So much on this 1957 Oldsmobile 88 depends on vacuum. I'm an admitted novice though I'd like to have a working heater, choke, wipers, washer, ventilation controls, etc. I am looking for a starting point to check for Vacuum and any leaks. I do know the windshield washer pump is in pieces. I am not sure if the heater control valve can be tested for proper function. The wipers will currently start 1/8th of the way up and more or less return to the parked position. Open to suggestions, David

 

Well, yes - we've had a fair share of the aged vacuum systems operations appear - they're a beast of burden. Someone might be able to quickly offer some insight (I don't know) but there are a couple threads where several members have assisted in troubleshooting the beastly system. I'll attempt to try to find one thread in particular w/ diagrams, illustration to provide some context while other members chime in to hopefully provide some assistance. Don't hold your breath, it'll take me some time to Search, which you can do on your own, as well using the Search tools. It's likely located in the Vintage/Classic Olds section.

 

Thanks Norm, I've searched a little - mostly before joining. I'm actually wondering if I should look for a general manual that explains and offers testing information for vacuum systems. If I find anything useful, I will share it as well.

 

I'm attempting to move on searching for you in between other dialogues. Charlie Jones might chime-in, he's well versed in the aged classics. I'll create a Search and post it here, I might not have time read each of the posts but like I said, I believe the one w/ diagrams, illustrations & discussion is located in the Vintage/Classic Old sub-forum. Search on the term vacuum in that sub-forum.

 

Here's results from a search in the Vintage Oldsmobile sub-forum for the term vacuum. The thread I'm looking for is date after 2018 because I joined in 2018 and the thread I'm thinking of has been w/in the last 7 years.

https://classicoldsmobile.com/forums...archid=7600149

 

#1 Do you have a 1957 Oldsmobile Chassis Service Manual (CSM) ?
#2 Have you checked all the vacuum lines for deterioration or cracks ?
#3 Is the heater core connected ?
#4 You may want to install an electric wiper in place of the vacuum powered one. There are a couple people on here know who sells them.
#5 Your carburetor choke is NOT vacuum operated. What carburation set up do you have on the engine ?
#6 Rebuild the windshield washer pump or buy a new one.

 

The best place to start is with a 1957 Oldsmobile service manual, if you don't have one.
1957 Oldsmobile Service Manual for sale | eBay
Original printed copies are preferred.

There are three vacuum operated systems involved in 1957 cars.
The heating and Air Conditioning (if so equipped) system
The windshield wipers.
And the power brakes
The manual should have diagrams of these systems.
The heat and air system, as well as the power brakes, are supplied by intake manifold vacuum.
The wipers are supplied with manifold vacuum, which is "boosted" by a small vacuum pump on the top part of the fuel pump.
This allows the wipers to work even through periods of low vacuum.
Such as when accelerating or going uphill.

A vacuum gauge and a small hand vacuum pump are two very useful tools to diagnose vacuum related problems.
Wiper motors can often be revived by disassembling, cleaning, and re-lubricating them.

 

Thanks Norm, I've started to go through the threads and there is some useful information. I'll keep reading and post more specific questions when I am ready.

 

Ralph to answer your questions:
#1, yes I have a shop manual, but may not have the specific Chassis CSM you reference - is it different?
#2, I'm in the process of checking lines, but I am not sure if there are missing components, parts, etc.
#3, it was connected until the top heater valve hose crapped out and I had to bypass it until I can get the correct molded parts (in process)
#4, For now, I'd like to stay with the original system, unless those efforts totally fail
#5, The carb is a 4BBL Rochester - oh, maybe its part of the throttle that uses vacuum? Anyway the automatic choke does not activate when the engine is cold
#6, I'd like to rebuild it or replace it - I'd like to have a better sense for the vacuum system and its state before touching the washer pump, but until then maybe I should block the vacuum line to it?

Much appreciated, David

 

Thanks Charlie,
I have the manual, a vacuum gauge and pump, though I will need to become more familiar with their use for any given scenario. My car is a base model, so no AC, or brake booster. I am thinking that a check of what is coming off the vacuum side of the fuel pump would be a good start, or maybe the manifold?. Where can I best do so with a vacuum gauge? I really appreciate the thoughts about revival, disassembly, cleaning and re-lubrication. Much appreciated.

