LUVTruck.com

Howdy folks,

Got a couple of questions that I hope you wise souls can answer. I am the proud owner of a 1980 Luv with 2WD, automatic trans., and the stock 1.8L.

A few months ago while driving to the beach, my brakes started to squeak horribly. An hour later I heard a loud snap upon pressing the break pedal and the pedal went to the floor. Since then the rear wheel can be turned by hand with the brakes fully pressed (on jack stands). Adding fluid to the brake fluid reservoir closest to the firewall (I assume this is for the rear) it seems to help, but the fluid leaked out within a few pumps of the pedal.

I removed the master cylinder from the brake booster and tons of gook and brake fluid poured out. After that I started the engine and removed the vacuum house. I held my finger over the end of the house to keep the engine idling and watched brake fluid being spit out of the booster every time the engine is revved.

Now for the questions…

1. I assume there is some sort of leek in my master cylinder. Should it be replaced?
2. Since the brake booster is full of gunk, is it safe to assume it is done for? Should it be replaced or can it be rebuilt? How can I tell which option is best.
3. For some reason my trans. Never shifts out of third. This causes the engine to rev high during highway travel and allows the engine to run hot…bad news. Is it possible I have brake fluid in my vacuum system and subsequently not enough suction to shift out of third gear? How else could I diagnose the tranny if this is not the case?

Any insight would be greatly appreciated.

Thanks,
-AJ

my first question would be.. is it brake fluid in the booster or tranny fluid? If it's for sure brake fluid, I'd say your master cylinder and booster should be rebuilt or replaced.

To check your tranny shifts, unhook the vacuum modulator and cap it off, then manually shift through the gears and make sure you have them all, if you do, use a vacuum pump and apply manifold vacuum to the modulator and see if it shifts on it's own.

Just a few starter ideas and I'm sure others will pipe in with some helpful ideas too...

First the booster. Is the fluid coming out of the vac line from the intake to the booster or just out of the front where the master cylinder bolts up? If the seals blew in the master cylinder (what I suspect) it would leak fluid into the outside of the booster, not past the diaphragm and into the motor through the hose to the intake. If it is just full of fluid from the leaking master it would kind of puke out the front when you rev the motor up and down with the line hooked up. Its probably not good, but if its not leaking through then its not that bad.

The booster costs a fair bit to buy a rebuilt, so I'd go to some lengths to avoid that. To rebuild it takes special tools and parts I don't think are commonly available. The master cylinder, that is fairly cheap and you need one.

On the auto trans, what do you mean by not shifting out of third? Does it never downshift, start out in third, or just not kickdown when you step on it to pass? Its not like its going into 4th.

Roadshow Bob: I have no clue how to differentiate between tranny fluid and brake fluid. It is darker in color than either one. I assume this is from sitting in the dirty booster.

To diagnose the tranny I assume you mean to put the rear end up on jacks and accelerate the engine to see if it shifts (after capping off the vacuum line)?

What do you mean by “vacuum pump and apply manifold vacuum to the modulator”? I’m a little fuzzy on the details.

800xl: Fluid is coming out of the part where the vacuum line attaches to the brake booster but only seemed to squirt out when the engine is revved.

Also there is a ton of funky gelatinous gook where the master cylinder bolts up to the booster. The brake booster doesn’t vomit fluid upon revving where the master cylinder bolts up. It just kind of sits there arbitrarily oozing about.

By not shifting out of third I mean that from a stop it shifts from 1st to 2nd to 3rd fine, but it never shifts into 4th, it just revs high in third and never reached speeds higher than 50 MPH without sounding like it is about to have an aneurism.

1. Your stock tranny should be a 3 speed not a four speed.

2. To tell the difference, open the master cylinder cap and smell the fluid in there and compare the smell to the fluid you have leaking.

3. What I meant by use a vacuum pump is to beg, borrow or buy a little hand vacuum pump and use it to aplly a low amount of vacuum to wher eyour vacuum line hook to the transmission to see if it will shift with vacuum.

