A spark plug extender? WTF for?
- JLT
- Old School!
- Location: Sacramento CA
- Status: Offline
A spark plug extender? WTF for?
Hi, all.
As a few of you know, something bad happened to my engine as I was traveling to BBB. It had all the earmarks of a burned valve ... lotsa noise, lower power, vibration. I'd done a compression test the weekend before, and the results were 140-140-130-140.
I pulled the engine out of the bus today to find out what went wrong, and when I pulled out the number one spark plug, this is what I saw. The upper plug is a normal plug (#4 in this case) and below it is what was in the number one socket:
As you see, it looks like an extension or extender ... in this case, an extender with a muckin' great hole burned into the side of it. The hole shows up nicely when I rotate the plug:
In all my years working on VWs, I have NEVER seen one of these things before, and I can't for the life of me figure out what it was supposed to accomplish except for maybe making the spark plug a little easier to get into the socket. Was there supposed to be some virtue in putting the spark plug electrodes an inch or so farther from the piston head? Was it supposed to prevent burned valves? Considering the dramatic failure mode of the part, I'm not surprised that I haven't seen one before, but why was it in there in the first place?
As it is, I'm tempted to just liberate the spark plug from the "extender" and screw it back into the head to see if it holds compression, but there's a little bit of aluminum at the base of the extender that must have come off the head threads, and since I've got the damn engine out anyway, I might as well take the heads off and see what the domes look like. (I hear my father saying "If you go looking for trouble, son, you're bound to find it.")
Has anybody else come across this sort of gizmo? Do you know the PO might have installed it?
As a few of you know, something bad happened to my engine as I was traveling to BBB. It had all the earmarks of a burned valve ... lotsa noise, lower power, vibration. I'd done a compression test the weekend before, and the results were 140-140-130-140.
I pulled the engine out of the bus today to find out what went wrong, and when I pulled out the number one spark plug, this is what I saw. The upper plug is a normal plug (#4 in this case) and below it is what was in the number one socket:
As you see, it looks like an extension or extender ... in this case, an extender with a muckin' great hole burned into the side of it. The hole shows up nicely when I rotate the plug:
In all my years working on VWs, I have NEVER seen one of these things before, and I can't for the life of me figure out what it was supposed to accomplish except for maybe making the spark plug a little easier to get into the socket. Was there supposed to be some virtue in putting the spark plug electrodes an inch or so farther from the piston head? Was it supposed to prevent burned valves? Considering the dramatic failure mode of the part, I'm not surprised that I haven't seen one before, but why was it in there in the first place?
As it is, I'm tempted to just liberate the spark plug from the "extender" and screw it back into the head to see if it holds compression, but there's a little bit of aluminum at the base of the extender that must have come off the head threads, and since I've got the damn engine out anyway, I might as well take the heads off and see what the domes look like. (I hear my father saying "If you go looking for trouble, son, you're bound to find it.")
Has anybody else come across this sort of gizmo? Do you know the PO might have installed it?
-- JLT
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
- vwlover77
- IAC Addict!
- Location: North Canton, Ohio
- Status: Offline
I have never seen one, but a little web searching supports Bill's suggestion that it's supposed to prevent the plug from getting fouled by oil.
Does your engine burn oil? Since you've got it out, maybe you can do a leakdown test to see if the rings are bad (before you pull the head!)
Does your engine burn oil? Since you've got it out, maybe you can do a leakdown test to see if the rings are bad (before you pull the head!)
Don
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
- JLT
- Old School!
- Location: Sacramento CA
- Status: Offline
I thought leak-down tests are only informative when the engine is warm. How does one do it with a cold engine? Just screw in the compression tester and hand-crank it a couple of times?vwlover77 wrote:I have never seen one, but a little web searching supports Bill's suggestion that it's supposed to prevent the plug from getting fouled by oil.
Does your engine burn oil? Since you've got it out, maybe you can do a leakdown test to see if the rings are bad (before you pull the head!)
-- JLT
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
- vwlover77
- IAC Addict!
- Location: North Canton, Ohio
- Status: Offline
A leakdown test is done with an air compressor to supply pressurized air to the cylinder with a special tester like this one from Harbor Freight.
http://www.harborfreight.com/cpi/ctaf/d ... mber=94190
It tells you the general health of each cylinder by how much of the input pressure is lost through leaky rings or valves. You can tell by listening at the intake, exhaust, and crankcase vent where the leakage is occuring.
