Should I be scared of trying to rebuild an automatic transmission?

There is a car nearby for sale at a rather ridiculously low price due primarily (from what I've heard, haven't been able to get out and look at it yet...) to having wrecked threads on a spark plug (replacement junkyard heads should be plentiful- it's a Ford 3.0 V6) and reverse on the transmission (CD4E) is slipping.

The engine issue doesn't scare me (perhaps as much as it should...), but automatic transmissions have always been like a magic black box to me. Assuming I check it out and find that these issues are indeed all that would need to be fixed on the car, and I could turn around and sell it for 3-4x what the parts I'd need would cost, should I suck it up and take a crack at the transmission, or look for something simpler to try and flip?

For a fix and flip a good used trans is probably the more economical option. If you want to learn I guess the CD4E wouldn't be bad for it though, common as dirt and failure prone, so you should be drowning in documentation.

They are not that big a deal. Similar to rebuilding a motor in complexity. A clean work environment etc. Every transmission seems to have "special" tools some you need some can be replicated with duct tape and crazy glue. You just have to know what is what (similar to motor rebuilding). There is no substitute for experience (same as engine rebuilding). I have done a couple with success. I moved on from it and just pay my local trans shop to do it as every trans I rebuilt was a research project. I would spend more time learning about the trans than actually rebuilding it. My local shop has a great warranty and with the exception of one trans (they replaced under waranty due to a broken center section with out any questions) every other trans has been perfect. The down side is it runs between $2400 - $3500 for the transmissions I have taken to them. This includes removal and installation. To me this is worth it for my cars that are keepers.

For a flip I get a used one with a decent warranty and slap it in and go.

Other than that I would recommend getting the rebuild book for what ever transmission you are looking at and read it and see if you are comfortable with it.

Kenny_McCormic wrote: For a fix and flip a good used trans is probably the more economical option. If you want to learn I guess the CD4E wouldn't be bad for it though, common as dirt and failure prone, so you should be drowning in documentation.

That's definitely an option- just as I should be able to find plentiful cylinder heads I should be able to find and pull the transmissions too... it's just that it's more difficult to tell if a used transmission is going to be decent vs. the cylinder head. Though I suppose I could pull one from a yard and overhaul it and then swap it in...

Ever see "Raiders of the Lost Ark?" Don't open it. And if you do, don't look at it. KEEP YOUR EYES SHUT!

First thing to do is a fluid/filter change.

I have "repaired" several bad transmissions that way.

the only thing complicated is the valve body.

As others have said there may or may not be special tools/knowledge/voodoo involved depending on which transmission you want to rebuild. If it a Jatco (which I think it is) then you'll want to get your passport in order and RUN AS FAR AWAY AS YOU CAN. Perhaps an early booking on the next Virgin Galactic flight would be a good idea. Seriously, those things were marginal when new.*

For the head there are kits to repair spark plug threads in various Ford engines without removing the heads. That right there should tell you 1) a good head might not be so easy to find and B) replacing the head is a crappy enough job that there is a kit to avoid doing it.

Some extra research on these specific engines and transmissions is definitely recommended.

*If it IS a Jatco be sure you don't remove the Oh E36 M3 bolt. That's the one that looks kinda like a drain plug but renders the vehicle immobile until the transmission is rebuilt and a sacrifice is made to the sun god Ra. I'm only kidding about one of those things.

I don't think it's a Jatco- the CD4E I believe was Ford/Mazda, a quick search shows threads on replacing one with the other, so I'm assuming they're not the same.

Apparently the spark plug thread repair was already attempted and didn't do the trick. I won't complain about pulling the head too much- this vehicle (2002 Ford Escape) is the sister of my wife's (newer) Mariner and this one has the same engine (though my wife's isn't 4wd like this one is) so getting more experience with the engine is useful for working on hers down the line.

Depends on the tools needed.

I asked this same question regarding a ford AOD gearbox. Rebuild kits are under $100 and the Transmission shop wants $1500. So there is a bit of margin, and I figure busting my autobox cherry has some value, so I am going to go ahead. The only tool that I don't see as optional for the AOD is the seal protector, so there goes $200.

The negative value proposition is that I wont have the confidence that it is going to work until I bolt it all back up and put it in gear. For that matter, even if it does work, how long before I relax and trust it?

I have actually seen Lucas Stop Slip do what it claims to do, so that might be another step to add to the fluid & filter change. My old van also had a terrible slip to 2nd that developed not long after I bought it. I changed the fluid and filter and it was rock solid for another hundred thousand miles, many of which involved towing. So definitely worth a shot before doing anything else. I'd also go for a used one. Look for a donor with some good body damage and try a swap.

For better or worse, the CD4E does not have an easily replaceable filter- it's supposed to last the life of the transmission and you can't change it without taking the whole thing apart. Changing the fluid would be the first step, if it still slipped then I'd probably try something like the Stop Slip.

If it's a fix and flip, (or if you're keeping it too I guess), check the brake hoses for wear. Pretty common problem on those so it's a cheap fix

In reply to NOHOME:

When pricing rebuild kits, don't forget the cost of a new/refurb converter.

And, it's now a moot point as it sold before I could get out to look at it. Sometimes having a full-time job and something resembling a life gets in the way of my buying cars.