OM606 fuel lines - skip the o-rings & use epoxy? - PeachParts Mercedes-Benz Forum

mcreynol · #1 08-20-2008, 12:49 PM

I'm getting to the point where the fuel system needs another round of o-rings. This brings me to the recurring thought:

Why not just epoxy the plastic heads into their respective holes and use some trusty 1/4" Viton hose with spring clamps? Threading in metal fittings has some appeal too, but is less reversible.

I gain:

long term reliability
ease of carrying extra hose rather then a passle of o-rings
no more air leaks (see below)

I lose:

the ability to look through the pipe
ease of dropping by the dealer for the standard parts

I suppose I could add a sight glass section in the return line as a tell-tale for any leaks.

One factor in my decision is that this is not on the E300DT but on a G300DT. MB dropped the same engine in this truck, but didn't think through the fact that the engine & fuel system was going to sit nearly 2 feet higher than the tank. The increased height increases the vacuum in the lines and thus the air leaks. The junction out of the coarse filter leaks a small amount of air even with new lines.

While we are at it, has anyone dismantled the EGR to find out the size of the o-ring (assumption) that seals the egr shaft? Mine is leaking some blow by oil.

Hatterasguy · #2 08-20-2008, 03:05 PM

Epoxy won't stick to plastic.

nhdoc · #3 08-20-2008, 03:13 PM

The rings are cheap, easy to replace and last at least a couple of years so why would it be worth experimenting with a "cure". Sure, they are a maintenance item to remember but frankly there are far worse problems that need solving than these o-rings. If you have the time to spend then sure, but in the grand scheme of things I think you will waste more time up-front in trying to come up with something that works rather than just replace the rings when needed over the lifetime of the car. Just my $0.02.

mcreynol · #4 08-20-2008, 04:26 PM

re: epoxy & plastic:
Epoxy certainly bonds to many plastics, but some experimentation is clearly warranted. The sockets represent a huge bonding area. The stress is going to be very low. I'm more worried about bad interactions with oil, oil additives and bio-diesel.

re: too much hassle - go with the stock setup
Even with new lines & o-rings air was getting in. The factory setup is just awful. Try this: shine a flashlight through your lines and rev up the engine to >2500rpm. I'll bet you see bubbles. Now try it again with the vehicle tilted up. Bubbles show up at lower rpms.

Climbing steep desert grades with a fully G (>7000lbs) involves 15 minute stretches of wide open throttle. Performance is noticeably different with a near-empty tank. I need to do something, the question is what?

The other thought was to put in an electric fuel pump at the tank to lift the fuel up to the engine, perhaps even ditching the pump on the IP.

rrgrassi · #5 08-20-2008, 04:48 PM

You can get brown colored viton o-rings.

tankowner · #6 08-20-2008, 04:52 PM

1. Are you using viton o-rings already? If not, just switch to viton and see how that goes for you.

2. I would hesitate to use epoxy, if only because when the time comes to replace it (and sooner or later it will), boy what a PITA that would be - don't you think?

mcreynol · #7 08-20-2008, 05:15 PM

Quote:

Originally Posted by tankowner

1. Are you using viton o-rings already? If not, just switch to viton and see how that goes for you.

2. I would hesitate to use epoxy, if only because when the time comes to replace it (and sooner or later it will), boy what a PITA that would be - don't you think?

I guess I didn't write up my proposal so well. The point is to remove the plastic nipples from the ends of the plastic pipes. Then permanently bond them into their respective sockets. Slip Viton hoses onto the barb that used to hold the hard plastic hose. Ensure that they stay in place with spring clips. This is how engines were plumbed for decades (with poorer quality rubber to boot). Replacement is easy: Expand spring clip, pull off hose, replace with new section of hose. The parts are actually cheaper than the factory hoses and o-rings.

ds190 · #8 08-20-2008, 05:21 PM

How about coating the new viton O rings and the line end connector with a light coating of some kind of gasket maker goop as you slide it back in? Let it cure. It would have to hold up to fuel of course, but would seal air leaks and could be disassembled.

turbobenz · #9 08-20-2008, 05:22 PM

Epoxy will probably deteriorate quickly in contact with fuel oils

TMAllison · #10 08-20-2008, 05:37 PM

Quote:

Originally Posted by mcreynol

I guess I didn't write up my proposal so well. The point is to remove the plastic nipples from the ends of the plastic pipes. Then permanently bond them into their respective sockets. Slip Viton hoses onto the barb that used to hold the hard plastic hose. Ensure that they stay in place with spring clips. This is how engines were plumbed for decades (with poorer quality rubber to boot). Replacement is easy: Expand spring clip, pull off hose, replace with new section of hose. The parts are actually cheaper than the factory hoses and o-rings.

You'd still need an oring to get a cut off fuel line to seal to each port even if you could find a suitable bonding material. Then trying to crank clamps down to the remaining stub of soft plastic fuel line would probably cause more problems than you are having now.

Biggest downside is that you couldnt easily go back as the SOV, lift pump and fuel filter housing would all have epoxy stuffed in there ports. Those would be costly.

Member JADAVIS at fryerpower.com has a kit of orings for the 606.962. I've had them in mine for 1.5yrs w/o issue.

nhdoc · #11 08-20-2008, 06:15 PM

Well, as far as any air bubbles go that if they do exist they don't seem to do any harm in my case since the car runs fine all the time.

Unless mine is leaking fuel or having a problem starting (which it has never done) I see no reason to modify the stock system. Maybe you have a bad fitting or crack in the lift pump or shutoff valve that is causing your ongoing problem with air leakage...I can only say from my experience that with just a little attention the system seems to work fine for me and many others.

mcreynol · #12 08-20-2008, 07:18 PM

Where is the spirit of innovation?

Shown below is an example of the existing, and ever so leaky, hose end. They are quite rigid. The barb (.29") is exactly the correct size for a 1/4" hose. I've logged >300K miles now on the two OM606s I own and have replaced the o-rings several times now on each. The leaks are always at an o-ring site. This annoyance has been eating at me for a while now. I'm looking for a more permanent fix.

As stated earlier, new o-rings don't fix the problem though they do reduce the severity. The much rarer X Profile O-rings would probably do it, but they don't seem to come made of Viton or equivalent material.

Jadavis · #13 08-20-2008, 08:46 PM

Quote:

Originally Posted by TMAllison

Member JADAVIS at fryerpower.com has a kit of orings for the 606.962. I've had them in mine for 1.5yrs w/o issue.

It doesn't seem like it has been that long since I started selling the viton components.

http://www.fryerpower.com/store/page11.html

Coming soon to my site will be the little plastic gear that goes in W140 wiper transmissions. The dealer won't sell the gear and they want $1,450 for a new wiper transmission!

Maybe after that I will go after the plastic gears in my sunroof motor...

-Jim

777funk · #14 08-20-2008, 08:53 PM

So... fill me in on this. I don't have a 606. Are these lines/oring fitting used on the IP instead of the old Banjo fittings on the injection pump like on a 61x and the 601 2 and 3 engines?

I'm lost. What is this part?