Just how does tranmission fluid get into coolant?

The transmission cooler is submerged in the engine coolant (water). When it leaks, the two are connected via the break.

DT

# 2, possibly aggravated by the internal cooler plugging up with debris........pressure in the cooler circuit will rise to line pressure (up to a couple hundred pounds) if the cooler is plugged; up to the point at which it is stopped up

Basic concept at work in this one: "If you can't dazzle 'em with brilliance, baffle 'em with bullshit." Although your TC *MAY* have been chewing itself to pieces, which *MAY* have been forming a blockage in the tranny-cooler section of the plumbing, there's no possible way (As in none, zero, zip, nada, zilch) for transmission fluid to "spill over into the overflow reservoir". Somebody was feeding you a line of shit in an attempt to appear wise, when in actuality, they were clueless, and hoping you were too.

*MUCH* more likely. A hole in the loop that goes into the radiator would allow exactly this sort of thing to happen.

There is no theory #3. Theory #4: NO POOFTERS! Oh, wait... wrong skit! So sorry, old bean! :)

Probably because they figured out that there was a leak in the transmission cooler section of the radiator. Hopefully, they also sealed the in/out from the tranny at the point where it enters/exits the radiator when they did the bypass. If not, you're in for coolant leakage. Exactly how much/how bad isn't predictable from the information I've seen you give so far, but there will be leakage.

The tranny-cooler part of the circuit is usually (I'm sure there are exceptions, and I'm just as sure somebody will point to them in an attempt to "prove" me wrong) just a loop of tubing inside the radiator that the coolant flows around. There is no "separate compartment" or whatever that deals strictly with the tranny fluid. The loop is simply run into the radiator, and sits there submerged in the coolant that's normally present. No "magic" going on - It's just "Dump the heat from the tranny juice into the water in the radiator, then let the radiator worry about dealing with it."

A hole in the loop, whether from rust, mechanical trauma, or whatever other source lets tranny juice out, and water in. The result is (sooner or later) a dead tanny and a cooling system with transmission fluid mixed in.

Did they plug the transmission cooler lines coming from the radiator? If not, there has to be coolant running out the tubes OR there is nothing wrong with the radiator.

In any event, in cold weather the transmission fluid needs to go through the lines in the radiator to warn it, so I'd have a radiator shop clean and test it for leaks for peace of mind.

Tom J

Perhaps a bit of a sidebar to this:

At some point in the past couple of years, Monaco moved to an aluminum radiator. There have been numerous failures of the internal transmission cooler, with subsequent transmission failures. The story as I've been told is that it is an electolysis problem with different metals used.

In any case, a full recall affecting hundreds of vehicles was issued. Fix was a kit to mount a separate auxiliary cooler and cap off the internal cooler.

I received my recall notice about two weeks after I had the kit installed; I saw one on an unsold-but-built-later version of my '03 Safari, and since I was having transmission overheating problems I called to see about getting one. They didn't mention the failure problem to me, but were very quick to get me a kit and pay for the install. Overheating problems are very much gone, and it does take a long time to get very warm. Fortunately I don't do much (any if I can help it) cold weather travel, but from other posts here it sounds like there may be a different problem for Monaco when the cold weather hits in force.

One guy who I talked to who got the recall notice 9 days after his transmission had failed said Pacific Detroit Allison told him they had replaced 450 (with rebuilds) so far.

|> At any rate, when the transmission got rebuilt the shop also bypassed the |> main transmission cooler so that I am now using only the two auxiliary |> coolers. I am posting separately with questions about this. | |Did they plug the transmission cooler lines coming from the radiator? If not, |there has to be coolant running out the tubes OR there is nothing wrong with |the radiator. | |In any event, in cold weather the transmission fluid needs to go through the |lines in the radiator to warn it, so I'd have a radiator shop clean and test |it for leaks for peace of mind.

If you do not replace the radiator and restore the radiator loop to the transmission cooling circuit, you might consider moving the auzillary coolers behind the radiator, near the top if there is room. That will impart some heat to the trans coolers in cold weather. Rex in Fort Worth

Your second theory is correct. The factory cooler is located inside the radiator tank, physically surrounded by coolant. When it leaks, coolant gets in the trans, and ATF in the coolant. Not uncommon at all.

The Engine radiator is a Air to Liquid heat exchanger. The transmission cooler is a liquid to liquid cooler. The transmission cooler is located inside the "return" tank of the radiator. This water has already been cooled by the radiator and is on its way back to the engine. The engine coolant at this point is cooler than the ATF, so the coolant removes heat from the ATF.

