Tan, Refresh my memory. Did the problem happen overnight, meaning the car has been running at 100C for a while and suddenly popped to 120C? Or has it gradually been climbing from 100C to 120C over the past months/years? If it was an overnight thing, I'd lean towards the water pump as suspect - or at least worth a closer look. You can always re-install it if the impeller is properly attached and intact.
If the problem has been slowly getting worse, with temps higher every few months, I would *strongly* suspect the radiator is bad (corroded internally). It may flow just fine, but be unable to transfer heat properly. This assumes the fins are all clean in the condenser AND radiator. The bubble theory mostly applies to when the cooling system is first filled. If you've been driving the car for months, a bubble should NOT just suddenly appear out of nowhere. :-) -Dave M. > ------------------------------ > Date: Thu, 29 Dec 2005 07:22:51 -0800 (PST) > From: Tan Qu <[EMAIL PROTECTED]> > Subject: Re: [MBZ] SOS - '87 190Dt Overheat! -update > > I am pretty positive on the first two but not last > one. The thermostat on OM602 only goes in one > position. There is a tab in the thermostat housing > that sits in a small recess on the thermostat. Put it > in other ways the housing would not close properly. I > missed it when I put the second thermostat in and > found that out when I started to fill the rediator > from the upper hose. The coolant came out right there. > So that should tell me the radiator flows ok, right? > On the 190Dt it is hard to get the hose clamp for the > upper hose end on radiator so I detached from the > engine end and filled radiator from there. It is > possible there may be an air bubble trapped in the > head. How do you normally purge the air in the head - > by filling the engine from the upper hose? > > > Tan > > --- Jim Cathey <[EMAIL PROTECTED]> wrote: > > > > Did the boil test last night, the thermostat I > > just > > > took off the car opened nicely near the boiling > > point. > > > Fully opened when the water was boiling. Also > > checked > > > the upper hose again, no pressurized syndrome. So > > I > > > guess new pump is the next course of action. I > > still > > > have a Laso pump on hand. Would you all think > > dealer > > > parts is superior than the OEM parts on this one? > > > > I think the pump you have ready to put in is the > > superior one, but only because I'm still not > > convinced > > that it will make any difference and using it will > > allow > > you to conduct the test immediately. You're _sure_ > > the > > radiator flows well, the thermostat is in the right > > way around, and that there's no huge air bubble > > trapped > > in the head? > > > > -- Jim
