Engine builders please help. *Now with pics*

[GaWag]

I bought a reman 360 from Advance about 1 1/2 to 2 yrs ago. I noticed the other day while tuning it that the crank pulley would move front to rear with the rev of the engine. I thought to myself, this is bad! I got a long screwdriver out and could pry the crank pulley back and forth about a total of 1/4 in.

I decidied to pull the oil pan and inspect further. I'm thinking, surely the crank is not walking back and forth.

I was wrong. The crank is moving back and forth. There is wear on the sides of the bottom of the connecting rods were they run in pairs. The are seperated by cast pieces of the block as you know. This is what they are rubbing on.

I really don't think thi is right. What do you guys think? I have only replaced engines and cams. Not done any real engine building.

[ October 03, 2004, 06:59 PM: Message edited by: GaWag ]

[78indian]

the problem was buying a motor from advance. i recomend http://www.jasperengines.com/
3 year 75,000 mile warranty on parts and labor nation wide

[GaWag]

Looked into it and researched it. Didn't have the money for theirs at the time. Plus there was a big stink at the time about the reps down here giving bad info or poor customer service or something.

I knew this would come up.

[Sitting Bull]

Steve,

If you don't find out, call me. I can give you Myreons number (he's built more engines that I can think of), and he could give you some good advice.

[Madcobra]

AMC cranks take thrust on the center main bearing. I would look there for a solution. Perhaps the wrong type of bearing was installed, meaning that there would be open space. This would mean that thrust/ wear would then be taken on the connecting rods and rear seal lip. What's your oil pressure like?

[GaWag]

Oil pressure has always been good. Just below 40 at idle and almost 80 going down the road.

I am lost with the "thrust on the center main bearing" thing. Could you elaborate?

[AMX factor]

When you drop the oil pan and look at the crankshaft center main bearing you should be able to see the thrust bearing overlapping the main cap. Normal main bearings fit within the main cap, the thrust bearing is larger and overlaps the main cap to take up the space between the crank sections on either side of the main cap, this is just under 1/4" or so. If your crank is indeed moving this is where. You might be able to pull main cap and replace the thrust bearing. Another thing to check is your harmonic balancer. I've seen a lot of them fail when the rubber in them seperates,this could cause the pulley movement. I think Jeeps4ever can help with this problem.

[GaWag]

Just to clarify. The crank and pulley are moving together back and forth. There does not appear to be any movement between the two.

I will look again in the daylight. May even try to post some vid of the movement.

[billyrb]

Steve, just as an FYI, many re-man / rebuilt engines have crank walk issues. Doesn't mean your engine is shot, but it does mean that you need to have it shimmed properly. Any reputable shop / engine builder can do this for you.

[Retro93]

Originally posted by Madcobra:
AMC cranks take thrust on the center main bearing. I would look there for a solution. Perhaps the wrong type of bearing was installed, meaning that there would be open space. This would mean that thrust/ wear would then be taken on the connecting rods and rear seal lip. What's your oil pressure like?

Sounds like you have fallen victim to the dreaded "AMC Butter Crank". Check the backside of the #3 main bearing. I think you will find a deep groove cut into the crank. Sorry....but your engine is toast.

[ October 02, 2004, 09:27 PM: Message edited by: Retro93 ]

[jeepsr4ever]

Yeah I would invest in a main set for bearings and make sure you put in a new thrust bearing. Sounds like a poor grind on the crank (which is hard to believe) or just a bad bearing.

Retro has a good point you can also get a crank kit from popular auto parts stores for the AMC 360..however If he did have good oil pressure I dont think his crank was scored

[ October 02, 2004, 10:44 PM: Message edited by: jeepsr4ever ]

[Retro93]

The last 360 I had with crank walk never showed a decrease in oil pressure. Ran fine....except for the annoying rattle of the flex plate bolts hitting the transmission tin. I bet if he looks at the rear oil slinger on the crank he will find that it is also worn down. As soon as that wears through....ouch!

[trickc]

Steve if you need to rebuild the bottom end with another crank, Ive got that 360 in the backyard I was telling you about, come get whatever you need off it.

[GaWag]

Rear oil slinger?

I actually have a crank from the 88 I parted out. I didn't have the engine but had some engine parts. Go figure?

[GaWag]

Here are some pics. I tried to post a video on my site to show here but couldn't get it to work.

Same pics. One set just has the screwdriver in there for perspective. I did not see any groove in the crank. The last pic seems to be a groove that matches the bottom of the connecting rod. I would defo say they are rubbing unless this is supposed to be there.

[GaWag]

I know the pics are a little blurry. I took the tonight and the light was bad and I was trying not to get oil on my wife's camera.

[AMX factor]

Yes the pics are blurry but looks like the sides of the thrust bearing that actually wrap up the sides of the main cap are gone. If you were here in Wyoming I'd pop over and help you fix it. Hell I'd assemble a new engine for you for a 12 pack(to be consumed after assembly).

[jeepsr4ever]

wow, it almost lokes like the crank had a really seriously bad grind!! Those ridges around the cap and the block are the final machining for teh thrust bearing....looks like a new crank is in order

[GaWag]

AMX Factor Thanks for the offer! I love this board.

Jeepsr4ever I hope you are wrong but I believe you are right. We are going to talk to Advance tomorrow and see what they say.

I am not too picky, All I want are the parts to fix it and I can do it myself. They're warranty says that they will pay for a shop to pull the ngine for me if something goes wrong. I don't want anyone touching this thing but me.

[Crazy_Jeepman]

I have had Original engines do that, never been rebuilt or apart. My 79 J10 had 105K on it, Crank was Junk, 83 Chero about 85K Junk Crank. Many of the Parts Rigs I bought in the past, that would be the first thing I checked for, before pulling the engine. Sent lots of them to the scrap yard with the engines in them, because I was able to get excessive endplay out of the crank. I have sold Cranks to others, because this problem as occured. You will need a Crank Good Luck with the crank swap.