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themarshotel7
Samba Member
Joined: February 04, 2005
Posts: 336
Location: Valparaiso Indiana
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 Posted: Thu Mar 09, 2006 8:45 am Post subject: Fuel pump push rod FAQ |
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I have an electric fuel pump and do not have my push rod installed. I have one that I am going to put in but have a couple questions. First, Do I need to use the black spacer under the block off plate? Second, The rod I have is about 5.5 inches, is that the correct rod?
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1972 Super Beetle
2001 Eurovan
1991 Fox
"Going wrong this curve set up for that unless you got a flat or suspension change even but what I found out was I could throw anything into reverse under ten miles an hour aw gosh good old granny you can allways tell by the fear in your belly how limited y'ar."
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Spezialist
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Joined: July 01, 2005
Posts: 1941
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| Posted: Thu Mar 09, 2006 1:10 pm Post subject: |
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what do you want to do?
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themarshotel7
Samba Member
Joined: February 04, 2005
Posts: 336
Location: Valparaiso Indiana
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| Posted: Thu Mar 09, 2006 1:29 pm Post subject: |
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Well i have been reading posts about needing to keep the rod in there for proper oil pressure. I ve ran for 15000 miles without it but now Im worried. 
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1971 Westy
1972 Super Beetle
2001 Eurovan
1991 Fox
"Going wrong this curve set up for that unless you got a flat or suspension change even but what I found out was I could throw anything into reverse under ten miles an hour aw gosh good old granny you can allways tell by the fear in your belly how limited y'ar."
-Neal Cassady |
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SlowLane
Samba Member
Joined: July 11, 2005
Posts: 1044
Location: Livermore, CA
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| Posted: Thu Mar 09, 2006 1:30 pm Post subject: Re: Fuel pump push rod |
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| themarshotel7 wrote: |
First, Do I need to use the black spacer under the block off plate?
Second, The rod I have is about 5.5 inches, is that the correct rod? |
Second: Judging from the pics that ratwell posted, that sounds about right, but you're gonna have to make sure that it's short enough so that it dosen't strike the cover plate when the eccentric cam is at it's highest point. Which leads to the answer to your first question...
First: Not sure. What was the function of the black spacer to begin with? I suspect it isn't needed, but it may help to resolve the pushrod cutting question. If putting the spacer in allows the pushrod free movement under the block-off plate when the eccentric cam is at its highest point, then no cutting should be required.
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keifernet
Samba Search & Rescue
Joined: May 11, 2002
Posts: 19395
Location: Samba Center for Behavioral Science
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| Posted: Thu Mar 09, 2006 1:46 pm Post subject: |
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| themarshotel7 wrote: |
| Well i have been reading posts about needing to keep the rod in there for proper oil pressure. I ve ran for 15000 miles without it but now Im worried. |
Here is that other thread... but your right...no one ever posted a maximum length it could be to not interfere or a "known dimension" to cut it down too.  
http://www.thesamba.com/vw/forum/viewtopic.php?t=158744&highlight=push
I think even with the fuel pump spacer the rod would be too long... it has to still drive the fuel pump lever up and down, so it seems to me that some cutting would still be required. |
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thevanillaninja
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Joined: October 10, 2004
Posts: 704
Location: Scott, IL
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| Posted: Thu Mar 09, 2006 1:53 pm Post subject: Re: Fuel pump push rod |
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| SlowLane wrote: |
First: Not sure. What was the function of the black spacer to begin with? I suspect it isn't needed, but it may help to resolve the pushrod cutting question. |
The spacer (normally) creates the gap for enough clearance to allow the rod enough throw to move the diaphragm and create fuel pressure. This creates some resistance (very little) and is adjustable by adding or removing gaskets, therefore changing the amount the rod can push the fuel pump. I wouldn't think that something that small could effect oil pressure, except for the guide tube for the pushrod being open (and therefore creating a cavity, changing the amount of volume in the case and dropping oil pressure very, very slightly.)
In my unproffesional opinion, installing the rod, a spacer, and then the block-off plate is not going to make a difference enough to be noticed, let alone adversly affect oil pressure. I could be wrong, but personally wouldn't go through the trouble for something so benign.
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sluggo
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Joined: August 17, 2005
Posts: 946
Location: Portland, Or.
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| Posted: Thu Mar 09, 2006 2:15 pm Post subject: |
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That was my thread. It may or may not make a difference. But so far, it's the only reason I can find for my low oil pressure. I will be adding it and I'll post the legnth once i get it cut.
Not to hijack. But....Here's my new concern. Nothing is really holding the pushrod in place. It will just slide back & forth. So won't the push rod just keep whacking the block off plate? Even if you cut it shorter than the distance between the lobe and the plate it could slide over to the lobe and then get smacked into the plate. I posed the question of welding the rod to the plate and didn't get a response.
