TheSamba.com :: View topic - GoWesty Coolant Pipe Repair Kit

Wed Jan 27, 2010 5:30 pm

theoutlaw wrote: Straight from the horse's mouth.
One end or the other!

I hate to say this, but his rather fuzzy explanation bolsters the naysayer's position. It still comes down to the brute force of the clamp that holds the hose to the pipe. If that loosens, the game is over.

Wed Jan 27, 2010 5:33 pm

I read the update, but they're still operating under the same premise, just with more technical information provided.

Quote:
This happens because the coefficient of friction between the plastic and the steel insert is very low compared to the friction between the plastic and the rubber hose. Heat, coolant flow, and vibration cause the metal insert to wiggle out of the plastic over time. Eventually, the metal insert wiggles out from under the spring clamp, allowing the plastic tubing to collapse. When this happens, the clamp can no longer exert any force between the hose and the plastic. So, the force generated by the coolant pressure exerted over the cross section of the hose (pressure x area) is no longer counteracted by the frictional force between the plastic and the rubber hose (normal friction x µ). In engineering terms, this is called a "free body diagram that is no longer in balance." In layman's terms it is called, "Holy crap, what is all that coolant doing on the ground!" Result: The hose blows off, which leads to all of the coolant rushing out, which in turn causes the engine to melt down and ruin an otherwise perfect roadtrip.

Wed Jan 27, 2010 5:35 pm

I do not recall whether or not the other three coolant hoses are formed in a similar manner. It seems fairly irrelevant to me though as I have stated that I have seen several partial failures where the insert has come out partially but not completely and it in all cases the movement of the insert has been accompanied by the rubber hose moving with the stock insert and not the stock insert moving further into the respective rubber hose.

It's seems the you and the other folks that think the GoWesty kit is reasonable imagine that the stock inserts are just floating in the ends of the coolant pipes and a slight nudge will send them out. That is not at all the case. All the pipes I've dealt with, if the insert was only partially pulled out, then with the plastic hose heated and channel lock pliers on the insert you might be able to pull one out with considerable effort. With the pipes heated, to get the insert back into place required some good hammer blows.

Do I think it is possible for the insert to work it's way further into the rubber hose in any of the junctions? No. I do not and have stated such in several posts. In fact I would go so far as to state that I find the idea absurd and I say so honestly hoping not to offend anyone. There is no motive force that will push the insert out of the coolant hose and into the rubber hose. The friction just between the nub of the insert and the coolant hose in each of the intersections would be enough to hold the insert in place if it was not being pulled out of the coolant hose by some other force other than vibration and heat. The additional friction of the insert in the end of the plastic pipe is considerably more than that (I'm understating it there...). I cannot believe that heat and vibration alone would ever generate the force necessary to move the insert at all considering the amount of friction keeping it in place. Furthermore, my experience has supported my assessment.

I don't understand why you would believe GoWesty's assessment above and beyond logic, physics and all of the firsthand personal experiences so far related in this thread. Weird.

I just read the "update". I don't find it to be accurate or helpful [can I get an award for understatement?].

PDXWesty wrote: I read the update, but they're still operating under the same premise, just with more technical information provided.

I'd have to put the words "technical information" in quotes in that sentence. :lol:

Did they write the script for the turbo encabulator?

Wed Jan 27, 2010 6:24 pm

Quote: I don't understand why you would believe GoWesty's assessment above and beyond logic, physics and all of the firsthand personal experiences so far related in this thread. Weird.

As I stated above, I never said I believed them or not, and I agree that I don't know how the pipes fail. I was only trying to explain from their point of view what is happening and how the kit works, per the original posted question. I believe I brought some clarity to that point. If you believe their premise on pipe failure, the kit works. If you disagree, it doesn't work.

There is no cut and dry, right or wrong answer here. There are simply two different opinions as I see it, yours and GoWesty's.

Wed Jan 27, 2010 6:28 pm

Wow. What a wild discussion. Seems a couple [inexpensive] SS pop rivets, properly placed, would work beautifully and save a lot of moolah!

Wed Jan 27, 2010 6:31 pm

I think it's great everyone here gets to express their own opinions, and agreeing to disagree should be done with respect. Thanks Andrew for reminding me.

Wed Jan 27, 2010 6:40 pm

westyventures wrote: Wow. What a wild discussion. Seems a couple [inexpensive] SS pop rivets, properly placed, would work beautifully and save a lot of moolah!

The GoWesty article mentioned that this would cause the plastic to break. I would say that this could be a likely result.

If someone were to do this they might want to try 6-8 screws or pop rivets to spread the load.

Wed Jan 27, 2010 6:54 pm

Wildthings wrote:
The GoWesty article mentioned that this would cause the plastic to break. I would say that this could be a likely result.

If someone were to do this they might want to try 6-8 screws or pop rivets to spread the load.

Doubtful a 1/8" round hole would cause the entire pipe to crack. You'd only need one per insert to do the job, placed behind the clamping surface but well in front of the plastic barb. I have a set of pipes lying here on the ground, perhaps will give it a try.

