the radiator doesn't have a cap, the pressure cap is on the expansion tank. i am curious about greenacres' post. i noticed for the first time that there is a hose attached to the expansion tank. it goes down behind the battery towards the wheelwell. were is the overflow tank? i can't see where the hose ends...

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joE
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"
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That hose leads down into the third dimension a.k.a. the VOID. :p

The overflow tank is behind the inspection panel in the wheel well. If you take off the passenger side wheel and unbolt 5-6 bolts under there you'll see it. It holds about the same capacity as your primary expansion tank. I've never seen it in person, just ordered the wrong "expansion tank".

~Paul

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'91 300E, 210k miles

I wonder why it's hidden and so well protected? BTW Paul, I was wondering what happened to your mysterious elevated temp problem, your post on this thread clears that up.

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joE
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"
http://banners.wunderground.com/bann...L/Key_West.gif

I debated starting a new thread on M104 engine temps but I'll just jump in on this one. I have just had my car (1994 E320 wagon) serviced for high engine temperature which was related to a fuse element ($0.85) in the auxiliary fan relay. The temp is now OK during driving but still rises to 110 C to 118 C during idle. I just re-read the owners manual and it says that engine temps of close to 120 C can occur in stop and go city driving as well as hard driving. (Can this be the cause of all the head gasket failures and wiring harness failures associated with M104 engines?) I think I am going to try a lower temperature thermostat mentioned in several posts. It looks pretty easy but two questions:

1. Do the bolts for the housing require a specific torque for tightening?

2. How does one bleed air out of the system introduced by replacing the thermostat?

Yeah, that was the reason for my overheating problem. I was on the verge of purchasing a new Nissen's radiator when that blue rubber strip coughed up into the expansion tank. I should've updated that thread but it was pretty buried by then.

Feels like a brand new engine now. Power is just as good when it drove off the lot in '91 -- smooth as silk too. Engine temp never goes over 90 now with 45/55 antifreeze/water and a bottle of water wetter. Finally nice to see clean coolant in the resevoir instead of chocolate milk.

~Paul

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'91 300E, 210k miles

DTF,

I think that at idle, an M104 engine may go up over 110 degrees but usually this happens after the engine is well warmed up by highway driving for instance. Prolonged stop and go driving will do this too. In any case the auxilliary fans should kick in and cool it down fast, although it may cycle up to the high temps if the driving conditions persist. This happened to me over the winter in some monstrous holiday traffic jams around NYC - almost 3 hrs of stop and go traffic. It prompted me to install the resistor mod which is discussed at length in some other threads. My car has not seen temps over 100 ever since.

As to the thermostat cover, I would think that torquing it evenly is only due diligence. I haven't found the procedure in the CD to do it yet - if I were to hazard a guess about 15 ft-lbs, others please verify. There is a bleeder port right on top of the housingwith an allen screw.

Head gasket failures - tough call on the long block, new design on replacement gaskets seem to fix it. Wiring harness, definitely because the insulators do degrade faster with higher temps - but this was a materials issue.

HTH

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joE
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"
http://banners.wunderground.com/bann...L/Key_West.gif

Wo-ho!

My mech replaced the thermostat and its pretty much taking care of the problem.

With the temp @ 45 today...he changed the thermostat let the car idle for 1 hr with no problem...hovered just above the 80 hash mark the entire time.

When I picked up the car...went for a 20min drive of 70-80mph no problem. Ran with full A/C and also full heat...no problem...temp remained just a a little above 80. Came home let it sit for 15mins still I couldn't get the temp to rise to 85 or 90.

My mech said...drive around for a week...if its acting up then we'll try something else...hopefully this will be the only problem.

Talked with him for a bit afterwards.....said most of the time he's only found thermostats going bad. If it was ever a radiator problem its was from the older design like on the 300E that didn't have the metal neck. With all the difference in temp the neck would become brittle over time and crack.

Another happy E320 owner again :-)