K87ZZ4

This is kind of an intermittent problem... about half the time that I set the cruise on my 87, it works fine (takes control in a second, or so), the other half of the time it takes about 15-20 seconds before it kicks in. To the point that I get surprised, if I've slowed down a bit, when it finally kicks in and 'resumes'!

Any experience with this problem? Is this common? Any idea what might be causing it?

xrav22

Well I would check vacume ball and lines from d front to fittings all the way to manifold and brake pedal sounds like an air leak.

K87ZZ4

i checked the vacuum hoses and they all *look* fine (no obvious problems, though they ARE over 25 years old).

I checked the vacuum of the 3 lines at the T under the master cylinder. I put about 20-25 in of vacuum on each line and monitored for about 30 seconds.

The line to the servo held steady.
The line to the vacuum storage tank/ball held steady.
The line to the engine manifold dropped by 2 in. (this might be expected with the engine off?)

antfarmer2

Does this one have a line to the brake pedal?

K87ZZ4

Yes, it does.

antfarmer2

On my 94 that hose was like a dead night crawler by the firewall. I taped a wire in it from the inside and pulled it threw then used the wire to pull the new hose back Lubed up the hose both ways. I cut the hose on a long angle to tape the new hose on.

K87ZZ4

Even though I could only get one finger on it, because it's so hard to reach, it didn't seem in that bad of shape. Is there a way to test that hose (and the brake switch) to see if there's a problem there?

xrav22

You may need to remove the battery to check it out, but I just replaced all my hosed one by one because of the age and my cruise started working to my amazement and is still working, good luck

antfarmer2

On my 94 I pulled the battery the seat and the dash pad. If I ever do it again I can do it in ten min. Just reach up under the dash and cut the hose. And do as I posted before. Then just put a connector one the new hose to the old one.

K87ZZ4

UPDATE: the cruise finally quit working entirely. I had it into the shop recently for some engine work where they were messing with vacuum lines, so I thought something might have been left disconnected. This time, as I traced the vacuum line up toward the back of the engine, I found a hole (the hose had gotten too close to the exhaust manifold and melted!).

I replaced the vacuum hose, but couldn't get to the connection well enough, at the back of the engine, without removing the distributor cap. That was more hassle than I was hoping for, but not terribly difficult (just tedious and time-consuming working in a tight space).

I haven't had a chance to test it yet, at speed, but I'm going on faith that this fixed the problem.

K87ZZ4

The cruise control works great again! I've tested it a few times on the highway and there's no longer a delay in it engaging. Replacing the vacuum line up toward the back of the engine did the trick.

xrav22