I noticed my transmission fluid was very very low when a day or two ago it was fine. After adding a quart the fluid still wasnt any higher on the dip stick. I noticed the coolant in the over flow tank was a blackish color. I drained the over flow tank and added straight water. I ran the trans through all the gears and the coolant in the tank was a blackish color again. With the radiator cap off i can see the coolant overflowing into the tank and it is a dark green color. Does it sound like the trans. cooler inside the radiator is leaking? If so would it be easiest and cheapest to cap the radiator and add an external trans cooler or would buying a new or used radiator be better?

Probably cap it off. 30 dollars for an external transmission cooler. But mind you if it has a hole in the radiator only matter of time before it starts leaking as well. I would suggest another radiator 100 bucks new i believe and you can go to a junk yard and get one for pretty cheap well around here anyways.

I would say don't shortcut the cooling systems on these cars, they're already notorious for running hot, and heat lunches transmissions, quick. If you determine that's what your problem is, go with a new radiator, AND put an external trans cooler on it. You'll see a world of difference in transmission life. Besides, I've heard of bad things happening to people who completely bypassed the radiator cooler, I just wouldn't want to do it.

Just my $.02.

yeah replacing the radiator would be the way to go. a new one at that.

I'd make sure to change the trans fluid and filter too while you're at it. Never know if that fluids been going both ways a little bit.

Check your local junkyard for a trans cooler. Look on Suburbans, other big SUVs, station wagons, anything with a trailer hitch basically. Also, ex squad cars, cabs, etc almost all have 'em. Mine came out of a Ford ambulance, works like a charm, and is a super heavy duty unit.

-Levi

disconnect and replace the trans fluid immediately, you need to drain the converter too. The friction material is glued on with water based glue, coolant will make short work of it and will kill off your tranny in no time

Ok well it sounds like buying a new radiator is the best way to go. I will look into adding an external trans cooler along with the one in the radiator. I wont be able to mess with the car for 2 or 3 days so I hope the coolant doenst do any damage wile setting. The trans fluid on the dip stick looked the same as it always has so there shouldnt be much coolant in it.

how do u drain the converter? just remove it and dump out the fluid? lol

wow that sucks 89_roc-z28.... ive never seen that before but you def have a leak. dont bypass the radiator, fluid has better cooling capacity than air. the trans cooler in the radiator will help drop trans temps (always hotter than coolant) to or around the coolant temp then route the external cooler so it flows from the trans to the radiator then into the cooler and then back to the trans. HUGE diff in trans temp. also u might want to flush the trans... if coolant is in the trans then u got some probs. flush the trans, drain converter, replace filter, nows the time to add deep trans pan with drain plug, add external cooler and new fluid and call it a day!

also dont get used coolers they are cheap enough new. you dont know whats in the used trans coolers or the shape they are in. i have the 24,000 GVW B&M stacked plate one... its been really good so far and its stronger than the fuidyne etc ones. look it up on summit.

Drill a small hole and later braze it shut or use a sealed pop rivet. Do a search on it, theres a particular spot where you need to drill and I don't have a pic to show it here.

ouch! drill into the converter?! it makes sense but thats not something i would want to do. not to mention having someone braze it and it being a weak point in the case. id also be scared of getting metal shavings in the converter and then into the trans, could always do the "pack the drill bit with grease" to catch the shavings etc but i dont trust that. i kno what metal shavings can do to a trans... my last converter took a dump and thats what destroyed my trans, had to bring it back 3 times bc little metal shavings (after the rebuild) where finding there way back into the trans and making me loose 4th gear etc.

Im going to start working on it this saturday. I dont want to drill a hole into the converter. I will drain the fluid from the trans, then refill and run the trans. After I run it I will change the fluid again. I will repeat that until I feel i have gotten all the old fluid out. If I dont do that then I will take it to a near by shop to get flushed out good.

If you had dark fluid in your coolant, it isn't highly likely that you would get much water in the transmission fluid, unless it's a really big hole. Fluid flows down a pressure gradient, not up, so in this case, the Transmission fluid was entering the coolant, not vice versa, at least it shouldn't have in any large amounts. You might have gotten a smidgen of coolant in your fluid, so it's a safe bet to at least change it, but I probably wouldn't go bonkers trying to clean it out.

Just my $.02,

-Levi