mpeis

My 07 TC had been suffering gradual coolant loss for a few months. It was otherwise asymptomatic; no white smoke, it ran like a champ, no visible external leaks with die. Finally I had rapid coolant loss and the engine nearly overheated. I took the head to get pressure tested and the machine shop found a huge crack in the head.


Up to the point where I had rapid coolant loss, I had no visible coolant in the oil. After that point, the coolant mixed in the oil (no oil in the coolant though). I don’t know for sure how long the coolant was mixing with the oil.


So, given that I had coolant in the oil, am I okay replacing the head or do I need to replace the whole engine? Are the crankshaft bearings going to wear and fail?

That_Kid_Ju

You should have the block checked out. If coolant made it's way into the oil pan, there may be traces in the cylinders and all. Would really suck if it causes engine failure after you replace the head. Better to be safe than sorry.

Kik

Considering you already pulled the head then you've also pulled the timing cover, did you also pull the the oil pan? If not, take the 5 minutes to pull it, drop the covers and inspect the bearings. I believe that if you overheated and shut it down, you probably didn't do any damage, was there any knocking, grinding or squealing before being shut down?
By inspecting the bearings you'll be able to see if the is grooving on the crank and or heavy burn areas where bearings may have started to seize. If nothing is apparent then I would suggest, do and engine flush with some cheap Dino oil to make sure all the coolant is out of the engine and refill it with some good Syn oil like mobile1 or Valvoline full syn.
When I stripped the head bolts on my 05 and did the fix, I had coolant leaking outside and into the oil. I inspected the bearings and everything was fine on mine. My problem also was a slow process over about 3 months of losing coolant before I finally figured out where it was all going and I would have to guess that at least the last 3 - 5 days of driving it had to be mixing coolant into the oil.