Looking for insight: brake pad wear, head gasket leak and high idle

[nadodude111]

Hey everyone - thanks in advance for reading this long post. I’m concerned about a few issues I’m noticing with my new-to-me car. Am hoping you all can give insight into each issue so I can set my expectations and look for solutions. Car is a 1991 325i Convertible (late model). Everything is bone stock.

1. Brakes - The brakes in my car are awful and tend to wear quickly. I have to push the brake pedal with lots of force to slow and stop the car. I do not feel safe. I remember the brakes on my previous 1992 325i convertible feeling nimble, responsive and quick. Also, the car has 158,000 and the brakes have been replaced 14 times throughout its life according to the records I have. The brakes on every car I’ve owned have lasted me at least 50k miles so this car is eating through pads and rotors. Is this history normal?
   1. Feb. 1993 - 22,748
      • Front and rear pads
   2. Aug. 1994 - 33,638
      • Front and rear pads
   3. March 1996 - 44,172
      • Front and rear pads
   4. April 1997 - 50,021
      • Rear pads and rotors
   5. December 1997 - 54,691
      • Front pads
   6. Feb. 2003 - 83,138
      • Front pads and rotors
   7. July 2003 - 86,150
      • Rear pads and rotors
   8. Feb 2006 - 92,980
      • Front pads
   9. July 2009 - 102,342
      • Front and rear pads & rotors
   10. Nov. 2011 - 114,715
       • Front and rear pads and rotors
   11. Oct. 2013 - 117,241
       • Rear pads and rotors
   12. January 2017 - 126,315
       • Front and rear pads and rotors
   13. Aug 2020 - 135,759
       • Front pads and rotors
   14. May 2022 - 152,835
       • Rear pads and rotors

I bought the car a month ago with 157k miles and had a pre-purchase inspection done. The mechanic said the front pads were at 50%. I've put about 2k miles on it in the month I’ve had it and now the brake lining light is on. Does it seem reasonable for the front pads to wear down with just 2k miles?

2. Head gasket leaking oil

• BMW of San Francisco replaced the head gasket in Oct. 1996 (48,072 miles) and July 2005 (92,218 miles). Head gasket is leaking like crazy again. This isn’t normal for e30s to be leaking this bad after having the engine rebuilt twice. Annoyed.

3. High idle - car idles really high when in park - around 1500 RPMs but then drops to about 800 when put in drive. Car does not run rough, but it does eat fuel like crazy and seems a bit sluggish. I am getting about 200 miles to the tank - using the odometer against a full tank. Any ideas as to what’s causing this and what to replace to fix the issue?

Let me know if I can elaborate and provide more details to clarify. I appreciate all your help.

Thanks

[It's Soda Not Pop]

Probably time to replace your 02 sensor, as far fuel goes. Have you taken out your ICV and cleaned it? It could be sticking and/or you have a small vacuum leak somewhere. What brand of pads are you using? Also do you live in area with a lot of hills and mountains? Do you ride the brakes instead of engine braking?

[nadodude111]

Thanks for the response and suggestions. O2 sensor was replaced in March of 2022 at 151,616 miles so about 8k miles ago.

No to the ICV. What is that and how do I clean it? I know I can google and I will but since I already have your attention…

No idea on brand of pads as I just bought the car so I haven’t done the brakes yet. Looks like rears were replaced last year at Brake Masters.

[It's Soda Not Pop]

The ICV is the idle control valve. You can clean it with brake clean. Make sure when you shake it that valve moves freely. It's near the throttle body. When you have the key on but the car is not running it will be buzzing.

[It's Soda Not Pop]

Are there any codes showing up when you do the stomp test?

https://shop.sssquid.com/bmw-stomp-test/

[It's Soda Not Pop]

This post has a lot of info to help trouble shoot a lot of issues.

https://www.r3vlimited.com/board/forum/e30-technical-forums/e30-faq-and-diy/333798-diagnostics-tips-tricks-by-jim-levie-e30-jedi-master

[Boris3]

Burning through pads at the rate noted and the resistance when pushing the brake pedal (having to push it with a lot of force) is not right. Even with cheap pads 2k is really fast to burn through them. It might make sense if you were in San Francisco or making Pike's Peak runs, or the PO or you are riding the brakes like ISNP asked. Since you don't know the PO's habits, checking things out yourself to get a baseline of pad/rotor condition as you start driving would help.

Remember that the brake lining light can come on even if the pads are fine due to electrical issues (e.g., the sensor is shot, there is a sensor wire broken, the connector is broken, the wires from the connectors to the warning light, etc.).

To pin down what might be going on start with walking around the car and checking each wheel after driving a bit. Do one or more wheels feel hotter than others, are the rear wheels hotter than the fronts? This will help to narrow if it is just a wheel or two or system wide. Jack up the car and spin each wheel. Do you hear /feel it dragging? If so, check to see if its pads/rotor causing it.

Have you tried bleeding the brakes (not clear from the records above when/if this was done).

