Oil smells of fuel

Discussion in 'Mech Tech' started by Little Nellie, Sep 9, 2019.

  1. hi, I know much has been written about this, but I have a fuel pump question. So After changing oil bus had no smell. Gradually after a few journeys and standing the smell gets stronger.

    The point I’d like to highlight here though, is when I changed my fuel lines a few months ago I was surprised to see a steady fast drip of fuel from the outlet from the pressure regulator. So when hoses after the regulator were removed. I had to plug it temporarily with a bolt.

    As the van was on a flat surface I would have thought the rest of the lines were at a lower level, or the fuel pump would have been closed with ignition switched off.

    Is there a chance that my fuel pump could be passing/ failing? I also replaced the float valves so I’d expect these to stop flow anyway?

  2. Is the fuel smell in the engine bay or the oil on the dipstick. Has the oil level gone over maximum since you changed it. Leaking carb is such a common problem on here and more likely your issue. Why did you replace the float valves, what was wrong. You may have dirt or bits of rubber in the fuel lines getting in the carbs. Do you have a new fuel filter and where is it located and is the filter clean or dirty looking. Sorry for all the questions.
  3. Cheers, smell is from the dip stick. Engine oil level only falls, never rises as it’s a bit of an oil consumer anyway. I replaced float valves as after i replaced the lines I got lots of bangs and pops. Thought may have got dirt in the carbs, so I cleaned the chambers and put new float valve and gaskets in anyway. Totally fixed the running issue.

    Fuel filter is under the van and looks clean
  4. Beginning to thick this may be just a smelly old engine thing. In another post I asked about oil consumption and as I only get 400 miles per 1 litre of oil, it strongly suggests it’s burning oil. I’m getting the engine looked at next month re this.

    I’m thinking combustion products passing the piston rings, entering the crankcase, making the oil smell etc. The smell is kind of petrol/onion, quite nauseating when your working on it. Dipstick level falls, due to the oil usage issue.

    Wonder if anyone else has experienced these smells with worn engine?
  5. Inside the engine bay you would expect fuel smells from the carb and oily smells from your leaking or burning oil. If the oil level on the dipstick is noticeably falling then its a big issue and you need to find out where the oil is going, before taking decisions about rebuild.

    Fresh oil smells sweet, soon after use it smells fuel like, that's normal. What is nauseating to you is nectar to others. After a run out with the mgb and parked in the garage there is the classic car smell of fuel and warm oil, lovely.
  6. Ok thanks, yes smells sweet for couple hundred miles (Halfords Classic i like this), then starts to smell petrol/ onion like (unpleasant).

    Yes, I’m getting the oil loss looked at soon. Just didn’t want a newly sorted engine being supplied by a fueling issue. But sounds like there’s a fair possibility that the niffs are related to mechanical wear.
  7. Don't worry classic vehicles all have that certain smell and the smell of burning oil as they pass you out on the road. Maybe your oil loss is leaking rather than burning. Have you looked under the engine to see if oil is there and get an idea where its coming from. Rocker gaskets often leak and can leak a lot over time, push rod tube seals go and leak oil and oil between engine and gearbox suggests worn seals. Burning oil usually means blue smoke from the exhaust, can you see that?
  8. Was loads leaking from dipstick gaiter, pushrod tubes and rocker gasket. Have replaced all of these. Originally was 80 miles per litre of oil!!! And got it down to 400 miles per litre of oil.

    No visible blue smoke, drips under the van, now almost zero.

    Thinking, valves and piston rings...
  9. 400 miles per litre is not bad. If I push my new engine hard, it can get near half that. My old engines dropped as low as 1 litre per 20 miles (pinched rocker cover gasket)

    I wouldnt worry, just spend the money on an oil temperature gauge amd watch for the flickering light at idle in the long run.

    My new engine seems to use between 1 litre per 1000 miles and 1 litre per 2000 miles.
    Little Nellie likes this.
  10. Wow, interesting info
  11. If its not showing blue smoke and you have fixed previous engine leaks, I would just keep topping up the oil (using 20w50 of course, don't want to use thin dish water).

    As said, most of these old air cooled engines use oil and a lot leak as well. Yours doesn't sound any worse than many others.

    As you know it uses oil, you must check the level and top it up to maximum, do it often, if you let it go low you could bring on big trouble.
    Little Nellie likes this.
  12. The official from Vauxhall on a brand new engine is 1ltr per 1000 miles and I’ve seen them use this much without any blue smoke out the exhaust.
    Little Nellie and mgbman like this.

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