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| [GMCnet] Very noisy engine [message #276071] |
Fri, 17 April 2015 12:51  |
Advanced Concept Ener
Messages: 112
Registered: December 2014
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Lost a Buick front wheel drive engine to a transmission that kept shifting up and down. Believe it was a 700r4 trans. Download of data showed a bad sensor that was causing it. You couldn't really feel it but it was happening. Every time you load and unload the engine the change in torque causes lateral forces on the crank. Keep bouncing the shaft against the thrust bearing and you get wear and failures. Happens with pumps, compressors, turbines and all rotating equipment .
Jon Darcy ACES
North Jersey 76 stretch, flares, 4 bag, Alcoa's, bunkhouse,MAC Dash
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| Re: [GMCnet] Very noisy engine [message #276085 is a reply to message #276071] |
Fri, 17 April 2015 15:28  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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Well, help me along here. If all the gears to the cam are straight cut - or it's chain driven, and the output is chain driven, where does end thrust on the crankshaft come from? (No helical cut gears to produce an end load) I can see a torsional load but not an end one. How's it get there?
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Very noisy engine [message #276099 is a reply to message #276071] |
Fri, 17 April 2015 19:40 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Advanced Concept Ener wrote on Fri, 17 April 2015 10:51Lost a Buick front wheel drive engine to a transmission that kept shifting up and down. Believe it was a 700r4 trans. Download of data showed a bad sensor that was causing it. You couldn't really feel it but it was happening. Every time you load and unload the engine the change in torque causes lateral forces on the crank. Keep bouncing the shaft against the thrust bearing and you get wear and failures. Happens with pumps, compressors, turbines and all rotating equipment .
Jon Darcy ACES
North Jersey 76 stretch, flares, 4 bag, Alcoa's, bunkhouse,MAC Dash
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My thoughts are somewhat along those lines I keep thinking the higher pressure in the trans from the shift kit and the torture the engine goes thru climbing up and down mountain passes every time I go somewhere .usually towing something behind could have easily put more wear on the thrust but I'm no engineer so it is only a thought. I drained the oil and cut open the oil filter for a look see. Doesn't look bad just a trace of metal likely from the thrust bearing hoping not excessive damage it will be awhile before the engine will come out.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Very noisy engine [message #276112 is a reply to message #276085] |
Sat, 18 April 2015 00:17 |
LarryInSanDiego
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Registered: September 2006
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Johnny Bridges wrote on Fri, 17 April 2015 13:28Well, help me along here. If all the gears to the cam are straight cut - or it's chain driven, and the output is chain driven, where does end thrust on the crankshaft come from? (No helical cut gears to produce an end load) I can see a torsional load but not an end one. How's it get there?
--johnny
The torque converter exerts considerable axial thrust against the flexplate, similar to what happens when you depress the clutch. It pushes the flywheel with more force toward the engine when it's running. If main line pressure is pegged all the time (some shift kits include a stiffer main line pressure regulator spring), it worsens the problem more quickly. Some trans designs increase MLP when the selector is in second range, etc.
Larry Engelbrecht
San Diego, CA
'73 26' ex-Glacier
TZE063V100319 03/07/73
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| Re: [GMCnet] Very noisy engine [message #276129 is a reply to message #276112] |
Sat, 18 April 2015 09:27 |
James Hupy
Messages: 6806
Registered: May 2010
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Larry, are you saying that the torque converter in a TM-425 exerts a
forward axial load against the flex plate in the Olds 403 or 455? What
happens to the 1/2 +" or so end play built into the lugs on the torque
converter that engage the pump in the transmission? When a person installs
the engine in a GMC the fasteners are secured before the flex plate bolts
are. There is easily more than a 1/2 inch of distance between a retracted
torque converter and the flex plate before these bolts are aligned and
tightened. When the torque converter warms up the expansion goes towards
the transmission, not towards the engine. Same for axial thrust, if there
even is any present. Not just my opinion. I have a transmission specialist
fluent in TM-425 that I have known for 20 years or so. He agrees with me.
The only torque converters that he has had experience with "ballooning"
have been Ford products.
