I've been driving in 95 & 100 degr F heat for the past month at 85 - 90 mph with only slight heating above the 80C mark... the pointer get's as high as horizontal, but that's been the limit so far.
I've been driving daily 20 miles to work and back, plus other short drives 40-80 miles in this weather with top down at 80 - 90 continuous speed, so no added weight of the hard-top but added wind resistance to compensate.
My engine is rebuilt (my original block at Metric Motors in LA) ~4K miles ago, and I had the radiator re-cored at that time.... all new cooling hoses, thermostat, etc.
I have A/C (Kuhlmeister) I've been using while at highway speeds on the freeway, but not in any traffic or city driving that forces me to slow down much.... you might ask why use the A/C with top down?
?... 'cause at 95 & 100 F outside, a breath of cooler air wafting over you now and then is worth it.
I have 2 problems with the Kuhlmeister A/C unit ---
1) At idle or near idle the compressor's load (new compressor --- smallish unit, ~ 6x6x6 inches or so) kills the engine (it' can't recover). Hence, I don't use A/C in traffic or anytime I might have to slow to a near crawl -- low rpm condition.
2) The internal fan air distribution unit (inside the passanger compartment under the dash) can't be pushed far enough toward the front of the car to keep it from interfering with the under dash light (at driver's right side near the steering column). If I could locate the distribution housing about another inch back (toward the front of the car) it wouldn't interfere. I've had it out when instruments, clock, glovebox, etc were out and located the unit as far back as it will go --- the fan at the rear of the unit keeps it from going thru the passanger side bulk-head.
I like the use of the light, so I just let the unit sit on top of it, but so I can still barely actuate the switch. This forces a slight bend in the plastic housing (for which I support to the dash with 1x2" steel plates (as in huge 'washers') under the plastic housing to keep the plastic from ripping apart/cracking under the supporting load).
Does anybody else with a Kuhlmeister have this problem too? It was dealer installed in CA on orig. purchase (by orig. owner), so I'm surprised the unit would be designed to interfere with the under-dash light near the steering column on the right... or that it can't be installed without that interference. I can cant it (rotate) the unit so the front isn't parallel with the dash front, and so the left end of the unit is pushed back behind the light, but that looked goofy when I installed it that way. But the slight bend in the plastic housing to sit on top of the light looks a little goofy too.... just not as goofy as the rotated version.
I have 1 problem
with the fan clutch I think---- at least it's an annoyance if not a problem.
1) When the engine (cooling water) temperature reaches just a tad over 80C and at higher rpm's (over 3K or so) I can hear the high whine associated with what I assume is the fan trying to suck more air thru the radiator & A/C heat exchanger. I've experienced this sound effect before on my '65 Chevy pick-up when the fan shroud was slightly mis-placed. Anyway, the higher the engine speed, the louder the whine.
I assume that when the engine temperature reaches a tad over 80C the fan clutch engages and increases the speed of the fan.... creating the increasing suction thru the restricted air space, and hence the high whine of high velocity air going thru restricted orofices, increasing with increasing engine speed.
There's no extra whine when the engine's running cooler though... i.e. reaching running temperatures. I've opened the hood when the engines running at operating temps and verified the whine is from the air sucking sound by kicking the rpm's up to 3000 - 3500.... and when the engine's cooler at 3K to 4K there's no sucking sound. no pun intended, but this Sucks.
Does anybody know if this is common on 113's ('67 250SL, US) with AC heat exchanger restricting cooling air, or is this a problem with my fan clutch engaging pre-maturely?
Longtooth
67 250SL US #113-043-10-002163
95 SL500