 

I am not that years' expert, but I definitely would cap off optional things that are misbehaving to help troubleshoot on the engine side to avoid leaks affecting idle.

 

Put the Newport electric wipers on your car. It was one of the best improvements I made on the 54 I had. You will never get the vacuum wipers to work worth a damn. Never

 

Yes, you need to block off that washer pump . That's a vacuum leak.
Then you must find the fitting on the manifold where the heater system connects.
Disconnect that hose and connect your vacuum gauge.
Start the engine and let it warm up for a few minutes.
Observe the manifold vacuum reading. It should be at least 17 inches or so with a well adjusted carb and ignition system.
Next, "tee in" the heater system with the gauge to see if there is a loss of vacuum with the heater connected.
If there is, you probably have a leak. Sixty some year old hoses are likely suspects. as are 60+ diaphragms.
Diaphragms can be checked with a small hand operated pump.

The wiper system is a separate system that gets it's vacuum from a separate fitting on the manifold through a steel line to the fuel and vacuum pump.
Then it goes to the wiper control, and then the wiper motor.

 

While you're trouble shooting, you might want to pick up a hand vacuum pump and a vacuum gauge to test components on the workbench and keep a fair few feet of correctly sized vacuum hoses around your garage.

Follow the CSM as advised above and if you can get some 1 way check valves to isolate system components that may be leaking/cracked or otherwise have bad seals, it'll help.

GM generally used very good quality rubber hoses in those days, but you can't really ask rubber components to last 70 years.

Chris

 

I would mention that after almost 70 years, it is likely the windshield wiper are no longer connected to the vacuum side of the fuel pump. Look to see if they are connected directly to manifold vacuum.

 

Update: As you all can imagine, the assessing of one condition leads to the discovery of a new one (I won't go into details at this time). Anyway, staying with engine vacuum, I blocked off the vacuum line to the washer pump and took a vacuum measurement as close to the carburetor as possible and that reading was 18/19 at idle and with a throttle snap, vacuum dropped below 5, jumped to about 23 and then went back to steady 18/19. If I place my hand over the throttle body, the engine idle smooths out a little, so I think there is a vacuum leak that I need to chase down. I am not sure about the proper tuning of the engine, but that will follow my leak detection efforts. To do so, I plan to work through vacuum pressure and vacuum pump readings on all the heat and vent damper lines (vacuum hoses). I'll report back with my findings.

• Yes, to the best of my knowledge the wiper motor is connected to the vacuum from the fuel pump, not the manifold. I do need to test the vacuum coming into the wiper motor. What should that reading be?
• I am still looking to know if there is a difference between the '57 shop manual and the 1957 Oldsmobile Chassis Service Manual (CSM)

Thanks, David

 

• The wiper motor should be getting 17 inches of vacuum.
• Different years used different terminology, they are one and the same.

 

I finally got around to checking the vacuum from the fuel pump to the wiper motor and it was 18/19, steady. I then checked the vacuum from just past that point that included a tee to a smaller line that went through the firewall - that reading was not steady and bounced between 10 and 15. I have not yet been able to track that line, but that will be one of my next steps.

Does anyone know if i can 'bench test' the heater control valve?

Thanks, David

 

All, some of my vacuum woes are starting to make sense. I check all the diaphragms and they are holding with at worst a very minor decrease (this could be my hand pump). One diaphragm was in the trunk when I bought the car and I found it's proper location seems to be the diaphragm that partially closes the air louvers on the right side - plus its vacuum line was attached to the threaded end of a bolt - go figure. So I need to reinstall that line and diaphragm, and connect it to the lever it's supposed to pull.

I also looked into the windshield washer. T the fluid line is connected to the vacuum from the carburetor. I tried pushing water and compressed air through it and could hear it under the cowl vent. My guess is this should be connected to the washer pump water line and a 2 prong junction at the firewall which appears not to be connected to lines that go to the nozzles. I think the nozzle lines can only be reached by removing the cowl vent. Can any of you confirm this? Also my hunch that the water line should not be teed to the engine vacuum line?

Any and all comments welcome, David