4.3 question.

[johny5]

OK so i have a 2000 4.3 vortec in my buggy and recently replaced the flexplate(brand new) and its got about half and inch run out in it. It hits the nose off the starter .

The engine was from a standard transmission truck (pilot bearing in crank shaft)and Im running a th350

Do i need some kind of adapter in the for the nose of the torque converter into the crank, to help center torque converter ?

I never measured the two when the were apart.

 

[crash2]

So when the flexplate is bolted to the torque converter you have that much runnout?

 

[johny5]

yep. smacks the nose of the starter then kinda stops when I rev the engine then comes back on idle

 

[crash2]

Wow. Here is the odd thing. A new OEM flexplate is never totaly square. Its the torque converter that makes it perfectly square. if you think about it the flexplate is pretty thin material and the torque converter is pretty thick material. I would be looking at the torque converter for an issue. As for the converter using the hole in the crank as a pilot hole of sorts. I want to say yes but on the outer edge of the hole.

 

[johny5]

I looked on summit site and didnt see any bushings for the 4.3 but they have stuff for the gen 3 engines .

 

[Trevor]

The spacing on the flexplate is different on that 2000 vortec than it is on an older chev that the turbo 350 was bolted to. You have 2 problems going on here. One: it is trying to pull the torque converter off of the tranny, and 2: since it can't pull it all the way, it is flexing the flex plate.

Unbolt the flexplate, push the torque converter back onto the tranny all of the way, and put a spacer on each bolt to fill the gap you just created. Usually it is about 1/4", but I have had a few that were closer to 3/8".

Once you do that, hopefully the flexplate isn't permanentely warped (I've seen that happen once).

Good luck

 

[zukkev]

Make sure you have the flexplate in the correct way....I've seen this before---causes a very similar issue...

 

[Binder]

Is this one of the applications where you must remove the pilot bearing to use a torque converter?

 

[johny5]

The spacing on the flexplate is different on that 2000 vortec than it is on an older chev that the turbo 350 was bolted to. You have 2 problems going on here. One: it is trying to pull the torque converter off of the tranny, and 2: since it can't pull it all the way, it is flexing the flex plate.

Unbolt the flexplate, push the torque converter back onto the tranny all of the way, and put a spacer on each bolt to fill the gap you just created. Usually it is about 1/4", but I have had a few that were closer to 3/8".

Once you do that, hopefully the flexplate isn't permanentely warped (I've seen that happen once).

Good luck

Sweet thanks , I only ran the engine for less than 2 min on the hoist, with the new flex plate, but did run it that way for a year and a half with the old flexplate.

only reason I changed it was I broke a tooth of the flexplate when I hydro locked it

 

[johny5]

Is this one of the applications where you must remove the pilot bearing to use a torque converter?

the pilot bearing is in pretty deep in the crank,so i hope not

 

[crash2]

The spacing on the flexplate is different on that 2000 vortec than it is on an older chev that the turbo 350 was bolted to. You have 2 problems going on here. One: it is trying to pull the torque converter off of the tranny, and 2: since it can't pull it all the way, it is flexing the flex plate.

Unbolt the flexplate, push the torque converter back onto the tranny all of the way, and put a spacer on each bolt to fill the gap you just created. Usually it is about 1/4", but I have had a few that were closer to 3/8".

Once you do that, hopefully the flexplate isn't permanentely warped (I've seen that happen once).

Good luck

hmmm.. That doesn't make sense trevor. The torque converter can float in/out with no restrictions (till it bottoms out on the pump). Do you mean the pilot on the torque converter is trying to drive into the crank causing the flexplay to "bow" so to speak?

 

[CHOP SHOP]

hmmm.. That doesn't make sense trevor. The torque converter can float in/out with no restrictions (till it bottoms out on the pump). Do you mean the pilot on the torque converter is trying to drive into the crank causing the flexplay to "bow" so to speak?

The touque conv cant fit into the flexplate. Before the converter and flexplate are bolted up you should be able to pull it out till they are both together. It sounds like its not fitting together to begin with. Then being bolted together forcing the flexplate into a bowl shape.

 

[johny5]

Ok so I spent half an hour with a dial indicator and a pry bar and got the flex plate close.

There was only about a 1/4 inch that I could slide the torque converter back, so I shimmed it about 3/16 and put it back together.

Its not hitting the starter anymore. my guess is the pilot bearing needs to come out and it would have been fine.

oh well live and learn , at least I didnt have to pull the engine out again.:redneck:

 

[44newman]

Pilot bushing deff needs to come out. 2 methods Ive used.
1 find a bolt that fits the bushing tight enough to cut threads in it, thread the bolt in untill it bottoms and keep going, or pry on the bolt head.
2 pack inside the bushing and behind it with grease, find a socket that fits good(not loose) inside the bushing, put a extension in the socket, and slide it in the bushing then hit it with a dead blow. You might have to repack the grease, make sure its full. And I like to put the socket on the extension backwards, makes a more flat surface and dosent fill the socket with grease.

 

[johny5]

I should of done this for sure, but by the time i figured i had a problem it was already back together,
I bought this buggy mostly finished then finished it myself the engine/tranny were already bolted together.i have also ran it for a year and a half already too. I didnt know I had a problem till i bent the new parts.

I changed the flex plate because I broke a tooth off the flex plate because the wrong starter was bolted to the engine aswell.
oh and all the wrong bolts were used to bolt everything together too , It seems the vortec engines used a metric bolt not a standard 3/8 and a lot of threrd were damaged too.

oh well live and learn, it working good now