HT4100 4.1, 4.5, 4.9 Discussion, In search of a new/rebuilt vacuum pump... in Cadillac Engine Discussion; Is this the buzzing noise I hear when I turn the key into the run position (don't start it, just ...
Is this the buzzing noise I hear when I turn the key into the run position (don't start it, just turn it to run)? I've asked three or four mechanics about it and none of them seem to know anything.
My pump does the same thing, and buzzes while the engine is running. You can find it by reaching under the driver front fender, between the head light and wheel well. It supports vacuum for the brakes, cruise control, climate control, and releasing the parking brake, maybe more.
Almost forgot... I talked to my electrical mechanic about this today, and he said that the buzzing sound is completely normal, and that it should not be replaced until it starts to fail.
I spent a while looking through manuals and whatnot, and on my 85 Sedan DeVille the main vacuum pump is under the battery on the driver's side. One of my manuals (don't recall which) has a full diagram, and there is hosing that snakes all around the engine bay (the charcoal dehumidifying filter on the passenger side is part of the setup, for example), but the main pump itself (the thing that makes the buzzing noise) is under the battery.
Anybody found a suitable replacement for this? Do the later models have a similar vacuum booster? Are those interchangeable?
Mine has gone from a light constant buzzing to a major rattle and I've had to pull the fuse on it. Since the part is in the fender well, most of the yards did not pull it so there are very few original replacements.
I was looking for a replacement vacuum pump for my 86 Eldorado and found them in the Advance and OReillys online listing. One of them had the actual picture of the type of pump I have. I didn't pursue that farther since I have more pressing issues right now.... Did you check those places?
what part number is this universal pump and which parts supplier? I called Napa last night and they said a reman pump for my 1985 Caddy would be $189! If this pump is much cheaper, I will try and rig it up..
I was looking on ALLDATADIY for part numbers and found a TSB
MODELS AFFECTED: 1985-86 FWD DE VILLES AND FLEETWOODS 1986 ELDORADOS AND SEVILLES
This Bulletin supersedes Bulletin T-86-59 which should be destroyed.
Some 1985-86 De Villes and Fleetwoods and 1986 Eldorados and Sevilles may experience a moan or buzzing noise accompanied by vibrations in the steering wheel, instrument panel, and floor pan. A second design vacuum pump and mounting bracket is installed after VIN number 281300 for 1986 FWD De Villes/Fleetwoods, 607957 for 1986 Eldorados, and 805741 for 1986 Sevilles, to provide additional vacuum pump isolation. The redesigned mounting system prevents the second design pumps from being interchangeable directly with the first. Since the first design pumps have been superseded by the second generation pump, it is necessary to install a new mounting bracket when replacing first design pumps. The second design part numbers are listed below.
Part Number Description Usage
22062562 Vacuum Pump C,E,K
25527649 Bracket C
1633916 Bracket E, K
22055187 Grommets C, E, K
I called the local GM dealer about the replacement part (part no 22062562) and they said it was unavailable. I emailed newgmparts.com about it and they said it was not available in any of their dealer inventories.
Looking around, it also seems that the vacuum pump was only used on the HT4100. I'm guessing that the 4.5 and 4.9 produce enough vacuum by themselves to not need a helper. Therefore, I think I can forget about it, since I plan to swap in a 4.9 longblock with 4.5 intake later this year. I'd still like to get one though.
I've talked to some junkyards but since the pump is hidden in the fender well and not readily visible part of the engine they are hardly ever pulled. You'd have to find a chassis, which is becoming really difficult for this vintage. Maybe some of the Cadillac specific yards... dunno.
When I was looking around I noticed that most of the current references to "electric vacuum pump" were hot-rod sites that were using them for additional brake boost. There are supposedly a couple of companies that are making them, but they seem to be pretty high dollar.
Another option is to find another electric vacuum pump and adapt it.There are actually a fair number of cars that had these (especially the 4 cylinder stuff), but I think we would need to find out the PSI specs to get something usable. I haven't been able to find this info anywhere. The power part is simple--plug in 12v to accessory lead.
One more option worth considering is to replace the pump with a reservoir. For example, my Jeep Cherokee has a thing that looks like an oversized toilet float behind the front bumper, which is a vacuum reservoir canister. When the vacuum is initially created, air is sucked out of the canister too, and when the vacuum is consumed the additional volume in the canister helps to keep vacuum in the system for a longer duration.
So, basically replace the pump in the fender with a toilet float. Maybe.