Hi,
I'm not mechanical but this happened to me...2004 Limited V6, 120,000mile or so.
I drove up a very steep logging road with 5 people and a dog ...in lo 4.
Not very smart.
A month or so later, I experienced very rough idling on a cold day.
You could feel the car vibrate until for 10minutes or so.
The VSC off/VSC and check engine light came on.
Took to Toyota dealer and they advise something like #6 cyl was misfiring, etc so they replaced all the plugs and adjusted something (it was 1.5 years ago, do not remember)
same issue...then they checked again and
said, it wont be a huge problem to drive it for awhile.
They quoted a whole new gasket replacement and machining both sides, 20 hrs labour etc etc for about $4000.
I didnt have the money so I just left it but finally i had to get it repaired.
But i read somewhere,,,if the gasket is breached,,,fuel and coolant will mix in the cylinder?
So my take is.
your coolant level will be consumed faster than normal
your car will have vibrating cold starts.
you will have a 'milky' engine oil cap
and you will notice fuel in the coolant system (there is a bulb test kit to detect this)
anyways, i bit the bullet and did it at a toyo dealership and obviously replaced the waterpump , timing chain while there were repairing.
I blame myself for overstressing the engine on the logging road...
but also, I would have had to change the waterpump, timing chain anyways.
I'm not mechanical...so that's my take.
I can send you the repair summary, if you would like
John
[email protected]