2002 2.7L flexplate worn

Hi all,

I have a 2002 Xtra Cab SR5 4WD with a 2.7L auto trans. Recently, I discovered that the flexplate gear is worn to the point where the truck will not start now. I ordered a new starter and flexplate from Toyota and intend on replacing them. I think we are solid on what to do for that job.

My concern is trying to determine what caused this. I posted pics of the flexplate (through the inspection plate) and the starter gear. You can see the wear on one side (right) of the gear and taller teeth on the other (left). I've gathered that these engines tend to stop in the same place(s) when turned off. That would maybe explain why the wear is only occurring on one portion of the gear. But why is this happening to begin with?

I am assuming that the flexplate is original (it may not be) but we have only owned the truck for a year and it has 165K miles on it. Maybe once I remove it something will become obvious. The guy at Toyota said there are 18 in the US, this is not a commonly sold part and not a common problem. My research online jives with that, too. Goofed up trans replacements and aftermarket parts are usually the root causes from what I have seen.

I have owned 2 other 2.7L trucks myself (1999 manual and a 2010 manual). This truck starts "aggressively" compared to those other trucks - almost like it wants to start too quickly (like the timing is advanced). One of my theories is that the starter gear is remaining in contact with the flexplate gear after the truck starts. The bendix on the old starter seems fine. We did put a new starter (aftermarket) on the truck and it went for about a week before it finally failed.

The truck currently is showing an "EVAP emissions" (don't remember the #) code so we intend on having Toyota look at the truck once the repairs are complete. Not sure if that is a contributor or not - it has been flashing that code for a long time now (months). My son has been avoiding doing the repairs. I can't imagine this affecting the way the truck starts, but figured I'd mention it.

There is marker on the hood indicating a trans flush at 147K. The original owner did that. Thinking maybe a trans issue prompted that or normal interval for that service. The truck was well taken care of.

Any speculations as to a root cause here?

 

Not sure if I'm seeing this correctly (it's early and I am so far, insufficiently caffeinated), but it looks to me like the teeth on the flex plate are "stepped". The only cause for that I can think of is the starter gear and the ring gear not being square to each other.

 

there is nothing to be concerned about here flex plate and starter wise. The wear pattern on the teeth on the flex plate show that the bendix on the starter engages fully. Maybe the person before you did a lot of short trips every day and just plain ol wore the the parts out by use.

 

A flashing cel light indicates a serious engine problem. The flash is designed to get the operator's attention and resolve the matter as asap.

What makes you think a worn flex plate is causing your engine not to start? Have you check compression? Or know the engine is not turning due to the flex plate?

I would hate to do all that work and not solve the actual issue to began with.

 

I kinda second what he says, at least for now.
I see you say it doesn't start, does that mean it cranks and cranks but doesn't fire up? It doesnt turn over?
Very detail oriented first post, makes it much much easier to help when the person understands details are important

 

Thanks for the replies. The truck would start before but there was a clear mechanical issue at the starter. At this point it is clearly not starting because the starter gear is not engaging the flex plate gear. That I am 100% certain of based on the noises we have been hearing and the final events last night when the starter finally stopped engaging (starter grinding noise engine not turning over smoothly).

I mentioned the code only because I'm wondering if that condition would cause anything in the timing/starting sequence that could effect the way the truck starts.

 

Good point Glamisman, this truck actually gets exactly that kind of use. It goes for short trips, often 4 times a day so it does get started/stopped quite a bit. That said, I have never personally heard of anyone wearing out a flex plate before. It obviously does happen (haha)..........the whole reason for this conversation.

Consider too all of these new vehicles that turn off at stop lights and such. I wonder how many times they start and stop in a day?

 

Hey cruiserguy, it did crank and start, albeit quite a rough start, until last night. Now you can hear the starter gear grind and make occasional contact with the flexplate. Not enough to get the engine to start, though.

 

Okay I followed your other posts above too. I mean the logic behind it just being a worn out flex plate and starter is there, just never hear about it happening here in the forum.
You sound like you know what you're talking about with this crap so that makes it a lot easier... I guess the question is, is this the normal way to wear out of it was used for 5 or 6 short trips most days of its life?

 

Good question cruiserguy, wish I knew that answer. We bought it from the local Toyota dealer. The truck had 2 owners. #2 owned it for a month and traded it in. The original owner had it for 16 years and put 155K on it. That is about 10K miles per year so the short trip theory holds some weight.

