Does diesel eat rubber?

[Kelpie]

Been messing around with the fuel pipes on my boat over the last few days. The pipes are armoured and where the jubilee clips are placed, what I assume to be self-amalg tape has been wrapped round- possibly the jubilee clips are a bit on the big side and this helps them to pack them out.
Anyway, the rubber tape has turned into a sticky gooey mess, and might be the source of some problems I've had with air in the fuel. It seems like maybe the tape is breaking down. I know that you have to keep some rubber compounds away from diesel. Any suggestions for something more robust that I can put on in place of the gunky self-amalg tape?

 

[pvb]

Any suggestions for something more robust that I can put on in place of the gunky self-amalg tape?

I'd suggest using properly-sized clips!

 

[KellysEye]

Yes it does, it doesn't eat neoprene if you need to pack something out. However it sounds like a bodge job and the hoses may be damaged. Personally I would replace the fuel hoses and fit the proper size hose clips.

Out of interest when we changed from copper pipe to fuel hose we put two filters in parallel with on/off switches, as all motor boats have. If you do get air in a fuel line simply switch to the other filter. Good news if (say) you are close quarter manoevering under engine.

 

[Trundlebug]

Yes it does, it doesn't eat neoprene if you need to pack something out. However it sounds like a bodge job and the hoses may be damaged. Personally I would replace the fuel hoses and fit the proper size hose clips.

Out of interest when we changed from copper pipe to fuel hose we put two filters in parallel with on/off switches, as all motor boats have. If you do get air in a fuel line simply switch to the other filter. Good news if (say) you are close quarter manoevering under engine.

That sounds just like the mod I want to carry out. Do you have any photos of the revised installation?
(Apologies to OP for thread drift)

 

[KellysEye]

>Do you have any photos of the revised installation?

Sorry I don't and I'm a long way fom the boat, it's easy to do though. You need a Y splitter to split inlet hose to the two filters and a second one to combine the two hoses from the out side of the two filters. Obviously the single part of the outlet Y goes to the engine fuel filter.The on/off switches screw into the inlet side of the filters. I got all the kit to do that from ASAP supplies. www.asap-supplies.com. You will need to explain which filters you have in order for them to know the thead size for the on/offs. That should also tell them the hose size you need but it might be worth measuring it anyway.

Don't underestimate the amount of hose you need particularly if the filters are phsically in-line. It took a me about an hour and a half to do, mainly because of the measure twice cut once then check rule.

 

[Lady Campanula]

I'm told by a reliable engineer that diesel can/does attack the rubber used in raw water cooling impellers. That can come about when running the engine in a diesel-contaminated marina/harbour.

"Far-fetched," I thought at the time. Not any more.... It may take a while, but a film of diesel on one's impeller can destroy the integrity of the core which binds the rubber blades to the rotating shaft.

 

[PCUK]

Nitrile is the rubber that isn't affected by diesel.

 

[Kelpie]

Thanks, will see if I can get some better fitting jubilee clips.

 

[Joker]

Depends how hungry it is.

 

[scottie]

>Do you have any photos of the revised installation?

Sorry I don't and I'm a long way fom the boat, it's easy to do though. You need a Y splitter to split inlet hose to the two filters and a second one to combine the two hoses from the out side of the two filters. Obviously the single part of the outlet Y goes to the engine fuel filter.The on/off switches screw into the inlet side of the filters. I got all the kit to do that from ASAP supplies. www.asap-supplies.com. You will need to explain which filters you have in order for them to know the thead size for the on/offs. That should also tell them the hose size you need but it might be worth measuring it anyway.

Don't underestimate the amount of hose you need particularly if the filters are phsically in-line. It took a me about an hour and a half to do, mainly because of the measure twice cut once then check rule.

So when you open filter A whilst running on line B the engine will suck air you would need shut offs on either side of the filters for this set up to work as I see it

 

[prv]

That sounds just like the mod I want to carry out. Do you have any photos of the revised installation?

I did this too, although slightly differently in that my valves are changeovers rather than on/off. This removes the possibility of using both filters at once (why would you want to?) but does make operation easier as there's less to turn on and off and fewer combinations. I believe you can get banked valves which would make changing over as simple as turning one handle, but ASAP don't stock 'em and I bet they cost a fortune anyway.

A picture of my manifold is attached. After this was taken I cut the board down slightly smaller, made mounting blocks to support the valves, and sealed all the wood with epoxy.

The valves are arranged so that there's always one handle vertical and one horizontal (if they're both pointing the same way, there's no path through the system). The filter that's currently in use is the one with the valve lever across it, avoiding inadvertently removing the wrong one. The filter that is "wide open", with the lever out of the way, is isolated ready for changing (or swapping into use, obviously).

Because my fuel tank is lower than the filters (and the engine), I have an outboard-style bulb pump upstream of the filter manifold to help with bleeding. It all works pretty well given the awkward access I have to work with.

