So much for “The Conclusion” of this tale. The story until now:

  • my mechanic replaced water pump, belts, hoses, coolant reservoir cap and radiator in May when I got the car
  • car was running cold in July and getting poor mileage, I replaced thermostat with a cheap one I had (may have been an 88C thermostat)
  • car started overheating so again I replaced thermostat this time with with a Wahler 80C, flushed rad and put in fresh coolant
  • ran fine for a couple days then more overheating. I replaced fan clutch, relay K1 and tested aux fan by jumpering switch

The last repairs were last weekend. On Thursday:

  • suddenly overheats on a short drive and scares the crap out of me with visions of a blown head gasket, temp gauge got over 3/4! – turned the car off immediately.
  • top rad hose is hot, bottom is cold
  • coolant level is high, must be due to expansion I figure
  • left the car on the street for a few hours and went back to get it after it cooled down
  • top rad hose is still warm, bottom rad hose is cold
  • squeeze the hoses, before and after thermostat housing and level in reservoir goes up and down
  • top up my oil (didn’t see any water in it but i’m not sure what I’m looking for in the dark)
  • drive it home

Get home, let it idle. Temperature goes a little over halfway but not to 3/4. Tapping the gauge sometimes made the temperature go back down. Fan is spinning great, chews up a cardboard tube nicely. Turn the car off.

  • squeeze all the hoses and they are super firm, system has pressure I guess
  • take the lid off the coolant reservoir and coolant spills out everywhere. that seems like it means something.
  • coolant level appears to be a little over the cold level mark but under the cap it’s much higher, must be cause by a trapped air bubble

My conclusion is a head gasket problem, hopefully nothing fatal to the engine. I’m going to have it towed to Bavarian Motorsport tomorrow since the problem is beyond my resources to repair as I don’t have a garage. Here’s what I would need to check if I was doing it on my own:

  • coolant leaking into the crankcase (milky emulsion in the oil)
  • “foaming” in the coolant system as exhaust gases are ejected into it
  • coolant leaking into a cylinder (white smoke from the exhaust)
  • coolant leaking from the head 
  • oil leaking into a cylinder
  • oil leaking from the head seam
  • a leak from a cylinder to the cooling system
  • a leak from a cylinder to an oil return passage
  • a leak between cylinders

It will be a few days before my mechanic will be able to get back to me, I’m sure. Fixing this could be expensive so I’m thinking about my options:

  1. have the engine repaired (welded). may not be possible. $unknown
  2. get a new m20 block / head / engine. $200-1500 + labor
  3. perform an engine swap $2000-10,000 + labor

Really, option 3 is the most attractive even though it will financially set back all my other plans for a while. It’d be great to get a 240-300 HP engine in my little car and put a silver lining on all these problems. But it would be really nice if it was something cheaper to fix.

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August 25, 2012 mechanical