I'm wondering if my new RMS is too loose on the crankshaft. In preparation to swap this 185k B230FT into my 240, I just replaced the rear main seal with a Volvo brown seal (6842160). This is my first RMS, so I'm figuring it all out from Chilton, Haynes, the FAQ here, and the writeup on Art's page. I removed the carrier, cleaned the carrier and crankshaft, polished the contact surfaces with some Mother's, hosed them down with brake cleaner, and ran a light finger of motor oil on the metal and seal contact surfaces. I inserted the seal in the carrier, then installed the whole thingamajig onto the crank following these FAQ instructions:

[Editor] Volvo grey Viton seal p/n 6842160 is well worth the slight extra cost. When you get the seal, it comes on a round plastic carrier. Cut off the inner protrusion (the lip pointing toward the center of the circle) with a coping saw and an X-Acto knife, then use the carrier as the seal lip seating tool. It will fit perfectly over the 92mm crankshaft. Insert this after the seal is installed to make sure the lips are not curled under, since the Viton seal is much tighter than the silicone seal. Works like a champ. https://www.brickboard.com/FAQ/700-900/EngineSealsBeltsVent.htm#LeakingRearSealandReplacementTips

As I installed the seal I felt some resistance on the carrier side (it was firm but not difficult) but very little on the crankshaft side. Once installed, and with the plastic insert removed, I can slide a glossy business card between the seal and crankshaft and run it all the way around - with significant resistance, but it goes.

Is this normal? The old seal I pulled (looks just like the one I installed) was stubborn on both surfaces. I had to pry the carrier & seal off the crankshaft and tap the seal out of the carrier. Can I expect the seal to swell up under operating conditions or does this indicate a problem? Obviously I'm not going to get a look at it after I get it all put back together, so i want to make sure it's not going to be gushing oil.

Hello,

It sounds pretty normal to me.

As to your question, I don't think you can evaluate the seal's grip on the crank if you put it on with the seal in the carrier. Temporarily fitting the seal alone might give you a better idea. The locating pins on the carrier seem to be a light press fit that needs to be pried off and tapped back on, and any additional resistance offered by lubed rubber on the crank is negligible.

You didn't mention if you put any grease on the inside of seal. There is a tiny garter spring around the rubber that compresses it against the crank. It can sometimes pop off when you distort the seal to get it started, and the grease will help to prevent that.

Your business card test is interesting but without something to compare the results with it's hard to say. The Viton seals are much stiffer than the silicon, with or without the spring.

If the old seal was set flush with the carrier, did you set the new one an eighth or so inward to get on a new crank spot ? I recently replaced the one in my 90 240 with 300k and it had a very healthy groove in the crank. I replaced the front seal on the auto trans at the same time. I believe it's the same vintage as the motor but there was no groove at all. It may be because the tranny shaft is harder stuff than the crank, but I think more likely it's because motor oil has a lot more particle contamination than transmission fluid.

I don't believe the seal swells. What you see is what you get.

regards, Peter

Thanks, Peter. I did lightly oil the crankshaft and (temporarily removing the installing ring) inside seal surface. It occurs to me that I may not have followed the FAQ instructions precisely, since I installed the seal on the crank with the installer ring on it, then removed the installer ring after tightening the carrier bolts. That means I also set the depth of the seal with the installer ring. It's a few mm deeper than the surface of the carrier. I didn't observe the depth of the old seal or attempt to set the new one at a different depth. I took a picture with the old seal removed, and just now a couple more showing the new seal. There is a groove in the crankshaft, which I had assumed to be machined, but perhaps that is actually wear. I'm wondering now whether I should attempt to move the seal a bit deeper. I'm sure glad I'm doing this on an engine hoist instead of on my back under the car.

The tool is meant to be removed after the seal has been installed so that the edge of the seal can't get folded under during installation. It does appear you have the seal in the same position as the original and it should be moved further in. The groove is not meant to be there--it is wear. - Dave

Thanks, Dave. I'll do it.