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two weeks ago my rough start improved (got worse) to the point I think I found my problem. In my case, while backing out of the garage the engine suddenly went to a very rough idle, and I lost the brake boost.
clearly this was a vacuum problem going to the booster so I started there.
turned out that the brake booster vacuum line was pulling out of the hose where the clamp is about 6 inches out from the engine. even thought I've not found a diagram showing it, that line is vacuum for the brake booster, but also has a Y with a reducing insert (I''m sure there is a name for this insert - its about 3 inches long and is internal to the hard line coming from the manifold) that feeds a line that runs across the front of the engine and over to the vicinity of the auxiliary air valve. it looks like this line joins the vacuum provided from the transmission source on the front of the car. (lots of guessing on my part now).
bottom line - my line is separating from the reducing insert and causing a complete loss of vacuum impacting both brakes and engine performance when its completely open. I suspect i has a small leak there for some time that sealed up as the engine warmed and the vacuum held the hose in tight.
I'd love to find a diagram showing that cross line and describing its actual function as all the diagrams I've found don't appear to show it.
Happy to take the Drive to Austin one of these weekends and dive into these together if you like. if nothing else, we can get a beer and swap troubleshooting stories.
#20 (928-111-147-02) lets the converter/amplifier know how much exhaust gas back pressure exists in order to control EGR opening. Is there enough metal left to slip some silicone tubing over it?
Raymond
Came across this a couple years ago, it gives a great overview on the EGR system on the 78/79's:
I bought a cooper sleeve today and plan is to JB weld the sleeve over the break in the metal tubing.
God only knows if the EGR valve works any more. Let me patch the hole and get the clutch reinstalled - replacing the throw out and pilot bearings, and see what happens when I start it again. Thanks for the info!!
two weeks ago my rough start improved (got worse) to the point I think I found my problem. In my case, while backing out of the garage the engine suddenly went to a very rough idle, and I lost the brake boost.
clearly this was a vacuum problem going to the booster so I started there.
turned out that the brake booster vacuum line was pulling out of the hose where the clamp is about 6 inches out from the engine. even thought I've not found a diagram showing it, that line is vacuum for the brake booster, but also has a Y with a reducing insert (I''m sure there is a name for this insert - its about 3 inches long and is internal to the hard line coming from the manifold) that feeds a line that runs across the front of the engine and over to the vicinity of the auxiliary air valve. it looks like this line joins the vacuum provided from the transmission source on the front of the car. (lots of guessing on my part now).
bottom line - my line is separating from the reducing insert and causing a complete loss of vacuum impacting both brakes and engine performance when its completely open. I suspect i has a small leak there for some time that sealed up as the engine warmed and the vacuum held the hose in tight.
I'd love to find a diagram showing that cross line and describing its actual function as all the diagrams I've found don't appear to show it.
Happy to take the Drive to Austin one of these weekends and dive into these together if you like. if nothing else, we can get a beer and swap troubleshooting stories.
paul
Paul,
I have lost braking power before and found out that the line coming of the intake plenum on the drivers side had backed off the plastic insert.
Austin gang is meeting the weekend after next, delaying a Saturday for Valentines day!! Hopefully the clutch will be back in by then
Not yet. Three weeks ago I started having bearing noise when the clutch was depressed and had tp yank the clutch pack out to replace pilot and TOB. Got it all back together last Sunday and it was running but then Monday I had crank but no start.
I was actually wondering about potential low/variable volts to the ignition.
I had a 928 that would behave similarly when the regulator in the alternator got a little lazy.
car started running worse over the weekend after resolving the no start issue. Had to keep the park brake on at lights so I could give it enough gas to keep it running. I had a lo0ud intermittent rattle from under the car and gas mileage dropped to 5 MPG.
I got under the car Sunday and the CAT rattled like a can with rocks when I tapped on it.
Monday I had the CAT replaced and most of the idle issues seem to be gone. CAT was totally blocked.
I had to adjust the idle down and leaned the AF adjustment almost a turn. Idle seems very solid now.
Exhaust guy pointed out that I have wholes in both the mid muffler which looks original as well as the ANSA back muffler which I did not like because the exhaust tips went straight back rather then out the side.
02-09-2015, 06:01 PM
