Brake fluid went up...

[adallak]

I have made a 600 miles trip with no problems associated with cat converter. Got a 80/65 ticket from NY trooper though... Arghhh!!! Today, I have noticed the brake fluid went all the way UP (by about 1/2" from its level) in the master cylinder reservoir. It was steady for some 2,000 miles. What could cause such a strange change? Air in the system? Did not do anything to the brakes for many months...

[tysona23]

Usually, people will notice there brake fluid went up after changing the brakes. If you have not touched the brakes that is very strange. How old is your fluid? Could it be contaminated? Does anybody else drive your car that could have added some fluid? If there is any air in your lines your pedal would be extra spongy.

[adallak]

Usually, people will notice there brake fluid went up after changing the brakes. If you have not touched the brakes that is very strange. How old is your fluid? Could it be contaminated? Does anybody else drive your car that could have added some fluid? If there is any air in your lines your pedal would be extra spongy.

Did complete brake work a year ago, old fluid was flushed and the system was bled. Nobody touches or drives my car besides me. I did not notice any change in the braking power or pedal feel. As I said, the level was stable for many months and thousands of miles until the recent 600 mile trip.

[rockfangd]

that is totally weird. it reminds me of my 96 Deville. I have had it almost 3 years and check my transmision fluid about every 6 months. Have never had to add any but yet last time I checked the fluid it was mysteriously over by one quart exactly. I was stunned. I had to use a baster to pull the fluid out. I am still baffled.

Nobody touches my Deville at all but me.

Long shot but have you gotten your oil changed or tires installed?

[Ranger]

I could not even begin to guess at an explanation.

[JohnnyG]

The only thing I can come up with on the brake fluid is that a rear brake adjuster may have started working. Maybe you started using the parking brake more, which might enable the adjuster mechanism. But that's a huge gain in fluid.

that is totally weird. it reminds me of my 96 Deville. I have had it almost 3 years and check my transmision fluid about every 6 months. Have never had to add any but yet last time I checked the fluid it was mysteriously over by one quart exactly. I was stunned. I had to use a baster to pull the fluid out. I am still baffled.

This could be serious. I've had the transmission oil cooler, located inside the radiator, start leaking and cause antifreez to get into the transmission. Serious trans damage resulted.

[adallak]

The only thing I can come up with on the brake fluid is that a rear brake adjuster may have started working. Maybe you started using the parking brake more, which might enable the adjuster mechanism. But that's a huge gain in fluid.

that is totally weird. it reminds me of my 96 Deville. I have had it almost 3 years and check my transmision fluid about every 6 months. Have never had to add any but yet last time I checked the fluid it was mysteriously over by one quart exactly. I was stunned. I had to use a baster to pull the fluid out. I am still baffled.

This could be serious. I've had the transmission oil cooler, located inside the radiator, start leaking and cause antifreez to get into the transmission. Serious trans damage resulted.

JohnyG,

I have not touched the parking brakes for months.

Today, I removed about 4 oz DOT3 from both sections of the reservoir, brought the gasket to the proper configuration (it has some fancy cups) and marked the level. Will keep an eye on it. Thanks gents for all input.

[JohnnyG]

Those "fancy cups" are intended to keep air at a minimum in the reservoir, thereby lessening the chance that the fluid absorbs moisture from the air. If the folds were "popped out" it means that you actually lost fluid somewhere along the way. Yes, do fold those cups back in, but keep your fluid reservoir full to the max mark to minimize air space.

If the folds popped out for some other reason, it might give you a false reading indicating a high level of fluid in the reservoir with the folds taking up the excess air space. You can get replacement cups (therby a new seal as well) for that cover if you like. Brake fluid is hygoscopic, and the more water it contains, the lower the boiling point of the fluid. If moist air or water is getting into the fluid reservoir, a fluid change is in order immediately.

Rockfangd asked if you had your oil changed lately (by a quicky service I assume). I think he is thinking that some dummy may have either topped off the fluid or added something that wasn't supposed to be in there.

[BodybyFisher]

Here is an interesting story, it looks like someone has a similar experience and it was due to moisture and the cap seal

http://www.suzukisv1000.com/faq/brake_resevoir.htm

[adallak]

Those "fancy cups" are intended to keep air at a minimum in the reservoir, thereby lessening the chance that the fluid absorbs moisture from the air. If the folds were "popped out" it means that you actually lost fluid somewhere along the way. Yes, do fold those cups back in, but keep your fluid reservoir full to the max mark to minimize air space.

If the folds popped out for some other reason, it might give you a false reading indicating a high level of fluid in the reservoir with the folds taking up the excess air space. You can get replacement cups (therby a new seal as well) for that cover if you like. Brake fluid is hygoscopic, and the more water it contains, the lower the boiling point of the fluid. If moist air or water is getting into the fluid reservoir, a fluid change is in order immediately.

Rockfangd asked if you had your oil changed lately (by a quicky service I assume). I think he is thinking that some dummy may have either topped off the fluid or added something that wasn't supposed to be in there.

Okay, here are two pictures of the gasket placed on the cover. The upper side of the metal cover is obviously up side down. It has been my understanding that the gasket is there to eliminate the direct contact of the fluid with air inside the reservoir. The reservoir consists of two subreservoirs serving the front and the rear brakes. So, each subreservoir gets a cup. The cups are there to compensate for changes in the level of the fluid caused with natural wear of brake pads and shoes (they will be sucked down) or thermal expansion of the fluid (or change in the volume caused with absorption of moisture, contaminants, etc.).

