PPI Components

[coldstart]

Question for the all-knowing crowd out there:

I am purchasing a 1971 911T targa, subject to a PPI. I have made an appointment for the PPI with a very experienced, recommended Porsche expert (including early Porsches).

He has recommended that I do not need a leak-down or a compression test and that he is able to tell from driving/inspecting the engine whether the compression is okay. He also said he can do one if I insist (2 hours, $200 extra on top of the $100 for the PPI).

Should I get a leak-down or a compression test? There has been very limited engine work done on the car to date (100K miles) but supposedly it runs extremely well. Is it worth the money if the Porsche expert said no?

As well, does he need to remove the valve cover in a PPI?

Thanks for your help.

[blucille]

spend the money. $100 is a real bargain for a PPI, I would insist that the 'expert' spend as much time as it takes to give you a thorough evaluation of the car...I wouldn't hesitate to spend $500 on a PPI, knowing how much you could spend to correct items that might otherwise be missed.

-Lewis

[anthony]

This mechanic sounds like he doesn't want to bother with a compression check. I wonder why? The car could still seem to run good with one low cylinder.

FWIW, it took my mechanic less than 30 minutes to do a compression check. 2 hours sounds excessive.

[coldstart]

Thanks for the advice. Any other comments on what a leakdown test should cost and whether the porsche mechanic is incorrect in not recommending one?

[Grady Clay]

First read this thread. It is very worthwhile having a clear understanding and agreement with the seller.
“Purchase agreement:”
the buying process



A good PPI is progressive; you start with the obvious and inexpensive and progress to the more difficult, time consuming and costly. Over the years I have taken in many 911s where we never wrote a repair order because a quick look-see sent the car down the road. On the other hand, after checking the sump and exhaust gas and much more, both a cranking compression test and cylinder leak test were in order to be sure of the condition.

I agree with Brian. I can’t imagine anyone not recommending compression and leak tests at some point in the process.

There have been many threads on PPI and I would recommend you do a search on all of them and develop your own specific PPI sequence for this ‘71T Targa. Much of the preliminary stuff you can do yourself.

My own preference would be something like this:

1) LOOK – a careful visual inspection may stop the process without spending a dime. You are looking for prior crash damage and the quality of any repairs. You are looking for rust damage. Has it been repainted? Color change? What is the general condition of everything – carpets, upholstery, trim, glass, etc. Is the condition consistent or have some things been replaced, upgraded or updated? Look under the trunk carpet and floor mats (take them out for inspection.) What is the degree of originality? If something has been replaced, do you consider it an appropriate update? Look over all the paperwork. Is there provenance since new? What is the ownership, repair & service history? Is everything there – tool kit, jack, spare, Owners Manual, Targa top bag & latches, etc?

Additionally look at the tires and check pressures. Inspect the brake pads and rotors through the wheels. Are the lug nuts in good condition, center caps snug? Look at the visual condition of the batteries, connectors, and fuses. Look at the visual condition of the engine compartment – are all the hoses, hardware, insulation, etc. there and in appropriate condition? Any sign of a fire? Is the air filter cartridge clean? Does it look like the fuel filter, cap, wires, etc. have been serviced? Is the oil clean and level appropriate? Is the exterior of the carburetors clean and consistent (not just 25c car wash from the rear.) Any fuel or oil leaks?

A quick look under the rear will confirm an OEM muffler and good condition heat exchangers. Again look for signs of oil leaks including the oil tank.

Are the hood and deck lid lifts properly functioning? Do the trunk, engine and gas flap latches work properly? Do the doors operate properly and the restraint keep them open? Do the windows operate smoothly and fully? Does the key properly operate the door locks, ignition, glove box, and hood latch? Do the seats adjust properly both fore & aft and recline properly? Special note the condition of the screws that attach the recliner to the seat back. Do the seat belts work OK? Do the sun visors and mirrors adjust properly?

What is the condition of the Targa top? Does it come off, fold, unfold, and reinstall properly? When it is partially open, check for broken struts. What are the condition of the seals? Inspect with the side windows up and down. What are the condition of the seals for the trunk, doors, windshield, etc?

Does the accelerator pedal have any side play (wobble)? When you first push on the brake pedal note it’s position and apply pressure a second time. Does it pump up? Does the shift lever have any rotational play? Does the hand throttle work appropriately? Does the fresh air blower function properly on all speeds and does the control work? Do the heaters/defroster work properly? Does the windshield washer work? Do the wipers function properly on all speeds. Do all the lights work? Check turn signals, high-low beams, 4-way flashers, running lights, instrument lights, glove box light, and interior lights.


How does it drive? Does it drive straight or pull to one side? Do the brakes work smoothly on light application (no pulse feedback to the pedal)? Do they work properly on full use at high and low speeds? Does it feel like the brakes don’t fully release or “pump up?” Is there any sign of a “shimmy” or vibration at road speeds (50-65 mph)? How does it handle bumps and undulations in the road?

