Hi all

I took my 90 out for a drive to try and get the battery charged up but it seems it is not taking a charge! so looks like new battery there!
anyway
while braking i noticed a sort of air noise(escaping), Could this be the booster?
I have been disappointed with the brakes since i bought it 6 months ago, but just thought it was how they were! but now thinking it could be the booster! the pedal had 1/3 travel before it starts to brake and the force needed is harder than it should be and doesn't stop very quickly unless really pushing the pedal.
The ABS needs servicing too, but this shouldn't effect the normal brakes operation, right?
thanks

 

It definitely can be a booster. A quick check is to turn the engine off and wait a moment or two. Then press the brake pedal and see if it feels normal. It should hold vacuum for definitely a few minutes. You should be able to get 3 pumps out of it before it gets hard. As you hit the pedal the first 3 times you should hear the whoosh of the booster. If it is hard from the first pump the booster is probably bad. If you can hear a vacuum leak while holding the pedal down, then that sounds like a bad booster. Not a bad idea to look at the check valve on the booster but they hardly ever go bad.

What do you mean be ABS need servicing. Under normal circumstances they don’t need routine servicing. If you don’t think its working at all then it need repair. Why do you think it is bad, what are the symptoms. And also, if the brakes are not working right, you will never get the ABS the kick in on a road (maybe dirt or gravel).

 

The short answer:
1. A hissing while braking or a hard brake = you need a new brake booster.
2. Taking a drive to charge up the battery? Thats a good way to burn out an alternator. Use a battery charger or a trickle charger, its a better way to go.

 

The hissing sound if you could call it hissing(doesn't sound like air escaping from a valve or anything)! It's hard to explain but it is a noise only while braking! More like fluid passing through the lines(under pressure) but magnified!

We have a service in Perth that come out to you when in need of a jump start or what have you! and every other time i have had my engine(other cars) jump started they say go for a 30 min drive to charge it up! i don't see how it could burn the alternator out, it's not working any harder than normal! That's what the alternator is for, to keep the battery charged? right!

Anyway thanks for the response!

 

Okay thanks i will try the brake pedal with the engine off!

The ABS service soon light comes on as soon as i start it up and stays on!
Also i have locked up the left rear while testing for the ABS!
the brakes work but need a harder pedal force to brake like they should with less effort! i had to really press the brakes full on to get it to lock!

I have a 98 Holden Commodore which of course will have better brakes anyway(newer car) but it also has twin piston brakes etc...
and they only need a touch of the pedal before they bite!
thanks

 

Don’t have much 90s specific knowledge. On the later cars there is a sensor for fluid level in master. Make sure its full to line. Not sure if the 90 has codes for ABS. Need to find out per FSM what turns the light on so you know what areas to check.

 

Your battery problem could be your alternator - have it checked.

Brakes - sounds like a booster to me. When you replace it do a FULL brake system flush.
Check the abs sensors to make sure they are all in place and not covered with road junk.
I think on the 90 you can hear the abs pump either on startup or as you approach 5mph. The FSM will have the details.

 

I know we all are not rich & the economy sucks but,it would not be a bad idea to replace your booster & master cylinder at same time as well as a complete brake system flush.Remember your car is 20 years old & quoting another member-"it is not a bad idea to throw money & new parts at your brake system,because it is the most important thing on your car".If you want to go the cheap route,then I would recommend checking for vacuum leaks with car running with carb. cleaner.Also check vacuum check valve on booster.Check for brake fluid leaks.Check condition of brake fluid & change fluid if dirty or if not knowing was replaced last.Or you may have vacuum leaks under/behind dash.ABS light being on will mean ABS function will not work but brakes "should" work properly-some exceptions to this.Its a corvette,who likes driving around with a warning light on(it would drive me nuts!)?If you do not have alot of money, have it diagosed somewhere & fix the problem in the spring or when you have the money.

 

I have topped up the brake fluid as it was lowish, but the same!
I need a FSM they can be bought on ebay right?

Do booster's commonly go on these c4's?
With the ABS i looked at the left rear brakes once, but weren't too sure where the abs connection was, i saw two parts it could have been! is it the part closest to the disc? with the wire?
The only noise i hear is the fuel pump priming and then the v8 roar! probably not the ABS as it isn't working!

