hey everyone,
I have an automatic 240GL 1989. Recently I checked the oil and found pink oil emulsion in the top of the radiator reservoir. It has the consistency and colour of auto gearbox oil when you rub it on your fingers to remove the water.

There is no evidence of water in the engine oil and the gearbox dipstick shows clean transmission fluid. I also drained the sump of the gearbox a bit....clean fluid as well.

Consequently, I changed the radiator fluid and waited to see what happened. 1 month later there is again a pink emulsion in the reservoir. The gearbox oil appears to have risen over time (ie it is way overfull at cold temp) so I again drained the sump to see if there was any water sitting in the bottom but the transmission fluid is still clear. I am of the impression that water is heavier than transmission fluid.....is this correct?

To add to the problem- my overdrive wont engage and i am driving on the freeway in 3rd gear. Changed the old faulty overdirve relay 2.5 years ago. When the car is cold, the relay works, the arrow on the dash alternates on and off, but no engagement of overdirve. After about 25 mins driving, the car changes into 4th gear and the box will change in and out of overdrive by pressing the button after this. It seems that the overdrive will engage when the car is fully warm. Could this be related to water in the gearbox? I am assuming if the connections on the relay were cracked the cracks would open up and i would lose overdrive as the relay warmed up and anyway the relay seems to work ok, it seems the prob is closer to the box.

Having replaced my radiator 1 year ago, the transmission oil breach comes as a surprise and thus i was wondering. Can the auto fluid cooler communicate with the radiator cooler via any possible means?

I know this is long, but it has got me stumped with the little knowledge that I have of these cars. If anybody is willing to take 5 mins to offer me some advice I would be very appreciative

many thanks
Michael T

re: "...Having replaced my radiator 1 year ago.... the transmission oil breach comes as a surprise and thus i was wondering. Can the auto fluid cooler communicate with the radiator cooler via any possible means?..."

You installed the radiator by having someone do it, right? If you did it yourself, you'd know that there are two transmission lines that run ATF into and out of the passenger side tank of the radiator. Inside is a heat exchanger that lets the ATF cool down to the coolant temperature (which is about the proper temperature of a warmed up transmission) -- the ATF flows through a pipe that is surrounded by coolant -- heat passes through the walls of the pipe. But if the pipe has a leak, the fluids will transfer and mix between them. ATF runs at a very low pressure, much less than the coolant with the engine is running and warmed up; with a warmed up engine, coolant flows into the ATF through the leak; when the engine is cold, the ATF is under greater pressure, so it flows into the coolant. All in all, both fluids become contaminated, but the transmission suffers far, far more than the cooling system.

As for your problem, obviously the heat exchanger in your "new" radiator has failed, and the fluids (coolant and ATF are mixing). Far worse than seeing traces of ATF in your coolant is the fact that, since the coolant has much higher pressure when the engine is running, coolant has certainly contaminated your automatic transmission!

Do-it-yourselfing is a good way to learn about your car, and I highly recommend it even if you can afford to have a mechanic do every little thing for you. By the way, changing the radiator is one of the easiest jobs in the car -- just a couple of standard tools, and no unnecessary dirt; you don't even have to crawl under the car.

New radiators (either Volvo brand, or a metal one from Nissen) rarely fail so soon! You should try to confirm whether your "mechanic" really installed a new radiator, or just passed off a used one, with a paint job, as new! He might then be liable for the costs of the replacement transmission you'll likely need.

Good luck.

Thoroughly check the tranny cooling tank for a problem. If you find nothing, then do as the others suggest - replace radiator and flush tranny fluid ASAP. You should have some sort of warranty for that radiator!

Overdrive problem -
1. Replace OD relay with a used or new one and see if problem goes away. Can you borrow one to test OD operation? Just been through this with my car and it sounds like a defective relay to me.
2. If not relay, then check white wire running from shifter box to solonoid. Mine broke and was hard to find as it was hidden at back of tranny. Yours sounds like it could be grounding out against your tranny (as Cabbie mentioned) causing it to short at times....
3. Gunked up or bad solonoid. Tranny flush can cure clogged solonoid. Very doubtful that the solonoid is bad, but I guess it could be dying a slow death...

Lots more info in archives about OD issue. Do a search.

Good luck,

--
90 244DL 1/4 million miles - original engine/drivetrain :)

The od problem you mention is probably caused by water in the fluid. The od hydraulic circuit just barely works with pure low viscosity fluid; the water adds viscosity, hence the normal operation with hot fluid. The cooler has a pinhole in it, which is not unheard of with a "new" radiator. Transmission oil would bleed into the radiator during operation and the opposite would happen after shutdown. After changing the radiator, change and flush the transmission fluid at least twice over a 2-week period and you may be able to save the transmission-they don't like water.

I have an '89 that developed a radiator problem. End result was that the transmission fluid became contaminated with engine coolant. The transmission never worked good after replacing the radiator and several tranny flushes. I'm confused about your problem because it seems like the transmission fluid has leaked into the radiator (versus the coolant leaking into the transmission fluid). On my '89, I checked the auto tranny fluid level and it looked like pepto-bismol. The auto tranny fluid should be dark red...not pink.

If your tranny fluid color is normal, you should consider yourself very lucky. I had to replace the transmission on my '89 one year after I had replaced the radiator ...even after several auto tranny fluid flushes. You should NOT drive your vehicle anymore until you've put on a new radiator and you've completely flushed the engine coolant. For the tranny, I'd drop the pan and make sure no signs of water intrusion are present. The AW70s are tough..but anti-freeze/water in the tranny will certainly spell death for the tranny.

Until you've fixed the radiator problem, I wouldn't worry about the OD solenoid issue. The OD solenoid replacement isn't that difficult. The most common culprit is either the wire that runs from the shifter to the solenoid is bare and grouding out somewhere or the OD relay is messed up. Three things to consider: 1) OD solenoid , 2) wiring to the solenoid, and 3) OD relay.

Good luck.
Cabbie2169

The Gearbox Cooler is attached to the Radiator's Right Side, by two fittings. Maybe the new radiator was defective or corroded through, already. Only possibility.