Your opinion on compression 130, 145, 105, 135 please!

porsche912e · 01-09-2003, 08:03 AM

I contemplate purchasing a 71 914. The exterior is in acceptable shape. I am concerned about acquiring an oil burner or a candidate for an immediate rebuild. The owner told me that the last compression check revealed 130, 145, 105, 135 which does not look well balanced to me. The heads had been rebuilt some time in the past. What is your opinion on this?

Other than that the wheel bearings in the front are a little loose. One of the popup lights goes down and up and down when switching off the headlight, the windshield wiper motor is not working. Are these things hard and expensive to fix?

odie · 01-09-2003, 08:13 AM

that 105 reading has some issues (rings or valve guides). Could possibly be valves adjusted too tight. If the rest of the car is good and the price is right, might be worth buying. The seller could have just screwed up the compression check.

the headlight and wiper motors are probably Porsche and not VW. $$$ unless you can find used ones. Maybe just a relay or wiring problem.

Zeke · 01-09-2003, 08:55 AM

Standard faire for these cars. The owner obviously doesn't care to fix the problems so he obviously is not asking top price. This is a $1000 car at best. If not, keep looking. It's a buyer's market right now, big time. I saw a '74 911 Targa with $12,000 in reciepts go for $5600 last week. He was asking $10,500. No takers for months.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

The wheel bearings are quite possibly just in need of adjustment.

I'd be worried about 105 PSI compression. 100 is "fix it" time, and 105 isn't much above that. Plus a 40 PSI spread from lowest to highest is a lot, particularly when compared to even 145...

Sounds to me like it will need engine work in the near future.

--DD

Zeke · 01-09-2003, 02:01 PM

I would follow odie's advice and see how the compression was done and if there is a valve adjustment problem. Next step is leak down test, but if the comp is down, the leak down is just gonna tell you more about what you already know.

Bruce Allert · 01-09-2003, 02:12 PM

What's the leak down test?
bruce

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Step 1: Set cylinder to TDC.
Step 2: Swap spark plug for an air hose and fitting.
Step 3: Pressurize the cylinder, note the rate of leakage on the gauge(s) attached to the hose and fitting deal.
Step 4: Listen for hissing sounds at the tailpipe (exhaust valve leaking), the intake snorkel (intake valve leaking), and oil filler (rings leaking).

--DD