Wed Jan 27, 2010 6:55 pm

One of my pipes failed in front. Yes, the article is right. The barb is stressed, it cracks and then pulls away because there is no tension on the insert . Short term fix was a small SS screw through the plastic into the insert. The hose covers and hides the screw. Then I sold it ( Full disclosure of course. I recommended the gowesty repair to the buyer)!
Sorry it this sounds simplistic, but if you had it happen and get under there--then study the repair--it becomes clear why it broke and why it will work. One place where a worm gear clamp is better than those euro-spring clamps.
Solution is to change to SS coolant pipes and a ford Z-tech motor.

Wed Jan 27, 2010 7:20 pm

The barb doesn't break allowing the insert to then move, the insert moves first, breaking the barb on the way out and carrying it with it.

The GoWesty fix assumes the insert moves while the hose stays put. That is not quite how mine failed. The hose on mine moved out with the insert. The GoWesty approach can't seem to work if the hose moves too.

Maybe they don't all fail the same. Or maybe the hose doesn't move right away, but gets a growing pulling force on it as the insert AND BARB move into it eventually reaching the narrow part inside and then the hose clamp can't keep the hose in place. I don't know.

mark

populuxe59 wrote: One of my pipes failed in front. Yes, the article is right. The barb is stressed, it cracks and then pulls away because there is no tension on the insert . Short term fix was a small SS screw through the plastic into the insert. The hose covers and hides the screw. Then I sold it ( Full disclosure of course. I recommended the gowesty repair to the buyer)!
Sorry it this sounds simplistic, but if you had it happen and get under there--then study the repair--it becomes clear why it broke and why it will work. One place where a worm gear clamp is better than those euro-spring clamps.
Solution is to change to SS coolant pipes and a ford Z-tech motor.

Wed Jan 27, 2010 7:52 pm

I always assumed the barb/bead was part of/fused to the insert and not part the coolant pipe. I never saw anything that would make me assume that the barb had once been part of and then cracked off the coolant pipe.

Wed Jan 27, 2010 8:00 pm

westyventures wrote: Wow. What a wild discussion. Seems a couple [inexpensive] SS pop rivets, properly placed, would work beautifully and save a lot of moolah!

If you've read all the big to-do over electrolysis you'd make them rivets aluminuminum.

Wed Jan 27, 2010 8:43 pm

tencentlife wrote: westyventures wrote: Wow. What a wild discussion. Seems a couple [inexpensive] SS pop rivets, properly placed, would work beautifully and save a lot of moolah!

If you've read all the big to-do over electrolysis you'd make them rivets aluminuminum.

:lol:

Steel rivets then. Aluminium might not be strong enough. :wink:

Wed Jan 27, 2010 8:48 pm

man we must all be tired of the old material,
this is the new Oil, tire, shock, thread?

ok i'll add to context, how about JB weld? I hear we can use that on our heads? so why not our pipes :lol:

Dan in NY

Wed Jan 27, 2010 9:52 pm

I just looked at the ends of 6 pipes I have saved for future use. I'm fairly certain the plastic barb is part of the plastic pipe. It appears to me that the barb was machined into the plastic after the metal insert was installed. The barb looks like it was formed as part of the operation that made the recessed hose clamping area near each end of the pipes.

Look closely at the next photo. If you compare the ends of the 2 pipes I think you can see the problem in an early stage. The upper pipe has the insert still recessed in from the edge and the plastic barb has an angled slope. The lower pipe has the insert moving out and you can see a white ring inside where the bulge in the metal insert has moved about half way through the barbed section, flattening out the barb surface in the process.

Mark

Andrew A. Libby wrote: I always assumed the barb/bead was part of/fused to the insert and not part the coolant pipe. I never saw anything that would make me assume that the barb had once been part of and then cracked off the coolant pipe.

Wed Jan 27, 2010 10:45 pm

Thanks for the pics, Mark. Very interesting. All the separated inserts I've seen looked almost exactly like this pic from the GoWesty site but with the insert pulled out varying amounts:

The barb was attached solidly to the steel insert.

Wed Jan 27, 2010 11:01 pm

Yes it seems there may be some variation in the failure modes. Here is one of my pipes that has a tear starting in the barb as the insert pushes out. I think it is headed for the classic type failure with the barb detached and stuck on the end of the extruded insert. I have thrown away all my removed pipes with really ugly failures so what I have left are what I consider good or pretty good pipes. Even those are far from perfect.

Mark

Andrew A. Libby wrote: Thanks for the pics, Mark. Very interesting. All the separated inserts I've seen looked almost exactly like this pic from the GoWesty site but with the insert pulled out varying amounts:

The barb was attached solidly to the steel insert.

Wed Jan 27, 2010 11:06 pm

I think it's made of a piece. Seems to me the sleeve is cast in place with the plastic as reinforcement for clamping, the barb and clamp recess are formed by the mold. Then the pressure pulling against the back of the barb strains the weak point in the plastic which cracks along that line, and the barb with the sleeve start working their way out.

Vibration probably plays a role in initially fracturing the plastic behind the barb but also later in inching the sleeve out of the body of the tube, but I think pressure is the main force at play in pulling the juncture apart.

Thu Jan 28, 2010 12:12 am

Maybe it isn't the insert pulling out, maybe it's the plastic pipe slowwwwly shrinking....

Thu Jan 28, 2010 12:15 am

It really looks to me like it is a design flaw on VW's part to have such a sharp change at the toe of the barb. They should have had a nice large radius to eliminate the stress concentration.