74 bus sudden slight loss of power, #4 valves both tight

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whc03grady
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74 bus sudden slight loss of power, #4 valves both tight

Post by whc03grady » Thu Aug 06, 2015 7:33 am

Last night I was driving along at about 72 (by the Speedo which reads high) when alla sudden there was a loss of power. I checked for wind but that wasn't it though that's what it felt like. I made it to my destination but power was down the whole time...I had it floored and 69-70 was the best it could muster. I slept on it. This morning #1exhaust was a little tight and both valves at #4 were definitely to very tight. It runs but sounds a little off (imagination?). Did I drop a valve seat?
Ludwig--1974 Westfalia, 2.0L (GD035193), Solex 34PDSIT-2/3 carburetors.
Gertie--1971 Squareback, 1600cc with Bosch D-Jetronic fuel injection from a '72 (E brain).
Read about their adventures:
http://www.ludwigandgertie.blogspot.com

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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by whc03grady » Thu Aug 06, 2015 8:10 am

Test drive after valve adjustment shows no change. It still won't give me the 78+ (again, by the speedometer) at full pedal like it used to, topping out at about 71. Still sounds funny, more clanky if that makes sense.
Ludwig--1974 Westfalia, 2.0L (GD035193), Solex 34PDSIT-2/3 carburetors.
Gertie--1971 Squareback, 1600cc with Bosch D-Jetronic fuel injection from a '72 (E brain).
Read about their adventures:
http://www.ludwigandgertie.blogspot.com

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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by SlowLane » Thu Aug 06, 2015 10:18 am

whc03grady wrote:It still won't give me the 78+ (again, by the speedometer) at full pedal like it used to, topping out at about 71. Still sounds funny, more clanky if that makes sense.
Wow. 78+ in a VW bus?? :cyclopsani: That's pretty darn fast. I can only get up to that kind of warp speed on a good steep downhill.

A loose valve seat does indeed add a new clanky or clattery element to the cacophany of noises coming from the powerplant. A compression test may show a drop in compression, but then again, it may not if the seats are simply a little loose in their pockets. A leak-down test would be more telling.
'81 Canadian Westfalia (2.0L, manual), now Californiated

"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance."
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whc03grady
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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by whc03grady » Thu Aug 06, 2015 10:40 am

SlowLane wrote:Wow. 78+ in a VW bus?? :cyclopsani: That's pretty darn fast. I can only get up to that kind of warp speed on a good steep downhill.
Well, like I said, the speedo reads high at that end of its range. Like by maybe 5 mph or more. 78=73, probably. On the interstate I cruise at between 70 and 75 by the gauge, over forgiving terrain anyway. My watch, the milemarkers, and a little math tell me this is about 65-70 mph.
SlowLane wrote:A loose valve seat does indeed add a new clanky or clattery element to the cacophany of noises coming from the powerplant. A compression test may show a drop in compression, but then again, it may not if the seats are simply a little loose in their pockets. A leak-down test would be more telling.
After relistening it isn't really clanky, more like light knocky, tippedy-tappedy. I wonder if I didn't overcompensate on the #4 valves and now they're too loose. I'll check again this evening. Eight and-a-half hours is plenty of cooldown time to adjust valves, right?
Ludwig--1974 Westfalia, 2.0L (GD035193), Solex 34PDSIT-2/3 carburetors.
Gertie--1971 Squareback, 1600cc with Bosch D-Jetronic fuel injection from a '72 (E brain).
Read about their adventures:
http://www.ludwigandgertie.blogspot.com

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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by whc03grady » Thu Aug 06, 2015 8:33 pm

Tightening up those #4 valves got rid of the tap/click, but full power isn't back. Also there's a constant definite lurch, like a misfire. Pulling plug wires off the cap at idle, one cylinder, don't remember which and now it's dark, didn't seem to be fully participating.
Ludwig--1974 Westfalia, 2.0L (GD035193), Solex 34PDSIT-2/3 carburetors.
Gertie--1971 Squareback, 1600cc with Bosch D-Jetronic fuel injection from a '72 (E brain).
Read about their adventures:
http://www.ludwigandgertie.blogspot.com

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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by asiab3 » Fri Aug 07, 2015 12:38 am

When was your last valve adjustment before your first post in this thread? We should always make sure the "symptoms" we find are related to the "effects" we're experiencing. If it was thousands of miles ago, we will treat the problem differently that if your last valve adjustment was last week.

