When Ethanol Attacks Your Fuel System

What do you do when your car pours gasoline on the ground?  Do you run, light a match, or call your mechanic?  That is the question for today’s service insight.

Ethanol has snuck into automotive fuel systems over the past 20 years, with some states blending more than 10% into the gas you buy.  They say it’s an invisible change, and that may be true, but it’s not without consequence for your vintage car.

Newer cars (those made in the past 10 years) are designed to use 10-20% ethanol without damage.  Older cars are not so tolerant.  Ethanol can react with the rubbers used in hoses and seals, and cause them to crumble.  When that happens you have leaks, or worse.

 

Here is an example – a 1996 Bentley Turbo.  This car would be fuel-tight most of the time.  But every now and then – usually when it was cold – the car would gush fuel at a frightening rate.  As you can see, the engine bay in this car is jam-packed, and you can’t see the fuel line connections.  But they are in there.

A day of disassembly revealed the culprit – crumbled o rings on the lines that carry fuel into the injector rails.  There are four of these seals on this engine, and they all looked like this.

What about the other seals?  Carmakers buy their parts from a multitude of vendors.  In this case Rolls Royce Motors bought the fuel injectors from Bosch, and the fuel hoses from a supplier in the UK.  The Bosch injectors (Bosch being a more forward looking company) were supplied with o-rings rated to withstand 20% ethanol for 20 years, and they are fine.

The fuel pipe seals have no rating at all, or none we can find, and they failed.

Are there other lines and seals that can go bad in this car?  Maybe.  It’s hard to know.  The ethanol attacks hoses and rings from inside, so we won’t see the problem until it becomes a blowout.   Knowing that. I think I’d replace the fuel hoses on the car with new ethanol-rated line.

That brings up another problem.  Many of the service parts for vintage cars are new-old-stock, meaning they were made years ago and stored.  If those new/old lines are not made from ethanol resistant hose they are no better than what’s on the car now.  You may have to have new hose fabricated from modern ethanol rated line stock to solve the problem properly.

This is a significant safety hazard that every old car enthusiast should know about.  

Some people ask if there are ethanol-free fuels.  Aviation fuel is ethanol free, as is racing gas.  However both are costly and neither are legal for road use.  More importantly, if ethanol is the standard gas in your area, you would be wise to manage your car as if ethanol is going in the tank regularly.  Be prepared, because that's smarter than being broken.  Or being burnt.

John Elder Robison is a NY Times bestselling author and the founder of J E Robsion Service of Springfield, MA.  Robison Service is a long established Bosch car service specialist, with expertise in BMW, Jaguar, Land Rover, Mercedes, Porsche, and Rolls Royce/Bentley motorcars. Find them online atwww.robisonservice.com or in the real world at 413-785-1665