1997 Sentra. 87,000miles. Two weeks ago, the thermostat gave up, and it got hot. Replaced thermostat. Ran fine for two weeks, but now has anti freeze in the oil. Does not have a miss, suggesting the compression is not yet majorly compromised. Question: spend the time to see if just a new headgasket will fix it (including magnaflux and milling of head if necessary), or just go for a 'low mileage engine from Japan"?

Thank you, Bob

 

it could be three things thats causing the coolant in the oil and one is it could beblown headgasket and the other since you got it hot is possibly a warped head or cracked block, my guess without seeing the car is that you warped the head and damaged the head gasket possibly. cause the block is cast iron on both usdm ga16 and sr20 and the head is aluminum on both of those motors. theres a simple test is to remove your raidiator cap and make sure its full and start your engine and if you see small air bubbles in the coolant of the raidiator its definitly have to do with your head and gasket. I would remove the head and take it to a machine shop just to make sure if its warped or not and replace the headgasket while you already have the head off, and check for any obvouis damage to the block or water mains. is your sentra a ga16de or sr20de cause if its an sr20de then i would go with a jdm SR but if its ga16de you can find those a dime and dozen in the salvage yards for dirt cheap and possibly low mileage.

 

Thank you for such a detailed answer. The engine is a GA16. I was also fishing to see if there are any other possibilities, like the toyota 22re engine, where the timing chain will grind into the cover when the chain guide wears out. This is my first Nissan, and I am not well versed in Nissan yet. The other thought I had is; I have heard that once anti freeze gets into the cylinder due to bad head gasket, it instantly damages the cylinder walls, and replacing the head gasket alone is wasted time, without a bore and new pistons/rings.

Thank you again, Bob

 

no problem i used to own a ga16de sentra, but like i said if you dont want to even bother with that motor you can find those a alot of salvage yards with possibly low mileage and for pretty cheap cause the sr20 swap in a ga16 sentra is pretty exspensive unless you have a donor car but it really up to you. good luck