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Clatter Samba Member
Joined: September 24, 2003 Posts: 7527 Location: Santa Cruz
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Posted: Tue Apr 15, 2008 11:25 am Post subject: Where to get a relief valve reamer? |
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Aircooled.net no longer rents a reamer out to spot face the bottom of the plunger bore...
Anybody else out there offer this?
Who's got one? _________________ Bus Motor Build
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turboblue Samba Member
Joined: October 09, 2003 Posts: 4216 Location: Central Indiana
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Posted: Tue Apr 15, 2008 11:29 am Post subject: |
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It's a 16mm 4 flute end mill IIRC. _________________ Gary
Turbo VW Sand Drag Buggy
"If you don't run into the Devil every once in awhile, you must be going in the same direction!" |
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Jimmy111 Samba Member
Joined: October 05, 2006 Posts: 2643 Location: Wyoming
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Posted: Tue Apr 15, 2008 11:39 am Post subject: |
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You can face the seat but dont remove the taper. |
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Clatter Samba Member
Joined: September 24, 2003 Posts: 7527 Location: Santa Cruz
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Posted: Tue Apr 15, 2008 12:00 pm Post subject: |
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taper? _________________ Bus Motor Build
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Jimmy111 Samba Member
Joined: October 05, 2006 Posts: 2643 Location: Wyoming
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Posted: Tue Apr 15, 2008 12:09 pm Post subject: |
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On the bottom of the relief valve bodie is what looks like a drill taper. You need to keep that or you will have excessive oil pressure.
Read this. It is not complete yet but I working on it.
http://www.thesamba.com/vw/forum/viewtopic.php?t=280293 |
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Clatter Samba Member
Joined: September 24, 2003 Posts: 7527 Location: Santa Cruz
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Posted: Tue Apr 15, 2008 9:22 pm Post subject: |
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OK, trying to understand..
The body of the relief valve being the plunger itself?
It has a bit of 'crown' to it, or it is convex, to cover the hole more effectively?
Or, you mean the bottom of it, where the spring sits?
-or-
You mean the bottom of the hole where the plunger sets?
the bottom of the hole is tapered?
Thanks for the help.
People doing real tests like this help the hobby out a lot. _________________ Bus Motor Build
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Jimmy111 Samba Member
Joined: October 05, 2006 Posts: 2643 Location: Wyoming
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Posted: Tue Apr 15, 2008 9:29 pm Post subject: |
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You wanted to order the reamer to flatten the seat. Yes?
The spring sits on the threaded cap, then the piston sits on top of that. The piston seals against the valve seat. The valve seat is inside of the case. The valve seat has a taper drilled into it to increase the area of pressure against the piston. If you remove this taper, you will need much more pressure to open the valve and relieve the pressure. |
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Tvättbjörn Samba Member
Joined: May 07, 2004 Posts: 1431 Location: SoCal
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Posted: Tue Apr 15, 2008 11:26 pm Post subject: |
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Jimmy111 wrote: |
You wanted to order the reamer to flatten the seat. Yes?
The spring sits on the threaded cap, then the piston sits on top of that. The piston seals against the valve seat. The valve seat is inside of the case. The valve seat has a taper drilled into it to increase the area of pressure against the piston. If you remove this taper, you will need much more pressure to open the valve and relieve the pressure. |
I have seen cases they had a tube/fitting pressed in and used a steel ball with a spring. Looked and worked very good. |
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Jimmy111 Samba Member
Joined: October 05, 2006 Posts: 2643 Location: Wyoming
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Posted: Tue Apr 15, 2008 11:49 pm Post subject: |
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Ive heard of that but have never seen it. Any pics? |
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lostinbaja Samba Member
Joined: December 19, 2004 Posts: 4036 Location: Frankfort, Illinois
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Posted: Wed Apr 16, 2008 3:50 am Post subject: |
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I have used the reamer from AirCooled.net on several engines, all worked out very well. _________________ Jerry...
If it's being towed, it must be a trailer!
"Vee Grow Too Soon Oldt Und Too Late Schmardt"
RIP Morgan
My photos
http://www.manxgallery.org/gallery/album92 |
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Clatter Samba Member
Joined: September 24, 2003 Posts: 7527 Location: Santa Cruz
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Posted: Wed Apr 16, 2008 7:32 am Post subject: |
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I am chasing a low oil pressure issue with my type 4.
A year ago, i rented the reamer to do a couple of cases.
The old german cases i had, and my type 4 cases at the time had nice machining at the bottom of the bore.
The newer brazilian ones had a bit of a rough surface...
You could tellthat the tool that cut/bored the passage was getting dull, or didn't have the chips cleared right as it was finished.
Obviously, the chips had bound up and the bottom of the bore didn't finish clean.
Plus, the piston didn't have a nice tap, or tick sound as it bottomed home.
You could feel that the bore wasn't straight, or the finish was rough, so the action as the piston seated wasn't precise.
A few twists with the reamer, and it's a nice smooth slide, with a tight sounding 'tink' as it seats squarely.
Another issue is when you drill/tap for threaded galley plugs, the reamer can clean off a burr pushed into the bore by the tap.
This type 4 case I'm doing now had been sitting, or maybe suffers like the later type 1 cases in that the piston feels tight in the bottom of the bore, and doesn't feel like it's hitting against the bottom tightly.
