Rebuilt engine or not? Engine builders please.

[gotta240]

I'm tearing apart a ka24de i just purchased from an unmolested auto 93.
Leakdown test= 7 or 8 across. The head is immaculate(oddly clean) but the block has built up oil from a leaky front seal. When i pulled the oilpan i noticed "93" written in sharpie or something on the block where it meets the pan. The h20 pump is aftermarket, and front case gasket material, valve cover, and oil pan gasket maker is all aftermarket, i THINK. All the freeze plugs are silver EXCEPT the one by the tranny which is goldish. The top timing chain guide was removed.

1. Isn't it odd that 93 was written on the bottom of the block on the surface that meets the pan. Think this means it was rebuilt?

2. How do i tell if the timing chain has been replaced, or needs replacing?

3. Any telltail signs that the motor has been rebult without taking the head off?

4. Is it ok to just pop off the main and rod bearings and put them right back, or will that make future failure more likely? IE: bolt stretch or by breaking the perfect match that has been worn in the bearing halfs.


I dont want to tear the head off because i won't be rebuilding it anyways, as the leakdown test was ok. At the same time though, i don't want to skimp on doing something that is easy while the motor is OUT of the car.

[Signum Temporis]

number 1, who knows... i found "i <3 t-bird" and weird stickers in the most odd places you could ever imagine, but it sounds like someone wrote the engine year on there to me

number 2 can be found with pictures in the factory service manual (u can get it for free online or pm me and ill try to email it to u)

number 3, why does it matter? u can take it apart to find out, i dont know how to inspect internals from the outside know what i mean?

number 4, follow the factory service manual directions

so wait, ur tearing apart a great condition engine to not rebuild it? im confused on ur purpose

[murda-c]

He wants to make sure the motor is in good condition.

[Signum Temporis]

o... then take it apart, inspect it, then put it back together all like the FSM says... u probably wont mess it up if thats what ur worried about, the directions are clear and concise

[gotta240]

Bah. To put this even MORE simply, i have the pan off and the front cover off and want to know if there are any little signs to look for that hints a rebuild.

IE: some people re-stamp the main caps on a rebuild. Basically just wondering if there were any other little hints like that to look for. Also wanted to know how to tell if the timing chain has been replaced, NOT how to replace it.

thanks

[georgesal]

you can check the top of the timing chain cover for signs of machining if they decked the block its really likey that they machinged the cover to get the head to sit right. I have seen numbers written on blocks like you describe here but they werent nissan motors,

[gotta240]

That is the EXACT kind of info i am looking for. Thank you and repped.

[LA_phantom_240]

number 1, who knows... i found "i <3 t-bird" and weird stickers in the most odd places you could ever imagine, but it sounds like someone wrote the engine year on there to me

number 2 can be found with pictures in the factory service manual (u can get it for free online or pm me and ill try to email it to u)

number 3, why does it matter? u can take it apart to find out, i dont know how to inspect internals from the outside know what i mean?

number 4, follow the factory service manual directions

so wait, ur tearing apart a great condition engine to not rebuild it? im confused on ur purpose

I found "LULZ" scratched into the paint on the crossmember while doing some spring cleaning lol. :loco:

[lil240sx95]

the "93" could be from an auto dismantler my engine has 96 240 in yellow on it. but who knows

[LA_phantom_240]

Quite possible its from a salvage yard.

[lil240sx95]

yeah, wanted to say junkyard..

[LA_phantom_240]

'junk yard' has such a negative connotation though...

[lil240sx95]

yeah. thats why i just left it out..but good luck finding out to the op

[didderson]

Not sure about 1 or 3 but I can offer my experience on 2 and 4 for ya.
2: If your timing chain tensioner works fine, and you visually inspect the timing chain. As long as the chain isn't beat up too badly and you can't see scars and signs of it hitting the inside of the valve cover, then you shouldn't need to replace it. The timing chains are pretty bulletproof in my experience. If your timing chain tensioner is poopy, spray some carb cleaner inside the piston for the timing chain tensioner and watch it come back to life.

4: I would be very wary of re-using the main bearings and rod bearings. I re used them after a head gasket change and rod knock/death ensued. I torqued the rods correctly but I think I should have used loctite because the torque is such a small amount the nuts backed themselves out within a few hundred miles.
I'm sure the FSM says to use loctite, and if that's the case then go ahead and reuse your bearings. I need to read more in depth next time.

Good luck man. Sounds like a promising motor.