IR temperature gauges are great, you can do a lot with them. Check to see if catalytic converter is good (temperature at back hotter than front). Check to see which wheel has sticking breaks or bad wheel bearing (will be hotter than others). Thus it is a good investment!
The thermostat blocks water from going to the radiator. Thus with thermostat installed a very small amount of water is pumped through radiator. I am not sure where the temperature sensor is on your car, but because you said the aux front fans came on I would think the gauge is reading correct. Trampas -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tan Qu Sent: Thursday, December 29, 2005 5:04 PM To: Mercedes Discussion List Subject: Re: [MBZ] SOS - '87 190Dt Overheat! -update I don't have an infared temp meter so I have to come up with something else to get the block temp. Now, if the pump is ok, water should come out the upper radiator hose even with thermostat in, right? How likely is that the temp sensor is bad? Where is the sensor located that is connected to the gauge? I know there is one right below the thermostat housing and one near the upper radiator hose. I actually disconnected both both the gauge still registered 120C. Is there a third temp sensor that I don't know of? Tan --- Trampas <[EMAIL PROTECTED]> wrote: > First step is to start car cold, open hood check and > see if upper radiator > hose has pressure, if so you need a head gasket > and/or head. > > Now warm up car to normal operating temperatures. > Now go check and see if > the upper radiator hose is warm and has pressure on > it. If it does not have > pressure you need new radiator cap. > > Now it has pressure and normal operating > temperature, measure the block > temperature using an IR temperature gauge. Does it > match gauge temperature? > If not check ground straps, and try new sender. > Still bad, try gauge. Still > bad, check battery voltage and make sure alternator > is not over charging. > > Next step, when it gets a little bit warmer than > normal turn off car, take > hand and move across radiator is one section hot and > others cold if so you > have plugged radiator. If all are cold you have a > plugged radiator, bad > thermostat or bad water pump. Drain water and put > garden hose in top > radiator hose and see if radiator seems to flow, if > it does replace water > pump and thermostat. > > If radiator warm, run car a bit longer does the > clutch fan engage? If not > replace (normally this will cause over heating > either at idle or cruise but > rarely both). Yes I have seen where they over heat > at cruise but not idle > and vise verse. > > I have found water pumps last 100-150k miles. > Radiators are funny but > usually last at least 150k with proper maintenance. > Fan clutches seem to > last about 120k miles and need adjustment or > replaced. In 7-8 years of being > mechanic I have seen water pump impeller problems > maybe 5 times, out of at > least 500-600 over heating problems. It does happen, > just rare. > > To check water pump impeller problems, remove > thermostat. Fill radiator with > water, remove upper radiator hose, start car, does > water pump out like mad? > No, then replace water pump. > > Trampas > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] > On Behalf Of Tan Qu > Sent: Thursday, December 29, 2005 4:21 PM > To: Mercedes Discussion List > Subject: Re: [MBZ] SOS - '87 190Dt Overheat! -update > > Wife has been the one who drove the car. I > periodically drove the car and took care of the > things > I notice. But you know how women are - as long as > the > car seems to run they think everything is just fine. > Anyhow I was aware the operating temp sat at 84c > (with > a 80c Wahler thermostat) and in the summer it goes > up > to 90 - 93c after I replaced the water pump and > thermostat about 2 years ago. I noticed the 120C > just > this Tueday when she picked me up for lunch. She > said > that just happened that day. I'll just leave it > there. > > Anyhow, what I think we need to focus on is that the > lower radiator hose stayed cold after the test run > during which the temp shot up to 120C again. So the > coolant wasn't flowing through the radiator. If it > had > flowed at all I shouldn't have a cold lower hose, > right? > > Thermostat - this was ruled out by the boil test. > Plugged up radiator - very unlikely although > possible. > I bought this car while it had 103,000 miles. > Replaced > water pump around 180k miles. Between 103,000 and > 180,000 miles, the temp gauge was at 80C or 82c > solid > even with A/C on in hot summer. > Trapped air bubble - wouldn't they start to show up > as > soon as they were there? > > Tan > > --- "Dave M." <[EMAIL PROTECTED]> wrote: > > > 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 > === message truncated === _______________________________________ http://www.striplin.net For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net