When I serviced the brake system for the first time, the both cups were sucked down, and I left them like that when I refilled the system. There was a little gap (probably less that1/2") between the top of the reservoir and the level of the fluid , which allowed me to monitor it. That gap considerably narrowed after the trip, which attracted my attention immediately. I am particularly attentive to anything under the hood and elsewhere when I am far away from MA.

Now, I believe the configuration of the cups (or call them "diaphragms") was wrong from the beginning. I brought them to the neutral position shown in one of the pictures. I am a little curious if the volume of the air in the cups enough for thermal expansion of the fluid. If it is not, the expanding fluid will pop out the cover, which is not good!

[adallak]

Here is an interesting story, it looks like someone has a similar experience and it was due to moisture and the cap seal

http://www.suzukisv1...ke_resevoir.htm

Thanks Mike. BTW, the reservoir of my 1991 Seville did not have any gasket. Was it designed like that, or someone before me just got rid of it? Did your Seville have one?

[BodybyFisher]

That is a long time ago Adallak,

[JohnnyG]

I am a little curious if the volume of the air in the cups enough for thermal expansion of the fluid. If it is not, the expanding fluid will pop out the cover, which is not good!

There is plenty of space for NORMAL thermal expansion. In other words changes due to ambient air temp extremes. However, if you have a dragging brake shoe or pad, which could overheat or boil the fluid, it might force some out, most likely at the cover seal. When that fluid cools, it would then draw the rubbers down. Normal wear would draw the interior rubber cups down very slowly, not all at once. Also a leak would draw the inside rubbers down quickly, as well as bleeding the brakes if the cover is left on the reservoir (not the way to do it).

My 1976 HD Superglide had this problem with the rear brakes and was recalled. The fix was a different "O" ring inside the rear disc brake caliper that would retract the pad further, and DOT4 (or was it 5, silicone) fluid.

[adallak]

I am a little curious if the volume of the air in the cups enough for thermal expansion of the fluid. If it is not, the expanding fluid will pop out the cover, which is not good!

There is plenty of space for NORMAL thermal expansion. In other words changes due to ambient air temp extremes. However, if you have a dragging brake shoe or pad, which could overheat or boil the fluid, it might force some out, most likely at the cover seal. When that fluid cools, it would then draw the rubbers down. Normal wear would draw the interior rubber cups down very slowly, not all at once. Also a leak would draw the inside rubbers down quickly, as well as bleeding the brakes if the cover is left on the reservoir (not the way to do it).

My 1976 HD Superglide had this problem with the rear brakes and was recalled. The fix was a different "O" ring inside the rear disc brake caliper that would retract the pad further, and DOT4 (or was it 5, silicone) fluid.

Thank you. I do not really like the idea to fill the reservoir up to the gasket, hence leaving no air gap whatsoever. Probably will remove some fluid tomorrow and leave a 1/4" gap between the fluid and the rubber gasket. Most of reservoirs I saw were designed to have air in them.

[JohnnyG]

I do not really like the idea to fill the reservoir up to the gasket, hence leaving no air gap whatsoever.

If this is a steel reservoir, and your picture of the lid seems to indicate that it is, filling it to the top won't hurt a thing. That's what that special rubber lid gasket is supposed to do, allow the fluid to be used while keeping air space to a minimum. I used to keep mine where the inside rubber would touch the fluid when the cover was installed.

[adallak]

I do not really like the idea to fill the reservoir up to the gasket, hence leaving no air gap whatsoever.

If this is a steel reservoir, and your picture of the lid seems to indicate that it is, filling it to the top won't hurt a thing. That's what that special rubber lid gasket is supposed to do, allow the fluid to be used while keeping air space to a minimum. I used to keep mine where the inside rubber would touch the fluid when the cover was installed.

The reservoir is plastic and the lid is metal.

[JohnnyG]

I know I said steel, but even if it's plastic the same principles apply, the folds in the cover gasket won't let a vacuum develop in the reservoir. They'll suck down before sucking air into the res.

All of this does not answer the question as to why the fluid level went up. Have you decided that issue to your satisfaction?

[adallak]

All of this does not answer the question as to why the fluid level went up. Have you decided that issue to your satisfaction?

Nope, did not figure out yet. Will wait and watch. Nothing is wrong with stopping power. Lately, I have been noticing changes in my car most of people would not even notice leave alone pay attention. Getting old and paranoid, I guess!

[KHE]

When filling the reservoir, collapse the boots on the gasket.

[adallak]

When filling the reservoir, collapse the boots on the gasket.

I did. Do you full the reservoir all the way to the gasket, so there would be no air gap between the liquid and the gasket?

[KHE]

When filling the reservoir, collapse the boots on the gasket.

I did. Do you full the reservoir all the way to the gasket, so there would be no air gap between the liquid and the gasket?

There should be a min/max level molded into the reservoir. If there is only a min level, keep the level below the gasket or there'll be a mess when you snap the cover on.

[adallak]

When filling the reservoir, collapse the boots on the gasket.

I did. Do you full the reservoir all the way to the gasket, so there would be no air gap between the liquid and the gasket?

There should be a min/max level molded into the reservoir. If there is only a min level, keep the level below the gasket or there'll be a mess when you snap the cover on.

That's what I was thinking too. Will keep it some 1/4" below the gasket, so I could clearly see the level and the air gap. Thank you.