Having some noise at idle like a ticking or knocking, not rhythmic with RPM and does not sound like typical engine internals. More of accessory or rubbing type noise. Sounds like it might be coming from the vacuum pump and when I watch the pump the pulley will move in and out somewhat randomly maybe 1/8" or a bit more. Do not recall noticing this previously. How much end play is normal? I'd imagine it should be pretty tight like on the order of a few thousandths not a large visible amount. Still makes plenty of vacuum though. Gonna fail soon? This is an '86 with v belt driven off the alternator. Electric is not an option with vacuum brakes I'd assume?
Vacuum pump shaft end play?
- Thread starter dunk
- Start date
My vacuum pump bearings are bad. Has anyone rebuild the belt drive/shaft portion of one of these? Obviously they are rebuildable as I see both new and reman units available though at $100+. Mine pulls a steady 24" vacuum and builds it quickly so I don't actually need a new pump portion (I see they sell those separately), just a rebuild drive side or the bearings and seals to do it myself. Anyone have a source or know part numbers? Don't see any bearings or rebuild kits listed. I'd rather stick with what I know works vs China new or Mexico reman and be doing it again next year.
Managed to get a new Dorman pump, little tracking down to find one local but $115.50 out the door. New pump has an NTN 6203LU bearing on the pulley side, not sure if backside is the same. Will disassemble and measure bearings in old pump and see if I can replace and keep as a spare or sell. Seem to go for $30-$60 on ebay so if I throw $15-$20 in parts at it and clean it up it should be worth something.
GringoRick
Registered User
I just replaced my vacuum pump and neither my old one nor the new one had much play. The hydraulic pump is another storey... both old and new have play.
Yes the new Dorman pump has no perceptible endplay. I'm sure if I measured it, it would be a couple thousandths. The end play I observed in my old pump was surely the balls disintegrating.
I sandblasted the old pulley and bracket, and while waiting for paint to dry disassembled the old drive mechanism for the vacuum pump. Not exactly what I expected to find inside but just two bearings and a seal. I am disappointed in the construction as I expected to find a support bearing on each end and a lobe to actuate the pump itself... I was expecting either a cam lobe or fuel pump eccentric type thing. It's a little of both. There is a bearing at the pulley and a center bearing but the lobe end is unsupported.
In any event, here are the guts:
Very simple! Not sure why there is not a rebuild kit available. I will list parts as they are from pulley side to back side...
Snap ring 1.710" OD at rest
Straight ball bearing: NSK 6203DUS ENGLAND 1.578" OD, .668" ID - (New pump measures same and bearing is NTN 6203LU)
Standard type oil seal: ~1.240" OD, fits .668" ID shaft, .659" ID at rest
Needle bearing: Torrington F1720, .906" OD
Needle bearing (for eccentric): Torrington DD68424 , 1.460" OD, 1.124" ID, flange on one side 1.049", other side flange 1.141"
That last needle bearing is a tricky one I'm not finding it in a search. The number is hard to read, it may be DD66424, DD88424... The 3rd and 4th characters are difficult to read. Could even be G6 or G8. looks like a G, 6, or 8 though could even be an o or O but not 0. The flange on one end is larger (the inner end) so it is retained on the lobe on the end of the shaft.
I sandblasted the old pulley and bracket, and while waiting for paint to dry disassembled the old drive mechanism for the vacuum pump. Not exactly what I expected to find inside but just two bearings and a seal. I am disappointed in the construction as I expected to find a support bearing on each end and a lobe to actuate the pump itself... I was expecting either a cam lobe or fuel pump eccentric type thing. It's a little of both. There is a bearing at the pulley and a center bearing but the lobe end is unsupported.
In any event, here are the guts:
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Very simple! Not sure why there is not a rebuild kit available. I will list parts as they are from pulley side to back side...
Snap ring 1.710" OD at rest
Straight ball bearing: NSK 6203DUS ENGLAND 1.578" OD, .668" ID - (New pump measures same and bearing is NTN 6203LU)
Standard type oil seal: ~1.240" OD, fits .668" ID shaft, .659" ID at rest
Needle bearing: Torrington F1720, .906" OD
Needle bearing (for eccentric): Torrington DD68424 , 1.460" OD, 1.124" ID, flange on one side 1.049", other side flange 1.141"
That last needle bearing is a tricky one I'm not finding it in a search. The number is hard to read, it may be DD66424, DD88424... The 3rd and 4th characters are difficult to read. Could even be G6 or G8. looks like a G, 6, or 8 though could even be an o or O but not 0. The flange on one end is larger (the inner end) so it is retained on the lobe on the end of the shaft.