You turn the engine to get each cylinder at top-dead center (and hold it there so the compressed air doesn't push the piston down) and then perform the test. No need for a warm engine or to turn it over with the starter.
http://www.harborfreight.com/cpi/ctaf/d ... mber=94190
It tells you the general health of each cylinder by how much of the input pressure is lost through leaky rings or valves. You can tell by listening at the intake, exhaust, and crankcase vent where the leakage is occuring.
You turn the engine to get each cylinder at top-dead center (and hold it there so the compressed air doesn't push the piston down) and then perform the test. No need for a warm engine or to turn it over with the starter.
Don
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
- JLT
- Old School!
- Location: Sacramento CA
- Status: Offline
Ah. Since I don't have access to an air compressor, I guess I won't be able to use it. But since the compression was good all around until the gizmo blew, I'd assume that the rings, etc. were working as they should have been.vwlover77 wrote:A leakdown test is done with an air compressor to supply pressurized air to the cylinder with a special tester like this one from Harbor Freight.
http://www.harborfreight.com/cpi/ctaf/d ... mber=94190
-- JLT
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
- vwlover77
- IAC Addict!
- Location: North Canton, Ohio
- Status: Offline
Was your engine burning and/or consuming oil??JLT wrote: Ah. Since I don't have access to an air compressor, I guess I won't be able to use it. But since the compression was good all around until the gizmo blew, I'd assume that the rings, etc. were working as they should have been.
Colin, would worn valve guides show up in a compression test? I'm guessing not, yet they could allow oil to be drawn into the cylinder to foul the plug, yes?
Or, maybe the PO just hated changing that one plug and installed the extender as a convenience????
Don
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
---------------------------
78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
- JLT
- Old School!
- Location: Sacramento CA
- Status: Offline
You get the prize.bus71 wrote:It looks like the extension used to check compression on some gauge set-ups. You are supposed to remove it, then replace plug.
And I get the booby prize.
I should have added that the compression tester was new, and that I was using it for the first time. The vital clue was that it was cylinder #1. What's the first cylinder you check for compression?
As I look on the Harbor Freight web site at a picture of my compression tester, I discover to my chagrin that it shows the extension firmly screwed into place at the end. Then I look at the compression tester itself, nestled quietly in my tool box, and
AAAAAAAAAAAAAARRRRRRRRRRRRRRRRGGGGGGGGGGGGGHHHHHH
I never notice that the tester hose was a little shorter after I did #1.
I think I will hang that extension from my rear-view mirror, or at least keep it in the tool tray where I can see it from time to time. It will keep me humble.
-- JLT
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
- JLT
- Old School!
- Location: Sacramento CA
- Status: Offline
One last thing on this thread:
The #1 spark plug didn't survive the ordeal. But a friend who sold her bus found some Bosch W7A spark plugs in her garage and gave them to me. I know that the heat range is different from the W8As that I have now, but can they be used in a 1600 dual port? What are the advantages/disadvantages of using the W7As?
The #1 spark plug didn't survive the ordeal. But a friend who sold her bus found some Bosch W7A spark plugs in her garage and gave them to me. I know that the heat range is different from the W8As that I have now, but can they be used in a 1600 dual port? What are the advantages/disadvantages of using the W7As?
-- JLT
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
- Amskeptic
- IAC "Help Desk"
- Status: Offline
Type 4 plugs normally cannot be used in a Type 1 engine due to the longer thread reach.JLT wrote:One last thing on this thread:
The #1 spark plug didn't survive the ordeal. But a friend who sold her bus found some Bosch W7A spark plugs in her garage and gave them to me. I know that the heat range is different from the W8As that I have now, but can they be used in a 1600 dual port? What are the advantages/disadvantages of using the W7As?
I will be blowing away the chitchat on this thread.
Colin
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
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
- regis101
- Getting Hooked!
- Location: Livermore, Ca
- Status: Offline
The W8AC is physically different than the W8CC. His is a 71
I was looking for the colored chart about thread, reach etc but found this.
http://landiss.com/boschplugs.htm
The A and C have different reach.
I was looking for the colored chart about thread, reach etc but found this.
http://landiss.com/boschplugs.htm
The A and C have different reach.
- JLT
- Old School!
- Location: Sacramento CA
- Status: Offline
A follow-up of sorts
I was over at the Kombi Haus in Sacramento yesterday, and one of the mechanics told me that when he was changing somebody's spark plugs, he found an unusually high one. You guessed it ... that somebody left the compression tester extender in the cylinder head, the same as I did. Fortunately, he didn't try to drive it twenty miles.
I felt a little better about it then.
The moral of the story is that if you're using a new compression tester, be sure that all of it comes out.
I felt a little better about it then.
The moral of the story is that if you're using a new compression tester, be sure that all of it comes out.
-- JLT
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"
Sacramento CA
Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"