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View Full Version : Bad Vacuum Lines - M30 and others



mholbrook
03-21-2006, 09:29 AM
Just a quick note to the board. Previously I posted changing my injectors this last weekend. Engine 92 535 M-30.

One thing I did not mention was the condition of my vacuum lines and rubber.
There are two vacuum lines, one runs to a hose that is about 1" in diameter
that further connects to the air intake hose just in front of the throttle
body. That vacuum hose connects to the bottom of the intake manifold
closest to the firewall. Mine almost fell off the bottom of the manifold
when I changed it.

The other vacuum line goes to the FPR and mine just
crumbled in my hands it was so old. It connects to the bottom of the intake
manifold closest to the front of the car.

You need about 2 1/2 feet of vacuum line to replace these two hoses. If the hose from the valve cover is hard, you need to replace that as well. Ditto the rubber hose between the throttle body and AFM. The hose from the AFM to the air cleaner is usually not bad.

My car was probably wearing the original hoses and it is 14 model years old. My next project will be to replace all the water hoses under the hood and change the coolant out.

Bill R.
03-21-2006, 09:32 AM
fact that any unregulated air leaks around the old injector orings could also have had an effect raising it slightly making it rougher




Just a quick note to the board. Previously I posted changing my injectors this last weekend. Engine 92 535 M-30.

One thing I did not mention was the condition of my vacuum lines and rubber.
There are two vacuum lines, one runs to a hose that is about 1" in diameter
that further connects to the air intake hose just in front of the throttle
body. That vacuum hose connects to the bottom of the intake manifold
closest to the firewall. Mine almost fell off the bottom of the manifold
when I changed it.

The other vacuum line goes to the FPR and mine just
crumbled in my hands it was so old. It connects to the bottom of the intake
manifold closest to the front of the car.

You need about 2 1/2 feet of vacuum line to replace these two hoses. If the hose from the valve cover is hard, you need to replace that as well. Ditto the rubber hose between the throttle body and AFM. The hose from the AFM to the air cleaner is usually not bad.

My car was probably wearing the original hoses and it is 14 model years old. My next project will be to replace all the water hoses under the hood and change the coolant out.

genphreak
03-21-2006, 10:02 AM
Sounds like good work going down over there mate, I'd guess that most of us on the board could be doing this more often. I bet there are aawhole bunch of people reading that have never changed their vacuum lines, and do not know where they connect to once they head under the intake manifold... I remember it took me a while to 'dig in' and work it out for fear of breaking something. (My first expedition that way broke the stupid little bleeder pipe (the pin sized one with the deteriorated bung over it), sticking out of the non-return valve on the between the brake booster and the manifold...) :) Nick

ryan roopnarine
03-21-2006, 10:25 AM
one weekend, i attempted to replace all of the vacuum lines with hose i got from the discount auto parts (i had replaced the air intake elbow, so i decided to do them all at the same time). the discount auto parts didn't have anything near the correct diameter for the line that comes off of the nipple on the front of the valve cover and goes to the ICV nipple (IIRC), so i used a snug fitting hose obtained from discount for the same purpose. car is 92 m50, btw. i accidentally bumped that hose about 2 weeks ago, and found that it slid off with no effort. enough oil had gathered between the nipple and the hose that it was no use trying to put it back on without a zip tie or fastener, so i had to get the old hose (which i stored in the toolbox in the car), and use it. my personal moral of the story: if you are going to improvise with the vacuum lines, keep the old ones around (and handy). my fpr line was brittle, as well, but they didn't have a suitable replacement, so i had to reuse it as well.

RobPatt
03-21-2006, 01:42 PM
...and clean up under there, replace all hosts, etc, and prob put in new injectors as well... maybe then I'll get a peek at back of the intake valves and that'll either make me happy or worse.... someday... someday I'll also like to do the 5 speed swap (this is doable...) but someday I'd like to supercharge and that's going too far for the car now worth about $4K book.