Vacuum Pump Rebuild -Foolish Not to Replace Bearings?
 

I am considering rebuilding my vacuum pump (later style -'82 SD) and notice that the rebuild kit is fairly expensive and does not include bearings. Many suggest on this site that catastrophic bearing failure is what takes these pumps out along with the engine. Seems foolish to rebuild pump without pressing in new bearings which are apparently not difficult to source -thoughts on this?

Thanks for bringing up this subject.

There is 2 rebuild available kits. One for the Piston and another one that replaces all of the the complete Drive Arm and Bearing Assembly.

In my readings no one I can remember has smiply replaced the Bearing. This should be possible.
However, this will depend on how tight the pin the holds the Bearing in is pressed in.

Sice the Bearing is held in a Fork removing/inasalling a Tight Pin could warp the Fork. If the Pin is not tight it would not be a problem. Forsure another bearing with the Metal Shield; the number should be somewhere on the bearing.

A little more than a month ago I bout 2 bearings for a Chevy Van Alternator; both ball Bearings. There is an eBay seller that had USA Made and NSK Japan. The price was in the order of $3.50 and $4.50 with resonable shipping. I ordered 2 of each from him.
Bearings with ZZ in the part number are the Metal Shielded Bearings. In ads they are somtimes listed as 2Z.
Any way do a search for the Bearing Number on eBay and you will have to pick throught sellers.

There is a parts place that claims to sell $195 Vacuum pumps already rebuilt.

What in particular causes vacuum pump failure?
http://www.peachparts.com/shopforum/diesel-discussion/204187-what-particular-causes-vacuum-pump-failure.html

New Vacuum Pump Ruined due to too much Timer Shaft End Play (the title from my notes).
http://www.peachparts.com/shopforum/diesel-discussion/258062-second-vacuum-pump-help-trip-toronto.html?highlight=vacuum

http://www.peachparts.com/shopforum/diesel-discussion/258062-second-vacuum-pump-help-trip-toronto.html?highlight=.05-.12mm

Piston arm, vacuum pump
MB# 000 586 18 23

Fastlane: Vacuum Pump Repair Kit
http://catalog.peachparts.com/item.wws?sku=W0133-1600004




..

Yep, with the price of both Rebuild Kits it seems more cost effective to get a new Vacuum Pump or a Rebuilt Vacuum pump and there is the added bonus of having a warranty.

I actually bought one of those Thomas 12 Volt Vacuum Pumps that a year ago were plentiful on eBay; but have yet take the time to try connecting it up to see if it will work.
I did connect it up to a Jar with some Hoses and use it to Vacuum Bleed my Brakes and it worked well for that purpose.

It is a very simple and straightforward job to replace the bearings - Go For it! I posted this here about six years ago – Don’t know what kits are still available and prices are no doubt out of date. - Beagle

VACUUM PUMP - Are you neglecting yours??

The Vacuum Pump is a vital component of your braking system and its sudden failure will lose you about 70% of your braking efficiency instantly. Rambo should cope but your wife or daughter certainly would not - your life can depend on it. It is naïve to expect this important mechanical device to perform reliably for over 30 years without any servicing or inspection..

There are two types of vac pump fitted to the 123 series diesels – the diaphragm type, pre 1979, has two pipe connections and exhausts into the air filter housing. The piston type fitted to later models has only one connection and exhausts directly into the crankcase behind the pump through a pair of plate valves. Both types are interchangeable and have a check valve incorporated in the vac line pipe fitting after the suction plate valve. A twin lobed cam on the fuel pump timer reciprocates the piston (or diaphragm) via a rocker mechanism with a roller cam follower. The forward stroke exhausts air while the double spring return stroke draws the vacuum. The mechanism and piston sleeve are oil-mist lubricated from the timing chain. When >25 inch is reached this vacuum holds the piston forward against the springs keeping the rocker almost clear of the cam. As vacuum falls (e.g. at braking) the roller once again moves back to contact the cam and restore vacuum. Thus the vac pump should run for less than 5% of the time that the engine is running, 15 secs at idle to 25” at start up (i.e. FSM spec.) and less than 10 sec to top up after braking IF you have no leaks in the system and the plate valves are sealing perfectly! Any leaks in the system will cause the pump to run continuously and it is not designed to do so - no surprise then that these pumps are going to wear out and fail prematurely. If you have leaks in your lock system isolate it until fixed as this will also reduce braking efficiency.

