1994 Mark VIII Transmission Issue

F

Fife

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My wife reported that our 80K mile 1994 Mark VIII is acting up. When cruising at highway speed; with or without cruise control set, the car revs up from 1500 to between 3000 and 4000 rpm for a few seconds and then returns to normal. She said the car does not increase its speed at all and feels like its in neutral. It does this randomly. The other day I drove it thirty miles and did not experience it one time. I have been reading various blogs and haven't found a solid answer yet. Has anyone experienced anything like this and what was the cause.

I found the following on another site and thought it may be related but I am not a transmission guy:

When driving on the highway, my car feels like it's shifting into Neutral, then it goes back into gear. What gives?

The MLPS (Manual Lever Position Sensor) may need replacement. This is what 'tells' the transmission what gear you have selected. When it fails, it may intermittently report the shifter is in Neutral, causing the symptoms above. It is sometimes referred to as a 'neutral safety switch'.

Also, the transmission has another issue; the "shudder" occasionally at mid 30 mph. I am planning to have the transmission serviced with new fluid (Mercron V), new filter, new 1-2 accumulator, and maybe a trans cooler. I am wondering if I need to do all of this or just some of it?

I appreciate any help. I have already received a lot of great advice...hopefully as I get to know this car I will be able to share my experience as well.

Thanks,
Fife
 
You're on the correct path.

You may want to have the fluid transfusion first just to be sure before any internal mods.

Another suspect for the occasional neutral syndrome is a low fluid level with the standard transmission pan. This causes a momentary loss of fluid suction at the filter. Later models incorporated a dimpled pan with a different filter which kept the suction inlet under fluid at all times.
 
I had the transmission serviced yesterday and it works fine now...no shudder and just feels better all around. I had a transmission cooler (B&M Super Cooler, 14000 BTU) installed, fluid changed to Mercon V, filter changed, and did the 1-2 accumulator upgrade. The bottom (purple) spring was broken and that really suprised me because the shifts were not hard. The only real problem I was experiencing was the shudder at 37 mph. Anyhow, The car has 82k miles and I am hoping the nearly $385 I spent will get me another 100K on the transmission. That would be great. This job did not look difficult but having a car lift makes it so much easier and I don't have one of those. Plus its colder than hell out there right now...so I opted to pay the man on this one.

Fife
 
Fife said:
Anyhow, The car has 82k miles and I am hoping the nearly $385 I spent will get me another 100K on the transmission.
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You may get another 50K out of it...but probably not 100K.

Of course they are really sensative to the driver.

I break stock trannies in less than 10k miles, "so called" high performance trannies in less than 20k miles, and right now I am currently taking advantage of a REAL high performance tranny from Lonnie.
 
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logres said:
You may get another 50K out of it...but probably not 100K.

Of course they are really sensative to the driver.

I break stock trannies in less than 10k miles, "so called" high performance trannies in less than 20k miles, and right now I am currently taking advantage of a REAL high performance tranny from Lonnie.
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?! How and why?! lol The OEM trans in my mark lasted 80k miles, (the replacement had 50k miles on it and is still good as far as i know), the crown vic as at 195k, the one in the T bird lasted 105k before I sold the car. You must be doing some really wierd things to break the trans in 10k miles or you get defective units.

BTW OP I hope you realize that you need to service the 4R70W Every 30k miles.
 
maxmk8 said:
BTW OP I hope you realize that you need to service the 4R70W Every 30k miles.
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Actually, It is recommended by Ford to be serviced every 20K miles. A good tranny cooler should be able to double that interval.
 
driller said:
Actually, It is recommended by Ford to be serviced every 20K miles. A good tranny cooler should be able to double that interval.
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I guess it depends on the car and manual. I think my crown vic calls for 25k miles for severe duty and 50k miles for normal duty.

I have been changing it between 30-35k, it was looking excessively clean though.
 
I replaced my tranny on my 93 OEM at 155k, It had shudder at 130k, but I had it flushed and mercon 5 put in. It was still in running condition and no slippage or shudder after the service.
 
maxmk8 said:
?! How and why?! lol The OEM trans in my mark lasted 80k miles, (the replacement had 50k miles on it and is still good as far as i know), the crown vic as at 195k, the one in the T bird lasted 105k before I sold the car. You must be doing some really wierd things to break the trans in 10k miles or you get defective units.

BTW OP I hope you realize that you need to service the 4R70W Every 30k miles.
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Lot's of WOT and manual shifting. Plus I've had the luxury of dealing with Reinhart AND Art Carr.
 
logres said:
Lot's of WOT and manual shifting. Plus I've had the luxury of dealing with Reinhart AND Art Carr.
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my stocker had 230K on it when it finally went and I am probably harder than most on them. My rebuild is less then adequate though Ive already toasted the TQ Im pretty sure
 
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