paul's right. the rubber in brake hoses is generally very tough but the worst case scenario is really, really bad so it's definitely one of those top priority jobs.
here are a few really rough brake hoses i found on a VW westfalia my wife and i bought several years ago. it wasn't until we had driven it home that i found these and thanked my lucky stars that we made the trip home safely.
i often find the nut on the steel lines are pretty corroded in place where they connect to these hoses. i've found the best way to remove the nuts without mangling the steel lines is to soak the ends of the steel lines in penetrating oil a day or two before doing the job. then i use a flare nut wrench or even some vice grips done up as tight as possible. the nut will give just a little bit at first and then i just keep working it back and forth until it is pretty free and able to be unthreaded from the hose easily. otherwise you can end up twisting and destroying the steel line too, and have to replace it as well as the hose.
I presume you are talking about the brake flex hoses like everyone else, they hold high pressure hydraulic fluid when you press on the brakes. it is normal for them to have small cracks on the outer cover, this is not so much a problem, most of the older cars I have owned have been like this. There is an inner hose liner and with woven fiber strands over it, that is under the outer cover, the cover protects the woven sheath. the inner liner and woven sheath are what hold the pressure, if you can see the woven sheath, or it is swollen or distorted (like in the picture above) than it is unsafe and should be replaced ASAP. but minor cracks on the outer sheath can last for over 100k miles, some people still replace the flex hose when they see cracks preemptively, but usually there is no emergency because of the hairline cracks on the outside.
I once had a GMC van that had flex hoses that looked fine, but they broke down internally and the shreds of the inner hose liner acted like a one way valve. If you applied the brakes the front right brake would stay engaged, I had to limp it to the shoulder, open the brake bleeder to relieve the pressure and release the brake, and than drive very carefully so I would not applied the brakes to get it home. It did not take long for some fool to cut in front of me and I had to apply the brakes hard. So I had to release the bleeder again, several times in fact. I made it to an autoparts store that had the hose in stock, I replaced it and bled the line and drove home normally. I have owned lots of old cars and trucks, it was only on the GM van that I ever had the brake flex hose break down like that.
The brakes can cause a vacuum leak however. There is that large vacuum line that goes from the intake manifold to the brake booster, if that leaks it could cause a vacuum leak (as would a ruptured booster diaphragm). That is a thick hose and usually small surface cracks are not an issue on it, it is easy to test; spray carb cleaner or raw propane gas at the area you think might be leaking, if the engine speed changes than you need a new brake booster vacuum hose.
Yeah, didn't appear to be serious. Just cracks on the surface.
And I was trying to figure out the best way to diagnose a vacuum leak, I'll spray on the hoses and see if I can pinpoint it.
I just recently replaced my TVSV valve with a brand new one and tuned the idle, fast speed idle and diaphragm according to the FSM and seemed ok. But occasionally when coming to a stop I can feel the idle bog down a bit. There's also still a little hesitation when accelerating occasionally. My clutch needs to be replaced though so it's tough to gauge what is being caused by the clutch and what is being caused by something else.
when i was tuning the carb i just rebuilt, i sprayed carb cleaner around the base confirm there were no vac leaks there. the base was fine but i found a leak where the throttle shaft enters the carb body. i think i've read on here that this is a common vac leak due to the parts simply wearing away with use. i don't think anything can be done about that particular leak, short of re-machining the carb body or replacing the throttle shaft with a slightly larger one...way too much work. i'd probably just buy a weber at that point.
regardless of the throttle shaft leak, i was able to get the carb running great so i'm not concerned about it. might something else to check though.
Still considering selling it at this point. I've put in so much work, its really annoying and frustrating when that issue happens. Might list it soon if there would be any interest.
the throttle shaft leak is common on older carbs, there are some carb shops that just bush this location as a routine, it does not cost much to have them do it (oversize drill and epoxy or press in the correct size bushing).
I also just set my idle a bit higher, it causes no issues.
If the idle speed drops down and nearly stalls when you come to a stop it might be the adjustment on the front side of the carb (opposite the throttle cable bell crank on the main shaft). It has a diaphragm that holds the throttle plate open for a few seconds to prevent it from slamming shut. it has a screw adjustment like the idle screw, just give that screw a turn it, should stop the dying out at idle.
I know the FSM says 800 but I think that's to low I prefer 900-1000
I'll bet 800 was good when they were new but now most are still plugging away after almost 30 years.
