my car: 1982 300sd.

so, as mentioned in other threads, ive been having a little bit of an issue with my running temp. problems mostly occur when driving around town, at which time idling temps can reach up to 100 degrees. regular driving, and especially on highways yields temps from around 80-85 degrees. at the same time, i have had occasionally mediocre heat, which may or may not be related/imaginary.

with the engine cold, i can squeeze the upper radiator hose fairly easily, and there are no bubbles in the reservoir running with the cap off. i have no coolant in my oil, no oil in my coolant. engine has notable blow-by, judging from the amount of smoke visible in the valve cover with the cap off, and consumes maybe a quart of oil every 1500 miles. there is occasional white/gray smoke when leaning on the accelerator. my heat has also been marginal, at times, and today, after a fair bit of city driving, i noticed that the front of my radiator was cool the the touch, though the rear (engine side) was nice and warm, though not hot enough to prevent me from laying a hand on it.

anyhow, i dont think its the fan clutch, because the problem occasionally occurs just from warming the car up, and i can see the fan spinning well at idle. radiator cap is brand new. i was thinking it could be air pockets, but the coolant has been completely drained and refilled since, to no avail. also maybe a bad water pump? its not leaking. also, in the morning, after sitting all night, the cap opens with a crisp pop, though no coolant bubbles over.

should i be worrying about anything worse than a water pump/air pocket/clogged radiator at this point?

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1982 300sd, 230,000 miles, svo/wvo conversion... yellow

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