Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Fuel Hose Clamps

The original engine mounted crimped fuel hose clamps are a known leak problem and many owners have replaced them with screw type hose clamps. If you were lucky a leak around the injectors resulted in new windscreens, if you were unlucky a fire.

Following a report of a fuel leak on a car that has had new hoses and clamps fitted in the last two years I had a check on my car. I replaced the hoses (and clips) a bit over two years ago and was surprised to find all the hose clamps were on the loose side, not leaking but they all required a couple of turns to tighten them fully. Not sure if this is just the hose bedding in or the clamps working loose with vibration.

It may be worth a check on the hose clamps if you have replaced them. I have put some locking varnish on the clamps to show if they have moved now. If you still have the original crimped on clamps....why?

That is a very good reason to have someone make up injector tower clamps with AN fittings.

The hose clamp screws won't have moved Ian, even with vibration, but the hose wall will have distorted/settled with time allowing room for further nipping up.

I think you are correct Richard but a bit of locking varnish never hurts 😊.

Fuel hose tends to shrink a bit with exposure to modern fuels, especially non FI rated hose which can shrink rather alarmingly. High quality OEM FI hose that the major manufacturers use will exhibit almost no shrinkage. Note that most manufacturers today do not use screw clamps on their high pressure lines, but rather the crimp type which are much maligned and misunderstood on this forum due to using incorrect type, size and installed with incorrect tools.

I would add that to use crimp type hose clamps on high pressure FI systems there are requirements:

Use only stainless steel clamps to preclude corrosion related failures
Use only clamps that fully wrap around the hose (oetiker stepless type) sometimes called wrap and a half as they have an overlapping wrap
Use the smallest diameter that will slide over the installed hose to insure proper tensioning
Use the correct parallel blade 'pincer' tool to install

Using the above guidelines (which I have been doing for the last 30 years or so) you will not have a clamp related failure or leak.

If you are using the cheap parts store fuel hose, you will want to replace that every few years or better yet get OEM spec FI hose from a dealer (think BMW, Porsche, etc)

Unlike oetiker type clamps which maintain clamping pressure over time through constant spring force, screw type clamps are not dynamic, i.e. once set, you will have to nip them up over time to compensate for hose shrinkage. Screw type clamps, unless the double wrapped type, will also deform and perhaps damage the outer laters of the hose.

As an interesting side note and testimonial, stepless stainless oetiker clamps (along with smooth ring type copper clamps) have been used in millions of Pex type plumbing installations (in the U.S. at least) for over 20 years without issue.

bitsobrits
I agree with you, there is also a Norma quality collar that does not damage the hoses and is not easy to obtain.


The Oetiker collars are very good collars but do not allow subsequent tightening if they have been tightened to the maximum during assembly and the good clamp is appreciated.
I used Gates barricade to redo the two hoses with Oetiker collar at the bottom and Norma collar at the top and protect my hoses with fiberglass sheath, I hope it will last as long as the original hoses (8 years ).

Those top ones look like Mikalor ones?

Those look like the Norma ones that MMC use and they are infinitely superior to the usual ones available online which seem to be made from very thin, bendy metal. I've just been able to open a business account with Wurth and now have some on order. Not cheap, but worth every penny I reckon.

I see you threaded pipe fittings into the injector clamps/towers. Good idea.