White smoke at idle & oil leaks: help me diagnose in prep for drop

[r-mm]

My stock 87 has 105k miles on it and is using about a qt/500mi. I've noticed white oily smelling smoke at idle and searched the forum to find many posts suggesting this is a guides issue. Today I was trying to track down oil leaks and was revving the car lightly while cold and saw more smoke from the tailpipe than ever before, likely because the cat was not @ full temp. I then did a compression check (plugs out, WOT, healthy optima battery) and got healthy results:

1: 175
2: 187.5
3: 190 (plug slightly oily/some deposits)
4: 175
5:180
6:180

In addition, following previous advice I checked for oil leaks with the engine @ full oil pressure and indeed did see a not steady but significant dripping, mostly onto the crossover pipe, burning right up. That which didn't drop onto the xover seemed to weep onto the trans. The bottom of the case is dry. Do I need to diagnose this further or can I just chalk it up to the oil cooler / triangle of D and replace all those cheap little seals while the motor is out?

Basically I'm asking: what else should I do with the motor in to make life easier and less costly when it comes out? Is there any way to know if my oil control rings are suspect as well? From reading this forum it seems guides/seals are far far more common a source of smoke & consumption.

[docrodg]

Do a leakdown if you want to get an idea on the oil rings. If you are doing guides then you will be replacing all the gaskets anyway. You can always remove a cylinder and check wear, ring lands, and rings. Also pull that rod and check bearings to see if the case needs cracked open. The bottom end is likely fine as they are very tough. Plan on some hoses needing replaced from age.

[r-mm]

Leak down is a good idea.
However if the compression ring is good, will a leak down test show problems with the oil control rings? I'm not really sure how that works.

Also, anyone have an opinion on the PSI that should be used for a leakdown test? Harbor Freight, which is my source for tools like this that get used irregularly, sells a ld tester that runs on lower pressure (15psi I believe?). I recall that piston rings seal by the pressure in the cylinder. Is greater pressure required for them to operate as intended?

[T77911S]

thats the one i have. i replaced the input side gauge with one that goes to over 100psi, it came off and old AC gauge set. now i can use that one at 100psi pressure. be careful, the engine WILL turn over with that much pressure.

i would not sweat the leak down. i would just plan on rings and guides.
you also need to take into account the cylinders you may have, this could get expensive.
you can also do a leak down after you pull the motor.

[r-mm]

I see a lot of folks here leaving the P&C alone when they address valve guides. I know how expensive the P&C are, and re-ringing, while not expensive, does add a time, complexity and cost and would likely mean having the cylinders honed and require break in. Therefore I want to figure out as best I can if the rings are in good health.

Doing the leakdown with the motor on a stand is a great idea... I did not love getting the compression tester into the spark plug holes with the engine in situ.

Thanks for the tip on the HF gauge and running 100psi. I'll likely go for something a bit better with two gauges and run somewhere between 15 and 100psi. Amazon.com: OTC 5609 Cylinder Leakage Tester Kit: Automotive

[docrodg]

I ran a leakdown with engine out, it is easier. If your rings are bad the cylinders may not need honed IF there is good crosshatch pattern all the way around. I personally would still pull a cylinder (#6 cuz it is at end of oil circuit) to check ring lands, and rod beariings. It is little extra time and is good insurance to know you don't have to pull the engine again soon for bottom-end. That is up to you, I tend to treat my car like my patients... check everything even if it is unlikely to ensure that nothing is missed; makes you sleep better at night.