1988 bmw 735i. transmission has no 4th or overdrive. any ideas?
First thing is to check the fluid level and then check for leaks. It's highly unlikely that someone here could point you in the right direction with this matter, unless they were very lucky. The complexity of that transmission requires the technician to listen and feel the transmission while driving the car. Next, the tech may elect to hook up gages to measure pump and or line pressures. Also, that transmission has an EGS (transmission) computer which may have failed. Long story short: take it to a BMW specialist, whether it be the dealer or an independent repair facility which you're comfortable with. Hope this helps, good luck!
there is some truth to that. it is pretty much a computer controlled manual trans with a torque converter. the filter is internal and a nasty project to get to since the trans has to be pulled and the case split. if it is not broken, don't fix it.
get a new transmissionany work on a BMw is gonna cost you tons of money though. My gf brother spent $7000 on two transmissions within one year.
The 1988 3.5 Litre BMW engines didn't really have an overdrive in the transmission. All of the automatics that I have seen in the US had 4 speeds plus a torque Converter Lock-up. Any automatic will have some slippage most of the time. The Torque Converter allows this slippage at lower speeds and at stoplights so that the engine won't stall. It is possible that your transmission has the wrong kind of ATF installed? Have you checked the ATF level with the car sitting on a level surface, with the engine and transmission fully warmed up? Have you changed the ATF and cleaned the transmission filter screen in the last 6 months? If the ATF smells as if it has been burned, it probably has been overheated. It is also possible that the control lever that selects, 1st, 2nd, and 3rd gears has somehow become goofed up and is stuck in 3rd gear. Change ATF, clean filter-screen, refill with ATF Type A and recheck operation. The torque converter lock-up should cause the engine to slow down only about 200 RPM when the road speed reaches about 50 MPH. This is Often hard to see.
The filter is replaceable. Most manufacturers will ask you to replace the filter and fluid every 30,000 miles.
