V8 Transmission Sometimes Slams into 4th Gear

[BrianV]

Car Info:
98 Mountaineer V8 2WD w/ 114k miles

The slam isn't really bad and it rarely happens, typically only under medium throttle.

All gears shift perfect, but 3rd to 4th sometimes slightly bangs into gear. You can hear/feel what can best be described as a dropping feeling/slamming sound.

It hasn't gotten any worse or any better over time. I'm curious if this is a common problem.

Also sometimes when in fourth gear just cruising and I give it medium throttle, it shakes and stutters before it makes the downshift to third. However, if I use the OD off button it downshifts perfectly, also if I give it a lot of throttle it downshifts perfectly (making me feel that it's really not a big problem).

It's such a minor problem but I'd just like to know what it is.

Car History: I bought it about 3k miles ago. It has 114k miles now and based on the records I've seen it's never been tranny flushed. There is records of the fluid being topped off on occassion. I put LubeGuard Red in a few months abck and it seemed to help. The oil in the tranny is fairly dirty, but I fear doing a flush now may cause more problems. What's a rebuild cost anyway? Based on how the tranny is acting, I feel there's still another good 40-50k miles in it, especially since it's only one issue between 3rd and 4th under a very particular throttle level. I've heard of a lot of people complaining about minor tranny problems and not worrying about it and going another 75k miles, alternatively I've read of people changing their fluid and then only getting 5-10k miles left.

I also wonder if the problem is TC related? Any advice is appreciated.

 

[BrianV]

I guess either this problem is isolated to my vehicle or it's just so insignificant and rare that people don't report it or even notice it.

 

[BrooklynBay]

Drop the pan, retorque the valve body bolts, and replace the filter, and fluid.

 

[BrianV]

Yeah I'm thinking of just draining a filling and replacing the filter. I don't think I should flush it.

This thing uses Mercon-V right? Is there any brand/type people prefer here? How many quarts are needed for just a drain, filter replace, and fill?

 

[MountaineerGreen]

If your fluid has never been changed, go through the little bit of extra effort and drain the TC as well. If you don't, your not even getting half of the fluid changed. The best way to tell if it hasn't been changed is a plastic plug in your pan. It will take around 12-13 quarts to refill. I would put a bottle of Lucas trans additive in the pan before you button it up. Definitely worth the effort.

 

[BrianV]

If your fluid has never been changed, go through the little bit of extra effort and drain the TC as well. If you don't, your not even getting half of the fluid changed. The best way to tell if it hasn't been changed is a plastic plug in your pan. It will take around 12-13 quarts to refill. I would put a bottle of Lucas trans additive in the pan before you button it up. Definitely worth the effort.

My mounty is a 2wd, so the TC issue is non-existant.

13 qts, JEEZE; we just did my g/f's Camry and it was 4qts total. What about te filter; any specific brand of filter that is recommended.

I think I'm going to buy the Castrol Mercon-V and LubeGuard Additive. Just drain, replace filter, and fill. I'm definitely not going to flush at this point.

 

[BrooklynBay]

He was referring to the torque converter, not the transfer case.

 

[MountaineerGreen]

My mounty is a 2wd, so the TC issue is non-existant.

13 qts, JEEZE; we just did my g/f's Camry and it was 4qts total. What about te filter; any specific brand of filter that is recommended.

I think I'm going to buy the Castrol Mercon-V and LubeGuard Additive. Just drain, replace filter, and fill. I'm definitely not going to flush at this point.

Yes, I was talking about the torque converter. Think of it this way, if you only need six quarts for a pan and filter drop, then your only doing half the job. If your trans fluid is worn, then its only half as good. Draining the TC is relatively easy, remove the dust cover to access the fly wheel, remove the plug from the bottom of your bell housing, rotate the TC until you can see the plug and remove it. This isn't what I would call a flush, its just a complete drain. IMO, with 100k on the clock anything less is a waste of time.

My understanding of a flush is some kind of pump pushing a cleaner backwards and or forwards through the trans components.

 

[BrianV]

Yeah flush uses a pump to try and blow out all of the sludge that's on the moving parts.

The problem with that in an old transmission is some of that sludge is almost required as it's grown and formed on the gears. Blowing it out creates a radical change in the moving parts of the tranny.

The complete drain won't disturb the sludge on the moving parts.

I may just have my local shop do this since I don't have an oil catcher to catch 14+ quarts of oil, nor do I want to lug that around. I just need to find a shop that has Mercon-V.