Quick questions on crank pulley. 1981 300D
 

My apologies for the newbie questions. I searched around, read a number of threads that were related... but didn't quite come up with a difinitive answer.

'81 300D - Crank pulley removal and re-install

1) We got the 6 hex bolts off. Was wondering if someone could confirm the size. Since they were a little tricky to get off (as everyone mentions... they corrode over time)... We were planning to use new ones so that they don't become impossible the next time.

2) Is it wise to put a small amount of blue locktite on that bolts for re-install? I saw mention of these comming loose on a few people... yet the thought of making is harder to unbolt them the next time (and risking stripping the hex area) is not pleasant.

3) Once those 6 bolts are off, the crank pulley is supposed to just pull off, right? Any tricks for getting it loose beyond the usual penetrating oil inside the hub center? We tried last night a little, but it didn't slide off easy. So rather than get frustrated and break something... we stopped and plan to pick up today.


Not sure if it matters... but the main reason for taking off the crank pulley (and damper behind it) is to replace the alternator bracket (damaged by previous owner). Of course there would have to be one F'n bolt on the front of the alternator bracket that's hiding behind the pulley assembly.

My thanks in advance from myself, and my brother in-law (his car).

There are no quick answers on that one
 

That operation, to remove and re-install the front pulley damper has resulted in many major engine failures. I just did a quick check and there are very many threads to check. Did you pick this one up. Search for front pulley damper remove. http://www.peachparts.com/shopforum/showthread.php?t=183
Really, it is a major operation that if not done perfectly will end shortly with a totally ruined engine. If there is no other way to get the bolt out, then that is what you have to do. But read about it, study it and know what you are doing or your bro in law will be walking. I have an engine in my garage that suffered that fate. Not nice! I am about to pull the head off, the rest goes to the junk man.

I agree. I'd be looking for other alternatives rather than removing the crank pulley. I'd even consider cutting and welding to the existing bracket before taking off the pulley. Perhaps I'm just gun shy but I've read those threads over the years.

There are three separate components bolted onto the front of the crankshaft. Removing the pulley and vibration damper is not the same thing as removing the balancing disc.

The pulley and damper should separate from the balancing disc when the six bolts are removed. If they don't, they must be stuck togehther; a few taps with a soft mallet might be in order.

Yup, you knew which part I was talking about. That's the one.

I think it's the harmonic balancer that has been written about many times on this site (I found those threads... yikes!). That is the part that is secured by the big 27mm bolt on the front of the crank. NO, I was not trying to remove that. We had no interest in touching that.

We were only removing the pulley hub and vibration dampener. And yes, it did just slip off. Started with some good penetrating oil, let it sit for a while. The a couple gentle taps with a rubber mallet. Finally a couple of strategically placed mechanics pry bars (one top and one bottom).. some gentle (very gentle) pressure, patience,... and it came off fine.

With just the pulley hub removed... we got to the last bolt of the alternator bracket just fine. Only had to loosen one other line bracket a little to clear enough to slide the alt. bracket off.


So were in good shape now. Just trying to confirm the size of those six bolts to see if we can get them locally... or if we have to wait for wednesday to get them from the dealer. And of course any feedback on locktite or not....

Should be M8 X 30. You could always confirm that if you have a ruler. Or just do what we Georgia rednecks do. Take on old bolt to the hardware store and say "I need six of these."

I vote for a bit of blue threadlocker.

LOL - I'm in New York... we do that here too. I struck out at the first store (close to the house) using that approach. Was figuring to try to confirm size and make phone calls first. But there are three places about 15 minutes away and we do have the old ones to bring for comparison.

Thank you!

Well I took a look at one with a ruler... seems to be closer to 51mm long (including the head). We'll probably just take a ride out with one in hand and see what we can find.

Edit, so I gather you're suppossed to not include the head in the length measurement. So they are more like 45mm long.

I've had that damn thing on and off more times then I can count. My front main seal will not seal even if I encased the whole damn engine block in a big silicone box. That said I have had a pulley fall of the crank, in the middle of Detroit in January.

1)BUY NEW BOLTS. I went to the dealer to make sure I got the correct grade.
2)The new bolts come with blue locktite already applied
3)Those 6 hold the pulley to the harmonic balancer. The vibration dampner gets sandwiched between the 2. If you have all 6 bolts out, start prying the pulley off. They get stuck with grease and grime.

remember to torque them down in a star pattern to the correct spec. I think it was 25nm. Check with whunter on that.


http://www.peachparts.com/shopforum/showthread.php?t=176635&highlight=pulley

That's correct.

I had the pulley come adrift on my 79 240D. I put blue thread lock on those new allens.

And BTW Tangofox, thanks again for helping me make the decision NOT to pull my balancer :D

Can someone confirm the torque spec for those six bolts... want to make sure I do enough, but not too much.

I saw 24N/m mentioned in one thread, but just wanted to confirm, because I thought I saw 26ft/lbs in another thread.

270-300nm for the crank bolt and 25nm for the 8mm bolts.

Could that 25Nm be for a different year?

I checked all-data which said 35Nm (26ftlbs). I then checked the trunk (should have done that first...)... and there was a Chilton's hiding in there... which also confirms 35Nm/26ftlbs.

Should be all set.

Thanks all. Updates later after everything is back together.