I talked to John at ac.net yesterday, and he doesn't rent out the reamers any more.
Dickheads were keeping it, and then using the 'fraud protection' on their credit cards to unwind the deposit charge afterwards.
So a big high middle finger to anybody out there who did this. _________________ Bus Motor Build
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Clatter Samba Member
Joined: September 24, 2003 Posts: 7527 Location: Santa Cruz
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Posted: Wed Apr 16, 2008 7:38 am Post subject: |
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Oh, yeah, and Harley uses a round ball backed up by a spring in a similar manner.
Only, their use is to keep the oil from the dry sump tank from draining into the engine when it's not running.
I can speak from experience that it doesn't work that well over time, especially with ditry oil.
Has anyone ever found a smooth, maybe hard chromed ball to try in place of the piston?
If it was the right size, it might seat home tighter, and give better pressure...
Because it would be supported by the spring, it would be a lot less likely to bind or stick. _________________ Bus Motor Build
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nsracing Samba Member
Joined: November 16, 2003 Posts: 9437 Location: NOVA
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Posted: Fri Apr 18, 2008 11:58 am Post subject: |
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Where did you get that information? That is NOT true.
The "sealing" comes from the sides of the piston...NOT the crown/taper.
It does not seal like a valve. It is a piston-valve. So long as the sides of the shaft hole is NOT molested or the piston mangled, the plunger will work fine.
All the piston does is move up or down the shaft and either clear the window/hole or cover it depending on the spring and pressure of oil coming in. IT does not seal on the top.
That is why you do not insert a side-flutted reamer in there or an endmill.
You can only use an end-cutting facing tool designed for it...wth smooth sides sized to the that hole.
I make them and can grind one for you.
Taper? It is a countersink.
Last edited by nsracing on Fri Apr 18, 2008 12:14 pm; edited 1 time in total |
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turboblue Samba Member
Joined: October 09, 2003 Posts: 4216 Location: Central Indiana
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Posted: Fri Apr 18, 2008 12:04 pm Post subject: |
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If that is the case Nick, how does the check ball arrangement work?
I've seen those several times and they do seem to work.
If this schematic is correct and I think it is, the piston seats on the end when oil goes to the cooler.
When the oil is cold and bypassing the cooler, it diverts to that port you speak of.
_________________ Gary
Turbo VW Sand Drag Buggy
"If you don't run into the Devil every once in awhile, you must be going in the same direction!"
Last edited by turboblue on Fri Apr 18, 2008 12:14 pm; edited 1 time in total |
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Jimmy111 Samba Member
Joined: October 05, 2006 Posts: 2643 Location: Wyoming
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Posted: Fri Apr 18, 2008 12:12 pm Post subject: |
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Ok Nick. You have the correct terminology as far as machining. But the valve terminology is taper.
The piston does seal to the sides of the valve body but that has nothing to do with operation. The top of the piston must mate flush with the seat or the valve will open at a lower pressure. It the countersink is removed, the valve will open at a higher pressure. Much higher.
We tested 100 VW motors for that test.
Nick. Make the tools. almost every motor needs that surface resurfaced. |
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nsracing Samba Member
Joined: November 16, 2003 Posts: 9437 Location: NOVA
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Posted: Fri Apr 18, 2008 12:26 pm Post subject: |
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Gary, the "checkball" will seal like a valve. It is a ball-and-seat design. This one will most definitely need a taper or countersunk area for the ball.
If the VW plunger was designed to seal at the top, it would have been ground flush...and smooth. ...or the piston tip cut with a taper and plunge against a valve seat just like a valve head.
IT is the spring tension that will regulate the approximate release point.
You can't be messing with them springs.
Also, the hole or release point is strategically machined to reflect that pressure. It is like this... you push a piston with oil pressure in a shaft and when the right pressure shows up, below that is where you machine the hole. Neat, huh? |
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74 Thing Samba Member
Joined: September 02, 2004 Posts: 7376
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Posted: Fri Apr 18, 2008 1:26 pm Post subject: |
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Bernie Bergmann and Adriane at Headflow Masters can do the ball valve modification. The theory is that the roound ball and round seat in the case will not pund out and cause a ledge and leak like the flat piston top and flat machine in the case may do over time. |
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Clatter Samba Member
Joined: September 24, 2003 Posts: 7527 Location: Santa Cruz
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Posted: Fri Apr 18, 2008 1:27 pm Post subject: |
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Nick,
How much for a tool?
Maybe you could rent them now that nobody else does? _________________ Bus Motor Build
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nsracing Samba Member
Joined: November 16, 2003 Posts: 9437 Location: NOVA
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Posted: Fri Apr 18, 2008 3:07 pm Post subject: |
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Rent? How about buy?
YOu lend it out and it will never come back. |
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Jimmy111 Samba Member
Joined: October 05, 2006 Posts: 2643 Location: Wyoming
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Posted: Fri Apr 18, 2008 3:31 pm Post subject: |
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Ok Nick. here is the control valve page.,
Notice the surface area calculations.
Now if the bevel is removed, the amount of surface area exposed to the system pressure will be reduced and the valve will open at a higher pressure. If the seat is not fairly clean the fluid will get between the seat and the piston and cause it to open at a lesser pressure.
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