Front Main Seal Installation (DIY?)

[cobra]

Hi everyone,
I am installing a new front main seal as part of a larger maintenance/repair project that required timing cover removal. I have heard a lot of woes about leaks after installing a new seal so I would like to get your input.

I have a special tool for installing the new seal and pressing it in. It uses a tapered lead-in and a screw to allow me to precisely place the seal depth-wise.

While reading installation instructions for PTFE main seals, they all say that the seal should be installed dry and that it should NOT run in the same position as before. I measured the old seal at sitting 2.55mm below the top surface of the timing cover. I believe the reason for both of these recommendations is so that the new seal can "bed in" to the crankshaft sprocket. The surface of the PTFE seal must wear slightly during initial run-in, and by having an oily or polished surface it will not properly do this, instead having an imperfect contact and allowing oil to seep by.

Based on this, I am thinking of installing the new seal just flush with the timing cover or possibly another 2mm deeper so that it can run on a different section of the crankshaft sprocket.

Does anyone have any personal experience with this or comments?

[heinzboehmer]

This is what TIS says about it:



From personal experience, installing the seal without damaging it is both significantly harder and significantly more important than the oiling and positioning of the seal.

Btw, where did you find the special tool?

[cobra]

I don't trust the TIS. It says to oil the seal and every seal manufacturer appreciate says not to use oil

I made the special tool. I'll post up pics when I use it. It should remove all possiblity of damage during install.

[cobra]

Alright I think I figured it out. Hopefully this helps someone out there.

First step is to clean the bore and crankshaft sprocket really well with brake cleaner.


Next step is to install the new seal onto the taper adapter. No oil or grease can be present. It must be completely dry.




Then install the taper adapter onto the sprocket using the stock harmonic balancer bolts. (This pic was taken afterwards the seal was already installed...)


Then install the press cup and press it in.


The depth is very important. The timing cover bore is 16mm deep, of which the first 1mm is a lead-in chamfer. The seal is 10mm thick. The stock position of my seal was 2.55mm which is about in the middle. But you don't want the new seal to run on the same shiny groove created by the old seal. So it should either be installed shallower or deeper by ~1-1.5mm.

I chose to install mine so it passed the lead-in chamfer but was just shy of the shiny groove.



And here is the seal installed.

[Pklauser]

cobra where'd you get that tool?

[cobra]

cobra where'd you get that tool?

I made it because I couldn't find one for sale, and the dixie cup + bang it in there with a socket seemed like it would have a high rate of failure.

[Pklauser]

I made it because I couldn't find one for sale, and the dixie cup + bang it in there with a socket seemed like it would have a high rate of failure.

Oh nice. Yea the cup method sounds like a pretty big pain in the ass... I'm surprised the seal doesn't come with a plastic tool to help slip the seal over the crank, the rear main on my E30 came with one. Would you have any interest in renting that tool out? I'll probably give the cup a go, but I'm not optimistic.

[cobra]

Oh nice. Yea the cup method sounds like a pretty big pain in the ass... I'm surprised the seal doesn't come with a plastic tool to help slip the seal over the crank, the rear main on my E30 came with one. Would you have any interest in renting that tool out? I'll probably give the cup a go, but I'm not optimistic.

It does come with a plastic thing, but it's shaped in such a way that it wont let the seal transition onto the crank sprocket.

I'm currently looking into getting a few sets made but if that falls through I will consider renting it out.

[F1Dryvr]

The cup method worked for me, I did ruin 2 in the process, using other methods, but luckily these were only 6 bucks.

[Pklauser]

Was just working on this tonight a little, dang you're right! What the hell BMW, why not make that plastic piece a hair larger in diameter!?

[Casa de Mesa]

Hey cobra this write up is fantastic. Three questions for you:

1. Have you run the motor since doing this install?
2. How's the seal holding up?
3. Is that center "taper adapter" in your 2nd through 4th photos above actually tapered? i.e., conical shape. It's hard to tell for sure from the photos but I think the answer is "yes, dumb dumb Casa"

I'm getting ready to do this in the coming weeks (just ordered 3 seal, ha) and will be giving this a go. All the research I've seen too says "goes in dry" so I'm curious how yours is holding up. I need to try to fab up that tool...

-Casa

[cobra]

Hey cobra this write up is fantastic. Three questions for you:

1. Have you run the motor since doing this install?
2. How's the seal holding up?
3. Is that center "taper adapter" in your 2nd through 4th photos above actually tapered? i.e., conical shape. It's hard to tell for sure from the photos but I think the answer is "yes, dumb dumb Casa"

I'm getting ready to do this in the coming weeks (just ordered 3 seal, ha) and will be giving this a go. All the research I've seen too says "goes in dry" so I'm curious how yours is holding up. I need to try to fab up that tool...

-Casa

1. Yes, almost 2k miles
2. So far so good, no leaks!
3. Yes it has a small taper to help get the seal on and then slowly stretch it to fit on the crank sprocket thing.

I was very unsure about the dry thing. It goes against all conventional wisdom but it is true!

[F1Dryvr]

I tossed 3 fms away attempting this. Luckily they were only like 6$. Recommend just buying 2 or three so ur not left waiting one u ruin your first attempt! Finally got it with the solo cup method. U have to cut the cup up and not use the lip or the ridges obviously but it worked.

[Casa de Mesa]

1. Yes, almost 2k miles
2. So far so good, no leaks!
3. Yes it has a small taper to help get the seal on and then slowly stretch it to fit on the crank sprocket thing.

I was very unsure about the dry thing. It goes against all conventional wisdom but it is true!

1. Nice.
2. Nice x 2.
3. Cool.

Appreciate that. Now wish me luck. ha

I tossed 3 fms away attempting this. Luckily they were only like 6$. Recommend just buying 2 or three so ur not left waiting one u ruin your first attempt! Finally got it with the solo cup method. U have to cut the cup up and not use the lip or the ridges obviously but it worked.

I bought 3!