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10 Posts
Discussion Starter · #1 ·
Hi all :wavey
I'm trying to decide whether or not I am going to need a complete transmission rebuild to get my 1998 4.6 Mustang back on the road.
It has just under 200,000 miles and to my knowledge the transmission fluid was never changed. I will be limited on funds for the next 6 weeks, but after so will be able to afford transmission rebuild, this car is my primary source of transportation and I am in dire need of getting it back on the road ASAP. Any help, advice, experiences, or knowledge would be greatly appreciated. Thanks in advance!

First noticeable symptom was a delay of engagement of forward gear, initially I didn't think anything of it, but gradually it began to get worse, and before forward gear "failure" it was a 6-8 second delay from actual shifting, to forward gear engagement.

This went on for about a year. I had to drive the car up through the mountains, and luckily it waited until I got back to my hometown. But I was slowing down at a stop light and the car fell out of gear. When I hit the gas, and revved the engine up a little it popped back in. After I had stopped and was again leaving my friends house (10 min after stop light incident) I started the car and it would not engage in forward gear, reverse worked fine. After a few minutes of testing theorys I revved up the engine to about 3500rpm and she engaged, breaking traction when doing so. Needless to say, I drove the car home from my friends and during that time, the car continually slipped out of gear unless I was at a higher RPM, if idle, it slipped.

I would consider myself mechanically inclined, however before this incident I knew very little about the inner workings of an automatic transmission.

My first reaction was to change the transmission filter, as it seemed like a pressure issue, and I had read that often the filter gets stopped up, or actually slips out. I did so with no effect on the problem.

With my limited knowledge of automatic transmissions, and in doing research online I have come to believe that it is either the front pump seal, or the valve body.

The transmission does have a fluid leak, however prior to this incident it was not severe, and since said incident I have not notice any substantial increase in leakage, however the car has not moved from the location I parked it at when I drove it home from my friends house. I would assume that the leak could be a possible indication of front pump seal failure.

However, with the initial symptom of delayed engagement, and probable lack of transmission servicing it would also appear to be possible that "gunk" had built up in the valve body, causing internal parts not to move properly.

I have several questions if there is anyone out there that could answer one or more of them please do! :)

1. In your opinion, which of the two, if either would most likely be the problem. If neither, then what are the other likely issues?

2. If I am needing to rebuild the transmission, I have decided to go ahead and put a modified valve body on from bc automotive, which runs around $250. I was thinking of purchasing the valve body and installing it to test whether it was actually the valve body causing the problem. Would this be a good idea? If the valve body were not to blame, would there be a possibility of damaging the new valve body?

3.I do not want to buy a rebuilt transmission, I would like to have my transmission rebuilt. What are fair going rates for 4R70W rebuilds? The shop I spoke with (which came with multiple recommendations) said it would be between 14-1800.

4. Several people have recommended using several different stop slip chemicals, as I am limited on funds would this be a plausible temporary fix or would I just be wasting my money? Would it be likely to cost more to rebuild the transmission after using such chemicals due to possible "damage" from use?

5. Does anyone have any other recommendations for modified valve bodies? I do not wish to do it myself, I have the skill necessary for installing a valve body, but do not possess the confidence to modify it myself. I would prefer to purchase one that is ready to go and all I have to do is install it.

Thank you for taking the time to read this, and if you are able to help I thank you in advance for that as well. :)

· Registered
128 Posts
I'm sorry but I do not have the answers to all of your questions but I can help in some of them.

2. Personally I wouldn't change out the valve body as it would most likely be a waste of time in my opinion. I wouldn't change valve bodies until the trans was out and getting rebuilt.

3.The trans shop that you are working with 14-1800 is that included them removing the trans along with rebuilding it or is that just for rebuilding? If it includes removing the trans; I would go ahead and remove it myself and then deliver it to them to try and save some money. Now if it's 14-1800 for just the rebuild on the trans I would say do some calling around to different trans shop and try talking to them about pricing.

4.I personally wouldn't waste my time with the stop slip chemicals/liquids as it MIGHT only be a small band-aid on a big problem.

5.With the valve body are you looking to go full manual or are you looking for just firmer shifts? Cause if you are looking to get a firmer shift then I would just install a shift kit or purchase a tuner and turn up the shift pressure. I wouldn't waste my money on a valve body unless I wanted to go full manual.

Again these are just my 2 cents pm me if you have any other questions/answers. Hope this helps you out a little. :bigthumbsup

· Registered
1 Posts
Same problem on my 1998 GT

Hey man was searching on line about the same problem with my mustang. Didi you ever get it fixed? I took mine to a tranny shop they told me it was 1st gear???? A little Skeptical about the whole situation. The quoted me $2200 for a complete tranny rebuild. What are your thoughts?
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