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    Smoke from the wrong place

    Here's an odd one.

    When my stag is being driven it is usually smoke free.

    However I noticed (following the wife who was driving it) that when driving up hill (ie with the foot down a bit) that smoke(or steam?) comes from under the car.

    It seems not to come out of the exhaust but on the opposite side from well under the car.

    Yet there's no visible leaks or smells or noises.

    So - any ideas folks? Seems a bit odd....


    Cheers
    Steve

    #2
    imported post

    Oil on exhaust front pipe

    Comment


      #3
      imported post

      If its an auto with a bw35 gearbox I would have a good look at the breather pipe if its split of not connected properly it spits ATF over the RH exhaust under high loads, this will produce whiteish smoke as it burns on the exhaust. Looks really good if you are doing 70mph + in the outside lane of a motorway:shock:

      Did you notice what the smoke smelt like?

      Roger
      Now Stagless but have numerous car projects
      So many cars, so little time!

      Comment


        #4
        imported post

        marshman wrote:
        If its an auto with a bw35 gearbox I would have a good look at the breather pipe if its split of not connected properly it spits ATF over the RH exhaust under high loads, this will produce whiteish smoke as it burns on the exhaust. Looks really good if you are doing 70mph + in the outside lane of a motorway:shock: 

        Did you notice what the smoke smelt like?

        Roger
        Well thats interesting because I had to put about 8 pints of auto oil in (plus a small tin of auto box treatment) - which has confused the hell out of me. So the fact that you have linked the smoke with the auto box could mean we're on to something. It *is* whiteish but I can never catch a whiff. Although sometimes I can smell something that resembles cooking tyres but when I feel them they're ok.

        I'm useless at finding things (I still can;t find the coolant tap on the engine block!) so could you give me some clues to whereabouts to look?

        The smoke never happens when I'm on the flat - just when going up hills. The more I put my foot down the more the smoke comes out (I think).

        Thanks for your help so far, this forum is spot-on for experienced stagaphiles !

        Comment


          #5
          imported post

          Stimpy wrote:

          I'm useless at finding things (I still can;t find the coolant tap on the engine block!) so could you give me some clues to whereabouts to look?
          At the sides of the engine block underneath the exhaust manifolds.
          ZF 4 spd box, Datsun shafts, SS exhaust, 38DGMS weber 158.9bhp, BMW MC Tomcat seatssigpic

          Comment


            #6
            imported post

            Have a good look at the exhaust pipe as it passes the gearbox on the right hand side. If it is the breather spewing oil my guess is it will be evident as dark patches on the exhaust where it has burnt off. Also the rest of the underneath of the car will be "damp" with oil along in middle. finally wipe your finger along the rear bumper and around the rear number plate, if that is dirty and oily it adds more evidence. Are you sure you havn't over filled the box and its not just pushing out the excess?

            Roger
            Now Stagless but have numerous car projects
            So many cars, so little time!

            Comment


              #7
              imported post

              marshman wrote:
              Have a good look at the exhaust pipe as it passes the gearbox on the right hand side. If it is the breather spewing oil my guess is it will be evident as dark patches on the exhaust where it has burnt off. Also the rest of the underneath of the car will be "damp" with oil along in middle. finally wipe your finger along the rear bumper and around the rear number plate, if that is dirty and oily it adds more evidence. Are you sure you havn't over filled the box and its not just pushing out the excess?

              Roger
              Well - I've just been under the car (on 'ride-up' ramps) to have a look around.
              It was a bit wet. I then started 'er up and gave it a good rev. Managed to produce some smoke. A quick dart back under the car and I noticed that oil was dripping out of the pressure-gauge switch thing (I have a pressure gauge in the dash). So it looks like that needs a bit of tidying and tightening.

              That doesn't explain the auto-box oil level. Having checked the pipe involved in the box dip stick I noticed that it could easily be misread on an unlevel surface. My driveway goes up slightly - not much. I wonder if this faked a low reading.

              So the next item on the list is to get to a level carpark and take a reading there.

              I found a single drop of red AutoBox Oil clinging to where the dipstick pipe meets the box itself. Was this from missing the hole when filling? Not sure.


