The Return of Rusty

[ClayJ]

Umm not looking to reach 12k rpms. You're right it is my money and I'm having to spend it to correct a bad engine that has broken/cracked 4 flexplates. So forgive me if I'm looking for recommendations other than the standard steel welded plate. Maybe I'm just not picking up on your humor.

[Gary Lewis]

I'm not up to speed on flexplates as I've not purchased one.  Just used the Motorcraft ones that came on vehicles.

But, looking at Rock Auto I only see two brands for the 351M: ATP & Pioneer.  You've broken a Pioneer and the ATP is even less expensive.

But, that gave me a part number, D1AZ6375A the same as you have, and a search for that found this post by Bill/Numberdummy back on FTE.  At that time, 11 years ago, Bill found 32 of them in various Ford dealers.  But, the MSRP was $186.57, which may tell us something about the quality of the ones at about $30.

So, if it was me, I'd call the dealerships that had the flexplates way back then and see if they still do and at what price?  Bill supplied the phone numbers.  And, if that doesn't pan out I'd look for something stronger than the $30 ones - even if it means going billet.  In your shoes I'd be DONE with breaking them and wanting something that absolutely will not break.

In fact, in light of the Motorcraft unit being so expensive, I'd seriously consider using that money for a STRONG aftermarket one.

[ArdWrknTrk]

You're right, I should use the laughing smiley so I don't come off as an ass.

What I'm saying is the fault lies somewhere else.
Millions and millions of vehicles get by with stock or replacement flex plates.

Fix the underlying cause and the symptom goes away.

Again, it's your money and if throwing a new engine at it is a better solution that using a dial test indicator on the crank flange to see if it's bent or end float is unreasonable, that's up to you.

[1986F150Six]

Gary Lewis wrote

But, looking at Rock Auto I only see two brands for the 351M: ATP & Pioneer.  You've broken a Pioneer and the ATP is even less expensive.

But, that gave me a part number, D1AZ6375A the same as you have, and a search for that found this post by Bill/Numberdummy back on FTE.  At that time, 11 years ago, Bill found 32 of them in various Ford dealers.  But, the MSRP was $186.57, which may tell us something about the quality of the ones at about $30.

So, if it was me, I'd call the dealerships that had the flexplates way back then and see if they still do and at what price?  Bill supplied the phone numbers.  And, if that doesn't pan out I'd look for something stronger than the $30 ones - even if it means going billet.  In your shoes I'd be DONE with breaking them and wanting something that absolutely will not break.

https://www.ebay.com/itm/NOS-1971-1978-FORD-351M-400-C6-AUTO-TRANS-FLYWHEEL-FLEX-PLATE-D1AZ-6375-A-NEW-/371420869716
In fact, in light of the Motorcraft unit being so expensive, I'd seriously consider using that money for a STRONG aftermarket one.

https://www.ebay.com/itm/Ford-flexplate-70s-80s-engine-D1AZ-6375A-never-used-325/264753001876?hash=item3da4823594:g:598AAOSwGTBe2F8c

[Gary Lewis]

MY GOODNESS!  That is NOT GOLD!

[ArdWrknTrk]

But lots of people think NOS is.

I could understand IF you are looking for a concours vehicle.

But, I'd pay my money and roll my dice.

[ClayJ]

ArdWrknTrk wrote

Truck IS good and strong, but if Clay is going to toss it for reman, he more than likely's going to trade it for core.

Truck IS NOT good and strong. Rusty's engine is out for inspection and tear down. Crankshaft runout is excessive and the main bearing caps don't look good at all. Pretty disappointed for being a, "rebuild" with less than 10k miles. Engine mounts are cracked, 1 spark plug was completely fouled and another was cracked. So I'll probably tear this engine down after the shop gets the new 400 installed. The cylinder heads are probably good so I'll sell those and whatever other components that aren't completely "wallered out." I did decide to go with a TCI heavy duty forged flexplate with a SFI 29.1 rating, so it should outlast the truck which is good because I'm D O N E replacing $40 hecho en mexico flexplates. Seems I was mistaken in a previous post as the transmission shop had checked end play and not run-out. So there it is ladies and gentleman, the smoking gun.

[ArdWrknTrk]

Well I'm glad you got to the bottom of this!
 
Like I said in the beginning, I'd put a DTI on the crank flange and make sure the crank was straight.

I hope your new combo out-performs and outlasts your expectations!  

ETA: I can only really go by how Gary raved about Rusty's engine back in the day.
I never drove him, but trusted Gary's honest assessment at the time.

[Gary Lewis]

Well, in a twisted way I'm glad the crank had runout.  At least you found something.  I HATE it when I can't find the problem and then it goes away.  I never know how long it is going to stay away and when it might raise its ugly head.

And this does seem to explain why the flexplates broke.  When it appeared the tranny shop had given the engine a clean bill of health it looked like there was no smoking gun.  Like one of those mystery novels where the guy has been shot but there's no bullet, only to find out later the bullet was made of ice and it melted after killing him.

I'm certainly sorry you are having these problems.  Especially since I sold the truck to your FiL.  

[Ray Cecil]

Its an old truck Gary...you cant tell a buyer about something you didnt know. This happens sometimes. Not your fault.

[Gary Lewis]

You are right, Ray.  But I still feel badly.

[Ray Cecil]

Gary Lewis wrote

You are right, Ray.  But I still feel badly.

I probably would too.

Sold my uncle that red flatbed. He drove it for a couple months and the 9" went out on him. Cant remember exactly what happened. But you and I had that axle apart in your shop during a GTG one year. We did outter axle bearings and seals, and inspected the third member and it all looked pretty good....

This stuff dont last forever ya know?

[Gary Lewis]

I do remember refurbing that 9", and would have bet it was good for another 100,000 miles.  Goes to show what I don't know.

[old55pete]

Clay, Is there any way that you can get a outside measurement on the center main bearing and a measurement on the inside of the main journal on the crank? The center main bearing is what determans the end play on the crank......I am just quirous as I have run into this before building racing engines and have sent back NEW cranks with to much end play because the cranks were ground wrong.

It will need to be done with a micromiter and if you cant, or don't have one that's cool too.

I have been following this from the start and was thinking crank end play all a long but decide to keep my mouth shut because Gary paid someone to rebuild that engine. I guess they fell down on the job and dident do an end play measurement and for that I am sorry.

[Gary Lewis]

Steve - I think Clay said the tranny shop had checked crankshaft end play but not runout, and that the runout was excessive.

As for the rebuild, I bought Rusty with a "newly-rebuilt engine".  I didn't pay to have it done.  And when I asked who built it he said "my cousin".  

[grumpin]

Wonder where his cousin was from...

[Gary Lewis]

LOL!  Maybe so.  

[old55pete]

Ok, I guessed I missed the part about his cousin rebuilding the engine. I saw the strange wear on that rear main bearing and wondered what the thrust bearing looked like....I guess it is a moot point because they look like someone put standard size bearings in a crank that is undersized.

Sorry Gary, some how I had end play stuck in my head instead of runout.

[ClayJ]

Steve I'm sure I'll have more to share, measurements, pictures, etc. whenever I get the block home.

[ClayJ]

So still waiting on Rusty's 400 to be finished. Going on 2 months patiently waiting and MABBCO is telling me middle of August for the latest completion date. Original date was July 29. They claim they're very backed up due to Covid so who knows. In the mean time I kinda did a thing and upgraded out of the commuter car to a 2017 F150 King Ranch. So i know know what I'll use to go pickup Rusty's engine, Ha!