Sounds like you have got it. If you have an OBDII scanner or Ultra Gauge, you can read the coolant temp digitally rather than waiting for the gauge to slowoowwwllllyyyy react. Much easier to see temps rising above where you think they should be. I run a 180F stat in my 97 D1. 180 - 183 on roads, 187 maybe on expressway.

 

Well, towed a heavy trailer 350km in both traffic and freeway conditions. No overheat. There is reasonably heavy condensation on cold startup but this dissapears when engine warms. Slight coolant loss overnight but not quite sure how much as the expansion chamber is segmented and by the time you top up its overflowing then purges under heat. Many thanks for the advice and help on this I hope the condensation is normal and I hope the coolant is just sorting itself out.

 

For anyone else checking for the overheat problem, my radiator was %60 blocked and undetectable with internal camera only giving top 3 inches or so. Both end plates were completely clear. My mechanic (Belmont Motor Repairs) just got stubborn and found it by removing the radiator completely, 2000 km now and not a sign of overheating. For all intents and purposes this read like a cracked block/liner problem except there was no coolant loss. Only boiling coolant. Took a lot of advice from this forum and the good people in it and a bloody good mechanic .Hope this helps someone else. Harry

 

Great to hear. Here's a pix of a sludged radiator (demonstration). Hot on top, cool on bottom, because low flow on bottom. If sludge is high enough (more rows involved), it can also reduce the temp of air coming out of the rad that hits the face of the fan clutch. Then the clutch never warms up to re-couple and engage more fully, stays on low power setting, and overheat is even worse. When guys pour in the Leakz Stopz, it binds with the calcium buildup and closes off even more of the radiator. IMHO the practice of ten year or 150,000 mile coolant, spread across multiple owners, Iffy Lube top off, and lack of maintenance just adds to the problem.