Crankshaft end play on a 302

[Hal9000]

How much end play is normal/acceptable for a well worn 302? I just found out today that the engine in my '69 has excessive end play (like 1/4" or so). I'm not ready to rebuild the engine, so barring discovery of any other major issues, I'll probably just pull the pan and replace the thrust bearings with the engine in the vehicle (band aid repair till I'm ready to do a more permanent job).

The reason I ask about it is that my cousin, who is a master certified ASE mechanic, shrugged his shoulders at the end play. Basically he thinks it's a non-issue ?:?

 

[thegreatjustino]

the spec is between .004-.008 inch for the crank to move front-back. 1/4" is way out of whack

 

[bmc69]

If you really have that much end play..heck ..even half that much, your crank is beyond turning anyway and a new thrust beaing won't do a thing for it.I've thrown away many a 302 crank that had the thrust face in the center journal worn away too far to recover. And your advisor is full of beans; that much end play really messes up the rods and rod bearings over time. Too late for yours though..run it till it quits.

 

[Broncobowsher]

That engine is toast. More then likly at this point the crank and block are both damaged beyond repair.

 

[Scrapper_MV]

I say run it hard until it blows! Take it to the mud pit, or sand dunes and some high RPM fun! You might as well take her out with a bang!

 

[Hal9000]

Wow, you guys have so little faith! this is actually the first 302 I've owned, but I've seen enough other engines with serious end play that just have had the thrust bearing go south on them that I figured it was worth pulling the pan to check. Are you saying that the crank is more likely to be worn than the thrust bearing? Pan gaskets are cheap, if it is the crank, I guess I won't be out much and in that case I'll just drive it. I've got a spare 351 block and heads anyway. I could just build that in my spare time over the winter.

FWIW, I knew (KNEW!) Sean was wrong, but I was surprised enough to hear him say something like that that I figured I'd better fact check myself. He is the service manager for a big dealership after all....

 

[Skiddy]

FWIW, I knew (KNEW!) Sean was wrong, but I was surprised enough to hear him say something like that that I figured I'd better fact check myself. He is the service manager for a big dealership after all....

I have never heard of any engine with that much end play to be good, more than likely as others have said your crank and block are toast. get to building that 351;D

 

[Broncobowsher]

I just happen to have a thrust bearing out of a 302 in my hand. Don't have a mic, but a good scale shows 3/32" thickness per side. That is a totale of 3/16" of bearing and backing plate. So if you completely removed the bearing you would only get 3/16" of play. the only way to get 1/4" of play is if the crank is worn into the block. Hence it is toast. Find another engine and start prepping it as this one won't live forever.

 

[Hal9000]

I just happen to have a thrust bearing out of a 302 in my hand. Don't have a mic, but a good scale shows 3/32" thickness per side. That is a totale of 3/16" of bearing and backing plate. So if you completely removed the bearing you would only get 3/16" of play. the only way to get 1/4" of play is if the crank is worn into the block. Hence it is toast. Find another engine and start prepping it as this one won't live forever.

I was just estimating the end play based on how far I could move the crank pulley. It's probably less than 1/4", but if you've ever had one move more than it should, it always feels like a lot.

I've got other fish to fry before I tackle the engine. Once I get the axles/suspension/weatherstrip/brakes/steering taken care of, I'll evaluate whether it's worth assembling my 351, or just buying a take-out 5.0 or 5.8L EFI engine to slam in (which is my eventual goal).

 

[bmc69]

Its not a matter of 'little faith'..heck I have faith in the fact that the thing will probably run a long time with all that slop.

That said..unlike yr buddy, I've been an engine machinist/rebuilder since 1981..and like I said before, I've tossed many a 302 crank in the scrap pile that had the thrust face completely worn out on the rear face side of the #3 main journal..some so bad I could have fit TWO thrust bearing flanges in the wear groove and still not filled it up.;D

 

[Hal9000]

Its not a matter of 'little faith'..heck I have faith in the fact that the thing will probably run a long time with all that slop.

That said..unlike yr buddy, I've been an engine machinist/rebuilder since 1981..and like I said before, I've tossed many a 302 crank in the scrap pile that had the thrust face completely worn out on the rear face side of the #3 main journal..some so bad I could have fit TWO thrust bearing flanges in the wear groove and still not filled it up.;D

No worries! I wasn't questioning anybody's level of knowledge on the subject.