The most common failure is the rocker arm bearings – the bearing cage wears out releasing the balls (dirty oil is a factor here!) By the time that you hear mechanical noise from the vac pump at least one of the bearings or the piston have already failed. While the pump may continue to function for a short time the cam is now rubbing on the rocker arm instead of the roller and the mechanism will soon disintegrate. Balls and other debris are caught in the sprockets breaking the timing chain and from there on it’s a train crash.

Servicing and Rebuilding

Several kits are/were available from MB. Prices are very approx.

1) Complete Piston Pump:- MA 000 230 13 65 $580
2) Diaphragm Kit:- MA 000 586 41 43 $45
3) Piston Seal kit (with piston):- MA 000 586 17 23 $187
4) Rocker Complete with Brg's:- MA 000 586 08 43 $300
5) Plate Valve Kit:- MA 000 586 40 43 $50

The vacuum pump is a simple devise that can be stripped cleaned and rebuilt by any average DIY’er. Replacement of the bearings and plate valves can restore your pump to new condition for around $50 and 4 or 5 hours work. You will have little or no warning if your pump fails and I would suggest anyone running the original pump, regardless of whether you have a problem now, should consider a rebuild. You will be astonished at how much better your brakes are. A good pump will restores vacuum to the booster as you are braking.

The rocker roller bearings are available from any specialist bearing store (choose a reputable brand! SKF etc.) and are easily replaced. Plate valves too are standard and available from pneumatics stores cheaper if you are prepared to search. The rocker and bearings are identical on both types of pump. They are a standard No 626 "precision" deep groove journal bearing 19mmØ x 6 x 6 (6 balls) @ about $7 each. A parallel 6mm pin is a press fit through the bearings and roller and can be pressed (preferably) or driven out with a punch.

N.B. Use ONLY an open six ball "Precision" 626 (Grade 50 or better) without metal dust covers even if they have been removed. "Precision" bearings never have metal dust covers. The eight ball 626 is a light duty utility bearing, with or without dust covers, and is intended for use in draw sliders casters etc. Care is needed here to avoid damage to the new bearings when installing – support and do not side load the ball races when fitting!

Have a nice day - Beagle

I thought the majority of vacuum pump failures were related to the 603? I have to say that I cannot remember reading about a 617 related pump failure (disintegration). Although I'm sure it is possible.

I rebuilt the pump in my 5 last year (seal and check valve kit). I have to say that it looked pretty good in there considering the miles.

So.... Should I have replaced the bearing?

That would suggest a major shortcoming in your research.

Not really... I never cared about it enough to worry about it until this moment.:rolleyes:

And again... Should I have replaced the bearing and fork assembly even if it appeared to be OK (with 216,000+ miles and slow ODO).

I suspect that a shielded bearing (if that's what you mean) would not be suitable for that application.

BEAGLE, Thank You for that Great write up. I always wondered if the later type pump could be used on an engine with the early type.

Charlie

Years ago I ask what Folks though caused Failure. Some said they thought the Vacuum Pump Failed and dumped parts inside.
MY Question on Timing Chain Failure
http://www.peachparts.com/shopforum/showthread.php?t=203364&highlight=timing+chain

When in doubt replace it with the exact same Bering that is already on the Vacuum Pump.

Now that I think about it; it may be that my interpretation is wrong but I remember reading that the older Vacuum Pumps had unshielded Bearings and that when they became worn the Ball Bearings would come out and ounce that happened you had no bearing at all and things began to get torn up.

From what I read it said that the fix was a Shielded Bearing.
Did this mean that the Bearing had an integral Shield built in or did it mean there is some sort of separate Washers that that act as the shields and go on each side of the Bearing?

When I had my Vacuum Pump off I do not recall how it was shielded but I do not remember being able to see any Ball Bearings so it was shielded some way.

Which pump is more reliable????

In order to work, the "shield" would have to separate from the bearing. An integral dust shield would not last three microseconds in the event of a catastrophic bearing failure.

Thanks Beagle -I think I will pick up a used vac pump for my car, dissasemble and go from there and source bearings etc. Hopefully, I can press bearings in myself correctly without distorting anything - my pump seems fine on my 617 but at 345,000 miles, I may be driving on borrowed time and I would rather be safe than sorry! I also have a lead on on a new pump that I may be able to purchase for 150.00 which would be great -deal! I lean towards preventative maintenance especially when the age of the component is uncertain which makes long road trips much more pleasurable and worry free