Gang,
40 years ago, I added factory vacuum power door locks to my '66 2 door 98 convertible.

The Olds/GM system It was/is a Trico-manufactured option system which all the "Big 3" used in one form or another. Later I added these accessories to my '66 Starfire too. It's wild, but my Starfire holds vacuum for >24 hours after engine shutdown. So I know this system can be made to really perform well. Problem is, my 98 doesn't perform that well on this admittedly trivial item. I'd like to bring the 98 up to the same performance level as the Starfire.

Not long ago I picked up restored vacuum actuators for my 2 doors. I can replace the actuators easily enough.

All my vacuum accessories on the 98 - power trunk lock, power door locks, even the heater/vent system don't hold vacuum much after engine shutdown. The heater is not a problem, who needs heat when the engine is off? But, the trunk release and door locks are a different story. Usually I stash stuff in the trunk after I've shut the engine off. Usually I lock the doors after the engine is off too. So, across these remote operation features, I'd like the vacuum accessory system to hold vacuum well after engine shutdown.

You can guess I'm interested in going through all these accessory systems and replacing the flexible hoses. But the question is do I use latter day thinner rubber vacuum hoses, or jump to modern same-size silicone/vinyl hoses which didn't exist when these system were built?

Back in the '60's, Trico/GM used extra thick-walled rubber vacuum hoses in 5/32" and 7/32" sizes for these systems. Latter day rubber vacuum hoses are not as thick-walled, so I'm worried they won't work as well as the old stuff. Like maybe they'll collapse under vacuum load during actuation.

60 years later, the most common way the original vacuum system hoses fail is in the driver's door-to-body gap. Over time the hoses crack from bending open & closed every time the driver's door, and 2ndarily the passenger door gets opened & closed.

Would you all send me your views on vinyl/silicone/rubber hoses in 5/32"'s and 7/32"'s sizes? I'd like to do the job once with the best stuff and never worry again, but I don't know which are the best parts. I can get yards of any of these hoses, but the question is which one to bet on for function and durability.

Just for fun / future reference, here's my diagram of the system. Hose lengths and sizes are my estimates, not factory. I figure I'll need 20' - 30' feet of hoses so I'd like to get the best stuff...
65-66 Oldsmobile 88/98/Starfire vacuum power door lock system. Logic and color should apply to GM cars of the same vintage since the system was built by Trico.

Looking forward to your views.

 

I wouldn't use modern silicon/vinyl hoses. Use the modern rubber vacuum hose.

I've had modern rubber vacuum hose in the engine bay of my 71 98 for at least 10 years. I replaced the vacuum advance and transmission kick down hoses when I first bought the car and did a tune up. They still work great.

Come to think of it the power trunk and door locks on my 71 98 still work with the engine off. I guess I'm just lucky, I never thought about those vacuum hoses before. 🤔

 

If the system works but does not hold vacuum after shut-off, don't bother replacing the door actuators, as they do not get vacuum until the switch activates the vacuum relay (remote valve). Focus on finding leaks in the supply side of the switches, remote valve, and vacuum tank. With vacuum applied, try using a stethoscope to listen for leaks around the door switches and remote valve. The remote valve leaked really bad on my Toronado when I got it. I got it much better, but it still holds less than an hour after the car is shut off.

 

Gang,
Some of you know I switch back & forth between my '66 Starfire & '66 98 convertible. More or less Summer/Winter, but you'll also know it's a good idea to run the cars in the off season to keep the seals fresh when the car is generally not in regular use. This week that's what I was doing with the 98 convertible. So I got it out of storage with a fried battery, replaced that and did a few trips.

Back in the 80's I got a power door lock system for my 98 from the boneyard for maybe $30.00. It worked well, used for 40 years, until the past year or 2 when the whole system just didn't work after the car shut down. So I had large vacuum leak. The typical culprit here is cracked/broken hoses inside the driver's door rubber boot, or cracked/split/fallen off vacuum hoses at one nipple or another. Secondary culprits can be the passenger door, but that's really rare since passenger doors get a tiny fraction of the open/close use of the driver's door.

Why the problem occurs is really easy: every time you get in/out of the car using the driver's door, the rubber vacuum hoses inside the door conduit bend. So after 60 years of this, they can crack or break. In my case, they finally broke. All I had to do was remove the driver's side kick panel and give a tug, 3 of 5 lines pulled free instantly since they were already broken.