Jim Hupy
Salem, Oregon
78 GMC ROYALE 403
On Apr 17, 2015 10:17 PM, "Larry Engelbrecht"
wrote:
> Johnny Bridges wrote on Fri, 17 April 2015 13:28
>> Well, help me along here. If all the gears to the cam are straight cut
> - or it's chain driven, and the output is chain driven, where does end
>> thrust on the crankshaft come from? (No helical cut gears to produce an
> end load) I can see a torsional load but not an end one. How's it get
>> there?
>>
>> --johnny
>
>
> The torque converter exerts considerable axial thrust against the
> flexplate, similar to what happens when you depress the clutch. It pushes
> the
> flywheel with more force toward the engine when it's running. If main line
> pressure is pegged all the time (some shift kits include a stiffer main
> line pressure regulator spring), it worsens the problem more quickly. Some
> trans designs increase MLP when the selector is in second range, etc.
> --
> Larry Engelbrecht
>
> San Diego, CA
>
> '73 26' ex-Glacier
>
> TZE063V100319 03/07/73
> _______________________________________________
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| Re: [GMCnet] Very noisy engine [message #276130 is a reply to message #276112] |
Sat, 18 April 2015 09:40 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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LarryInSanDiego wrote on Fri, 17 April 2015 22:17
The torque converter exerts considerable axial thrust against the flexplate, similar to what happens when you depress the clutch. It pushes the flywheel with more force toward the engine when it's running. If main line pressure is pegged all the time (some shift kits include a stiffer main line pressure regulator spring), it worsens the problem more quickly. Some trans designs increase MLP when the selector is in second range, etc.
I am not arguing here, just trying to understand. If the designers knew the torque converter was going to push the crank forward, why would they not allow for clearance? The flex plate, by the nature of its name, must flex in this movement and while it is not that flexible it must be sufficient. TH425s and a zillion other setups are not taking out engines and run thousands of miles. Neither do clutches.
If shift kits do this it seems they would get a bad reputation very quickly for everything but the racer who pulls the engine down every few runs.
Sure hope my main line pressure is what it is supposed to be. (Trusting Manny with this one.)
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] Very noisy engine [message #276178 is a reply to message #276130] |
Sat, 18 April 2015 22:24 |
LarryInSanDiego
Messages: 336
Registered: September 2006
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Fair enough. The forward axial thrust I'm referring to I recall reading in an article I read about ballooned converters where it made that conclusion. Made sense to me then but I see your point too. Statement retracted until I can conclusively prove otherwise either way since I had not measured it myself personally.
Larry Engelbrecht
San Diego, CA
'73 26' ex-Glacier
TZE063V100319 03/07/73
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| Re: [GMCnet] Very noisy engine [message #276184 is a reply to message #276178] |
Sat, 18 April 2015 23:57 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
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LarryInSanDiego wrote on Sat, 18 April 2015 20:24Fair enough. The forward axial thrust I'm referring to I recall reading in an article I read about ballooned converters where it made that conclusion. Made sense to me then but I see your point too. Statement retracted until I can conclusively prove otherwise either way since I had not measured it myself personally.
Larry,
I don't think you need to retract, as something caused the problem. I am just trying to figure out why this happens on rare, but devastating, occasions. I too have heard about ballooning. I certainly didn't mean to say you were wrong. Just puzzled and hoping we can sometime figure out what happens and why.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] Very noisy engine [message #276202 is a reply to message #276184] |
Sun, 19 April 2015 07:31 |
Mr ERFisher
Messages: 7117
Registered: August 2005
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Some history
On this
http://gmcmotorhome.info/CRANKS.html
On Saturday, April 18, 2015, George Beckman wrote:
> LarryInSanDiego wrote on Sat, 18 April 2015 20:24
>> Fair enough. The forward axial thrust I'm referring to I recall reading
> in an article I read about ballooned converters where it made that
>> conclusion. Made sense to me then but I see your point too. Statement
> retracted until I can conclusively prove otherwise either way since I had
> not
>> measured it myself personally.
>
>
> Larry,
>
> I don't think you need to retract, as something caused the problem. I am
> just trying to figure out why this happens on rare, but devastating,
> occasions. I too have heard about ballooning. I certainly didn't mean to
> say you were wrong. Just puzzled and hoping we can sometime figure out what
> happens and why.
> --
> '74 Eleganza, SE, Howell + EBL
> Best Wishes,
> George
> _______________________________________________
> GMCnet mailing list
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Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
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