OM603: Vacuum pump explosion, bearing intact! Injection Pump Timing device wrecked

[gsxr]

Originally Posted by sixto

When's the next dyno run?

The Idaho Turbo Diesel guys said there might be another session this fall... stay tuned!!

[babymog]

Seems that any parts that are pulled into the oil pick-up would affect the oil pump, but then be filtered out.

[gsxr]

Originally Posted by babymog

Seems that any parts that are pulled into the oil pick-up would affect the oil pump, but then be filtered out.

Correct. The screen on the pump pickup should keep out anything big (but I really think I removed anything that big already). The little bitty stuff, assuming it doesn't damage the pump, should end up in the filter. The more miles I put on the car, the less nervous I'll be, lol... so far so good, though.

[babymog]

"if this problem exists on models manufactured prior to this date, which do not have a second drilling in the oil spray nozzle for the oil supply of the piston vacuum pump, or for performing work which requires taking off the vacuum pump, remove the centering sleeve and install in modified seal for improving the oil supply." - PR 07.1.1064 /6

What is this centering sleeve and does it exist in any M/Y 1987 603 engines? The "modified seal" is the gasket with the dam across the bottom.

[gsxr]

The centering sleeve is needed if the injection pump will be removed. Mercedes used to leave the centering sleeve in the engine, up through the late 80's. Then they started removing it. Most 1986/87 engines came with the sleeve from the factory, but it may have been removed by a previous owner if the vac pump had ever been replaced in the past. Photos are shown below.

[JHZR2]

Originally Posted by gsxr

The centering sleeve is needed if the injection pump will be removed. Mercedes used to leave the centering sleeve in the engine, up through the late 80's. Then they started removing it. Most 1986/87 engines came with the sleeve from the factory, but it may have been removed by a previous owner if the vac pump had ever been replaced in the past. Photos are shown below.

Sorry, one more blast from the past quotation of a good post…

The FSM says the basket is there so the engine can be turned easier. I kind of get that. If you wish to turn the engine over by hand with the IP removed, this would keep the timing device gear in place good enough that it would engage with the timing chain and keep everything working in time.

If all I’m doing is locking the IP in place with the pin, removing tension on the TC, removing the IP, and then installing it back, not much could slip. Is the timing device somehow indexed to the IP and chain that it matters? It seems that as long as the crank and cam aren’t moved, and the IP is locked, how can timing get messed up?

Is there a requirement to crank the engine for some reason that I’m missing? My plan is merely remove, replace seals, reinstall.

Thanks!

[babymog]

Thanks Dave, sounds like leaving it is not preferred. I'll check my spare engine, looks like the original pump.

[gsxr]

Well, one school of thought is that leaving it in place can catch vac pump parts if the pump explodes, and/or offer some protection to the timing device cam. The basket can be left in place if you use the "outline" gasket, but the basket MUST be removed if you use the "dam" gasket.

[wyrick]

Why must the basket be removed if using the "dam" style gasket? I'm a little worried b/c I just replaced my original vacuum pump and did not remove the basket in there.

[gsxr]

Originally Posted by wyrick

Why must the basket be removed if using the "dam" style gasket? I'm a little worried b/c I just replaced my original vacuum pump and did not remove the basket in there.

The basket is fastened to the timing cover with three M6 bolts. The head of the bolt interferes with the "dam" gasket, and when you try to tighten down the pump, it will deform the gasket badly - most likely causing an oil leak, and possibly not letting the pump fully seat. The "outline" gaskets go around the bolt heads so there's no problem if you leave the basket installed with the "outline" gasket.

[wyrick]

Wow, I feel dumb. I do have a little oil wetness underneath the pump. New gasket is already ordered. Thanks.

[sixto]

Originally Posted by wyrick

Wow, I feel dumb. I do have a little oil wetness underneath the pump. New gasket is already ordered. Thanks.

Clean the pump and confirm it's leaking from the gasket. A more likely source is between the pump's front cover and case. My guess is the update from crimped to screwed front cover improves the seal.

Sixto
87 300D

[theref]

I seem to recall that you once said that the one type-either the old or the new-could be identified by the boltheads on the front of the pump. I cannot remember which was which. And, by the way, do you mean the front as seen in the car-or is that a cover that has to be removed to see the actual front of the pump?

[gsxr]

Torx-head bolts on the external cover indicate that the pump is likely not original, especially on 1986/87 engines. I am not sure what year the Torx screws appeared in production by Pierburg. However, I believe Aaron confirmed that the early Torx-screwed pumps may still have the "bad" open bearing internally. This doesn't seem to be very common though, most pump with the Torx screws on the front cover also have the improved bearing design. I suspect the first improvement to the pump design was the front cover screws, which helped sealing, and reduced oil leaks. The second improvement was the enclosed bearing. There may be others as well, but those are the two I am aware of.

In general:


1) The presence of four Torx screws on the front cover simply means the pump is not ancient - but if you have never removed it, it would be good to do so and see if the bearing is open or not. If it's the old open-style bearing (with exposed balls), replace the pump ASAP.

2) I believe all pumps without the Torx screws will all have open bearings, and these should likewise be replaced ASAP.

3) The date code stamped into the front cover should tell you the year of manufacture, which can be useful in determining the miles on the pump, if at least some maintenance records are available.

4) Based on my "new style" pump explosion, as detailed in this thread, and also based on the data below... I would recommend proactive replacement of even a new-style pump when it reaches the 150-200kmi range, regardless of age, even if it otherwise appears to be working ok. It's relatively cheap insurance, given the potential for catastrophe when metal parts drop into the timing chain cavity & oil sump at freeway speeds...! Besides, there is precious little evidence that these pumps last much past 200kmi.



Here are some interesting data points on the four 1987 300D's in my family:

• Blue car: Original pump failed at 117k, pump 2 failed at 139k (after only 32kmi!), pump 3 failed at 293k (154kmi)
• White car: Original pump replaced before it failed, at 220kmi (not sure if it really was original, though! Was leaking oil at front cover.)
• Dad's car: Original pump failed around 175kmi
• Sis's car: Original pump replaced before it failed, at around 175kmi

[theref]

And by the way in reference to one of your other warnings about the absolute need to reinstall/replace the little brackets that separate the fuel lines from the IP to the injector: When that cracked -22 head was replaced last Mar by the dealer, they did not do so. This resulted in 3 leaking fuel lines. Leaking at the points where they rubbed and also the vibration caused a leak where one (#4) attached to the IP.

I do have the records all the way back to when new, and will check the date on the VP cover. I have no records that show it being replaced but it might have been on the factory crate engine that was installed 5 years ago.