And I agree that it is a totally logical root cause, it probably does happen and just never becomes known on the forums. I'm really hoping that you are right and that there was just some excessive use scenario in place. My fear is putting this all back together and having the same issue a year from now. I am certainly not a mechanic, but I am mechanically inclined and I do work in engineering as a career. I replaced the engine in my first car and try to do all of my own work when I feel comfortable with it. I trust myself enough to do the repairs and spot some obvious issues. My father in law is also assisting me with this and he is a lifelong tinkerer of all things mechanical. We are both kind of stumped as to how this has happened.

I'm going to try to take a lot of reference measurements and check for alignments on everything before reassembly. Also not ruling out some issue with the torque converter, but I think that is a reach, at least at this point.

 

It sounds to me like you have a solid plan on going about this. Nothing comes to mind on suggestions that you haven't mentioned or likely will be looking into or checking. I do know that parts stores reman starters suck. You didn't happen to open up the original Denso starter did ya? Or the reman?
I guess we'll just have to wait and see what you find with the flex plate.

 

I have the original Denso starter, but never opened it up. I may turn that one in for core charge, we'll see. We took a look at that one today and I don;t really see anything wrong with it. Very little shaft play and the bendix seems tight and functional. The reman is still on the truck. I ordered a new Denso. My original diagnosis was a bad bendix and he wanted a quick fix. Nobody had a new one in stock. I've had pretty good luck with aftermarket stuff, but I am starting to look at things differently here lately. I told him we can just chalk up the $120 on the reman starter as a lesson learned and keep it as an emergency back up. After all I am probably saving him $2000 by doing the work in our garage instead of at the dealership!

I'll probably start working on this on Friday so I'll post some pics and an update on Friday. Maybe some new information will stir up some new thoughts on a cause.

 

Yeah man, definitely keep this thread updated, I enjoy following along and learning as you guys go

 

Ok, so I was able to get the new flex plate and starter installed. We started on Friday morning and finished up Saturday afternoon, so all in all not too bad.

Unfortunately, we are kind of where I thought we would be - no real root cause that is satisfying. The new (Denso reman) starter and flex plate (Toyota) work great. The old flex plate was roached at what looks to be the starting position. From what I can tell, this engine comes to rest in the same place, or in one place very frequently. It is clearly worn in about a 3 inch section with no significant wear on the rest of the teeth. No sign of cracks, no signs of warping. Looks like this is good old fashioned "normal" wear. I put normal in quotes because it just seems crazy for this to have worn in 165K miles. But if it lasts another 165K I'm happy.

The parts guy at Toyota said there are 18 flex plates in inventory in the US. This is not a commonly sold part nor a common problem.

 

Nice job man, that's no easy feat. Glad it went well.
My experience is limited, but I don't think that looks like normal wear, per se. I see the same things you do. Why are 4" of teeth on ring gear worn flat and the rest have low wear? That's weird but it is awesome that that's what you were expecting to find when you opened it up. Just wouldve been nice to see some indication of why it wore that way, meaning why was the starting always done there on the fly wheel? Flaw in the metal when it was manufactured? Nah. How did the motor always stop in that position? Tons of questions, would be nice if an old pro showed up and explained it to us. Not even a pro or old even, just if you know please enlighten us lol
Good job on the repair though

 

I can only guess just a strange unexplained wear pattern.

If that was original it could be a bunch of strange things.

alignment problem causing that section of ring gear to mesh that much harder with the starter drive

It might be possible something happened in the ring gear heat treating.

Water over the dam but a hardness test on the worn area compared to the rest of the ring gear .

I am sure with lots of testing and time the original cause could be figured out .

As things seem to be corrected I would put the blame on Gremlins or aliens from another universe and call it good.

 

Yeah you've been around the block, been around a few vehicles. What a weird condition huh?

 

I think that is where we are leaving it. I am putting it on on unusually high number of starts along with what seems to be a single stopping position. Like you said, with a bunch of testing and research we could get a root cause. If the new one goes 165K I'm ok with it. Might be time for a new motor at that point!!

 

Thanks!!

 

Oh, and by the way when I put everything back together we did not have working 4WD. The lever was not moving into any of the positions. Found out that the lever can be re-inserted improperly and still allow for the locking collar to be re-installed. Found a Youtube video showing how to insert it properly (moving the fork to the right of the "spring" piece down in the housing). .

Anyway, that topic has probably been covered here 100 times already. Add me to the list of people who did it wrong!!