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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whc03grady
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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by whc03grady » Fri Aug 07, 2015 8:19 am

asiab3 wrote:When was your last valve adjustment before your first post in this thread?
The last valve adjustment before the first post in this thread was about 2000 miles previous.
Ludwig--1974 Westfalia, 2.0L (GD035193), Solex 34PDSIT-2/3 carburetors.
Gertie--1971 Squareback, 1600cc with Bosch D-Jetronic fuel injection from a '72 (E brain).
Read about their adventures:
http://www.ludwigandgertie.blogspot.com

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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by whc03grady » Sat Aug 08, 2015 5:47 pm

Today I adjusted the points. They were a little tight but not horribly so. I put them back to 0.016".
Contrary to my last plug wires pull test, each cylinder seems to be participating.
Yet the lurching persists. Melissa was in back this time during the test drive. She definitely could feel it; before I even asked she said "is that it?" Yes, that was it, the chugginess*. Mostly in certain rpm ranges, mostly under load. "Can you hear anything?" I asked, looking for confirmation of my own experience. "No." That's right, it sounds fine, even when it chugs. No backfiring, no sound of a misfire. Also, power is fine. Mileage is fine. The engine doesn't smell or feel at all hot. Wouldn't power, mileage, and cooling suffer if it was misfiring?

So here's another observation and a question. There is obviously an oil leak at the front of the engine. Could I have a leaky front seal causing this leak and causing some clutch slippage--hence the chugging?

*"What does he mean by "chugginess" and "chugging?" ask the more eloquent members of our panel.

I means it feels like, especially under load, someone is tugging on a rope tied to the back of the vehicle. Tugging irregularly (i.e., there's no periodicity to it). That's the best I can describe it.
Ludwig--1974 Westfalia, 2.0L (GD035193), Solex 34PDSIT-2/3 carburetors.
Gertie--1971 Squareback, 1600cc with Bosch D-Jetronic fuel injection from a '72 (E brain).
Read about their adventures:
http://www.ludwigandgertie.blogspot.com

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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by asiab3 » Sat Aug 08, 2015 10:26 pm

whc03grady wrote:That's right, it sounds fine, even when it chugs. …

So here's another observation and a question. There is obviously an oil leak at the front of the engine. Could I have a leaky front seal causing this leak and causing some clutch slippage--hence the chugging?
Sounds fine? What's fine? Who's fine? I'm in trouble when things are "FINE!" Do you have a tachometer? If not, can you hook one up during the test? A slipping clutch can manifest into a raise of engine RPM while vehicle speed remains constant. A slipping clutch can usually manifest itself at the upper end of a VW bus' speed range; here the engine is working hardest against loads from wind resistance and rolling resistance, while generating significant torque because you're standing on the pedal and asking it to do all kinds of work. A well-trained ear will pick up a static state of engine RPM while the vehicle slows while the clutch slips. A tach will also.

I am speculating wildly because I do not have the car in front of me, but the persistence of chugging in lower gears indicates that the clutch mechanism is not to blame, yet. What RPM ranges do you feel it at?

(Do you know what a burned clutch disc smells like? I don't, but I might sniff around the bell housing area after you repeat the symptoms.)

I don't think most misfiring engines would show up on a temp gauge; if there is no combustion there is almost NO heat generated. OVER-advanced timing shows up in head temps for sure, but also doesn't feel like a shaking or chugging.

I don't know Melissa, but she sounds like a reliable helper; can she watch a fuel pressure gauge while you create the chug?

Are you factory dual carbs or fuel injection?

