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Discussion Starter #1 (Edited)
Just completed changing out a leaking rear main seal in my sisters F150 4.2L. Got it all back together and running a couple hours ago. Didn't run into any major problems took it slow to reinstall everything to make sure I didn't miss anything.. But I as soon as I take it out for the first test drive it's shaking like crazy. And it only happens while the engine is under load between idle and 2000 RPM. If I let off the gas and let her coast she's smooth as glass same as if I'm accelerating or cruising at 2000 RPM and above. She also does it while in park and I rev the motor - She shakes from idle to 2000 RPM. If I go over 2000 RPM she's smooth.

Thoughts? Looked for vacuum leaks -found none. Cleaned MAF. Checked oil and tranny fluid all good. No codes. Kinda sounds like spark plug wire to me.. Need some input ASAP as my sister needs her truck back to get back and forth to work.
 

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Does sound like spark plug wires. If you R&R'd them, did two get switched by chance?

Al
 

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Discussion Starter #6
I didn't know they had balancing weights. I didn't find anything extra laying on the ground. Expcept a small piece of black rubber about the size of a worn out pencil eraser. Could have been there before and completely unrelated.

It shakes bad in park too which leads me to believe it's not transmission or drive-terrain. I was thinking u joints at first but can't be if it does it in park.
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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Unhook one injector/spark plug at a time and start the engine. If the miss doesn't change with the injector/plug disconnected, that cylinder is missing. Conversely, if the engine fails to start/run or is worse, that cylinder is fine.
 

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Yup just got done doing that test. Should've done it with the car off shocked me pretty good lol. But no luck they all make her run worse....

Damn. I'm runnin out of ideas..
This may sound stupid but have you double checked that you go the firing order from the distributor correctly?

I made a mistake when I was first getting my V8 up to speed in the car and it was because I had mistakenly swapped two of the spark plug wires so the firing on those two cyl was out of time. The car still ran but it was rough.

-g
 

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Discussion Starter #10
Someone on the Facebook TCCoA mentioned TC shudder. Seems like it fits except for it only does it at certain RPMs..

Last time spark plugs and wires were changed was a few years ago when it was my dad's. And he took it to a shop like always. I'll look into it though
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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It can't be TC shudder if it does it with the car in park.
 

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Sometimes when you pull a trans the engine can sag in the rear. I would check all vacuum lines and the main air intake tube and make sure it didn't pull off a little from the throttle body. Also if it were plugs/ wires you would get a check engine light and a scanner would show what cylinder misfired. Also did you make sure that you didn't pince and wires between the bell housing.
 

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Discussion Starter #13
Thanks Brandon I didn't think that was right.

Jason, that's exactly what I've been thinking. Something got pinched when I dropped the trans and engine was tilted back. I don't think anything got caught in the transmission but I'll check it out. I'm also thinking maybe the wire is on it's way out and not completely busted yet maybe that's why I'm not pulling any codes.
 

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Discussion Starter #14 (Edited)
So my dad got in it and said it felt like the flexpate was out of line or missing a bolt. I marked the flexpate with the back of the crank and torqued everything down with an impact gun. No left over bolts.. Maybe the torque converter is not lined up properly with the flexplate? I can atleast get to the TC bolts without dropping the trans.. What do you guys think?

Edit: Well it does it in park so it cant be the TC. And the flexplate was marked and installed exactly the way it came out. I even torqued the 6 bolts down correctly in the star pattern...
 

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The Driveshaft may not be installed correctly..

Remove the 4 bolts retaining it to the Pinion Flange, and turn the driveshaft clock-wise until you've reached the next set of bolt holes..

Reinstall the bolts, and tighten them back down..Not installing the Driveshaft in the exact orientation as it was removed can cause major vibration issues..

That's why you're supposed to mark the rearmost Driveshaft Yoke Flange, and the Differential Pinion Flange before removal...


My other thought was along the same lines as what your dad was thinking..It possibly being a flexplate/ torque converter issue..

After installing the rear main seal..Here's what you should have done..

Before removing the Flexplate..Take note of it's orientation, and mark the plate so when you go to install it's in the same position..

