Engine Rebuild:Top only or complete?

[dhopkins]

Does it make sense to take an engine out and just do a top-end rebuild? Or once the engine is out should a complete rebuild be done? How much should a top-end rebuild cost?

don
______________________
1963 356B
1969 911S
1981 911SC

[fryardds]

What type of problems are you having that would lead you to think of a partial or complete rebuild?

[Chuck Miller]

Don,

We need MUCH more information to give constructive advice...

What's it do'n? - What's it not do'n?- What do you want it to do?

Mileage, oil consumption, blow buy, blow through, leak down, compression?????

All of this info will help us with advice... the more info the better the advice

A 'top end' and a 'complete' is MUCH different in price...

Hope this helps,

[dhopkins]

It seems to be smoking too much and not just on start up. I thought I could just do the valves and rings.

don

[PStey]

On every engine I took apart (5 until now) there was severe wear to the rod bearings and some main bearings. If the engine is smoking because it is worn, and not because of some mixture problem I would not risk a top end rebuild only. Sure there is extra cost involved, but if you are already in there it seems foolish to cut corners.

[cabrachian]

I'm in a similar quandary.

What if the problem is valve guides?

[pwd72s]

I suggest a book: "how to rebuild and modify Porsche 911 engines" by Wayne Dempsey. It's first chapter covers all the good questions that Chuck raised, and more. It covers the diagnostic tests, how to interpret their results, and more. You can buy it through Pelican Parts or motorbooks. I suggest it as a "must read" for people who are even thinking of an engine rebuild. Even if you don't plan on doing the rebuild yourself, the info is golden, because you can then understand and question your mechanic about what is happening with your engine. Don, you'd think a college professor would know the value of homework and research... I think it would pay you to spend some time in those areas.

[dhopkins]

I already have all the books and have read each of them 5 times. None of them answers the question of partial vs. complete rebuild. They assume a complete rebuild and don't discuss partial rebuilds. I think this is a shortcoming of Wayne's book. To contain costs it makes more sense if X broken to only fix X rather than replace everything. That would be like going to the store b/c you need a shirt and then deciding to buy a complete wardrobe since your already in the store.

don

[sithot]

Don:

JUST doing "Tops Ends" were not an uncommon practice. If they suggest a full rebuild I'm guessing that the authors believe the subjects involved are high mileage cars which "should" need this by now.

I recall quoting a price for a top end of around $1,200 in the days of old...

(when men were bold and toilets weren't invented. You dropped your load along the road and walked away contented.) But, I digress...

Valve guides were usually the culprit. The bottom ends are "Hell for Strong" and should be good to 125,000 miles OR MORE with normal maintainence. The SC's are so over-done that they are known to pop 200,000 and more without issue.
Our engines have 8 main bearings! (check your Chevy) If you have a rod or main bearing problem it is likely due to long periods of storage without proper care. Condensation, oils, and fuel contamination can cause all kinds of problems (acid/rust)in your cylinders and your bearings as well. It's better to drive them than to let them sit. Run the piss out them and do it regularly getting your oil up to temperature to boil out any condensation. MAINTAINENCE IS KEY TO LONGEVITY.

If it can be determined that all you have are guide and/or ring issues I'd do the top and move on. It's quicker, cheaper and will get you on the road. If it's leaking like a sieve then perhaps you want to split the case but most leaks are the front main (behind your fan pulley) oil return tubes, rear main or thermostat housing.

BTW, Bruce Andersons "Porsche 911 Performance Handbook" is a better read imho.

Tom

[dhopkins]

According to my records the bottom of my SC engine was rebuilt at 55K. They found some broken bolts. If I rebuild I would only do the top. What do people mean when they say their engine has been freshened?

don