I'm hungry for answers, I imagine you are too.
Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by whc03grady » Sun Aug 09, 2015 6:36 am

asiab3 wrote:Sounds fine? What's fine? Who's fine? I'm in trouble when things are "FINE!"
I dunno, 'fine' as in 'when I'm tooling down the highway this engine sounds as good as or better than any acVW engine I've heard over the last 25 years'.
asiab3 wrote:Do you have a tachometer?
Volkswagen didn't deign to put one in my bus.
asiab3 wrote:If not, can you hook one up during the test? A slipping clutch can manifest into a raise of engine RPM while vehicle speed remains constant. A slipping clutch can usually manifest itself at the upper end of a VW bus' speed range; here the engine is working hardest against loads from wind resistance and rolling resistance, while generating significant torque because you're standing on the pedal and asking it to do all kinds of work. A well-trained ear will pick up a static state of engine RPM while the vehicle slows while the clutch slips. A tach will also.
I can hook up my tach/dwell meter but that won't do much good on a moving car.
asiab3 wrote:I am speculating wildly because I do not have the car in front of me, but the persistence of chugging in lower gears indicates that the clutch mechanism is not to blame, yet.
It's not just lower gears, it's any gear. It's any gear when it encounters a load. In fact, it happens most in fourth because that's the gear the bus spends most of its miles in lately.
asiab3 wrote:What RPM ranges do you feel it at?
Absent a tach and hence an accurate rpm figure, I'll say I feel it at the bottom up to about the middle of the rpm range of any gear.
asiab3 wrote:(Do you know what a burned clutch disc smells like? I don't, but I might sniff around the bell housing area after you repeat the symptoms.)
I don't but haven't smelled anything odd or off.
asiab3 wrote:I don't think most misfiring engines would show up on a temp gauge; if there is no combustion there is almost NO heat generated. OVER-advanced timing shows up in head temps for sure, but also doesn't feel like a shaking or chugging.
'Temp gauge'? My temp gauge is my hand on the fan housing after pulling over. The reason I thought misfiring would lead to heat is because the lazy cylinder is making the others work harder, and therefore hotter.
asiab3 wrote:I don't know Melissa, but she sounds like a reliable helper; can she watch a fuel pressure gauge while you create the chug?
She cannot. A complicated living situation precludes my having any help.
asiab3 wrote:Are you factory dual carbs or fuel injection?
Like the signature says, factory dual Solexes.

You make me think about fuel supply... while plugging the wire from the fuel pump relay back into the barrel fuse from the blower fan, I noticed the wire from said fuse that goes into that big plastic block was a little frayed. It didn't look fantastic. But would a fuel pressure problem manifest itself only under load?
Ludwig--1974 Westfalia, 2.0L (GD035193), Solex 34PDSIT-2/3 carburetors.
Gertie--1971 Squareback, 1600cc with Bosch D-Jetronic fuel injection from a '72 (E brain).
Read about their adventures:
http://www.ludwigandgertie.blogspot.com

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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by Amskeptic » Tue Aug 11, 2015 12:10 am

whc03grady wrote:would a fuel pressure problem manifest itself only under load?
Sorry I am late.

a) do NOT drive through a loss of power. As you noted, you had two tight valves on one cylinder, and the engine cannot maintain speed. No matter how much it sucks, you need to track it down or the engine can be destroyed. Compare spark plug colors. Is any bleached white with a white ground electrode? Lean! Find it!

b) dual carbs, make sure you do not have a split vacuum line somewhere, a split boot at the brake booster? These engines help you track down problems because they have the most redundant carburetion in existence. Did you do the left/right "pull the cut-off solenoid" rpm drop test? With a warm engine, experiment! Go to each mixture screw, (note how much and in what direction you turn the screws) and what the hell, check to see if turning the left mixture screw out increases the idle speed. It is subtle, but so are you. Now check the right. Note if it responds in a similar way or not.

c) Now that we are concerned about engine damage, we need to have correctly adjusted valves (you do NOT compensate for a tight adjustment by making them "extra-loose-like" to "compensate". That is not how this works!) and a compression test.

