What happens if I replace the cigar hose with standard fuel line hose?
 

The car is a 1985 300TD.
I noticed the cigar hose on my fuel injection return side was leaking
A little fuel so I replaced it with standard fuel line hose.
Seems to run the same, does it hurt anything.
Does it make the idle surge a little since the pulsing pressure has no place to go.
Curious what to look for if it does present a problem.

I've been running mine without one for the last 35k miles without any noticeable side effect.

if your car was totally stock, and perfect, free from any rattles, and such... having standard fuel hose there would cause a pulsing noise at idle...
if you don't hear anything, it's fine.

Thanks for the replys that what I figured.
I may order one next time from pelican when I get some
other parts.

You should be able to get some from the dealer for not much $$.

hey Rocky,
Mines been running with regular fuel line for about the last zillion miles with no problems. I wouldn't worry about it!
Cheers,
Chris

A friend has done this, no issues.

Gentleman the hose has a function other than noise abatement I have always suspected. Some cars do not tolerate the absence as well as those reported on this thread.

If your fuel pressure is not high enough to keep the relief valve open it will not matter what is there. In fact technically you would not need a return line as enough fuel pressure would not be present to even open the relief valve.

Following up on what vstech posted, the cigar hose is shaped that way to dampen pulses in the line. It is not particularly expensive, I think I got the one for my 300d for around $12.

A regular piece of fuel line will work, but on a previous group I do know that a couple of people who purchased cars with regular line substituted, reported that their cars idled better once the cigar hose was installed.

The high idle on my 1978 300D exibited some "sawing" before I replaced the cigar line.

Phil Forrest

I know of one car that was fuel level in the tank sensitive. It operated great below 1/4 tank or so. Above that fuel level there was an issue. Car was acquired without the cigar hose present.

I suggested over some objections that the cigar hose was needed. The objections where that the only function was noise reduction. The fuel level operational problem was then gone when a new cigar hose was installed for the tube.

If the fuel pressure is normal. The relief valve will always be open or at least 95 percent of the time. There are fierce hydraulic pulses inside the injection pump.

The cigar hose being of softer rubber mitigates their severity. That is also a reason to compare a really old heat baked cigar hose especially in the southern states with a new one. If the cigar hose has become hard of course there will be no difference with substitution of a solid tube for it.

There may also be no apparent differance with the hose being soft and substituted with a stiff hose. I would want to know the operational pressure in the base of the injection pump if that was the case. It may be below the opening pressure of the relief valve. A simple test may be to look for fuel returning to the return line.

Their are some issues in this area as well. Some euro cars with the same euro injection pump where manufactured with and without the cigar hose. We got a diferent injection pump in north America. I never researched that to find the reason and do not know if it is mentioned anywhere or not.

So with regular hose instead of cigar hose could it cause the idle to be sort of lopey? My car has always idled a little lopey, and I've never had a cigar hose. I always attributed it to the rack damper being worn out or something

true...and it is usually replaced by simple 8 return hose... but those are all
M pumps...




you can easily test that one,take the return hose off and place it directly
in plastic bottle/can ( 2 or 3 quarts capacity minimum and extra guy behind a wheel) if looping is still around go for gold rack dumper...or higher idle rpm's :D:D


.

I wish life were that simple. Still since it does make some apparent differance on some cars is factual. At least grab one at a pick and pull if in decent condition.

The effects of no cigar hose seem all over the place. Then again a lot of these older fuel systems are no longer functioning as designed and need a tuneup or at least checking.

One of the posters on this thread mentioned a sawing type of issue without one. This could be construed as loping perhaps.

Only if there is accumulated fuel in the collection container from the return line. If there is not do the relatively minor things to get the return flowing.

Actually a good test to see if the idle is impacted on cars with no cigar hose present. No return flow could also be construed as having no cigar hose effectively dampening spikes..