Compression & leak down results

[Wew]

Hi all,

Had a local porsche mechanic do a compression and leak down test on my 78 Cali with 188000 miles on the odometer. The guy who I bought the car from didn't have squat information or receipts on what had been done to the car. (Long story). Any, it's been running now and I am going through it. Getting ready for my first engine drop and plan on addressing a a lot of things while the engine is out. Distributor rebuild, rear main seal, thermostat seal, vacuum lines, coupler, valve adjustment, turbo valve cover, oil cooler washers etc. pretty much everything mentioned in Wayne's book as far as addressing common oil leaks.
What I am looking for are your opinions on my readings for compression and leak down.
1- 150. 5%
2- 150. 5%
3- 150. 5%
4- 140. 14%
5- 150. 5%
6- 150. 5%

He also drove the car for a while and said it drove strong and thought it was fine.
His opinion on cylinder 4 was a possible valve out of adjustment and thinks if I address that it will probably address the variance in the reading for cylinder 4.

I don't know if the engine has ever been rebuilt or the new timing chain tensioner s installed, although I plan on checking when I have the engine out.

What I would like to hear back from the brain trusts on this board are do you think the mechanics explanation for the cylinder 4 reading is plausible?
A motor with this many miles on it, is it reading mileage appropriate?
Any other things to look for or check while I have the motor out?

Thanks for you input.

Gary

[T77911S]

valve adjustment on #4 could fix it. would be a good place to start.

[BK911]

Part of a leak down is listening to where the air is leaking from.
I would do it again with properly adjusted valves, but listen this time.

Good luck!

[Wew]

Do you think these numbers look good other than 4?

[Reiver]

Yes they look good. Unusual to see everything so even across the board.
If everything else checks out looks like a solid lump.

[SCOTITUDE]

almost too even

[Wew]

Is it surprising or concerning that they are that even?
mechanic who did it is reputable and been around a long time.
So assuming the readings are correct and his recommendation of the valve adjustment to probably fix that cylinder 4 reading and a motor with 189K miles on it, would these reading indicate a rebuild somewhere along the way? Engine number and car match, so it's the original engine.
Thanks,
Gary

[Reiver]

Compression tests often come up even...leak downs rarely do as it is a more definitive test with more control.
I've never seen one that even (minus the 14).
If the readings are correct you are a long way from a needed rebuild/top end. You could go another 100 k with those numbers or further all things being equal.
The other measurement is oil usage. Porsches use oil in varying amounts depending upon your driving and the top end health.
You don't appear to have worn compression rings but the oil rings are another issue as are the valve guide seals.
Any idea how much oil it uses in miles to a quart? Lots of opinions on how much is too much so you should use the search engine on that subject.

[Wew]

Thanks for the feedback reiver. The car is a leaker hence the engine drop. Vacuum and oil. So it's hard to say. In the 800 miles I put on it I did add 1 quart.
Oil pressure always looked good, but the oil level gauge is spotty. Sometimes shows level sometimes show nothing. I heard the are finicky. Thanks for the input again.
Gary

[Reiver]

No one uses the oil level gauge for exactness, it only gives an indication of level when the car is fully warm and stopped on a level flat surface. Driving it barely registers, that's normal.
I suspect you know to only check your oil with the motor running, fully warm and sitting still for 30 sec or longer on a level surface.. Never fill to the top mark, only 1/2 between the marks.
Keep track of your oil usage but 1 qt. for 800 miles is ok and does not indicate action on your part.
I had a 930-16 (US spec 3.0) that ran great with good leakdown that got about 600 miles per qt. and I drove the hell out of it no problems. Every indy shop owner that drove it said 'just put more oil in it' as it drove so well.
When they get a bit south of 600 mpQ (some say at 300) but it's a personal thing depending on your professional source then you should deal with it.
The bottom ends are good for 3 to 400k no sweat if the oil is changed regularly.
If it was leaking badly you may have dripped more oil than you used so you might be better off than you suspect.
Use a good zddp oil in the proper weight and change it every 3k....then they seem to run forever.

[Wew]

Awesome... Thanks for the advice and insight.

Gary

[Reiver]

Forgot one thing.
When checking your oil (motor running) as you remove the oil cap your engine will change it's idle, run a bit rough....this is normal as you've now induced an air leak in the vacuum system .
If it does not change tempo then you already have a leak somewhere that needs addressing.
Good luck.

Pat

[Wew]

On board. hence one of the other reasons for the engine drop. rocker shaft seals, adjust valves, turbo valve covers with new gaskets. All new vacuum hoses and intake sleeves too. rebuild the distributor, new wiring harness to install, oil pressure warning lamp switch, oil cooler thermostat o ring, oil cooler seals, s shaped rubber hose, new oil return tubes, cam housing covers, flywheel seal and the main shaft pulley seal, cis fuel injection seal/gasket. Hopefully that takes care of the oil leaks I will also check the flexible oil cam lines to be sure they are good otherwise I will change those out as well. Am also going to do the rear wheel bearings, and rebuild rear calipers. (front end including turbo tie rods control arms, wheel bearings, brake calipers rebuilt, new rotors, ball joints and sway bar bushings already done. And still more to do
Good clean fun!

[Reiver]

Good plan.
How old are your sending units (in the triangle of death...major oil leakers too)....if you are doing all of that might be a good call.
Check your shocks all around too...the torsion bars can hide blown shocks really well...mine were toast and it was not overly noticeable. Big improvement with new ones.