(Apologies to OP for thread drift)

Indeed

Pete

 

[Trundlebug]

A picture of my manifold is attached. After this was taken I cut the board down slightly smaller, made mounting blocks to support the valves, and sealed all the wood with epoxy.

The valves are arranged so that there's always one handle vertical and one horizontal (if they're both pointing the same way, there's no path through the system). The filter that's currently in use is the one with the valve lever across it, avoiding inadvertently removing the wrong one. The filter that is "wide open", with the lever out of the way, is isolated ready for changing (or swapping into use, obviously).

Pete

We're liking that! Very good, and thanks for the photo.
Do you have to be a bit nifty with the valve changeover whilst the engine is running?

 

[prv]

Do you have to be a bit nifty with the valve changeover whilst the engine is running?

I've never yet had to change over while running, but I doubt it's a problem. When I first installed it I managed to get one of the handles backwards on its valve, and so ended up turning off the fuel by mistake. The engine still ran for a while, presumably on what was in the pipes / its own filter / etc. So the time it takes to turn one valve and then the other should be no problem.

Pete

 

[Scotty_Tradewind]

Does diesel eat rubber?

Using the heading only as a question rather than the OP's total question, I understand that engine mounts can be badly damaged by diesel. Especially if diesel components are directly above a particular mount that require maintenance and the risk of dripping diesel on the mount regularly/seasonly.

 

[prv]

I understand that engine mounts can be badly damaged by diesel. Especially if diesel components are directly above a particular mount that requires maintenance and the risk of dripping diesel on the mount regularly/seasonly.

So like the stbd fwd mount on a 2GM20 then? What about engine oil - if that eats rubber too then we can tick off the port fwd mount as well

Pete

 

[KellysEye]

>Nitrile

Oops, I said Neoprene but meant to say Nitrile. Sorry about that.

 

[Bilgediver]

Thanks, will see if I can get some better fitting jubilee clips.

For that sized hoze jubilee clips are usually too big as the saddle around the screw is the wrong radius. Try Halfords or a car parts distributor for the correct clips which may have a nut and bolt method of tightening as well as providing a uniform clamping force all around the hose. Alternately get a diesel injection workshop to crimp on kosher fittings which are preferable.

 

[KellysEye]

>So when you open filter A whilst running on line B the engine will suck air you would need shut offs on either side of the filters for this set up to work as I see it

Once you have fitted the parallel system bleed both filters at the engine. Leave both on/off switches on and run the engine for half an hour at 1,200 revs to be certain there is no air in the engine. Then turn one filter off. If you get air/dirt in the on filter turn the other one on and then turn the blocked one off. Normally you get notice of air or dirt beacause the engine starts to lose revs or the revs go up and down, so do the changes fairly promply before the engine cuts out.

 

[bluedragon]

Getting back to the original question again...

"Rubber" in a the last 50+ years or so is a meaningless generic term. There are as many types of "rubber" as there are plastics, or woods in the forest. Some "rubber" quite happily seals aircraft fuel tanks...or is so stable it is sent into outer space...or is so inert it is used for medical implants. But these are all chemically as different as chalk & cheese. Their only similarity is that if you stretch them, they snap back into place (usually!)

Natural rubber (from trees or its synthetic equivalent) has no fuel / oil resistance and is not often used nowadays. Nitrile, Neoprene, fluorocarbon and other types do. Many modern synthetic rubbers will not be harmed by the the occasional splash with fuel so long as it's transient. Many are quite happy in hot engine oil for extended periods. Generally what happens is the rubber swells and this weakens it. If the swelling is reversed (the fluid dries out) then often there is no permanent damage.

Not sure if any of this helps the OP, but perhaps puts the record straight!

 

[Scotty_Tradewind]

Getting back to the original question again...

"Rubber" in a the last 50+ years or so is a meaningless generic term. There are as many types of "rubber" as there are plastics, or woods in the forest. Some "rubber" quite happily seals aircraft fuel tanks...or is so stable it is sent into outer space...or is so inert it is used for medical implants. But these are all chemically as different as chalk & cheese. Their only similarity is that if you stretch them, they snap back into place (usually!)

Natural rubber (from trees or its synthetic equivalent) has no fuel / oil resistance and is not often used nowadays. Nitrile, Neoprene, fluorocarbon and other types do. Many modern synthetic rubbers will not be harmed by the the occasional splash with fuel so long as it's transient. Many are quite happy in hot engine oil for extended periods. Generally what happens is the rubber swells and this weakens it. If the swelling is reversed (the fluid dries out) then often there is no permanent damage.

Not sure if any of this helps the OP, but perhaps puts the record straight!

I suppose it's worth ensuring that an engine mount below a fuel filter/seperator is well covered up and washed off with detergent if splashed though. An experienced marine mechanic gave my engine a good checking over recently and apparently diesel drips can accelerate a mounts disintegration in his experience/opinion.
John Cutler... http://www.cutlermarine.com/