351 installation problem
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Freshman User
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351 installation problem
HELP! My son and his friends are trying to replace a 400 with a 351m in a 79 f150 w/ automatic trans. The converter turns freely before the trans is hooked up, the engine turns before hook up. The studs on the converter line up. Everything goes together but the engine won't turn once the trans is hooked up. We're missing some detail but don't know what. Any help would be greatly appreciated. Thanks in advance.
Hotshot
Joined: Dec 2003
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From: iowa
Are you sure that the convertor is into the pump correctly, if it is not all the way into the pump gear then when you pull it together, and bolt it up you would be binding it up, and probably breaking the trans pump
Elder User
Joined: Sep 2003
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It would cause a bind.
There are 3 things that have to engage - the pump, and the 2 splined shafts. Getting the second (and last) splined shaft to engage can be difficult sometimes. Also, it's easy to overlook.
Put your hands against the converter, and spin it back and forth while at the same time rocking it up and down and from side to side. When you feel that last shaft engage, you'll know it.
There are 3 things that have to engage - the pump, and the 2 splined shafts. Getting the second (and last) splined shaft to engage can be difficult sometimes. Also, it's easy to overlook.
Put your hands against the converter, and spin it back and forth while at the same time rocking it up and down and from side to side. When you feel that last shaft engage, you'll know it.
Last edited by scroob; Feb 7, 2004 at 01:42 PM.
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Freshman User
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I think that's the problem. We've been able to get it to engage two times but can't get the third. We've tried rocking back and forth and up and down with no luck. Tried it with the trans in neutral and in gear. Any suggestions?
Elder User
Joined: Oct 2002
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If you already bolted it together mis-match you may have broken something in the pump.
The best way I ever found was to get the engine away from the trans completely. Then sit down in front of the converter and spin it slowly while rocking it up and down and pushing in. Once you get it in right when you bolt the engine up to the housing there will be a small gap between the converter and the flex-plate. If you don't have this play something isn't right. The bolts have to pull the converter out several thousandths of an inch till it is flush with the plate.
Take the converter all the way out, then put it back in and spin/push/wiggle until you count 3 clunks. That's the only way to know for sure.
The best way I ever found was to get the engine away from the trans completely. Then sit down in front of the converter and spin it slowly while rocking it up and down and pushing in. Once you get it in right when you bolt the engine up to the housing there will be a small gap between the converter and the flex-plate. If you don't have this play something isn't right. The bolts have to pull the converter out several thousandths of an inch till it is flush with the plate.
Take the converter all the way out, then put it back in and spin/push/wiggle until you count 3 clunks. That's the only way to know for sure.
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Freshman User
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Thanks everyone for the help. We may have jammed things up in the converter. Still can't get that third "clunk" after working on it all afternoon. Guess we'll go at it again in a day or so. Again thanks for all the input.
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New User
Joined: Feb 2004
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From: Illinois
Re: 351 installation problem
Originally posted by tnwalker01
HELP! My son and his friends are trying to replace a 400 with a 351m in a 79 f150 w/ automatic trans. The converter turns freely before the trans is hooked up, the engine turns before hook up. The studs on the converter line up. Everything goes together but the engine won't turn once the trans is hooked up. We're missing some detail but don't know what. Any help would be greatly appreciated. Thanks in advance.
HELP! My son and his friends are trying to replace a 400 with a 351m in a 79 f150 w/ automatic trans. The converter turns freely before the trans is hooked up, the engine turns before hook up. The studs on the converter line up. Everything goes together but the engine won't turn once the trans is hooked up. We're missing some detail but don't know what. Any help would be greatly appreciated. Thanks in advance.
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Elder User
Joined: Feb 2002
Posts: 987
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From: East Bend, Carolina, U.S
The inside of the transmission isn't the only thing that could be damaged by now. The convertor may have damage as well. Better pull the engine and transmission apart and inspect the convertor, flex plate and the pump in the transmission.
I made this mistake on an engine swap once and had to replace all of the above parts. Consider yourself lucky if the bellhousing is still all in one piece.
I made this mistake on an engine swap once and had to replace all of the above parts. Consider yourself lucky if the bellhousing is still all in one piece.