4. 800xl will get you headed in the right direction.. he's the man on these little trucks....

The difference between ATF and brake fluid is atf looks like power steering fluid (red-ish) and brake fluid is a very light brown.

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Currently no more luv's... But in search of one!

The difference between ATF and brake fluid is atf looks like power steering fluid (red-ish) and brake fluid is a very light brown.

_________________
Currently no more luv's... But in search of one!

sorry about the double post, my computer is being a bastard.

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Currently no more luv's... But in search of one!

technology sux....

Bob is right, its a 3 spd automatic, so its never going to shift into 4th. I'm not up much on the auto tranny stuff, but I'd guess it is slipping, like it is either needing fluid or something wrong with it. I don't think the two problems are connected. I cannot see how ATF could ever get anywhere near the brake booster unless someone poured something in the wrong place. Check the fluid level in the trans and add some if needed. If that doesn't get it, take it to a transmission shop and let them diagnose it. Should not cost you anything to have them give you an estimate.


If I understand you correctly, you get fluid out of the vac hose or the port on the booster that it hooks to. If that is the case, then you are probably right that you need to replace the booster. No fluid should ever make it into that part of the booster. You could take it off the firewall and clean the gunk out of it, but if brake fluid can get into the engine through that hose, then air will leak there even with a new master cylinder on. Must be that all that brake fluid and gunk has just killed the booster seal.

What I don't really understand, is how revving the motor makes any difference. You'd only see fluid if you have the rubber vac line unhooked, and then there would be no reason for the booster to do anything different with the motor rev'd up or not. I guess vibration is make some of the gunk inside of the booster spit out the hole.


Ok, one last thing to consider is that you might also have a leak in the wheel cylinders. The master cylinder can fail on only one part, front or rear, but you might have a leak somewhere in the rear brakes that made the problem show up. Look for signs of wet around the brake drums and where the brake line hooks up at the end.

Thanks for all the help gentlemen. You have helped me out a great deal. I think the vibration is the reason for gook spillage. I also do not think that there is a leak in my wheel cylinder, I checked everywere and could'nt find a leak. Should the stock 3 speed tranny be capable of running faster than 50 MPH without straining the engine?

I am in the proccess of making a new post with some other questions.

Thanks,
-AJ

yes, I had my 76 auto up to @90.
BTW I pulled a drum off a back wheel off a luv I had and was a pretty severe leak inside, I had no idea it was even there...

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Resident lurker

its probly not geting out off 2nd then

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If you cant find it grind it

79 4x4 1.8 liter
75 K 10 Lifted with 383 stroker
69 Jeepster comando v6

I've had about the same experience, pulled a drum and found fluid all over inside without much sign at all on the outside. So, a wheel cylinder leaking can hide pretty well, but it sounds like most all your fluid is leaking out the master and into the booster. You do need a master cylinder for sure, and the booster sounds suspect. Fluid should not be able to get through the booster to come out the vac port. I've never had a booster go out on me (knock on wood) so you should have good luck getting one from a junkyard if you can find a LUV to pull it from. http://www.rockauto.com lists them rebuilt I believe, but they are upwards of $200 if I recall.

The tranny sounds like it isn't working right either. I've never run a stock motor auto trans LUV, but 50MPH should not be your top speed. diarmadhim's testimonial should tell you that. The motor will rev up there (especially at 90 ) so if you have loud exhaust and/or other motor noises it might sound like it is coming apart, but 50 shouldn't sound that bad. I'm no auto trans expert, so I'd probably head to a tranny shop and ask them to give me an estimate or whatever they'd do for free/super cheap. Make sure it has enough fluid in it though. Just being a little low they can slip, shift funny, not go into reverse, or all sorts of goofy stuff.

Chavy has a point too, if you don't feel two distinct shifts it might be stuck in 1st and 2nd, never hitting 3rd. That would get pretty high in the RPMs at 50MPH.