I replaced the rear main seal on my 945 last weekend. I was very careful and ran my finger around the crank before instlling the new seal (Volvo brown one). I didn't feel any rough areas. I checked the flame trap and it was clear. I did not remove the seal carrier. I've done this procedure before on my 740 and didn't have any problems, however the rear seal still leaks on this car. I see in the FAQ that this is not unusual, however the car now uses oil to the tune of 1 quart per 400 miles. What did I do wrong? I fear I'm going to have to takle this difficult job again. Is there anything I can do to keep from removing the transmission again? Thanks.

The new gray Viton seals are more difficult to install: the lips are stiffer and can end up not seating. I have made an installer using the seal carrier, on which it is shipped, by filing away the inner lip so the plastic piece fits on the crankshaft. In the process, the horizontal bands end up ensuring the seal lips do not curl under as the seal is installed. An alternative is to run a curved piece of plastic sheet around the crank, pushing the seal lips into place as you rotate the plastic around the crank. Make absolutely sure the seal lips are in place before you button this one up. And look elsewhere for a leak: the turbo oil drain line o-ring is an all-time winner in the leak category, as is the distributor o-ring seal.

Are you sure it is still coming from the rear main? Wherever it is coming from it sounds like a gusher for sure. You could have screwed up the new seal or you could have a leak from the housing that it seats into. I always snug the bolts on that housing when I am in there replacing the rear seal. I also replace the input shaft seal on the trans while I have it out. Check all of your other stuff real good, hose it all down with some brake spray clean and check again and then when you have established that all of that stuff is dry and tight take an inspection mirror and a light and look up around the rear main. Once you take that saddle piece off that covers the access to the torque converter bolts you will be able to get a real good look at the rear main with the mirror and light. If it is the rear main the only way you are going to get around having to do the bear of a job all over again is to pay someone like me to do it for you. Sorry, no magic wand there. Heck you wanted some more practice pulling transmissions anyhow, didn't ya?

Mark

I'm relatively sure it's the rear main seal area. The oil is not red, and I did replace the front trans seal at the same time. I did not tighten the carrier bolts when I installed the seal. I wish I had, because when I went to the other end of the engine and installed the front seals the next day, I noticed that the front seal carrier for the I-shaft was very loose and tightened all those bolts. Using the mirror is a good idea. I'll try that. Can the seal carrier bolts be reached without removing the transmission?

You know you could probably reach the bottom two but that is about it. Tightening that up is not a cure all either. I know techinicians that swear that is the worst thing you could do because you risk cracking the hard paper gasket underneath.

Mark

I cleaned up the bottom of the engine, crossmember, bellhousing. I doublechecked the front seals and they look ok. I removed the oil fill cap and blew through the flame trap (after cleaning) and oil separator to make sure there wasn't any blockages. That all seemed fine. I even changed the oil filter to make sure it wasn't that gasget. I started the engine and looked directly at the rear main seal, but couldn't see any fluid coming out, however after a 200 mile trip I could see the telltail drips of engine oil coming from the bell housing vent. I ordered a new rear seal and seal carrier gasget. Man, I'm not looking forward to taking that oily transmission out again, but the good news is that all the necessary tubing has already been cut and spliced, fill tube nuts have been loosened, and the bellhousing bolts shouldn't be as difficult.

Hey Marlin,

I think I'm dealing with the same situation as you did on my 240. Had the trans down Monday and replaced the seal. Last time I did one of these was a stick and I did the housing gasket and the piece of the pan gasket as well, but this time I just did the seal. Leak is back, though not nearly as bad. What have you learned since your original post?

Thanks,

DS

I removed the seal carrier, buffed the crank with sandpaper, scraped the old gasget from the seal carrier, reinstalled the seal about 1/8" in from the outside of the seal carrier, measured the seal to make sure it's not in the carrier crooked, used rtv sealer on the bottom of the seal carrier where it meets the oil pan gasget and the corners where the oil pan gasget and carrier gasget meet, ran the smooth tip of a plastic cable tie under the lip of the seal and all the way around the crank to make sure the lip of the seal wasn't turned under. But other than that, nothing special....
Marlin