300TD catastrophic vacuum pump repair adventures - PeachParts Mercedes-Benz Forum

ROLLGUY · #1 05-28-2016, 07:48 PM

A friend of mine bought a wonderful 300TD for cheap because of a catastrophic vacuum pump failure. He had a rebuilt engine ready to go in it (it will be the subject of another thread), but I suggested that I would try to repair the engine in the car before committing to install the rebuilt engine. He brought the car today, and I decided to start working on it. Upon removal of the cam cover, I found a broken timing chain, all but one of the cam towers broken, and the cam in three pieces. Upon further tear down, I found a two-piece vacuum pump. My iPad will only allow one photo upload, so I will just do the vac pump for now. I will try to post more photos with my laptop later. I was able to weave in a new timing chain only after removing the pan and oil pump. I had a challenge getting the old chain to move, as it was balled up between the lower guide rail and timing device sprocket. I was able to tie a wire on the end, and pull it through, and then turn the crank and pull the chain up and into position next to the upper guide rail. I wired the end up, and call d it a day. My next job is to put all the new parts on, crimp the timing chain, re-time the injection pump, and then hope to get it running again. I will post photos of the progress. Wish me luck!

ROLLGUY · #2 05-28-2016, 07:55 PM

Beautiful car with a perfect dash, perfect wood, perfect carpet, better than average Palomino upholstery (notice I did not sat pink-omino) on the driver seat, the rest of the upholstery is perfect. The body is near perfect, with only the smallest dent just above the driver side corner light. The fairly new Michelin tires have 90 percent tread. The former owner just put a lot of money in rebuilding the front end as well.....Rich

Mike D · #3 05-28-2016, 08:10 PM

¡Buena suerte! Pomaika`i. Bonne chance.

KrustyKustom · #4 05-28-2016, 08:14 PM

I guess the timing device which the vac pump rolls on is removable for the roller surface only? My later 95 606 engine is all one piece.

Just curious....

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ROLLGUY · #5 05-28-2016, 08:20 PM

Quote:

Originally Posted by KrustyKustom

I guess the timing device which the vac pump rolls on is removable for the roller surface only? My later 95 606 engine is all one piece.

Just curious....

Sent from my SM-G920V using Tapatalk

Yes!

Mike D · #6 05-28-2016, 08:22 PM

When all else fails, "Desenrascanço".

ROLLGUY · #7 05-29-2016, 10:41 AM

Broken parts

ROLLGUY · #8 05-29-2016, 10:44 AM

New timing chain installed (well at least routed around all the gears)

ROLLGUY · #9 05-29-2016, 10:47 AM

The underside with oil pump removed. I had to remove it to get to the broken chain to tie a wire on the end.

ROLLGUY · #10 05-29-2016, 10:56 AM

Another body photo

funola · #11 05-29-2016, 11:28 AM

Shame it happened to such a nice wagon. Were there tell tale signs before the vac pump grenaded?

Did you check for bent valves before deciding to roll in a new chain?

ROLLGUY · #12 05-29-2016, 11:51 AM

Quote:

Originally Posted by funola

Shame it happened to such a nice wagon. Were there tell tale signs before the vac pump grenaded?

Did you check for bent valves before deciding to roll in a new chain?

I pushed on each valve, and none felt like they were sticking. I also turned each one, and they all had the same resistance. I am confident no valves are bent. Although I have not heard of too many people repairing this kind of damage without removing the head or entire engine, I have done one other repair of this kind, and the car is still running to this day. Both the owner and I thought it was worth the parts and labor to try to fix the existing engine before just replacing it with the rebuilt one. I will know for sure in a couple days after the parts arrive, and I get it back together.....Rich

BWhitmore · #13 05-29-2016, 01:12 PM

Rich - a fellow I know recently bought a very nice 300CD in Colorado and felt confident to drive the car back to Southern California. Somewhere in Arizona the vacuum pump exploded taking with it the timing chain, breaking the cam in half and destroying several of the cam towers. He had the car flat bedded to Monterey Park where I saw the engine. He was able to get a good engine from a wreck but I cannot imagine the total cost for all of this. I now always replace the vacuum pump as a maintenance item every 130,000 miles and always use a new pump as opposed to rebuilding the vacuum pump. Cheap insurance.

dkr · #14 05-29-2016, 04:18 PM

I was wondering that as well as I've heard about this a few times. If anyone knows, I would really appreciate knowing:

- What causes the vacuum pump to fail?
- I've heard the vacuum pump rebuild kits don't always work right. Why is that?
- Are there warning signs before the vacuum pump fails? Is it enough to drive home and fix later or will it just die and spit it's guts into the engine?
- Can inspecting the existing vacuum pump help to determine it's condition and longevity?

Dkr.

BWhitmore · #15 05-29-2016, 05:14 PM

Generally the bearings in the vacuum pump fail and then it explodes. The pump will make some strange noise before failure but it is difficult to tell the difference between normal diesel sounds.

A total rebuild of the pump involves parts that equal the value of a new pump so why bother other than the feeling of rebuilding the pump yourself. You can buy a new pump from the classic center for around $340. Once again, cheap insurance.