I was just surprised by the automatic judgment that the engine is DOA. It's one thing to know that this is a common failure point (which it sounds like it is) and still trying to see if the engine is savable; and another thing to say "don't bother pulling the pan. Just drive it till it dies" which seems to be the consensus.

 

[Broncobowsher]

I never said to stop driving it. I was simply stating don't expect it to be rebuildable. As long as it is running, might as well keep driving it. But keep in mind that a replacment engine will someday be needed instead of a rebuild.

Note; If it is a stick shift, try and start the engine with the clutch out and the engine in nuetral. The clutch puts a thrust load on the now missing thrust bearing. Starting in nuetral will give the oil a chance to start flowing before putting the thrust load of releasing the clutch. This is simply a crutch to keep it running even longer.

 

[bmc69]

Just drive it till it dies" which seems to be the consensus.

The 302s and 289s are..frankly..amazing when it comes to refusing to die. I wish I had a buck for every one I've torn down that had ALL of the below and still ran OK:

1. 1/8" crank end play and no thrust face left on crank.
2. Literally none of the piston skirts still on the pistons..all in a pile in bottom of oil pan.
3. 2 cam gears worth of nylon teeth and a complete set of valve seal pieces clogging the pan and oil pickup.
4. myriad 'silver slivers' in the oil pan..what were once the lower third of the cam bearings and the cam is now riding in the block journal directly on the cast iron
5. .015" stem wear on half the valves...with all the exhaust valves receded 1/8" or more in to the head.
6. Nothing but copper showing on every bearing insert.

tough little buggers they are;D

 

[Skiddy]

The 302s and 289s are..frankly..amazing when it comes to refusing to die. I wish I had a buck for every one I've torn down that had ALL of the below and still ran OK:

1. 1/8" crank end play and no thrust face left on crank.
2. Literally none of the piston skirts still on the pistons..all in a pile in bottom of oil pan.
3. 2 cam gears worth of nylon teeth and a complete set of valve seal pieces clogging the pan and oil pickup.
4. myriad 'silver slivers' in the oil pan..what were once the lower third of the cam bearings and the cam is now riding in the block journal directly on the cast iron
5. .015" stem wear on half the valves...with all the exhaust valves receded 1/8" or more in to the head.
6. Nothing but copper showing on every bearing insert.

tough little buggers they are;D

now how many chebbies have you seen run like that:-X ;D

 

[bmc69]

now how many chebbies have you seen run like that:-X ;D

quite a few actually..the old 283s and 327s were pretty tough too. But for the ultimate in 'hard' engines, I have to give it to the IHC 304. Of course..there is enough iron goes in to making one of those to cast two 302s...
;D

 

[Broncobowsher]

The 302s and 289s are..frankly..amazing when it comes to refusing to die. I wish I had a buck for every one I've torn down that had ALL of the below and still ran OK:

1. 1/8" crank end play and no thrust face left on crank.
2. Literally none of the piston skirts still on the pistons..all in a pile in bottom of oil pan.
3. 2 cam gears worth of nylon teeth and a complete set of valve seal pieces clogging the pan and oil pickup.
4. myriad 'silver slivers' in the oil pan..what were once the lower third of the cam bearings and the cam is now riding in the block journal directly on the cast iron
5. .015" stem wear on half the valves...with all the exhaust valves receded 1/8" or more in to the head.
6. Nothing but copper showing on every bearing insert.

tough little buggers they are;D

You forgot about my first 302. Broken main bearing cap. Bore wear so bad .030 overbore wouldn't touch it. I thought I would pull it down and just freshen it up a little. The standard cam/bearing/timing chain wear. Broken part of a piston ring in the bottom of the pan, still can't explain that one.

But my toughest engine was the 2 cylinder in my Honda N600 Sedan. Every ring shattered. Not broken, shattered. One was in 8 pieces. Cylinder wear? How about a .040 feeler gauge in the gap and that was without removing the carbon buildup. Ever seen silver oil? That bastard would still get the car up to 70 MPH (redline in top gear).