I went to Midas today to have my exhaust leak fixed. The sound of the valves ticking is just about driving me mad. The leak is on the passenger side, right where the manifold bolts to the head. They wanted $380 to fix it. I had to say no. I just can't afford that much so I'll have to live with the ticking valves. Hope this doesn't cause any damage.

While they had the car on the lift, they noticed the master cylinder is leaking at the rear seal where it goes into the booster. I think I can change the master cylinder myself. NAPA sells a reman master cylinder for about 25 bucks. Anyone have any experience with these or should I go for the new one for $80?

What are my odds that the booster has not been damaged? I bought the car last spring so who knows how long its been leaking.

 

Make sure the "leak" is not just over-fill dribbling down the side of the M/C.

There should be a boot/seal where the rod comes out of the booster and into the M/C. This will normally keep the fluid out of the booster. You can pop it out and stick your finger inside to check.

1st choice for me: rebuild the current M/C if it's not pitted.
2nd choice: install a new one
3rd choice: try a rebuilt (bore is already worn down.... maybe excessively)

With a new or rebuilt, you still should disassemble the M/C before you install it and check for rust. They are bad right off the shelf many times.

 

First of all that is not your valves ticking, it is a exhaust leak that you hear. That sounds like alot of money ($380) to repair it. Did they say that the exhaust manifold was cracked or just that a gasket needs replacing?
As far as your master cylinder is concerned is it defective or is it just the gasket leaking on the top lid of the master cylinder? If the master cylinder was defective your pedal would be going down to the floor when trying to stop your car. Is this happening? If not your master cylinder may be ok and you could replace the upper gasket. Now if the leak is coming from where the pedal push rod goes into the back of the master cylinder you should notice your brakes not working right and the pedal going to the floor because this is a leak in the system. Usually this happens when the master cylinder is going bad. If this is the case you could purchase a rebuilt master cylinder or a new master cylinder. I have used both in the past but most Vette owners would rather have a new one. Your odds are very good that you didn't cause damage to your power booster. You may want to clean that area up where the booster joins the mast cylinder if you end up replacing the master cylinder with a rag and maybe a little brake cleaner. Have you ever replaced a master cylinder before? If not don't forget they need to be bench bled in a vise before mounting it and hooking up the brake lines. Once this is done you sometimes can get away with having a helper just push down on the brake pedal while you open one of the side fittings to bleed the air out of the lines. You will have to do this twice, once for each brake line. If you have a good pedal after that you are good to go. If not you will need to bleed all four calipers to get a good pedal and sometimes that could be a real pain on these cars doing it manually.

 

Thanks for the reply

yup, thats the first thing I checked. Was hoping, but the fluid is coming from underneath where the MC bolts to the booster.

Ok, so there is still hope for the booster. Thats a good thing and I will check it when I pull off the MC. Maybe I will go for the rebuilt kit, but its actually more ($32) than the reman MC. But I'd rather keep the original anyway.

If I do rebuild it, will I need to hone it? I've rebuilt wheel cylinders before - Is it much harder rebuilding the MC?

 

Ahh, I see. I was under the impression it was the valves I was hearing. Thanks for clearing that up. No cracks, just a gasket. I think it came from the factory without gaskets in 1980. But they were going to put a gasket in (some type of metal, but not copper).

The brakes feel fine as they always have. I can't see any fluid coming out of the lid, but its wet with fluid underneath the MC. I had just filled the MC the other day and was very careful not to spill any.

 

Yup.... many times the rebuild kit does cost more then a rebuilt unit.
Go figure.

Some master cylinders are unique (or sort of unique)... like the one with built in bleeders as on my 70. I would never trade that one in as a core.... get it sleeved instead.

RE: Honing... yes... you can hone it. But you can't "over-hone" it or it will fail again soon. If the damage is only mild pitting/rust and worn out seals, then a re-hone will probably work fine. If there are pits, and the pits are deep, then it won't work.

Get a 3 stone hone (not a 2 stone hone), fine grit, or a flex hone. I finish up with extra fine steel wool wrapped around a 3 stone set for the final finish. Edit: I prefer the stones over the flex hones for situations dealing with rust.... the stones are more aggressive and help maintain the concentricity of the bore. The flex hones "go with the flow".

I use WD40 as a "honing oil" and then finish up with brakleen.
There are no contamination issues with the WD40 as long as you finish up with a strong solvent such as acetone, lacquer thinner (contains acetone) or brakleen.

I was in business with a 7 bay facility and machine shop until 1996... this is what I did for a living.

 

It seems like by the time I finish with the cost of the rebuild kit, the hone and the solvents that I might as well buy a new unit.

 

That's great! Ya know, the weather is real nice and perfect for a nice cruise in the vette to NY...and while you're up this way stop by and rebuild my MC

 

Yah.... I moved here to get away from the beautiful weather up there... LOL.

Was born & raised in Syracuse NY... land of the never rising sun... was on the gymnastic team with Dick Geere.... he wasn't "Richard" back then... just Dick).

 

heh, we get 2 really nice months a year - what more could you want?

Sometimes, the name fits.

 

The rebuild kit costs a bit more, but in my case I wanted to keep the proper date code master. The re build was quite easy. It took abou tan hour for removal, bebuild and reinstall. Has worked perfect ever since.

 

If you have the time, the leaky exhaust manifold is all labor. If you can do the M/C, you can do that job also.

 

I just did this Sunday, Mine was leaking from the same spot. I opted for a new master cylinder since I have heard that rebuilt are a 50/50 chance and saving $50 and risking not stopping the car does not make sense. Anyway, I bench bled, cleaned the bosster and bolted the new one on and no more leaks!

 

I definitely agree with you. Stopping the car is the most important thing. Glad you got yours working good.

 

Keep the original MC and just bite the bullet on the core charge. OTH, rebuilding a MC is a one hour job and gives you the satisfaction of knowing you did it. That way you get a new MC and keep the car original.

Gary

 

I wish I shared your confidence in me but those bolts are really rusty and I can almost guarantee at least one will snap off. I think I'm going to just wait and maybe someday I'll have money for headers which will cost about $1200 with installation.

 

I think thats what I'm going to do - go new and keep the old.