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I bought a set of fuel injection hose clamps and updated all the fuel lines in the engine bay about 6-8 months ago. Twice now all of the clamps have managed to work themselves loose and started to leak fuel. That seems like a pretty important jobof being a clamp - actually staying clamped... Short of using Loctite and never getting them off again, are there some other clamps you guys recommend that actually perform their expected job and stay clamped tight?


Here's a link to the clamps I bought. AVOID AT ALL COSTS.

Fuel Injection Hose Clamps Range 11mm 13mm 7 16" 1 2" 1 4" Hose Ideal 52F13 | eBay
 

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Funny you should mention this. I have exactly the same problem, using exactly the same clamps, in my '91 164S. I have had to re-tighten them twice in about 6 months since changing the hoses and installing these clamps. As soon as I get a whiff of gasoline, I pop the hood and there they are, leaking. My solution so far is to tighten the clamps and keep driving for three more months until they loosen again :)

Nothing like good repeatable data, eh? As an engineer I'm pleased. As a clamp-buyer, not so much.....
 

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I might ask what size hose did you use 5/16" (7.9mm) or the better fitting correct 7.5mm fuel injection hose?

I have used those clamps you have shown with tighter fitting 7.5mm hose with little drama but had had to retighten them in the winter using the 5/16" hose, too.
 

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Steve, I used 5/16" hose knowing full well it was just a skosche (sp?) too large. That's why I'm not up in arms about the occasional leaking.
 

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Man, you guys really need to use the right size hose. Those lines are at 40PSI.

Maybe you'll catch a leak in time, maybe you won't. All it takes is a bit of fuel and an ignition source and your whole engine could go up. It's not something to mess around with.
 

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But Mad North-Northwest
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I have the 7.5mm hose purchased from IAP.
Well, that's a good start.

Those clamps you linked to have a clamp range from 11-13mm. If that's what you used then I think that's your problem: they're too big.
 

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Tom (Gubi) -- Right you are. I shall revisit my fixes.

Let's talk about the time the pressed-in(!) fuel inlet fitting on my Fiat 850 Spider pulled out of the carb while I was driving causing a 3/8" hose of 3-psi fuel to squirt all over the highway......(no fire by the way, got lucky!). Have since bonded and safety-wired the fittings into the carb on that car, so never again.
 

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That is an important point about the Fiat, as Alfa used Solex carbs with a pressed in fuel pipe at the carb. These should all be safty wired or changed out for a Weber !
 

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But Mad North-Northwest
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I'm pretty sure the outside diameter of that 7.5mm hose is 13mm, so a 11-13mm range for the clamp should be right. No?
Ah, good point. I got confused about how hoses are measured vs. how clamps are measured!
 

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101/105guy: The carb on my 850 Spider (with the pressed-in fuel fittings) IS a Weber, a 30DICA. It isn't just some Solex models with that lousy design feature.
 

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I tried the 7.9mm hose too and noticed the two hoses on the fuel rails had a tendency to leak unless the clamps were screwed down tight. I think the problem is that one hose turn at a tight radius and the other kinks slightly (at least on the 24V valve), which causes the ends to open up. I've since replaced them with 7.5mm F.I. hose from my local Mercedes-Benz dealer and have had no leaks since. The lines from the firewall to the fuel rails did not leak when I used 7.9mm but I replaced them anyway to stay on the safe side.
 

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I used the Oetiker style crimp clamps, and haven't had any leaks on either of the cars I've replaced all the hoses on, done 3-4 years ago. I highly recommend them.

The crimp tool will set you back a few bucks, but the clamps are inexpensive, and very good at keeping the fuel where it should be. McMaster Carr has a full assortment of sizes, I found the 14.5 size perfect for the fuel hoses.

Edit - The 14.5 hose clamps I used are McMCarr #52545K53. They fit my hoses better than the next size down. Depending on the outer diameter of the brand of hose you use, though, the smaller 14.0 (McMCarr #52545k52) might be a better fit. The tool, "Pincer" is about $25, but who doesn't need more tools in their tool box... The tool works great on OE style CV joint boot clamps too.
 

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Yup, tongue and groove, stainless. Around $10 for a pack of 25.

One of the larger sizes works good for the 6ea intake runner rubber boots too, to replace the factory crimp-style clamp.
 

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Discussion Starter #18
I installed these crimp clamps today so we'll see how they hold up. One caveat though - the crimp tool was too wide to fit between the intake runners where I needed to clamp down a fuel rail hose. I had to loosen the bolts of the left-most intake runner, undo the intake runner hose clamps, and shift the runner over a bit to fit the tool in the gap. Otherwise it was easy and should solve the fuel leak. And I scored a new tool in the process :)
 

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I installed these crimp clamps today so we'll see how they hold up. One caveat though - the crimp tool was too wide to fit between the intake runners where I needed to clamp down a fuel rail hose.
I've always used regular carpenter's pincers to replace these clamps. If you buy some cheap pincers and modify them with an angle grinder, it may just do the trick.


These clamps are superior because compression around the hose is uniform.
With worm drive clamps, areas of decompression form under the blocks. With screw clamps, the whole area under the screw is only as compressed as the rigidity of the metal being pushed down allows it.
All threaded fasteners tend to come loose with vibration but regarding hose clamps, most on the market are just junk.

A few months ago I had a problem in one of my wells. I had to pull an 80 kg pump by myself 20 meters up the shaft. The reason it didn't work? A #$%&/ clamp that rusted to bits!

And regarding fire, be happy you don't have one of those BMW style plastic valve covers.
 

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"I've always used regular carpenter's pincers to replace these clamps"

That's what I use as well, no mods required.
 
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