79 NinetyEight 403 -- Need advice

regencyrunner · #1 06-28-2004, 01:40 PM

Hello, I just stumbled on to this forum looking for some help for my 79' 403 Olds.(120,000miles) Does not use any oil or smoke, compression tested good.

Car was running perfectly until vacuum advance diaphram on the distributor dry rotted. Once I replaced it with a stock tension the car developed a surge at cruising speeds. Since then I have tried new counterwights and spriings in the dist, new cap, rotor, plugs, wires, new egr valve and gasket, new coil, reset timing twice(chain has very little slop), replaced transmission modiulator.
As of right now the car idles rough on startup, but has no surge until warm. Once warm idles good and acclerates nice, but will stall at low speed driving with the throttle part way opened and surge crusing at any speed.
Anyone who could give me some advice as to what you think is would be appreciated. Thank you
jason

regencyrunner · #2 07-03-2004, 03:12 PM

I can't wait any longer for advice. I am going to pull off the Intake , replace the carb, and eliminate the emissions crap.
I will post what I find when I am finished.
If anyone has advice on what possible problems to look for on removal it would be appreciated. Thank you.

Bill V · #3 07-03-2004, 09:26 PM

You have a bad pick up coil (pole piece) in the distributor! This was very common on that engine...

regencyrunner · #4 07-06-2004, 05:23 PM

Going to pull distributor and rebuild. will post after I get it back in. Thank you To Bill V for advice.

regencyrunner · #5 07-09-2004, 04:08 PM

I have replaced distributor and carb. Still the same. Surge at cruising speed, cuts out and stalls under low speed load. When idleing if you pull the throttle about 1/4 inch it will cut out and almost stall. Acceleration still good.
Any other suggestions before I rip off the intake?
Thank you.

Bill V · #6 07-09-2004, 10:04 PM

Only thing that comes to mind is EGR. Could you have a mis-routed vac. line? Try disconnecting the EGR and let me know what happens.

regencyrunner · #7 07-10-2004, 04:31 PM

I blocked off the egr. SMOOTH ! Running almost normal.
Thank you Bill V for your advice, I never thought of totally blocking egr. PA has tough emissions law.
Also, I now have fresh dist, and carb which makes driving this excellent , rust free, new coil suspension chassis relaxing again.
Bill V please feel free to e-mail me anytime.
Thank you.

Bill V · #8 07-11-2004, 12:39 AM

Glad to have helped track it down.

It shouldn't need to be blocked off, though.

As I recall, there was a delay or modulating vac setup to control this problem. Do you still have the vac diagram under the hood to use as a guide?

regencyrunner · #9 07-11-2004, 09:58 AM

Yes, There was a vacuum control valve in between the egr and carb ,and I do have vacuum diagrams under hood and in a book.
In my mind I still think replaceing or cleaning the intake would be the only way to actually get complete problem free operation.
I still hear an intermittent air leak and can't figure where it is coming from.
Thank you

regencyrunner · #10 07-23-2004, 02:06 PM

I snaked out the egr ports with an old hood cable. The vacuum control between the egr and carb that bill V mentioned is most probable cause. I remember changing the oil sending switch, which is located next to this valve on top of the timing cover. Oil had blown all over everything. I used brakekleen to clean up the mess. Probably got into the diaphram of this valve. Going to try and find one, local parts stores do not carry this so I will have to go to a dealership or grab some from a junkyard.

regencyrunner · #11 04-13-2005, 07:03 PM

I am still driving this car throughout the fuel price increase.
It is running good, but has developed a Major oil leak at the oil pan gasket.
my question is --- Because the EGR is blocked off is this cause for increased crankcase pressures?----- I want to know before I repair the gasket which includes hoisting the engine off the mounts and removing the crossover pipe.
Any comments or suggestions would be appreciated.
Thank you.

diesel1962 · #12 04-23-2005, 09:15 AM

Hello! Being that it is an old car,Maby the oil pan gasket was ready to fail anyway.It probley was the original gasket.About the EGR creating more crankcase pressure,I do not think it has anything to do with that.If you do replace oil pan gasket,I would suggest Cleaning oil pump pickup screen,Or consider replacing the oil pump.It would be a shame<knowing that you had everything apart,And have other problems cropp up after you reassembled everything.Just "Food for thought" ..Have a good day!! Diesel 1962

regencyrunner · #13 11-13-2005, 09:03 AM

I have decided not to replace the oil pump. The last 403 I replaced the oil pump and it thru out a rod bearing 1000 miles later. It was running good up till then.
before I pull this motor I need to fix a mysterious steering/brakeing problem.
The right front will klunk after you let off the brake pedal. I have checked wheel bearings, upper and lower ball joints, control arm bushings, center link bushings, and calipers.
Any Ideas on this would be appreciated.

1968 Pontiac · #14 02-14-2006, 06:34 PM

I get a clunk like that in my 85 Lesabre (with 307 olds engine

). I've checked all that stuff too. All is ok, so I'm beginning to wonder if it's a bad body mount.

regencyrunner · #15 02-14-2006, 07:31 PM

Hello, Pontiac68. I have found the clunking. It was the upper control arm alignment bolts. They came loose believe it or not, and the alignment shims fell out allowing the wheel to move side to side. I replaced the shims and tightened them up. These bolts are located at the top of the upper control arms next to the exhaust manifolds.
Also, check the body mounts at the back of the gas tank. sometimes these go bad and allow the rear bumper to flap around when you hit bumps.

I recently purchased a 1970 Pontiac Tempest , and will be starting a thread when I do the disc brake conversion.

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