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SlowLane
Samba Member
Joined: July 11, 2005
Posts: 1044
Location: Livermore, CA
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| Posted: Thu Mar 09, 2006 2:20 pm Post subject: |
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| keifernet wrote: |
| no one ever posted a maximum length it could be to not interfere or a "known dimension" to cut it down too. |
That's because it was only last week that the light bulb went on in Colin's head about this issue. It hasn't been around long enough for anyone to actually implement the solution and report back on what length the pushrod should be cut to.  I believe sluggo is the first to be trying it out, though.
| keifernet wrote: |
| I think even with the fuel pump spacer the rod would be too long... it has to still drive the fuel pump lever up and down, so it seems to me that some cutting would still be required. |
Depends on the design of the pump, I'd say. I wouldn't know, I've never worked on an early type IV. I'm just guessing based on photos I've seen posted.
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Present:
'81 Westfalia: 2L, manual. Originally Canadian, now Californiated
Back in the day:
'72 Super Beetle
'69 Camper Van - Corvair powered
'71 Window Van - Transferred Corvair from '69
"With sufficient thrust, pigs fly just fine." - Internet RFC 1925
"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance." - Sir Terry Pratchett |
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keifernet
Samba Search & Rescue
Joined: May 11, 2002
Posts: 19395
Location: Samba Center for Behavioral Science
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| Posted: Thu Mar 09, 2006 2:34 pm Post subject: |
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| SlowLane wrote: |
| keifernet wrote: |
| no one ever posted a maximum length it could be to not interfere or a "known dimension" to cut it down too. |
That's because it was only last week that the light bulb went on in Colin's head about this issue. It hasn't been around long enough for anyone to actually implement the solution and report back on what length the pushrod should be cut to. I believe sluggo is the first to be trying it out, though.
| keifernet wrote: |
| I think even with the fuel pump spacer the rod would be too long... it has to still drive the fuel pump lever up and down, so it seems to me that some cutting would still be required. |
Depends on the design of the pump, I'd say. I wouldn't know, I've never worked on an early type IV. I'm just guessing based on photos I've seen posted. |
I can see by your "eyeroll" that you interpet something in my post differently than intended....
I doubt that Colin in all his infinant wisdom and knowlege was the first to contemplate/think of whatever this scenario.... But maybe anyone who has is just not a member of this forum  So no one posted a dimension yet... was all I was pointing out. Whether or not the theory is 100 percent accurate may become a hotly debated topic, I admit I never thought about the possibility  but then again I have seen engines with no pushrod in go many tens of thousands of miles with seemingly no ill effects or evidence that oil pressure was a problem.
But I think it is a good idea to cut a rod and install it anyway.. any modification that is so simple and can benifit the life of these engines is welcomed.
As far as welding the rrod in place to the block off plate that could be done but you would have to have it positioned pretty precise or maybe the holes of the block off plate could be opened up for a little room for adjustment. |
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SlowLane
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Joined: July 11, 2005
Posts: 1044
Location: Livermore, CA
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| Posted: Thu Mar 09, 2006 4:30 pm Post subject: |
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| keifernet wrote: |
| I can see by your "eyeroll" that you interpet something in my post differently than intended.... |
Ok, maybe I was a bit tetchy...
| keifernet wrote: |
| I doubt that Colin in all his infinite wisdom and knowledge was the first to contemplate/think of whatever this scenario.... But maybe anyone who has is just not a member of this forum |
Well, the fact that the pushrod intersects an oil gallery is not glaringly obvious, unless you've just pulled the gallery plug behind the flywheel and noted "Hey, what's that rod doing there? I'd better remember to leave that in there when I replace the mechanical fuel pump with an electric one". You'd pretty much have to be musing on the intricacies of the type IV oiling system, as Colin was, for the connection to be made.
| keifernet wrote: |
| So no one posted a dimension yet... was all I was pointing out. Whether or not the theory is 100 percent accurate may become a hotly debated topic, I admit I never thought about the possibility but then again I have seen engines with no pushrod in go many tens of thousands of miles with seemingly no ill effects or evidence that oil pressure was a problem. |
If you didn't think of it either, with your considerable experience, what are the odds that some random contributor, new to Samba, would say "oh, yeah, I knew that..."?
As far as debate goes, I'm sure there will be a number of folks who will say "My engine ran forever like that. I don't think it makes a difference." More power to them...
| keifernet wrote: |
| But I think it is a good idea to cut a rod and install it anyway.. any modification that is so simple and can benefit the life of these engines is welcomed. |
Yeah, it's one of those "gotchas" that you wouldn't normally think about when performing a seemingly innocuous upgrade. Maybe there should be a sticky describing such "gotchas". 
| keifernet wrote: |
| As far as welding the rod in place to the block off plate that could be done but you would have to have it positioned pretty precise or maybe the holes of the block off plate could be opened up for a little room for adjustment. |
I think welding the rod to the plate would cause more trouble than leaving the rod floating free. Getting the alignment correct would be a royal pain.