So o.k., I found the problem, now on to the fix. To get at the system, you must first remove both passenger side and drivers side door panels, any waterproofing and both kick panels. I went at this aiming at a complete fix, not piecemeal, so I did both sides in the name of future maintenance and not having to remember which side I'd fixed...

All you need to repair broken hoses is 5/32" windshield wiper hose and 3/32" windshield wiper hose. But you need a _lot_ of hose. In my car I used 96" of 5/32"'s for each actuator hose (1 unlock + 1 lock), plus another 60" of 5/32"'s for the vacuum power to the switch, plus another 3/32" x 60" x2 for the lock & unlock switch lines. That's a lot of rubber hose. Since I have 2 such cars with this option, I just got a roll of 5/32" and a roll of 3/32" so I can repair them as needed. The reason for these long lengths is mostly to keep them out of the way of windows that go up & down and to allow enough length for a loose but out-of-the way hose routing to minimize stretch stress on the hose. My doors are 4' long or so, plus I needed 16" of vertical hose in the front of the door plus the back of the door. So, tons of hoses... Plus you want a few extra inches per hose so that when the hoses stretch/crack on the pot metal nipple, you can snip .5" or so every few few years & keep the seal tight.

For 40 years or so, I remembered struggling with the very thick GM-original rubber hoses from 1966. They were hard to put in place in my 20's -- pulling them up behind the dash, across the car, etc. They were also very hard to pull through the door conduits. The good news is new hoses are thinner and pull easier and this time I sprayed the lines with silicone lubricant to get them to pull easier. I also used a fiberglass fish tape which made easy work of replacing the lines. With grease, decent labels on each line, and a fish tape, I think I had maybe an hour or so in to line pulling itself. Not bad at all! Modern hoses don't have the stripes GM used, so you have to labeled each line on each end to know which line you're dealing with. Very much like labeling speaker cable - left, right, center, etc. I use a Rhino 6000+ to do this with its "Cable Wrap" settings to recreate the colors and purpose for each line.

So thus far we have 5 lines per door: Unlock Actuator (5/32" Orange), Lock Actuator (5/32" Yellow), Switch Vacuum Supply (5/32" Red), Switch Lock (3/32" Green), Switch Unlock (3/32" White). There are 5 other parts: the "Remote Valve" (aka main valve behind the glove box), a right hand actuator at the passenger side latch, a left hand actuator at the driver side latch and 2 switches.

My actuators and remote valve worked fine. But after 60 years, my door switches were leaking. I'll post more later on that, but the short version is I had to regasket (aka custom cut rubber) the Trico power door lock switches. This is time consuming. The switches are a 4 layer sandwich of pot metal and rubber gaskets. The tough part is making new gaskets that work and seal (aka don't leak down). I got there, but I'll skip that here. The highlights are each gasket needs 4 x 1/8" holes at the corners to allow the securing screw to torque down and establish a seal. The middle gasket needs a further 2 x1/4" hole for the lock/unlock functions, plus a 1/8 - 3/16" hole in the middle for vacuum supply. As I said more on that later when I can provide pictures. What worked best was a set of punches and hogging the 1/8" holes (only - not the 1/4" holes) out with a Dremel to clean up the edges.

The big deal for this post is simply, if your vacuum accessories don't work well after engine shutdown, you have a leak. Fixing that needs some tracing, but today's hoses can be greased with silicone spray for easy pulling, labeled with Rhino labeler (or h*ll just blue tape & a sharpie). As of this afternoon I can get 4 or more up/down cycles from my power door locks after shut down and I can rely on the system now. Nice.

More to follow on these arcane systems. With luck, I'll photograph and post details on how to remake the gaskets in a few days.

Cheers
Chris

 

Just a codicil -- I didn't pull and replace all the hoses. I left those behind the dash alone. I added union joints to the new door hoses at their entry to the vehicle behind the kick panels. Yeah, I have to live with joints that might leak, but the whole system will be more serviceable. And anyway Trico/GM design joints in on the passenger side anyway.

In my case all the lines going into the doors are new, the lines going from the kick panels to the remote valve are original. I may go after those remaining original lines one day, but Advil says today is not that day. I may have a leak at the remote valve, but it's inahard to hear with the engine running.

Chris

 

Very nice write-up Chris.

That's not in the service manual by any means