1993 Saab Transmissions
Question: I have a 1993 900S with an automatic transmission, 115K miles, which I bought as the teenager’s car about 1.5 years ago. The transmission oil was low about 1 year ago, and I had the tranny filters changes, oil changed, and so forth by the local dealer. No leak was found. The oil continues to drop slowly, but where it’s going nobody knows!
Well, now it doesn’t want to engage into reverse… just acts like it’s in neutral. Eventually it goes into gear, my daughter claims that reving the engine helps. She also thinks the ambient temperature may have an impact (we live in Maine). Once it decides to get into gear, you can go in/out of reverse with no problem. Forward gears work just fine. I was a mechanic years ago (Audi/Honda/Toyota), and my guess is that a valve is hanging up.
Does anyone have experience with this kind of symptom?? It appears to be getting more frequent, so I’ll have to have it fixed soon. I assume this is a repair that should be brought to a dealer only. Should I swap out the tranny or go for a repair?? Any other questions I should be asking??
Answer?: Hello, I’m a veteran transmission specialist for the past 30 plus years. I specialize in theory, diagnosis and rebuilding. Your daughter is not far off, she has great insight, I believe she hit the nail on the head when she mentioned ambient temperatures. You have a leak for sure, it simply is not an external (leave a mark) leak.
Transmission fluid is sensitive to heat. Meaning that if the fluid level is checked properly when the temperature is 80 degrees outside, and, you do nothing other than wait until you have a 45 degree day and recheck the fluid level, due to the fact that the fluids, naturally contract (except water, it expands) when it gets cold, the fluid level will be lower. And vise-versa from cold to hot. So ambient temperature plays a role.
Knowing that, there are two ways to lose fluid internally, without leaving any spots. The T-37 Borg Warner transmission is similar to the T-35 BW tranny. It uses a modulator. If the modulator diaphragm ruptures, it will suck or literally vacuum (a modulator gets it’s signal from engine vacuum) transmission fluid from the transmission to the engine and get burned. Thus keeping you adding fluid regularly. Not a serious or expensive repair.
The other way you can experience fluid loss without marking the spot is if you have a radiator separation between the engine cooling portion and the transmission cooling portion of the radiator. It is separated into two sections, however if the wall that separates the two sections fails, the transmission fluid, due to extreme fluid pressure, it will be forced into the radiator engine section.
If you take the radiator cap off (a cold engine) and examine the engine coolant and it is full of oily stuff and looks like a milkshake, that is your fluid loss. You need a radiator or external auxiliary mounted transmission cooler.
Having set the stage, with the mileage and problems (forcing it to move by revving it is abuse) you are mentioning, you very well may have a problem with your transmission anyway.
My advise is to get it diagnosed by the most reliable transmission shop in town. If you are advised to rebuild or exchange your transmission, be smart, call the most respected transmission replacement company online today and speak with a transmission ‘man’ about it. We won’t ruin your budget and the value we built into every transmission we sell insures your success. GotTransmissions.com @ 866-320-1182.
