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to rebuild or not to rebuild???


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ok for starters i just brought the car 2 months ago. i have noticed that i have an oil leak. i do not know exactly where it is coming from. one guess is the gasket is leaking, another one is that it is burning the oil. it was rebuilt once at 117,000 it now has 206,000. so whould it be worth rebuilding or should i look at buying a new motor for it???

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You may be jumping ahead of yourself here. Just because you have an oil leak doesn't mean you have to rebuild or replace the engine.

How is the engine running? Check the plugs to see if it's buring oil. While you're checking the plugs for the presence of oil, do a compression check to get an idea of the condition of the engine. A compression check will tell you more about the condition of the engine than trying to guess the cause of leaking oil.

As far as finding the source of the leak, go down to the auto parts store and pick up a can or two of engine cleaner. Thoroughly clean the engine and you'll have an easier time of telling where the leak is coming from. May be just the valve cover gasket, could be the head gasket, the main seal, or a myriad other places. However, a leaking engine does NOT indicate a tired engine in need of a rebuild.

Even with 100,000 miles on the rebuild, if it has been well mantained, you should probably get another 100,000 miles out of it. The L-series engine are very dependable and robust.

Best Regards,

Landmizzle '72 240Z

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I agree with landmizzle, if you haven't spent any time looking for the source of the leak I would do so first. It may be something very easily fixed. You want to find out if it is internal or external. Does it drip on the ground when parked overnight?

Are you the kind of person that want's to check it out yourself or would you rather take it to a shop? Most of the external oil leaks will come from the oil pan gasket or the valve cover gasket. Either the bolts are loose or the gasket is damaged. If you tighten them remember they do not need to be real tight, they key is evenly tight! I don't remember the torque specification but I would say two finger tight, that is as tight as you can get it with only two fingers on the end of a short wrech. Or maybe the oil pan is a little warped. Other sources are the front or rear crank seals. The front seal is not too hard to change but the rear seal requires disconnecting the transmission, clutch, flywheel, etc. Cleaning up the bottom of the car will help determine where the leak is coming from. Remember oil flows rearward as the car moves so you typically want to find the forward most point that is wet with oil.

Internal leaks could be determined by a compression check or a leak down test. These could be things like worn rings, valve guides, or valve guide stem seals. Usually, you will see blue smoke at startup if it is valve guides or vavle guide stem seals. If it is rings then there will be smoke when the car is driven, hard to see while driving.

A L6 Z motor doesn't necessarily need to be rebuilt when it reaches 110K miles. It just depends on what you want to get out of the car and what you want to put into it. What are your goals for this car?

Also, welcome to the club! I work just down the road in Rocklin! There are many Z folks in the Sacramento area, and several are members of this site, so let me know if you would like to get together and met some local Z folk.

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thanks for the tips guys. but i thought about it at work and the first thing that i am going to do is to see if i can find the leak. but i guess my theroy is that i don't know how the last owner treated the car so i'm thinking that the best way for me to figure out how it was kept is with a rebuild. than i also thought that if i rebuild the engine first than i won't have to worry about it when i get the car's extireor fixed. but yeah my basic goal is to basicly restore the car, with some personal touches to it.

and yes i would like to get toghether and meet some local people with z's.


and thanks for the advice again.

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You can find out how the previous owner treated it by looking at the results of a leak down test, compression test, checking your oil pressure, check the valve timing and valve settings and giving it a good tune up. Then if everything checks out enjoy the drive and hang out here on this web site where you can read the different things people have done to put personal touches on their Z engines and plan your next engine!

Have fun!

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a complete rebuild is not cheep, you are looking at four figures at least. If you need to have it all done by others. I agree with Royce and landmissle . unless you have deep pockets then go for the rebuld . enyoy the ride!

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