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  #1  
Old 10-25-2009, 11:56 AM
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Bad News for the 450sl

When replacing the timing chain and tensioners I came across this. As a warning to fellow V8 SL owners out there watch your tensioners and timing chain guide pins. If the tensioner goes out and binds too much the pins might be too hard like the one pictured below.
On the driver's side head where the top chain tensioner lies there are two pins that are used. This one looks to be too hard and not like soft ones I noticed on the passenger side.
On one hand I have half a mind to scrap this car and get another.
On the other hand I can repair it. There are compounds that are stronger than the aluminum you see.
I can drop in a helicoil centered from the bolt going in.

Lessons learned? the next time I pick up a 450sl I will be looking at the work history, maintenance records and the ownership of the vehicle. I don't mind restoring but at this point the 450sl's can be had fairly cheap. They are demanding vehicles to restore if found to be neglected.
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Bad News for the 450sl-wallow.jpg   Bad News for the 450sl-broken-pin.jpg  

Last edited by Genbiltstein; 10-25-2009 at 12:21 PM. Reason: Getting over the shock
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  #2  
Old 10-25-2009, 12:53 PM
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I don't quite understand what you mean by hard and soft pins.

How did that pin hole get so boogered? What did you use as a puller? That pin doesn't look long enough to to span the rail and outer and inner head walls. Was the pin internally threaded, doesn't look like it from the picture.
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Old 10-25-2009, 01:16 PM
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Looking at it further the second half of the pin is not original. The first half is.
I think the original probably snapped and a makeshift repair was done using an inner pin
The inner pin is chamfered where they meet in the middle.

There was no support to the chain support guide and the inner pin ate a nice hole.
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  #4  
Old 10-25-2009, 05:59 PM
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Wow, that's quite a butch job by whomever did it. What the hell were they thinking?

When I did mine, I had trouble with one pin because the extracting tool wasn't flush against the head(the head had a ridge that prevented a stable mount) . When I began the extraction, the 6mm threaded stud bent and screwed up the internal threads on the pin. Thankfully, I was able to get it out using the washer/bolt method. Went to the dealer and ordered a new pin for $12 bucks and all was good. Screwed up my pin extractor tool though.

Changing the rails in not a difficult job, but not a job I would recommend to less experienced DIY's. Lots of disastrous things can go wrong if not very careful. I was quite on edge the whole time.
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Last edited by 450slcguy; 10-25-2009 at 06:14 PM.
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Old 10-25-2009, 06:45 PM
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Changing rails is not a beginners venture I'll say that. I used a bushing and a 6mm bolt with nuts to start. They came out.

To borrow a picture from another thread I cropped it to show where the problem is. The wallowed area lies where the pin anchors into the head.
Also the bottom of the chain guide where the bolt feeds through split along the bolt hole length. The top of the chain guide was heavily worn.

I also posted a picture where inexperience shows when someone was trying to pound the pin through without lining up the chain guide.
Had he changed out the timing chain tensioner and replaced the timing chain guides properly things would have been fine. The uninformed tech probably didn't know about the timing chain tensioner problem.
The timing chain tensioner should tension and "give fairly steady" instead of a dead stop like I experienced when I removed it. When you replace the tensioner remember to bleed it by submerging it in oil and actuating the tensioner.
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Bad News for the 450sl-arrowed.jpg   Bad News for the 450sl-arrowed1.jpg  
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  #6  
Old 10-25-2009, 09:55 PM
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Quote:
Originally Posted by 450slcguy View Post
When I did mine, I had trouble with one pin because the extracting tool wasn't flush against the head(the head had a ridge that prevented a stable mount) .
I also had this problem with the 380SL, but strangely, NOT with the 560SL. I made a small shaped block of aluminum to get around the ridge problem and keep the tool perpendicular to the head. I now keep this block of aluminum with the tool. I'd say that more than a few degrees off will screw up the tool's puller thread (which on mine, is replaceable and they sell it as a replacement part).

Another trick I used was cut-up washers. No matter what tool you use, you have to keep the pulling angle near 90 degrees. Breaking a threaded rod inside the pin is VERY bad. And some of mine were really, really stuck and took quite a bit of force.
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  #7  
Old 10-29-2009, 06:58 AM
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Quote:
I don't quite understand what you mean by hard and soft pins
As strife mentioned someone broke a pin. In this case a subsitution was made with a very hard pin an inner pin. The outer pin is original but the inner pin is an adaptation. When the installation was made he slipped it in the guide rail and slid the guide rail in place driving the outer pin in. It held fine until the tensioner stiffened too much and the load created was too much to bear. The vibration cause the wallowing to occur thereby ruining the head on the inside.
The steel pin looks to be taken from a solenoid.
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Old 11-09-2009, 04:56 PM
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I ordered two heads from Fleabay that have been refaced and triple angle ground. I will be taking the entire top and front of the engine apart.

From the front all the way back. Improved exhaust and intake. Throttle body will be machined open a tad.

It will be a winter project.

I will be posting.
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