completely right at the crankshaft. You probably couldn’t even see it with a mirror and light. The only way to tell for sure is to drop the transmission. It might be an easy fix, although it might still be time to say goodbye. That’s up to you.
More than likely a broken flex plate. Many things can cause one to fail in a short amount of time. Broken cranks are rare. Remove the starter or inspection cover and see if you can see the bolts where the flexplate attaches, then have someone turn the motor from the front crank bolt, any movement will indicate your crank is still in one piece.
Greetings, All, I’m dropping the transmission tomorrow. At this point the crankshaft is pretty much out of the picture as the problem. Since I drove this around running errands, then backed it in the driveway, I can’t see the shaft being broken. It was running as smooth as, (insert ajective here), I’m convinced the flexplate went. I’ve already had this up on ramps, removed the starter, tested it here and at the parts house. Also, with the starter off, I can turn the flexplate by hand, but I can;t see far enough up to check the where it meets the shaft.
I have seen a few flexplates with the centers spun out of them so maybe that’s what happened here.
If that’s the case it could possibly be caused by one of several things.
One is that the flexplate was bowed or stressed during a transmission install when things did not slide together easily enough.
Two is that the converter may not have been fully seated on the splines. Once bolted up tight this concaves the flexplate a bit. Hitting the starter motor may then fully seat the converter but the stress due to being concaved has already been done.
Just some random theorizin’ there… 
Here’s the flex plate for your vehicle.
http://www.rockauto.com/catalog/moreinfo.php?pk=5899140&cc=1119619
The inner bolt circle bolts to the back of the crankshaft, and the outer bolt circle bolts to the torque converter.
Tester
" At this point the crankshaft is pretty much out of the picture as the problem. Since I drove this around running errands, then backed it in the driveway, I can’t see the shaft being broken."
How did you start it??
Maybe a rope around the balancer and two strong guys? Excellent question, @Caddyman.
I think he’s referring to the last drive prior to the no-crank.