1977 Fleetwood cruise

[Dan LeBlanc]

Does anyone know if a new cruise control vacuum bleed switch is still available new somewhere?  I've checked the usual suspects, and am coming up blank.

When I engage my cruise, the transmission downshifts and ac goes from vents to the floor. I noticed a hiss under the dash Saturday that went away when the cruise was turned off.

If I'm going to contort myself to get under there to replace the hose, I'm replacing the switch too. I only want to get up there once.

On a related note, when I turn on the switch, it takes about 5 seconds before the amber light comes on to indicate the system is ready to engage. Should it be instant or is the delay normal?

[Cape Cod Fleetwood]

I had a 75 and 76 SDV, amber cruise light went on immediately when flipped. FWIW.

\m/
Laurie

[TJ Hopland]

Does 77 still have the inline speedometer gearbox dodad?  That was about the time they switched to an electronic pickup in the speedometer head and an electronic control module.   I have had both styles and I don't recall a delay in the power light with either. 

Vacuum bleed switch?   The release on the brake pedal?   I have not ever had to work on one of those before.

[Dan LeBlanc]

TJ, yup, it's the electronic one and, yes, I'm referring to the brake pedal switch.

The car works beautifully until the cruise is switched on.  It will drop in speed slightly from the set speed, but I know I have a leak.  It takes 5 or so seconds before the transmission downshifts, and about a minute before the vents go to the floor.  The hiss is coming from that area.  Maybe I'll just have to take a look and see if the hose is broken or just plain disconnected.  System is undoubtedly dumping vacuum.  I just absolutely detest working in that area - legs up and over the back of the seat, trying to fit myself between the seat and steering wheel - it's plain just not fun.  Should've looked at it when I had the front seat out to replace the driver's side power relay, but I had totally forgotten about the cruise issue.

[TJ Hopland]

I have not had to look into those systems or even where the module is located.   I assume it doesn't have a vacuum connection/sensor in it but maybe it does?  And that is what is leaking?  Maybe that would explain the delay in the light too?  It would not seem like it would be that complex of a system but maybe it is?

Got any way to get the car up higher?   Maybe on ramps?  Sometimes that helps for working under the dash.  Puts you on your knees but sometimes that is easier than the other options. 

Curious to hear what you find.   If it is a problem with the switch and it comes apart take some photos.   I really have no idea what the design is or what it uses for seals. 

[6caddy2]

Hello Dan, I've been working on a 78, had same problem, upon many nights spent looking under dash, and following the vacuum hose, I discovered that the hose had cracked where it came through the firewall, and also at the point where it is pushed onto the bleed switch which you referred to, the one that is directly above the brake light switch,  where I also heard a hissing noise from as well, I have searched high and low for the switch with the same result as you, except for of course buying one used from a donor car?! So I removed it and blow it out with the stuff in the can that the wife uses for the computer key board, then reinstalled.                                                                                                                                                                                       
I replaced the vacuum line with one as close to factory as possible(NAPA), for this car, it has solved the problem, the light is about a second an a half to 2 seconds delay, but no tranny issues and the air stays in the AUTO position, BI-LEVEL position, and DEF position, when set to any of those position when cruise is turned on, I also replaced all vacuum lines leading to the cruise unit under the hood, I also pulled the cruise switch from dash and used some die-electric cleaner on the contact points and inside the harness itself.
                                                                                                                       I hope this helps you out?! Joe

[Dan LeBlanc]

Thanks Joe. The intent is to replace all the vacuum hoses anyway. I think the cruise vacuum leak is significant enough to affect the transmission (via the modulator valve) and the accessories. 

I bought 4 50ft rolls of vacuum hose of the 4 most common sizes on Ebay in a closeout sale. The hose for the level ride compressor snapped in two when I moved it. Replaced it and the car idles better and the pump runs faster. Haven't tackled the other ones yet as I ran out of wood to heat the garage and had a bad experience heating with the salamander a few weeks ago. Those puppies are dangerous.

[6caddy2]

Dan you are correct on the modulator value and the acces. that run off of vacuum!
Oh I know about the salamander heaters, bet you had a bad headache for awhile... And yes very dangerous even to those of us,who know about carbon monoxide, fumes, confined spaces, etc... Glad you,the caddy, and the garage are all good to go!
Can't wait to see the Fleetwood after a long winters tending under your care!
                                              Joe

[Dan LeBlanc]

Turns out it is the switch and not the hose. I put a hand vacuum pump on the switch and it bleeds down in less than 5 seconds.

