| Author | Message | ||
     Stefan Morley Prolific User Username: myupctoys Post Number: 165 Registered: 7-2009 |
Hi, I finally found the source of a knocking sound I have in my car when at higher rpm. The knocking is only there over about a 300rpm range. It is definitely coming from the pipe leading to the heater in the car. I was looking in my manual to try and figure out what this system entails and where possible problems might be. There is a simple picture in the cooling setion but not quite enough detail. I saw else where on this forum, that the spring in the "tap" gets weak. Seems there is a kit to overhaul the unit. I assume the tap is leaking slightly, extra rpm increses the water pressure, forcing the tap to chatter until the pressure is so great that the faulty valve is finally forced open. Hence why the knock is only in a small range. What I want to know, is there anything else that is actually in the core, like a valve or something that could also contribute to this. Or is it just a simple radiator. Reason being is the knock feels like it comes from here, but perfectly understand the source might just be the tap and the noise is propogating through the piping. Thanks Stefan | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 496 Registered: 6-2006 |
Stefan, The core is just straight through. It is possible for the noise to be caused by the pulsating fluid, Just as a house can resonate with a water pipe. You can also get them from the hydraulic pipes that run the other side of the bulk head. Try a hose clamp on the heater hose? | ||
| Stefan Morley Prolific User Username: myupctoys Post Number: 166 Registered: 7-2009 |
Paul, Thanks, will give that a try. Certianly make life simpler. Stefan | ||
| Richard Treacy Grand Master Username: richard_treacy Post Number: 2030 Registered: 4-2003 |
Stefan, Co-incidentally I am replacing my water tap insert yet again (SCBZS0T09HCH20037) at this moment. I am only doing it as it is inexpensive at around $150. BUT. I can actually see no reason for the water tap being there at all. The air is cooled, then either partially or fully reheated by the heater core or sent directly to the cabin in extremes. Normally the cooled/dried air is reheated partially by the blending flaps individually for upper and lower needs. So what if there is coolant flowing through the heater matrix if the air flow is blocked by the air flaps ? If the tap is left open (electrically deactivated), then the flaps keep the air unheated when not needed. To me, the heater tap is redundant. This particular Bosch part is the worst creation that Bosch has ever produced, and that is why they sell so well in Australia: 100 in stock in Melbourne for the unfortunate Mercedes-Benz and BMW cars, those needing the dashboard assemblies to be removed to repair them when the passengers fry. Those poor sods need the tap to keep themselves cool in Summer. We need ours so not to freeze on the Autobahn in Winter. I may add that two of my BMWs had the identical tap and have had this silly Bosch failure too. Ours is the reverse problem of the BMW/Ferrari/M-B situation. On our cars, the passengers freeze at highway speed when the tap fails to open when deactivated due to the weakened internal return spring, Once the tap release spring, encapsulated inside the insert, becomes really weak, the tap will close itself even deenergised whenever your motor exceeds just 3000RPM, and will stay closed until it drops to 1000RPM. Regardless, this part is unfit for purpose. That applies to the applicacation in our cars, and even more so for the MBBMWFetcs. In short, at higher engine speeds, the water tap may close on our cars and fail to reopen once de-energised. So, I shall replace mine for fun again, but will recommend that, on 20k+ cars in future that it simply be replaced by an open pipe ! In any case, I shall put the tap back in as-built and play around in the lab to find an improved configuration using the old one. Watch this space. RHT. | ||
| Stefan Morley Prolific User Username: myupctoys Post Number: 167 Registered: 7-2009 |
Richard, Interested to see what develops. Getting the tap out looks like a pain, hidden underneath lots of pipes. Considering it seems to be closed by application of power to the tap. Might just try and unplug it and see if the noise stops. Keep us posted if you find a solution. Cheers Stefan | ||
| Larry Halpert Prolific User Username: larry_halpert Post Number: 126 Registered: 9-2003 |
Water tap insert is Bosch part #1 147 213 007 $150 is actually a lot of money for most people especially in this case since you can get these for less than half that. (and less than $40 US): http://www.autohausaz.com/search/product.aspx?sid=3s3u0rqzwwaapw45cyym4c55&partnumber=1147213007 Even shipping to australia won't bring it close to $150 (The whole heater valve new is only $166 US) Larry http://mutley.hypermart.net/RollsSubstituteParts.html (Message edited by Larry_Halpert on 06 December 2009) |
