Hi,

My 92 245 auto showed the check engine light, the code checked as O2 sensor. It was replaced 20K ago. When I looked at it, there was some oil on the wires, not much but just an overall glaze. There was however a good coating on the center brace, transmission, and some on both sides of the undercarriage, but not enough to drip anywhere. The valve cover and rear plug are spotless as is the rest of the upper engine. There is no oil on the oil pan. There is a film of fresh oil on the transmission housing. The plastic grid opening in the transmission housing has fresh oil on it, but also above it. The flame trap is spotless and all hoses to it are new. I clean it with every oil change. A couple years ago I noticed a small drip but it went away before I got a chance to check it its location. Do you think this might be the rear seal?
Thanks

Thanks for the ideas everyone,

It looks like its the rear main seal. I've never replaced one on a 240, but have on several different cars. Are there any tricks I should know?
I also was going to replace the O2 sensor since it triggered the check light, but I'll fix the oil problem first. Is it possible that the sensor is still good, can the oil be cleaned from it? Thanks

Hi, I've been a Volvo tech since '86. It may well be your rear main seal leaking. I'm used to checking them from underneath while the car is on a lift. There is a brace thats held on with 6 bolts at the back end of the engine that butts up against the bottom of the transmission bell housing. If you take that off you can shine a light with a mirror and inspect the seal for leakage. Another hint is that if you see oil seeping from around where the starter bolts to the block, thats a pretty good sign that oil is getting flung around in there. Another common leak that occurs at about the same mileage as a leaky main is on the transmission between the bell housing/overdrive housing and the transmission main body. There's a couple of O-rings that get brittle in there. This repair requires expertise, because you can damage the trans. if you don't know what you're doing. But it only takes about an hour to do it, and it makes for a nice dry transmission. Maybe you could get a trans. shop to do it for you if you brought it in. Its important to know if your engines breather system is working properly too. Just changing the flame trap usually won't do it. The orifices in the oil trap and intake manifold get restricted from carbon build-up and need to be dealt with. The engine is designed for there to be a vacuum inside the crankcase, when the breather system plugs up, you get pressure, which pushes oil out wherever it can go. There are handy tools available to check what is going on with that system, you just take off your oil cap, place the tool over the opening, and it tells you whether you have pressure or vacuum. I hope this has been of some help. Chris

Make sure the transmission cooler lines haven't been rubbed through by the mounting block and the engine/trans interface. This can produce an oil like leak which is near black. Most likely though, it is a slow rear seal leak.

good luck!

jorrell
--
92 245 245K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently in pieces

On my 1987 740 the rear seal leak should be obvious - dripping from below, where the motor mounts the tranny.

I've also had leaks from:
1- the oil sensor/sender located just beside the oil filter
2- My B230F has the distributor mounted to the rear of the valve cover and when o-rings go bad, it drips down the back of the motor.
3- Dipstick leaks from the cap.

I'd check if these apply.