Yes i agree parts that concern safety should be replaced, but i bought this c4 thinking that it was in good condition, but having to fix the heater core, the under seat transmission, flushing the radiator and new coolant/water, new battery, spark plugs, hood release cable, i just haven't the money just yet! but it will be next on the list!

I am in Perth W.A. so it doesn't get stored anytime of the year!
i also have smelt some oil burning after idling for awhile! is this the intake manifold gasket? or most likely?

 

runner140* is right. Although the alternator does charge the battery it is more like a battery maintainer. It's not designed to charge a dead or very weak battery. It circuitry will get hot and bye,bye alternator.

 

it's only once in a while, constant, no.

 

Welcome to older/c4 corvette ownership.They will drain your wallet but,look on the bright side-you own a nice corvette.My suggestion if you don't have alot of money & your car is due for an oil change,bring the car to a known repair shop & have them do an oil change & pull your ABS codes.At my shop when doing oil changes we try & find as many problems as we can because we don't make money on oil changes.Or if car is not due for oil change bring it there & ask them if they can see any leaks(oil or coolant).You should be able to negociate a low price for oil leak inspection & pull codes.At my shop I would charge $45.00.Getting the ABS code may point you in that direction-example:code 55 right front ABS circuit fault,you would be almost certain that it is either a right front wheel bearing or right front sensor wire.I hate giving bad news but an oil leak can cause other problems as well(fire hazard,if oil gets on rubber components-it can damage rubber-i.e motor mounts,control arm bushings etc. & become more work & money depending on how bad & long oil has been leaking).
If no leaks(oil) are found, it may be burning oil.Burning oil overtime will damage catalytic converters & spark plugs.I hope this helps

 

Hey all, ok so i have learnt something new about alternators! thanks to runner140 and Weav's vet for backing him up!

As i live in Western Australia there is only a couple of shops that work with American cars! I will probably have to see them about my ABS and would have the tech to gets codes!, although most reputable shops should be able to handle any ABS systems! they would be very similar to our cars i would think!..... but i will see!
Apparently the air con system( which needs gas) is very similar to our VN commodore 89-93 model, so it seems the similar years use pretty much the same setups! From your GM to our GMH dealerships!
anyway back on topic!

yes i do need to get those codes! i might try it myself, the paper clip method!
with the ABS connection, how do i get the wire off? does it unscrew or is a wrench needed? thanks

oh i tested the brake pedal(engine off) after running the car, and it only takes 1 and a bit pushes until it is hard! so i am guessing a leak somewhere! i can hear the noise coming from under the dash near brake pedal-to-booster!

 

the vacuum reserve tank and not the 'booster?

It's the round plastic 'ball' in the front left corner of the engine bay (on my '91).

It's supposed to 'hold' vacuum when the engine is not running for things like the HVAC etc. not sure if it's connected to the power brake booster or not...just a thought...

 

Sort of like "if you keep doing that, you'll go blind"......"can I do it till I need glasses" ?

 

I changed out my alternator on my 86 for a 93 LT-1 alternator. It steps up the output from 105 amps to 125 amps, and allows more low speed charging while you are at a stop.
The low speed charging capability s more important than the maximum amps anyway.
To change out the alternator, you have to file out the top bracket and ream out the battery lead that fits on the back of the alternator.

 

never thought of it quite that way, but yeah!

 

Well i checked the vacuum reserve tank, but couldn't see any lines going to the booster!, doesn't mean there isn't any, i just couldn't see them

but i did find that the line going to the cruise control was so deteriorated, the hose was flat. so that needs replacing

 

doesn't have a direct connection to the power brake booster, not on my '91 anyway, it has some small vacuum hoses going to a tee which then go the HVAC and cruise controls.

Well you found some old hoses so it wasn't a complete waste of time LOL

 

Yeah it is good to go over the whole engine bay(especially when i am new this car) you find all sorts of things! lol

I saw that t-piece that connects to the vacuum tank!
What is a HVAC?
Thanks!