If engine no longer does 78 mph readily, you must investigate for a cause, not just slow down some.
ColinItSureIsHOTInPhoenix
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by whc03grady » Tue Aug 11, 2015 10:20 am

Amskeptic wrote:a) do NOT drive through a loss of power. As you noted, you had two tight valves on one cylinder, and the engine cannot maintain speed. No matter how much it sucks, you need to track it down or the engine can be destroyed. Compare spark plug colors. Is any bleached white with a white ground electrode? Lean! Find it!
After adjusting those valves out the engine can and does maintain speed. I'll check the plugs.
Amskeptic wrote:b) dual carbs, make sure you do not have a split vacuum line somewhere, a split boot at the brake booster? These engines help you track down problems because they have the most redundant carburetion in existence. Did you do the left/right "pull the cut-off solenoid" rpm drop test? With a warm engine, experiment! Go to each mixture screw, (note how much and in what direction you turn the screws) and what the hell, check to see if turning the left mixture screw out increases the idle speed. It is subtle, but so are you. Now check the right. Note if it responds in a similar way or not.
The brake booster is a known problem.
I did not do a left/right "pull the cut-off solenoid" rpm drop test, but I will.
Amskeptic wrote:c) Now that we are concerned about engine damage, we need to have correctly adjusted valves (you do NOT compensate for a tight adjustment by making them "extra-loose-like" to "compensate". That is not how this works!) and a compression test.

If engine no longer does 78 mph readily, you must investigate for a cause, not just slow down some.
ColinItSureIsHOTInPhoenix
In my own defense, I didn't compensate for a tight adjustment by making them "extra-loose-like", at least not consciously. My thinking wasn't "they were tight, so I'll set 'em loose". I was just sloppy (which I suppose is as inexcusable as adjusting loose to compensate for tight would be).

The stutter or chug or whatever you want to call it persists. The lack of power does not. I wonder if I didn't hit some rogue wind (not unknown in these parts) that evening because on my weekend trips I am getting up the same hills (with the same downshift points) and making the same times and getting the same mileage I was before. It's just that damn chug.
Ludwig--1974 Westfalia, 2.0L (GD035193), Solex 34PDSIT-2/3 carburetors.
Gertie--1971 Squareback, 1600cc with Bosch D-Jetronic fuel injection from a '72 (E brain).
Read about their adventures:
http://www.ludwigandgertie.blogspot.com

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whc03grady
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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by whc03grady » Wed Aug 12, 2015 12:20 pm

This is a bad picture of the wires going into (or coming from?) that big plastic block at the blower. The fat red one powers Ludwig's fuel pump. Even in this picture you can see some fraying. I crimped on a new terminal (not shown).

Image

While I was looking down at the engine I pulled #1's spark plug, even though time was tight for me getting to work. It wasn't pretty.

Image

Image

Not bleached white, not oily, but the gap was damn near zero, plus the ground electrode was off-center about half the width of the center electrode. I bent everything back.

And guess what? The stutter/chug has disappeared. Unfortunately for science and the purposes of this forum I didn't isolate my changes so it's tough (for me anyway) to say which fixed it.

The question is, how did that electrode get so bent? Violence during installation? I don't think I've ever been that much of a brute. I'd think if the piston had whacked it the results would've been much more deadly. It's an NGK B6ES.
Ludwig--1974 Westfalia, 2.0L (GD035193), Solex 34PDSIT-2/3 carburetors.
Gertie--1971 Squareback, 1600cc with Bosch D-Jetronic fuel injection from a '72 (E brain).
Read about their adventures:
http://www.ludwigandgertie.blogspot.com

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Amskeptic
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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by Amskeptic » Fri Aug 14, 2015 12:56 pm

whc03grady wrote: #1 spark plug wasn't pretty.
gap was damn near zero, plus the ground electrode was off-center about half the width of the center electrode. I bent everything back.

And guess what? The stutter/chug has disappeared.
You fixed it, you fixed it, you FIXED it, you fixed IT, YOU fixed it!

:wav:

Yeah, so what the hell is with that plug?
Note to self: that bend is the last bend that plug ever gets. It is now structurally weaker.
Did you inspect for ANY evidence of physical contact through the normal carbon deposits?
If no evidence of any physical contact was evident, then we call it An Anomaly.
Colin You fixed it, you fixed it, you FIXED it, you fixed IT, YOU fixed it!
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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asiab3
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Re: 74 bus sudden slight loss of power, #4 valves both tight

Post by asiab3 » Fri Aug 14, 2015 2:42 pm

Nice find Mitch! How's the drag link?

No rest for the wicked,
Robbie :bom:
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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