I did find one for 71/72 NOS and after checking the parts books on GM Parts Wiki, it appears as if that switch was superceded by the 76-79 version, so I'm hoping it works. It appears as if the only difference is the newer switch has a barbed end for the hose connection that the earlier one does not.

Now to figure out how to get the old one out. I'm thinking it just pulls out. Someone correct me if I'm wrong.

PS. The hose holds vacuum. I plugged one end and it held.

[Dan LeBlanc]

I can't take any credit for this solution - that all goes to Mike Cascio.

So, in 2015, long before I got the car, the carburetor had been replaced.  In the process of doing so, they plumbed in the transmission modulator and cruise/climate control vacuum circuits incorrectly.

On the right rear of the intake, there is a vacuum fitting with two tees.  One is to go to the air cleaner for the Thermac valve and the other feeds the cruise and climate control.  The transmission modulator is supposed to be plumbed into a fitting on the back of the carburetor.

Mike had mentioned this to me a couple of times.  The line I thought was supposed to be for the modulator was for something else.  Had him on the phone last night and got into detail.  It turns out they had installed a tee in line with the cruise/climate control vacuum circuit and fed the transmission modulator valve off of it and left the vacuum port on the carburetor capped off.  Plumbed it in correctly and, well, everything works as designed.  On the flip side of the coin, everything on the vacuum side of the cruise has been replaced including NOS vacuum solenoids.  Probably needlessly so, but, at least everything is new.

I had noticed also that the transmission was very eager to downshift under light acceleration when speeding up.  Of course, seeing as how the transmission modulator was running off of a manifold vacuum source, slight drops in manifold vacuum resulted in an unnecessary downshift.  Running off a more stable vacuum source from the carburetor, the transmission is less eager to downshift as it should.

That was the last big bug to sort out on this car.  I should note that this car and the 70 both came from the same owner who rehabilitated them and mechanical work was done at the same shop.  Both cars had a litany of minor things that shop touched that needed to be corrected.

Two more things left to fix - inoperative trip odometer and a wind noise at the left rear door.

[Scot Minesinger]

Dan,

In referring to the end of your last entry on this post, where you wrote about a shop messing up everything they touched ...Welcome to America!  I don't know what it is here, but have not ever found a mechanical shop that does not screw up, mainly because they do not read or take the time that owners are willing to pay for!!??

[Dan LeBlanc]

What's sad is that the guy who has this work done usually drops the cars off with an unlimited budget and a blank check and says fix everything, from what I understand.  I bought this car from the guy he sold it to.  My former 70 I bought directly from him through the agent selling his car.  Spoke with him on the phone once after I picked up the car.  Nice guy, salt of the earth, but his mechanic shop is hosing him big time.  I'll kindly suggest if I ever meet him that he find a new shop and leave it at that. 

I did talk to the shop about some work they did that I had questions about on the a/c (it's working and cold), but didn't get a good feeling about the whole place from the guy I spoke to on the phone.  It should be fine, but I'm going to take that back to square one this winter so I know exactly what I've got (R12 and mineral oil).

I live in a rural area, we have a couple of small mechanics that are ok, but I wouldn't send them anything.  Found one real good guy, works out of his garage, did some work on the stepdaughter's car, and it was right.  If I have to send anything out, I'll likely send it to him. 

The daily driver VW's - that's another story.  They go to VW and VW only as you really need to think in German engineering terms to work on them.

[gkhashem]

Dan what is going on with the odometer?

Reading  off or not working?

The reason I ask is my 1978 is off some.

Also routing vacuum lines takes some patience, common sense and a diagram in the shop manual.

Even I have fixed vacuum lines with some patience. Some of these garages do not have the time to spend on such trivial details.

I diagnosed and correct the heating system on my 1959 Olds 98 and it is all vacuum operated and it actually worked when I got done. So a master mechanic is not needed all the time.

Good work and satisfying when done!

[Dan LeBlanc]

Trip odometer does not work at all.  I found a cluster on eBay that is at my Maine address at the moment for $20.  I'll either harvest parts out of it or swap it out completely if it's cosmetically ok and fully functional.  The odometer reading is within a couple hundred miles of what I'm at now, so, I'm holding off driving until it's swapped.

The trip odometers are known to be inaccurate in these cars and indexing of the numbers is almost always an issue.

The main odometer in my car is fine.  But seeing that trip odometer not moving is driving me nuts.

[gkhashem]

Dan

Can you explain what you mean by indexing of the numbers?

[Eric DeVirgilis CLC# 8621]

Dan

Can you explain what you mean by indexing of the numbers?

I think he means the numerals often don't align well on the trip odometer.

[Dan LeBlanc]

Eric is correct.  That's what I meant.