              So I suspect that the smoke is the dripping from the oil pressure connection (which also explains why it would happen under load) on to the exhaust.

              Even if the angle of the car is quite important 4 or 5 pints of the red stuff sounds like a wee bit too much.

              Comment


                #8
                imported post

                Stimpy wrote:
                A quick dart back under the car and I noticed that oil was dripping out of the pressure-gauge switch thing (I have a pressure gauge in the dash). So it looks like that needs a bit of tidying and tightening. Go careful with the tightening. It is a taper thread into an aluminium casting. They can break. BTDT

                I found a single drop of red AutoBox Oil clinging to where the dipstick pipe meets the box itself. Was this from missing the hole when filling? Not sure. Probably due to a leak from the banjo fitting. This has copper washers either side and unless they have been annealed or replaced will go hard. Best option is to use Dowty washers. Either way the box has to be drained to remove the dipstick tube.
                Dave
                Dave
                1974 Mk2, ZF Auto, 3.45 Diff, Datsun Driveshafts. Stag owner/maintainer since 1989.

                Comment


                  #9
                  imported post

                  hi,

                  You may be right about the drip from the oil pressure connection but i am not sure, the oil pressure shouldn't be dependent on engine load - only on engine revs - even then it shouldn't vary much - only dropping down at tick over. Also engine oil tends not to produce white smoke unless you have lots onto something very hot - eg the manifolds. I still think its ATF being dumped either via the breather or out of the top of the filler - this definately produces quite a lot of white smoke that is not that smelly - or at least it did on mine when the breather split. It also fits with being worse when the engine/car is underload up hill.

                  a single drip from the banjo is not too bad - I would leave it unless it get worse.

                  Roger
                  Now Stagless but have numerous car projects
                  So many cars, so little time!

                  Comment


                    #10
                    imported post

                    marshman wrote:
                    hi,

                    You may be right about the drip from the oil pressure connection but i am not sure, the oil pressure shouldn't be dependent on engine load - only on engine revs - even then it shouldn't vary much - only dropping down at tick over. Also engine oil tends not to produce white smoke unless you have lots onto something very hot - eg the manifolds. I still think its ATF being dumped either via the breather or out of the top of the filler - this definately produces quite a lot of white smoke that is not that smelly - or at least it did on mine when the breather split. It also fits with being worse when the engine/car is underload up hill.

                    a single drip from the banjo is not too bad - I would leave it unless it get worse.

                    Roger
                    Invariably the revs go higher when you go up a hill (later gear change and all that). I took a look down into the engine bay while revving the engine at the carbs and you can literally see the oil coming out and falling downward and onto the exhaust just after the manifold.

                    Anyhoo - today I decided (just to be on the safe side) to buy a new set of those special washers for the banjo connection - these cost 75p. I got them from Rimmer Bros. And then I started surfing. After which the bill came to £300. Damn I'm so weak willed.

                    Later in the day I took the car to a flat car-park and took an ATF reading. It was above maximum - thus confirming that my driveway exaggerates the lack of oil. At this point I noticed my petrol pipe was leaking at the filter! Looks like almost everything is independently leaking ! (Fortunately a quick twist on the jubilee clip sorted that one).

                    The oil pressure switch is damn hard to get to but I'll (carefully) tighten that next.

                    Thanks for all the advice folks

                    Comment


                      #11
                      imported post

                      Hi Steve, it does sound as if you've located the prob, one suggestion, get the connection out of the block and give it five turns of ordinary PTFE tape, as Dave says, it's a taper thread and doesn't need to be very tight. Martin.

                      Comment


                        #12
                        imported post

                        Martin Stevenson wrote:
                        Hi Steve, it does sound as if you've located the prob, one suggestion, get the connection out of the block and give it five turns of ordinary PTFE tape, as Dave says, it's a taper thread and doesn't need to be very tight.      Martin.
                        Will have to give that one a go - although I'll have to break my arm in several places so I can twist and turn it downward until I get to the damn sod!

                        That's very good advice about the PTFE tape - I wouldn't have thought of that.

                        Ta

                        Comment

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