When you install the Flexplate..You should hand tighten all the bolts initially..Then using a Torque Wrench..Torque them to spec in a star pattern..

Torque the bolts to spec in a star pattern is crucial to the Flexplate itself..It's similar to the way you tighten lug nuts on a car..

If you don't tighten them in a star pattern..You risk warping the Flexplate..Same as you would risk warping a Brake Rotor if you do not tighten in a star pattern..

Not only must they be tightened in star pattern, but also torqued to spec..Ok you get the idea...Impact Gun..Bad Idea.. :(


Moving on..


Let's talk about how you installed the Torque Converter on the transmission..

When seating the Torque Converter on a 4R70W you should feel "two" clunk sounds while rotating the Torque Converter..This ensures it's all the way seated..

Once that part is done, and you go to raise the transmission up to line the Torque Converter up to the Flexplate..

After aligning the studs of the Torque Converter up with the holes in the Flexplate..Careful not to unseat the Torque Converter here..

You should be able to freely move the studs with your hand while they are protruding through the flexplate..Any binding here is bad..

Once you've established there is no binding then you can start tightening up your Bellhousing bolts..

After you get all those tightened..Then you can tighten the Torque Converter to Flexplate nuts down..


Did you do anything differently than the way I described?..If yes..What did you do differently?


I'm sure I missed something..Just trying to help you sort things out.. ;)




Rayo..
 

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Well he said it does it while not moving while in park so not a drive line issue. Also the flex plate will only line up on way as per how the holes a slightly offset drilled so it can only line up one way. If the converter isn't seated in the pump you would know it immediatly after starting somtimes you can hear a loud whinning noise and sometimes the trans won't engage beacuse the pump gears are not being turned. Also driveshafts are balaned to themselves not to the third member beacuse when balaning a drive shaft it isn't attached to the pinion, it's spun up alone out of the vehicle thats why the flange isn't drilled offset like the flexplate. Now it may be possible to install a flex plate backwards with the rear faceing foward then when you install it , the flexplate would be 180 degress out because of the offset drilled crank bolt holes. However most Ford flexplates are concave on one side thus preventing the ability to install them backwards because it would bottm out against the motor plate. Just some helpful info. So is it a slight vibration or a harsh shaking like it's stumbling or running rough? Also what year is it '99 and older models will not always throw up a misfire code. Also I would check the EGR system and make sure nothings cracked and leaking or the EGR valve isn't stuck open, also the hose from under the IAC valve to the PCV valve cracks. If you unplugged the MAF while its running does anything change?
 

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Discussion Starter #17 (Edited)
Thank you Rayo for the very informative post. My gfs dad helped me with putting the seal in and the transmission back in he has done a few of these and was very helpful to have around. From the looks of it we did everything just like your post. The only thing we might have goofted is using the impact gun on the flexplate. But we did this the same way on my tbird when installing the mark 8 TC and everything was fine.

I did not mark the driveshaft. But considering it does the shaking/missing in park it can't be drive terrain related right?



Jason, thanks again - good stuff keep it coming. No whining sounds from the TC.

It has the stock exhaust so I can hear just about everything but the engine lol. Makes it harder to determine if there is a miss or not. When I unplugged the spark plug wire it acted the same way it does now only noticeably worse. I would describe it as a harsh shaking very similar to a misfire. It is a 2002 but still zero codes. I even drove it around a little to see if it would throw one. No codes makes me think that I have something other than a misfire or vacuum leak.

Mike and I marked the flexplate with a paint pen before we took it out so we know it was installed exactly the same way we found it.

I'll check MAF and EGR
 

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Discussion Starter #19
I just read all 4.2s are internally balanced. So it doesn't matter which way the flexplate goes on the motor...

Spark plug wires are all good. Bought one and changed them one at a time.

EGR and MAF are good.

Harmonic balancer? I'm out of ideas now..
 

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I just read all 4.2s are internally balanced. So it doesn't matter which way the flexplate goes on the motor...
QUOTE]

I just learned something.

So I assume it's vibrating and not " shakeing" for lack of a better term?
 
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