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1985 300TD
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Discussion Starter #1
I was having issues with my '80 300d on Friday. Mid-drive, the brake boost gave out and the engine would not turn off, locks no longer worked after using up the vacuum left in the reservoir. I did the basic test for vacuum in the booster line and found nothing coming from pump.

I set out to change the check valves and rebuild the vac pump today. I got the pump off to find with horror that there is a huge groove in the cam contraption that interfaces with the cam in the engine block! See attached photos!

Additionally, the wheel that sits inside that cam is just freely woobling inside the housing. Is this supposed to have bearings? If so, there is no sign of them?!

My question to you community: How screwed am I??! Are the bits from those bearings dancing around my block just waiting to deliver their final blow to my timing chain (and my spirit)?

Please advise. I'm willing and ready to change the pump out, but is it deeper than that? What could have caused this?
 

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1985 300TD
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Discussion Starter #4
Thanks so much.

s there a potential that those bearings went into the block? Am I potentially in more trouble than just replacing the pump would fix? I wasn't hearing any terrible sounds coming from it even after the vacuum went, but I have to see after reading the horror stories that I'm afraid I may be one of those who had the bearing bust and cause damage inside beyond the pump.

How worried should I be? Should I put another pump on and cross my fingers? What are my chances?
 

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1985 300TD
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Discussion Starter #5
Anybody...any advice??

I need to figure out how much trouble I'm in with this. Any body have any advise on how to proceed?
 

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That bearing definitely went out. You are better off buying a complete new or used pump. There are different pumps. Your 1980 model likely has the old diaphragm pump. Not too long after that they changed to the piston type. They bolt to the engine the same, but the piping is different. Check the cam on the engine to make sure it has not been damaged.

As for the missing parts, other than some metal filings, looks like only the balls from the bearing would have fallen into the engine. But those most likely got ground up pretty good before falling out. If it were me, I would drop the tin part of the pan from the engine and clean it and the oil screen on the oil pump. The metal most likely accumulated there. You could also pull the valve cover and inspect the timing chain for any damage. If everything looks good, I would just replace the pump, change the oil filter, and get it on the road again. Since it was running fine before you pulled the pump, you're probably won't have any problems.
 

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That bearing definitely went out. You are better off buying a complete new or used pump. There are different pumps. Your 1980 model likely has the old diaphragm pump. Not too long after that they changed to the piston type. They bolt to the engine the same, but the piping is different. Check the cam on the engine to make sure it has not been damaged.

As for the missing parts, other than some metal filings, looks like only the balls from the bearing would have fallen into the engine. But those most likely got ground up pretty good before falling out. If it were me, I would drop the tin part of the pan from the engine and clean it and the oil screen on the oil pump. The metal most likely accumulated there. You could also pull the valve cover and inspect the timing chain for any damage. If everything looks good, I would just replace the pump, change the oil filter, and get it on the road again. Since it was running fine before you pulled the pump, you're probably won't have any problems.
I think KCM's advice is absolutely correct. I lost my pump some time back and picked up one in the local pick and pull junkyard for like $20 and popped it in without a hitch. The nice think about pick and pull is you learn how to do the job on THEIR car before you do it on yours!
 

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1985 300TD
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Discussion Starter #8
so far, so good...

KCM and all, thanks for the comments. I pull the pan and the oil pump screen and things looked pretty good. There was a bent up piece of metal in the pan that looks like it could have been one of the rings around the bearings. Other than that, there were some metal shards, but nothing else troubling. Pulled the valve cover and everything in there (timing chain etc) looks ok. Thanks for the advice I was spooked there for a bit.

The new vac pump came today as well, so I'm ready to put it on. BUT the big question is: what caused the damage to the cam in my previous one? Is this sort of wear normal?! Did someone install it wrong previously? Is there a special way to reinstall the new one? I made an alignment mark before pulling the old, but don't necessarily want to follow that...if it was the cause of the problem. Any thoughts?

FYI, I do indeed have the older pump version; the one with a single line coming out of it.

Thanks again.
 

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I wouldn't put too much thought into it. Parts fail, and in this case, the ball bearing simply busted. There is no special instructions or way to install the pump. Just rotate it so the line comes out where it needs to and bolt it on, which is most likely the way it was. I suppose in theory it could be rotated to any position and it would still work. The pump is concentric with the ramp on the pump.

The only reason I can think of why the bearing would fail other than normal wear is if for some reason the bearing would loose contact with the ramp, which would cause a jackhammer effect. You would definitely hear some ticking or tapping by the pump with the engine running if this was happening. But there would have to be something like a broken or missing thrust washer behind the timing device (which the ramp is integral to). Try moving the ramp/timing device in and out. If you can't, or can just a little, I'm sure everything is fine.
 

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Discussion Starter #10
I guess I'm more concerned about the deep rut that was created in the cam of the pump. Doesn't seem natural to me to have that kind of wear. It feels like I should be worried about the same issue with the new one, but maybe not...maybe the old one was just that old that it happened over time.
 

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The rut in the pump occurred when the bearing/roller failed and the outside surface of the bearing went below the mount/cam. The ramp on the timing device of the engine then made contact and ate away at the bearing mount/cam. The bearing outside surface should be sticking above the mount so that it is the only part that contacts the ramp. The ramp is hardened, and since the bearing mount is soft, it took the abuse. You should inspect the ramp for wear before installing the pump, but I would guess it is still okay.
 
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