The engine RPM sensor in my '90 245 is flakey. I can see it sitting there where the bell housing and engine meet. What is the best way to reach it? It looks I need very long, very thin, arms and hands. Don't tell me I need to pull the engine/tranny just to replace the sensor...

TIA!

-Ron

Ron,
There is enough room between the transmission bell housing and the body to get an open end or box wrench to remove the locking bolt for the sensor. At least there is in ny '89 244 DL. You will need to reach in to re-install the bolt and get it started and it is tight but it will work.

Good Luck,
Dom

Thanks for the tips, all of you! I'll install the new sensor as soon as it arrives.

-Ron

It's been a while since I did mine, but I seem to recall using a rachet with a long extension with a woble end at the socket

Believe it or not, it is possible to reach down there. As I recall, I sort of worked my arm down around the passenger side of the back of the engine (but it's been five years now.) To remove the bolt holding the sensor in place, use a 1/4 drive long extension and a socket (it's not that big: maybe 10mm). Use a magnetic insert so you don't lose the screw. The sensor pulls right out. You'll get grease on your arms.

One word of warning: If you break the bracket that the RPM sensor fastens into, you WILL have a transmission coming out of your car to repair it. That is the one and only way to put a new bracket on the back of the engine.

I've seen this happen; it isn't pretty. Not that it happens much, but it's worth a word of caution.

I'd recommend either a box end 10mm (shorty) or a very long 10mm socket/extention combination on a 1/4" drive. If you're lucky, the sensor will come right out. You might have to wiggle it CAREFULLY to extract it.

When you put it back, put a LIGHT film of grease around the perimeter of the hole into which the sensor goes. Just enough to make it slippery, not enough to foul the sensor. Put a little anti-seize compound on the threads of the 10mm bolt that fastens it, and you're back in business.
--
Chris Herbst
1992 745, 68k

And others:
93 944, 150k
90 245, 110k
88 744, 160k
87 245, 185k

I use a 12" 1/4 drive extension with a 10mm universal joint socket and a magnet to loosen and retrieve the bolt. Then a combination of gently tugging on the wire, nudging the sensor with a long screwdriver, and a looooong set of needlenose pliers. They got em at sears. Make sure the engine is cold when you get to it.