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surging and rough running

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tahoe healey

tahoe healey

Yoda
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Getting ready for spring, I checked the plugs and all were even in color except the rear most one which was very white. I figure if they were all that way then it was the fuel mixture but with only one plug off I'm suspicious of the tappits due to a rhythmic clicking or ticking sound. I am also getting a slight surging when at constant speed. Any ideas cause I'm planning of the drive to San Diego and don't need any problems?
TH
 
Hey TH,

I'm no mechanic, but the fix would be to drive the suv. Yup, no problems that way.

I'm thinking about going too.
Lots of other shows before that one. Hopefully I see you at some of them....all of them!

Till then, good luck with getting your car running in tip top shape! Sorry I can't help with your question.

Happy motoring!
Roger
 
I'm gonna through out a wild guess here and say vacuum leak. Prolly in the rear carb since you got that funky colored plug back there.
 
I agree with Greg that a climb in RPM usually equals a vacuum
leak. But the ticking and only one plug is white ? Perhaps a stuck valve ?
Three quick checks;
1.. Any sign of water in the oil ? ( look closely at dipstick )
2.. Any sign of oil in the water ? ( look closely where the radiator cap seals inside the neck )
3.. Is there any change in the way the engine runs if you disconnect the plug wire from that cylinder ?

Dave's turn
 
GrEd, wouldn't all the back three plugs be white also?
Ed, no water on the dip stick or in the oil which I just changed. Radiator fluid looks fine as did the cap. There was a small beige deposit on the inside of the oil filler cap though which I thought was condensation. Good thought about disconecting the plug. I'll give that a try. I'm thinking stuck valve due to the tapping sound. Any quick checks with out removing the head?
I had the rocker rebuilt a year ago. I adjusted the valves (clearence)4 months ago and not driven much since (winter).
 
I agree with Greg. The most likely cause is a vacuum leak at the brake booster, either in the plumbing or in the booster itself.

The booster vacuum connection is right at the rear cylinder manifold branch. A vacuum leak here would pretty much affect the rear cylinder only. Related to this, an internal leak in the booster "could" allow brake fluid to be drawn into the rear cylinder. This would normally cause some white smoke in the exhaust & the brake fluid level would be lower.

As the leak could be either in the booster itself or in the manifold to booster connecting hose, a simple check would be to remove the manifold to booster hose connection at the manifold & plug the manifold. This will at least give you a starting point to find the problem. You can drive without the booster but pedal pressure will be somewhat greater.

Glad I don't have a brake booster. :yesnod:

Don't know about the "tapping sound" - Check one thing at a time. After the brake check, look at the rocker arm adjustments.
D
 
I had a similar "ticking" problem that you have and here's what I found out...

A very loud clacking sound started and afer fifteen minutes it went away about 10 years ago, but a moderately soft clicking sound remained for several years. The loud clacking sound came back after a long trip of 250 miles last April and did not go away this time.

After a friend of mine(very mechanically inclined and a Healey owner) and my wife(smart, good looking and with excellent hearing), used my newly purchased engine stethescope to locate the noise and determined it was coming from the number one cylinder valve train area. I decided to remove the head. I had the valve guides knurled in the late seventies because I couldn't get new guides and I felt that was probably the problem.(BTW: the reason that I couldn't use the stethescope is because I wear a hearing aid in one ear and just had a cochlear implant for my other ear).

I pulled the head and immediately found the problem...the number six piston was coming apart!! The first clacking sound was a warning...the second was the final end.

The intake manifold had a mounting ear cracked all the way through and to the head. The plugs looked fine and the compression was even all the way across the board even with the top ring and piece of the piston gone! I think the freeway speeds of higher rpms must have been too much for the already weakened piston.

I asked the Implant surgeon if there was an attachment device available for the Implant processor to mate to a stethescope and he said "not yet"(no kidding!!)

