Announcement

Collapse
No announcement yet.

M42 hissing/whistling???

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    M42 hissing/whistling???

    So I recently had my belts snap on me when I was driving on the highway and got my car home to get all the parts and everything, replaced the belts and replaced my water pump as well as a plastic hose that is connected to the cooling system so after I took my car to bavarian auto jays in my town to replace my thermostat and thermostat housing gasket, after I got the car back everything runs fine but now my thermostat sits a millimeter or two from the halfway point which is the normal temperature, it doesn't ever get close to the 3/4ths mark, and when I accelerate and shift around 3500 to 5000 RPM's I notice the faint hissing/whistling noise rise and fall with the Rpms. I check mostly all my hoses, the ones I could get to, and I noticed my coolant was low after driving it home from bavarian autohaus. Anyone have any idea please?

    #2
    First, use more punctuation and paragraphs, as it makes your issue easier to read.

    Hissing could be a hose with a vacuum leak, but you'd notice that at all RPM and especially not just at 3500-5000. Therefore, you might have a coolant leak, but it's odd that it wouldn't cause overheating.

    Whistling is usually a vacuum leak, normally between metal surfaces of the intake manifold or their gaskets, which can get much louder at RPM.

    Which hose did you replace anyway since I cannot think of a plastic hose in the system?

    Comment


      #3




      the first picture is what it looks like with the part number.

      Second photos is diagram of where it kind sits at in the engine, which is low under the intake manifold and tucked behind the wiring harness on the bottom of the block behind the water pump I believe

      Comment


        #4
        Ring the place that "fixed" it would be my first thought. You wont get any noises out of water pipes. But if belts were replaced maybe they did one up too tight or did one up too loose?

        First step in trouble shooting new noises is look at the thing that was last touched....

        Comment


          #5
          They just fixed my thermostat I replaced the water pipe connector myself as well as the belts but I'm sure they took them off to access the thermostat

          Comment


            #6
            Originally posted by dktmllr View Post
            They just fixed my thermostat I replaced the water pipe connector myself as well as the belts but I'm sure they took them off to access the thermostat
            Since you replaced the water pipe, you took the throttle and upper/lower manifolds off. Clearly you have a vacuum leak there. It's also possible that you didn't seat the o ring for the water pipe properly, or that the rear hose connections aren't tight since you're losing coolant, but can't see exactly where from.

            Like I said in the last post, a whistling is probably a leak between the manifolds. If it sounds like this https://photos.app.goo.gl/zzKHZZOq7MxPDfrl2 it's probably a metal/metal leak.

            The shop probably didn't remove belts to replace the thermostat, so I'd check them, but not suspect them.

            Comment


              #7
              The weird thing is it's not loud like in your video and it doesn't sound like metal more like escaping pressure I I get high in the rpms, I also didn't remove either parts of the manifold cause it sits pretty low under the manifolds on the block so all I had to do was undo the five bolts that hold the wiring harness in the place and kind of took it out of the way when I removed some of the electrical plug-ins seated it in there tightened the coolant pipe down and connected all the hoses back on

              Comment


                #8
                I wasn't saying it was a metallic sound. However if you removed the water pipe without taking the manifold off then you have narrowed down the possible vacuum components that you could have disturbed. However it's still unusual that you would have vacuum leak without having an idle issue.

                Comment


                  #9
                  Yeah my idle is normal, it sits around 800-900 RPM's , it rumbles a tiny bit for a second in increments when it's cold but I believe that's just normal with these old cars am I correct? I'm stumped because I tried the cold idle and spraying around the hoses and I take manifold and there was zero change in the idle. That's the only reason I posted in the forum cause I'm stumped honestly

                  Comment


                    #10
                    800-900 seems high. Is that normal? I sit around 650-700.
                    1986 325e Maaco Black M62 Project [SOLD]
                    2008 135i Alpinweiss III Cabriolet 6MT [SOLD]
                    2013 Subaru WRX [SOLD]
                    2011 BMW X5M [Daily]
                    1991 318is Slicktop Diamantschwarz Metallic [Thread]
                    1973 BMW R75/5 Toaster Tank [Summer Daily]

                    Comment


                      #11
                      Originally posted by dktmllr View Post
                      Yeah my idle is normal, it sits around 800-900 RPM's , it rumbles a tiny bit for a second in increments when it's cold but I believe that's just normal with these old cars am I correct?
                      The M42 is actually pretty modern as far as these things go. It behaves more or less like any new car would if it's running properly. It's no M10, and certainly not like any old '80s or earlier American stuff with goofy emissions controls or very limited computer control.

                      Project M42 Turbo

                      Comment

                      Working...
                      X