cptpandamonium

RESOLVED: Broken Flexplate

I have a 01 Honda CRV SE B20Z (2.0L DOHC 4cyl) Auto AWD that Ive had since October 2016. Engine has 201k. 2 weeks ago I was speeding up on a on ramp to the freeway full pedal when all of the sudden my revs went into the red. The car slowed down and I was trying to make it go but it was really boggy. I pulled over and the engine was trying to run really hard, revs all over the place. I turned off the car checked the engine compartment and everything seemed fine. I tried to start it back up but it wouldn't crank. You can hear the starter going but no engine movement. Anyway... I had it towed to my house and Ive finally have been able to look at it. I really thought it was going to be a case of a broken timing belt. I took off the valve cover and inspected the timing belt from up top. I hand cranked the engine with a socket on the crankshaft and I could rotate the whole assembly with ease, while watching the timing belt for any tears and there was none. I checked the spark plugs that I replaced in November and they had all even wear, no major or minor damage. No damage from what I can see in the valve/rocker valley either.

The only code I have is P0730 Incorrect Gear Ratio and that was already preexisting. I was able to fix it for a couple of months by changing out the really black trans fluid with genuine Honda trans fluid and I was going to do it again soon before all this happened. I thought then that the starter was just free wheeling so I took it off and bench tested it, all good as you can see in this video.

I then took off the lower timing cover so I could get a full view of the timing belt and it is all intact, maybe a little loose but I also checked the timing marks on the camshafts with the crankshaft and its timed to a tee. Here is a picture of the timing belt. Sorry that its sideways.


This is rotation of the timing belt by hand:

I was really confused why the starter wasnt turning the engine so I took the flywheel inspection cover off and took a video of it while I tried to start the engine with the starter and its turning, but no movement of the crank whatsoever!

Here is also a video of me trying to crank the car over with the starter while hand cranking the engine in between. You will see toward the end of the clip that the crank tried to turn with the starter but didn't catch.

So so confused on what is going on.... so now I am in the process of removing the transmission to see if the flywheel bolts sheered or maybe the rear end of the crankshaft snapped.... which would be so so rare right?

Any suggestions to what is the problem or any next steps would be greatly appreciated! Hopefully I was detailed enough for you to understand my problem.

bbarbulo

the revs being all over the place (I'm assuming on your tachometer) is an indicator - the tach signal would have come from the distributor, meaning the engine was still trying to run, if the bolts on the flywheel sheared, the engine would have ran perfectly but without forward motion.



I conclude from this that the crank is broken somewhere. Drop the oilpan next, rather than removing the trans.

Another way to check is to remove all spark plugs, and look into the ones closest to the transmission with a flashlight while someone cranks the car, you may see pistons going up and down, or not at all... that would help figure out if the issue is the flywheel bolts or the crank.

If the crank is broken, the pistons that are going up and down may have contacted valves (since those pistons are moving out of time with the front of the engine), so the head would be suspect too at this point.

UK-Kev

Your starter motor does not sound correct – I believe it is not producing full torque to turn the engine over at the required RPM speed to start the engine.

Also looking at your videos I would suggest you adjust the slack out of the timing belt and re-check your timing marks.

Rgs
Kev

Caoboy

Stop turning the motor backwards. I needs to turn counter clockwise only. You risk slipping the belt and putting your engine out of mechanical timing, which will result in valve and pistons colliding.

Caoboy

If the crank is broken somewhere, would it not cause more chatter in these videos? Wouldn't the pistons be hitting the valves?

bbarbulo

not producing the required torque?? so that is causing the flywheel to turn, but it's not enough torque for the crank to turn? think about what you're saying for like, one minute. just sit there in the glow of your screen and think about what you're saying

i don't know what kind of noise a broken crank would make. more chatter? really, I have no idea. but what I DO know is that the flywheel is attached to the crank, and the crank is attached to the crank timing belt sprocket. so if he can turn the TB sprocket and make the cam move; AND he can make the starter turn the flywheel... then logic dictates that there is a disconnect between the flywheel and the TB sprocket. I've laid out a clear troubleshooting plan. Shine a light into each cylinder hole while cranking. If there is no motion, flywheel bolts are gone. If there is motion in one, move down the line from cyl 4 toward cyl 1. If they ALL turn, then the key from the crank sprocket is gone. But that's hard to believe since turning the crank bolt spins the cam, meaning the crank bolt (middle of the crank) has traction on the crank TB sprocket, so the key is likely intact. Which brings us back to a broken crank. So oil pan drop is the next step before transmission removal.

UK-Kev

Dear bbarbulo,

In answer to your comment (not producing the required torque?? so that is causing the flywheel to turn, but it's not enough torque for the crank to turn? think about what you're saying for like, one minute. just sit there in the glow of your screen and think about what you're saying) You sir have never seen a lazy starter motor hence my original comment still stand.

UK-Kev

I’ve had over 45 years working on all types of engines and I do not believe the crankshaft is not broken from what I have seen in your videos.

Easy way to check.

Remove starter motor and with the aid of second person hold a screwdriver against the flywheel ring gear so as it does not turn. Then you need try and turn the front pulley bolt on the crankshaft in a backwards and forwards motion – If you feel movement on one end of the crank and not the other, then the crank is broken - This test will prove whether the flywheel bolts or fly wheel as sheered.

Rgs,
Kev

cptpandamonium

Thank you for all the replies so far! I did check each piston from the spark plug holes and they all came up to tdc normally. I removed the oil pan/baffle and the crankshaft was spinning normally but the flywheel was not. So I took out the transmission which was a lot harder then I thought it was going to be, mostly the biggest pain was not being able to get the driveshafts out of wheel bearings. After removing the transmission... guess what spins now? The whole freakin assembly, as in the torque converter/ fly wheel assembly spins with the crankshaft as where before It wasn't... I had very mixed emotions seeing that after removing the transmission, but I'm happy that it may not be the crankshaft now.

I noticed that the torque converter/flywheel assembly has a lot of play to it, is it supposed to have this much play? Here is a video:

Tomorrow I will unbolt the torque converter from the fly wheel to take a closer look.

Some questions, Could there of been a bind in the transmission that would cause the torque converter/flywheel to turn but not the crank? And for me to be able to turn the crank but the torque converter/flywheel wouldn't? This all was supposed to be an easy fix! lol... I guess it never is.

But the crank should still be able to turn, even if the starter was weak, it would just move slowly like when you have a low battery. As you can see the original post, in one of the videos the flywheel is spinning fast enough to be able to turn the crankshaft.

Caoboy

No, that play is not good. There should be no play.

UK-Kev

Sorry didn’t fully comprehend your video of the flywheel spinning when starter engaged.

From you latest video looks like you have sheared the flywheel plate, please unbolt the stator and let us all know.

Kev

cptpandamonium

and the verdict is....



Broken! It was actually still attached by all of the flexplate bolts, just the middle where it was welded in. Looking up other example of broken honda flexplates, this seems to be the weak point where they all break.

Honda does not sell these anymore, out of stock forever. Also I cant find any aftermarket support for flexplates for the b20, so to the junkyard is where I found another one.

This is a compare broken vs used


Thank you for all your help again! Hopefully this will help out others in the future! Now time to put it all back together, already cleaned and painted the trans!