there is one vacuum line that runs to your brake booster, if you have poor vacuum then this will cause you to have a hard brake pedal. the booster uses vacuum to help you when you brake. Definitley check this line and replace if needed. Easy way to check if booster is bad is to start engine and then disconnect the vacuum line from the booster. The car should stall. Older mechanic taught me this trick. Cheack all your vacuum lines under the hood. it could be that check valve on top of the intake which is connected to the cruise control unit before it enters the firewall.

CAT

Found the posts below with a search for "vacuum leak." There was also a post here a few weeks back on checking for leaks in the vacuum bottle under the dash. Good luck

http://www.brickboard.com/RWD/index.htm?id=413838

I take it your motor is injected but not turbo'd? (please Lord, let it be un turbo'd!)
Most of your vacuum lines will terminate at the throttle body/intake plenum area, so thats where to start looking for a vacuum leak.

Regards,

Big Rich.

http://www.brickboard.com/RWD/index.htm?id=413826

Two ways to check for a vacuum leak. You can visually inspect the suspected hoses or, even better, remove them so you can flex them and check for cracking, splits etc.

Alternatively you can use a spray such as WD40, or lighter refill gas with an aerosol nozzle. Spray the suspected area - if the revs rise slightly then there is a vacuum leak through which this flammable gas is being drawn. Obviously, take care whilst doing this
--
Jim (90 244DL 170K miles)

hi there i have read here alot about the spark plugs. most dont like the preformance of the bosch platinum.

Sounds like vacuum to me too. Good advice in the previous post--find the location of the sucking under the hood--it is under ther hood, right? My guess is brake booster too.

Nice to see fathers and sons still working on cars together. The 240 is a GREAT car to help your son learn how to do-it-yourself. Nothing on it is excessively complex or unforgiving. If you don't already have it, the Bentley book on the 200 series is indispesnsible and worth the $50 bucks or so. It will pay for itself before you're done with the first repair.

And of course, as you've found in the last few months your new friends here on brickboard will offer the best advice. Since we've collectively driven millions upon millions of miles, pretty much every issue has been encountered at least once. Good luck to you!

Sounds like more vacuum leaks.
I guess you have already examined the hose and valve that connect to the
brake booster...
Get out under the hood and listen the next time someone shuts it down and
you can probably tell where the sucking sound is coming from.
--
George Downs, Bartlesville, Oklahoma, Central US