Does the clutch operate properly? Any noise when fully depressed? Does it fully release so it doesn’t grind going into reverse? Are the syncros OK? Is the shifting proper, both up-shift and down-shift, in every gear? Any rolling noise or whine? Any “clunks” when on & off the gas?

Does the engine start and run properly? Is idle OK? Any hesitation on accelerating? Will it run full throttle to redline in 2nd and 3rd gear? Any noises? Any smoke? Try a long deceleration from high revs in 3rd gear just using compression to slow the 911, then apply power and see if it smokes.


Now you are ready to take it to a mechanic or few for a repeat of the above and a PPI.

2) Most reputable mechanics will give you a thorough look-see and not continue if it is obviously an undesirable purchase. With the 911 up in the air inspect the underside as you have the top side. Check for crash and rust damage and repair. Does it have the original struts and ball joints or have they been updated? Any sign of brake fluid leakage at the flex hoses or calipers? Do the wheels spin properly and have appropriate free-play in the front and none in the rear? Any sign of leakage from the fuel tank & lines, CV joints, transmission, and engine? Do a thorough inspection of the exhaust system.

This might be a good time to check the ignition timing and ignition with a scope and an exhaust gas test.

3) Note the condition of everything. Does anything look too new or out of place? Check for someone bending a rear control arm. Check the rear sway bar mounting and links. Check the condition of the clutch linkage, particularly the support cast in the transmission differential side cover. With a light check for contact between the clutch release arm and the pressure plate. Check the throttle cushion. Check the throttle linkage at the transmission bell-crank.

4) Drain the engine oil and carefully inspect the sump screen. Note if it has been recently off. Your mechanic should pay particular attention to the small area between the outer diameter of the screen and the case. A Radio Shack 10X hand microscope helps us old guys. Anything metal or plastic deserves attention. Many shops have a large “can opener” type tool to disassemble an oil filter. Carefully inspect the magnetic drain plugs in the sump plate and oil tank. Your little finger can feel inside the oil tank for rust debris. A bore scope is very useful for looking at inaccessible places. Install fresh oil, a new filter, and new sump gaskets & Nyloc nuts.
Check the transmission magnetic drain plug. Note the condition of the lubricant. Remove the shift pivot piece and inspect the gears for rust using a light on the end of a flex-wand. Fish around with a little magnet. Replace with a new pivot gasket and fresh lubricant.


By now you have a pretty good idea if you want to continue or not. You have invested some labor, mostly your own, and some inexpensive parts & lubricants. If you walk from the deal, the owner should be happy with the information and fresh lubricants.

5) Cranking compression and cylinder leak tests both reinforce each other while testing slightly different aspects of the engine. Do a Pelican search. I prefer to do the leak test first while removing one sparkplug at a time in firing order sequence. This prevents any little piece of carbon from getting on an exhaust valve and fooling the test. The cranking compression should be last with all the sparkplugs out and the ignition disabled. If the tests indicate a low cylinder, put everything back together and go out for some extended spirited driving. Repeat the tests. Never make a decision based on a single test.

6) Remove the valve covers and inspect the cam lobe surfaces. Check for proper valve adjustment. Torque the head nuts. Torque the rocker arm shafts. Check the cam timing. Reinstall covers with new gaskets and hardware. This is really maintenance for you but serves well during a through PPI.

7) Have the mechanic do an extended test drive with you as passenger. Have him explain all the good, bad, and ugly. What is normal for the age and mileage and what maintenance and repairs are to be expected in the short run. Don’t expect him to be a clairvoyant.

You can repeat this with several different mechanics. You can get other knowledgeable Porsche enthusiasts to help you look. You can look at many other 911s of the same vintage (for sale and not) and hone your ability to recognize what you are looking at. Educating yourself will pay off in spades. Spending US$1K+ is worth it for the right 911. There are some cars that are a bad deal to have in service even if free.

Now comes the moment of truth – the decision to buy or not. You are now armed with as many facts as are reasonable. You are also in a position to renegotiate the price if you want.

As you can see, you can stop the PPI process at any point to not waste money on something you don’t want to buy.

When you buy a nice old 911 like this, be fanatically and emotionally prepared to spend the money to fix everything that needs attention. That will probably be a lot. The return is having a really cool nice early 911 Targa.

Good hunting.

Best,
Grady

[coldstart]

Wow. Thanks Grady. Those were some helpful hints. I likely am going to stick with the mechanic as he is the "early Porsche guy" in the area but order both a cylinder leakdown and a compression test.

[Steve87-911]

Ya, I would not feel comfortable driving a new-to-me p-car without compression test and leakdown. I had both done over a year ago for US$120.00 . Made me less worried as i drove her on the 300 mile trip home.