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I am not thrilled with the new Dorman pump. It is a bit lazy to come up to full vacuum, and it drops much more rapidly and lower when pressing the brake pedal than the old pump did. That's at cold high idle too. 23" max vacuum and it's slow to get the last bit. The old pump pulled 24" at low idle I couldn't really make the pedal hard when pumping it, this one goes hard in 3-4 pumps. I'm guessing this is another example of cheap foreign parts working, but not as well as the old made in USA parts. In all fairness I don't know if the old pump was OE Ford, a cheap reman, or a new China. I'm guessing it was Ford/Motorcraft though since it had Torrington bearings which would put it before the turn of the century (bought out by Timken) and rebuilders typically don't use American bearings.
Yeah I could throw my old pump on the new drive, and I may, but I'll first see if I can get new parts for the old drive and make a freshened up pump of it. Not sure if new diaphragms are available or how difficult that would be to replace. It's a crimped can, so I'm guessing it wouldn't be terribly different than rebuilding/resealing old motorcycle gauges. I wonder if there's a difference in stroke of the Dorman vacuum pump. Is it a sloppy diaphragm that doesn't perform as well? Is it a shorter stroke on the eccentric? Something else? Maybe this is entirely too much thought put into a vacuum pump and the answer is hydroboost... and if it wasn't right before Christmas and my daily driver I would probably just order the parts to convert. I like driving my other truck but it's not emissions legal here so it's random $200 fines when I drive it and it's too cold to to ride my Honda (I never would have said that 5 years ago!). The truck still needs vacuum either way for the HVAC though. Time will tell as I drive it and see if the pedal gets hard is normal driving. Until I had an 80s truck everything I ever drove was manual brakes so I'm used to high braking effort, but I don't want random pedal effort. That would be unacceptable to me.
Yeah I could throw my old pump on the new drive, and I may, but I'll first see if I can get new parts for the old drive and make a freshened up pump of it. Not sure if new diaphragms are available or how difficult that would be to replace. It's a crimped can, so I'm guessing it wouldn't be terribly different than rebuilding/resealing old motorcycle gauges. I wonder if there's a difference in stroke of the Dorman vacuum pump. Is it a sloppy diaphragm that doesn't perform as well? Is it a shorter stroke on the eccentric? Something else? Maybe this is entirely too much thought put into a vacuum pump and the answer is hydroboost... and if it wasn't right before Christmas and my daily driver I would probably just order the parts to convert. I like driving my other truck but it's not emissions legal here so it's random $200 fines when I drive it and it's too cold to to ride my Honda (I never would have said that 5 years ago!). The truck still needs vacuum either way for the HVAC though. Time will tell as I drive it and see if the pedal gets hard is normal driving. Until I had an 80s truck everything I ever drove was manual brakes so I'm used to high braking effort, but I don't want random pedal effort. That would be unacceptable to me.
79jasper
Chickenhawk
Did you check the pumps end for oil?
Also, on the drive side, does it look like a grease zert could be added?
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Also, on the drive side, does it look like a grease zert could be added?
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I always drain them and fill with synthetic oil. and that eccentric needle bearing is a tough one to find. when I fixed a couple pumps i never could find it. but the old one was fine so it got reused.
I have an old Industrial catalog which shows bearings based on multiple standards; model, mfr, specs, etc....
I don't see why you can't rebuild the old unit.
And that pump bellow itself looks a LOT like the ones used by GM for their old 6.2s
I don't see why you can't rebuild the old unit.
And that pump bellow itself looks a LOT like the ones used by GM for their old 6.2s
w4dsb
Registered User
find a local bearing supplier and 'im sure you can get the bearings. We use Motion industries where we work and they have found some pretty rare ones for us.
icanfixall
Official GMM hand model
Some of the diaphragms have the suction line placed differently. Also the V belt body is threaded for the mounting bolts but the serpentine belt pumps are drilled with no threads. I believe the GM vacuum pump suction head is the same as ours all the way back to the 350 gm diesels.
Parts list:
6203 sealed bearing ($2-$11)
17X31.75X8 Single (or double) lip seal with tension spring (??)
F1720 needle bearing 17mmx23mmx20mm IDxODxL ($8.72)
Torrington DD66424 (DD??424) potentially unobtainable bearing
The seal seems a tricky one to find 17x31 is a more common size, as is 17x32. Timken does list a 17x31.75x8 seal but I don't see a PN in the catalog or availability anywhere except this australian site (http://sealnet.com.au/product_list.php?id_category=242&size_type=M&p=47). 17x32 would likely be a real tight squeeze as the bore in teh housing measures ~31.65mm which would be a .014" press fit for a 32mm seal vs a .004" squeeze for a 31.75mm seal.
Not sure on the oddball bearing but I'm going to try to track it down or see if the off the shelf closed end can be modified.Might be tricky finding a narrow enough bearing. Shame there are several oddball size parts in this drive unit or it would be an easy $20 or less rebuild with quality parts. This is the stuff I hate as you get into these newer vehicles, strange parts and sizes. I'd like to know what sadistic engineer designed this thing... And why engineers in general don't take their initial design/dream/vision and tweak it here and there to use standard or common parts. At least the outer bearing is as common as it gets and the middle needle bearing is not a goofy size. Shame as this is almost a simple $20 or less rebuild.
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