I fired my mechanic friend and divorced my wife(just kidding)
Patrick
 
T.H. ,
You can do a compression test to see if that cylinder is substantially different than the rest.
Start out with the easy stuff. plug off the brake booster port to see if the RPM remains stable.
Pull off a plug wire to see if anything changes, if it doesn't either that wire or plug is not firing for some reason. You can unscrew the plug, reattach the wire, turn over the engine and see if there is any spark. that will tell you which way to go,
electrical problem or mechanical problem.
If the spark is good and you still have the ticking sound, perform a compression test, if it is low in that cylinder, then you will probably have to pull the head to see what is going on. Hopefully it's a valve problem and not a cracked piston, etc. I think I remember a recent post you made that said you replaced the rotor ? The plug removed spark test will tell you if that is in the mix or not.
Happy gremlin hunting,
Ed
 
Here is the update. The brake fluid was down 3/4 inch or so. It appears that there is no drips in the servo. No fluid in the hose to the manifold. With the hose off the fitting and the manifold taped, I cannot tell a difference at any engine speed. The manifold suck quite a bit so I don't suspect any leaks in it. Seems smooth and even today. Cannot test drive it cause we got 5 inches of snow last night. Any suggestions?
I'll need to refill the break fluid but I don't know what is now in there. Any way to test or tell?
 
---- Any suggestions? -----
Wait for the snow to melt a bit!

If the existing brake fluid is NOT red or blue, it's probably safe to top up with any good Dot 3/4 fluid. I like Valvoline SynPower or Castrol GT LMA. But - 3/4" down is not bad. It needs a little space.

Drive it a bit & see if the rear plug shows some color. If it does, there must be an air leak in the booster somewhere. Better yet, interchange plugs # 1 & 6, see if they both change colors.
D
 
Thanks for responding, Dave. It is a little below the seperator in the resevoir. I was actually hoping it was the servo cause its never felt like it was assisting that much and I've always had a surge only not as bad as the other day when I started this thread. I will try changing the plugs as suggested. Can there be a leak at the manifold? I never understood how it can have a excess few out flow and still be a sealed vacuum.
TH
 
Hi TH,
It's ok to top it up a little above the separator, but not clear to the top.

The problem may well be an air/vacuum leak in the servo/booster. That's why I suggest driving it for a while with the vacuum line to the servo disconnected & the manifold fitting plugged. See if it helps. If it doesn't run any better, this probably rules out the booster as the cause of #6 appearing to run lean.

There could be a manifold leak. Considering the #6 plug color & the fact that the brake booster enters the intake manifold very close to the #6 intake port, the most likely place for this leak is in the connecting hose to the booster or in the booster itself. Possibly not - See below.

You can check for manifold vacuum leaks by spraying a little carb cleaner on the manifold to cylinder head joints & the carb to manifold joints with the engine idling. If the idle speed changes, you have sprayed the cleaner near where the manifold is leaking.

Not sure what you mean by excess fuel outflow. But, only the engine side of the throttle butterflys is exposed to full vacuum. The outboard side is free to leak anywhere it wants to.

Recap -
1- Run, drive the car with the brake booster hose disconnected & plugged at the manifold. If it helps - something wrong with the booster.

2- Check for manifold leaks with carb cleaner.
D
 
Just a thought from my own experience. If it is a high mileage care check the contact point plate for being sloppy/loose. If it is, then the point gap/dwell is unstable-symtoms are those you describe--as though the vacum advance is malfunctioning. I had that problem and took my distributor out, tore it apart and found many parts in the bottom of the dist housing. I rebuilt it from a spare distributor. My car runs better than it has in years.
bd
 
why said:
Patrick: Where did the piece of the piston go?
Jay '65 3000
Click to expand...

The ring and piston piece were nearly perfectly flattened to the top of the piston. Th clicking sound is apparently from the valve hitting the buildup on top of the piston.

I have photos of this.
Patrick
 
I got a very short drive in and tried the difference with and without the hose conected (plugged manifold without the hose). I couldn't feel the surge either way today. But boy, breaking was a real trip with out the assist!!! I will try all the suggested stuff over the next two days.
 
the clicking might mean a bent pushrod....
 
Well, I found many things today.The rear carbs took 3/4 turn on each of the mounting bolts to the manifold. The compression varied about 5 psi form highest to lowest both hot and cold. Most important and most confusing was the point gap. It measured .015 but the dwell was 22 to 25. I adjusted to 34 and she smoothed out and has greater acceleration. Re adjusted the fuel mixture richer and I'm good to go! It also seems that the noise is quit a bit less.
Dave, my comment about the intake manifold is that there are the two copper tubes coming from the bottom (that drip fuel below the exhaust). If it is a vacuum in there why doesn't air go uP those tubes?
 
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