Resistance when braking could be an issue with brake booster (vacuum line, check valve, or the booster itself), master cylinder, rusted/dragging calipers (pistons, slider pins), brake lines (old swollen soft lines, pinched or rusted hard lines), if the issue is the rears aside from the calipers and lines the T-junction under the subframe could be clogged or maybe is there an issue with the brake proportioning valve near the master.

Start with the easy things first. Good luck!

[nadodude111]

Thanks for suggesting all the possibilities! Perhaps we could use the car's history to deduce the most likely culprit for rapid brake wear? I think it's safe to assume the issue has existed since the car was new, so if we come at this problem as if it were a brand new car, and thus brand new parts, what would be the most likely or unlikely reasons? Here is my list, but you guys are the experts, so please edit and teach young grasshopper:

Most unlikely:
- items that tend to fail due to age such as rubber, hoses, lines, rust and clogs.

Likely:
- faulty hardware from the factory - brake booster, master cylinder


The original owner was an older female lawyer who did live in San Francisco but hardly put mileage on the car and it was garage queened. The car has had three other owners since 2019 in Sacramento which is flat so I am not convinced it was hard braking on hills. The original owner (lawyer) was religious with maintenance and spent ~ $32k on maintenance at BMW San Francisco where she had brake flushes done multiple times over the years.

[Boris3]

Go back to your start point: brake wear light on (could be front or rear sensor) and having to push pedal with a lot of force. The two may or may not be related.

Regarding the brake pads:

If I'm reading the history correctly, it's original owner until 2019. Older owner and San Francisco could certainly explain brake pad wear and intervals. Riding the brake pedal in SFO would not be uncommon.

So 2017 we see new pads and rotors front and rear from the first owner. Use that as a baseline. Car sold in 2019 and new owner changes front pads in 2020 with roughly 9k miles at 136k (wear could be part PO and part new owner if bought in 2019, or maybe the new owner wanted to run a different pad?). (Another?) New owner changes rear pads and rotors with 152k in 2022 which would be about 27k on them from the 2017 baseline. Those rates for rears would not be abnormal depending on driver.

You bought the car a month ago with 158k, and mechanic says front pads at 50%. OK, that's 22k on the front pads by the time you buy it. Again not unusual. Rear pads were at what percentage according to the mechanic ? It's not clear from your post.

So leads back to my original question which set of pads is tripping the wear sensor? Look at the pads on both front and rear and check the sensors to see for yourself.


Regarding a lot of force to push down the pedal:

-does this change if the engine is running? In other words does it make any difference if the brake booster is "on" ? This could help to pinpoint a booster problem.

-Bottom line as I said above check the wheels after a drive to see which might be hot and get the car up on stands and look at the brakes and wheel resistance to pinpoint what else might be going on.

Good luck.

[nadodude111]

For anyone following, I’ve got updates on the

High idle: the car idles perfectly after the timing belt change. 750 RPM whether in park or drive. The intake leak is still there though as I can hear the loud suction sound.

Oil leak: I changed the cam seal during the timing belt swap, so I’ll monitor and see if the leak is still there. If I’m lucky then I can check that off the list.

Brakes: just replaced the master cylinder with a new one, did a brake bleed and put new pads all around. Massive improvement. The brakes feel sensitive and the peddle is squishier and moves according to the speed. It feels right. Though it still doesn’t stop entirely on a dime. The mechanic said he thinks the booster isn’t working at its full capacity as he saw it shaking when he was testing the system. I told him about the big intake leak and we think getting that fixed will close the system and make the booster a bit more powerful. He said the calipers looked great. I’ll report back this week when I get the intake leak fixed.

What’s annoying is now the brake lining light is on after the brake service and we replaced the sensors. Any ideas why it’s illuminating? it was coming on and off intermittently before the brake service and the pads we just replaced had meat on them and the sensors were not exposed. So perhaps a wiring issue…

[dnguyen1963]

Hey dude, you joined this forum in 2009. You should know that the brake lining light has its own god. It'll come and go on its own term. If it bothers you so much then just yank the bulb out of the panel. This light has no direct relationship with the brake pads. A great idea that is no longer working for most E-30.

BTW - Fix the intake leak before you do anything else.

[nadodude111]

Update:

- vacuum leak fixed. The intake gaskets were basically non-existent. Car feels peppier and much quieter. Super exciting repair. Brakes feel even better too. Big improvement in gas mileage too. While the car didn’t run rough before, it felt sluggish and as if it were suffocating, so I’d have to floor it to get it to move. Gas pedal is much more sensitive.

- replaced the front brake pad sensor with a new one and the light is off now. The male pin in the first new one was super recessed and wasn’t meeting the female plug from the car.

All in all these were much simpler repairs than anticipated! Thanks for helping out!

[jeffnhiscars]

I didn't read every post in detail but did not see any mention of flushing the brake fluid or rebuilding the calipers (which would become essential if the fluid wasn't routinely flushed). I would have started there based on your history