. . . . Just how does tranmission fluid get into coolant? Group: alt.trucks.chevy Date: Tue, Oct 21, 2003, 6:03pm (CDT+5) From: snipped-for-privacy@amsat.org (S.=A0Miller) I had transmission fluid show up in the engine coolant reservoir of my

1999 Chevy Tahoe. I first noticed this sometime after also noticing an intermittent rattling (washboarding) which sounded like it was coming from the transmission. I made the mistake of continuing to drive, and about 25 miles later the entire transmission went out (only neutral "worked"). (BTW, the vehicle has TWO auxiliary transmission coolers in series with the cooler in the radiator.) Different shops give me different explanations as to what happened. I'd like to get YOUR experiences/opinions! Theory 1: The transmission was failing (possibly torque converter going bad), causing bits of metal particles and debris to plug the transmission cooler part of the radiator, which caused fluid to spill into the overflow reservoir (just how I don't know). Theory 2: The transmission cooler in the main radiator developed a leak and allowed fluid to leak into the coolant and coolant to leak into the fluid. The coolant, once getting inside the transmission, ruined it. Theory 3: ??? At any rate, when the transmission got rebuilt the shop also bypassed the main transmission cooler so that I am now using only the two auxiliary coolers. I am posting separately with questions about this.

I'd like to get your opinion on which theory above is most likely, but............

my main question is:

If only the transmission cooler in the main radiator developed a leak and not the engine coolant part, then how can the transmission fluid get mixed in with the coolant? (It *did* happen -- I'm just trying to understand *how* it was possible.)

--S. Millerd =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D theory #2

.... and to answer yer main question.......

Run on outside and get the garden hose and shove it in yer mouth.....now wrap yer lips around that sucker really tight.....

now cut on the spigot........and blow as hard as you can.....

imagine that yer tranny line is the garden hose.

now.....cut the hose off and let it drain fer a minute....

now.....blow again.....

imagine yer the radiator.....

got the picture? good....get back in the house ....the neighbors is uh stare'n.

marsh monster ~making things simple~

Tom,

Why, praytel, does the ATF need to be heated by the coolant? The ATF heats itself (that's the reason why you have ATF coolers). All the coolant does is keep it at 195* after the truck's all warmed up.

Doc

. . . Re: Just how does tranmission fluid get into coolant? Group: alt.trucks.chevy Date: Tue, Oct 21, 2003, 11:39pm (CDT+5) From: snipped-for-privacy@noway.com (Doc)

Why, praytel, does the ATF need to be heated by the coolant? The ATF heats itself (that's the reason why you have ATF coolers). All the coolant does is keep it at 195* after the truck's all warmed up.

Doc ======= =======

To keep it from turning into jello in extreme cold conditions.

respectfully, marsh ~:~

the 'gel point' of ATF is in the -70's C

Cold fluids not as efficent as warm fluid, too thick, and in sub zero temps, it can pay to have the engine run for a while heating the fliud for a few minutes before putting the auto in gear and moving off. Totally unessesary in Florida, but can be vital in Alaska.

at least thats my understanding from lurking around elsewhere.

rhys

. . . snipped-for-privacy@noway.com (Doc) writes....

Why, praytel, does the ATF need to be heated by the coolant? The ATF heats itself (that's the reason why you have ATF coolers). All the coolant does is keep it at 195* after the truck's all warmed up.

Doc =3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D To keep it from turn the 'gel point' of ATF is in the -70's C =3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D marshmonster writes....

or 20-30=B0F . Products - Transmission - Hayden Address:

=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D

Actually, the coolant isn't 195F by the time it gets to the ATF cooler in the bottom of the radiator, even though it entered the top of the radiator at that temperature. Wouldn't be a very good radiator if it didn't cool the coolant!

A friend in Texas had that experience with his Monaco. His first trip was trouble free-- the next 3 were disasters and he got towed in. As of the first year Monaco has spent $30,000+ rehabbing his new coach. He took it to Monaco factory in August, haven't learned what all his results were but I know he spent a week at the factory. This was AFTER he had the engine and transmission replaced. LZ

Others have already given you the answer, but if transmissions didn't need that liquid to liquid heat transfer, maybe you can explain why all automatic trans equipped vehicles come equipped from the factory that way

Tom J who is not trying to reinvent the wheel!!

I really have to wonder about that. How cold are you talking?

10C? 0C? -20C? -40C?

You can warm the fluid in the transmission easily. Put it in drive and keep foot on the brakes. The torque converter is turn horsepower into heat and that's circulating through the fluid...

All automatic trans equipped vehicles *don't* come from the factory that way. My '99 V10 has no connection to the rad . . . just a cooler. I would presume that if cold transmissions were a problem, they they would need new trannies every year in Alaska where the average tranny temp never even gets above 0F when the ambient temps are hanging around -40.

if the in-radiator cooler is SO necessary, perhap someone can explain why I've not had a problem with totally bypassing it in EVERY truck (and a lot of cars) in which I've overhauled the transmission SINCE 1997.

the VERY FIRST ONE, an F-350 7.3 PSD (Turbo) has over 330k on the overhaul, with only two fluid changes (hey, the owner 'doesn't have time' to have it done), and is still going strong, hauling a 30-foot stock trailer all over the country. This was equipped with a pair of Hayden 1679's, the big mothers, plumbed in series.