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Present:
'81 Westfalia: 2L, manual. Originally Canadian, now Californiated
Back in the day:
'72 Super Beetle
'69 Camper Van - Corvair powered
'71 Window Van - Transferred Corvair from '69
"With sufficient thrust, pigs fly just fine." - Internet RFC 1925
"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance." - Sir Terry Pratchett |
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busman78
Samba Member
Joined: August 17, 2004
Posts: 4659
Location: Oklahoma City, OK
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| Posted: Thu Mar 09, 2006 5:01 pm Post subject: |
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I suspect this is for a T4 engine. If so, slip the rod in, hold you finger on it and have a good buddy rotate the engine by hand. You will find out whether the rod needs to be cut. Just to be safe I always cut an inch off the rod and slip it back in. No spacer needed, a little gasket sealer and bolt the cover on. Without the spring action of the pump the rod will most likely remain away from the cam.
Another cure is to tap the rod hole and screw in a short set screw or allen head screw. |
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SlowLane
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Joined: July 11, 2005
Posts: 1044
Location: Livermore, CA
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| Posted: Thu Mar 09, 2006 5:23 pm Post subject: |
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| busman78 wrote: |
| Another cure is to tap the rod hole and screw in a short set screw or allen head screw. |
Er, that would block off the top end of the pushrod bore. How would you block off the bottom end (at the camshaft end)?
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Present:
'81 Westfalia: 2L, manual. Originally Canadian, now Californiated
Back in the day:
'72 Super Beetle
'69 Camper Van - Corvair powered
'71 Window Van - Transferred Corvair from '69
"With sufficient thrust, pigs fly just fine." - Internet RFC 1925
"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance." - Sir Terry Pratchett |
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busman78
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Joined: August 17, 2004
Posts: 4659
Location: Oklahoma City, OK
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| Posted: Thu Mar 09, 2006 9:49 pm Post subject: |
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| Haven't a clue, never done the screw trick. Been told and read about it. I have always used the pushrod. Get weak in the knees when it comes to tapping a hole on a motor that is already assembled, something about little particles of metal floating around bothers me. Simplest solution is always the best and the rod is simple. |
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Amskeptic
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Joined: October 18, 2002
Posts: 8586
Location: All Across The Country
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| Posted: Thu Mar 09, 2006 10:14 pm Post subject: |
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Just got back from a 3,750 mile banzai to Boston MA (Bentley) and Essex NY (mumsie and poppie) and Rochester NY (tedious lawyers) and thought about the pushrod deal the whole time. Personally, I think it is crazy that VW would have full oil pressure on the pushrod, it is in no need of all that. I do not know if VW had a restriction between the gallery and the pushrod bore, I do not know if they relied on the clearance between the pushrod and its bore to meter the oil, I do not know. I would slap a spring in there between the pushrod and the block-off, any old compressible spring, even a retractable pen spring, anything to keep a mild contact on the cam eccentric. Then the length of the pushrod would be irrelevant, and there would not be any banging around of loose pushrods. So, in light of the oil pressure question, it was a guess, might be a good guess even, but can anyone get a visual between the pushrod bore and the oil gallery just above it to see how/if it is restricted?
Colin
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Spezialist
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| Posted: Thu Mar 09, 2006 10:19 pm Post subject: |
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I got a simple solution thats a proof positive fix. Put the stock fuel pump on. Use it or not.
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Amskeptic
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| Posted: Thu Mar 09, 2006 10:22 pm Post subject: |
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| spezialist wrote: |
| I got a simple solution thats a proof positive fix. Put the stock fuel pump on. Use it or not. |
That's what I'd do. You do need it to hold oil however, and that means a decent diaphragm or a U-hose from inlet to outlet and keep an eye on that little breather hose that slips in the right lower tin.
Colin
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[email protected]
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Joined: September 26, 2002
Posts: 63
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| Posted: Fri Mar 10, 2006 4:59 am Post subject: |
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| No spring, no fuel pump. With no force pushing the rod back to the cam, it will only float. The ram on the cam is so slight that if the rod ever does drift into the cam (maybe if you parked at an exteme angle), the cam will push the rod away. The cam is not going to snap the rod out into the plate. |
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ratwell
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Location: Victoria, BC
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| Posted: Fri Mar 10, 2006 8:52 am Post subject: |
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The fuel pump push rod rides in a sleeve. The sleeve keeps the oil pressure up but it weeps in that area which is why there is a return hole to the sump.
Running the engine without the push rod shouldn't mean low oil pressure unless the sleeve has also been removed or is damaged.
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sluggo
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Location: Portland, Or.
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| Posted: Fri Mar 10, 2006 9:33 am Post subject: |
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| ratwell wrote: |
The fuel pump push rod rides in a sleeve. The sleeve keeps the oil pressure up but it weeps in that area which is why there is a return hole to the sump.
Running the engine without the push rod shouldn't mean low oil pressure unless the sleeve has also been removed or is damaged. |
Forgive me for being stupid. By the "sleeve" do you mean the tunnel the pushrod goes in or is the a sleeve you put in there to hold the pushrod? I don't see one in my manual but I was thinking the pushrod seemed a little loose in there.
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ratwell
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