Looking at a 55k mile 1995 993 from private party. Getting a PPI but seller and place inspecting the car say that compression and leak down not needed as car is running strong with no oil leaks. They will do it if I push them but they seem to think it's a waste of money. The car has been well looked after with two owners, current selling owner for last 20 years. The car has had clutch replaced in last 5k miles but has never had the head "resealed".

Wanted to get opinions from more experienced air cooled owners on if I should push for the test or if what I am being told makes sense.

 

A 95 ODB1 car at 55k miles doesn't need the heads resealed.

Has this car been driven recently? These motors will show terrible leakdown numbers if not driven and a garage queen.

 

Thank you for the input. Much appreciated. Approx numbers are 40k miles in first 6 years of duty. About 500 miles a year since then. I'm guessing that counts as a garage queen.

 

Here is some information you may find useful in a purchase:
Some of the items will not affect your buying decision or influence price but it is always worth going in with your eyes open:

https://993servicerepair.blogspot.co...-purchase.html

Here are my thought on cylinder tests:

https://993servicerepair.blogspot.co...-down-lie.html

Some of the above is just opinion,
Hope it helps,
Andy

 

Agree with Paddy, a car that hasnt been driven will likely show bad leakdown numbers. Also, two (or really three) questions:

1. Are you getting a PPI from a reputable indy who specializes in air-cooled Porsches? If yes, I would trust them.
2. Do you think the seller will give on the price further, or are you going to walk away from the deal if the leakdown test is bad?

I negotiated on a 97 C4S that was leaking oil (chain boxes, base gaskets, etc) after basically sitting for 18 mos (~500 miles in 2 yrs). PO installed a fresh battery, but would not pass emissions. I put a deposit down, then got a PPI from a recommended shop. I did it in this sequence b/c i only needed the PPI to me if it was something so bad i needed to walk.

The mechanic didn't do a leakdown, but he drove it and said it ran strong. Told me to drive it, and check the oil when warm. If I was filling more than a qt every 1000 miles to bring it back in. I found out later the mechanic drove 50 miles during the PPI....I wired the rest of the money 30 mins later. Drove it every day for a month and voila...all but 1 of the oil leaks stopped, and i think the last one is really just spilled oil when i added some in. Passed emissions without any issues either.

Off topic to leakdown..but the three things i would check are HVAC, driver's door check strap, and rust in the windshield corners.

HVAC - if the evap is leaking it is a pain in the butt to replace.
Door check strap - if it is broken, the A-pillar needs to be cut to reweld the strap in.
Windshield - if there is rust, well, it could be expensive to fix.

 

Very helpful feedback for me as a first time aircooled buyer. Appreciate all the pointers.

 

As others have noted, Make sure you have a reputable indy shop do the PPI but even at that, you need to level set the expectations of what that report will really show.

I recently bought a 95 993 from out of state from a car broker who suggested a local shop. The PPI didn't say a word about two items that needed immediate repairs costing over $1000. Distributor cap and rotors causing misfiring and all drive belts needed to be replaced. WTF? The best advice is know what to look for and have a well documented car so you can see what has been done.

Dont let this list scare you. Some known issues with these cars and areas to check into are:Compression test / leak down test

Check rust around the windshield and rear glass,

Check for worn suspension components,

Check inner tie rod ball joints in the steering rack,

Front lower control arms wear out between 70-100k (can crack—causing shimmy in wheel)

Look for corroded brake calipers and rust on the shield between brake caliper and suspension (that can rust)

Check for corroded bumper supports especially in the rear (move the bumpers around a bit for a quick check),

Check for decaying spark plug wires,

Check for worn engine mounts,

Check door check straps (do they make noise when opening or doors sag).

Engine case through-bolt O-rings leak oil

Dual-ignition distributor internal belt can fail

Drive-belt pulley

Engine wiring harness was recalled, check to see if the recall fix was performed

HVAC module parasitic drain can discharge battery

Clutch

Clutch slave cylinder can make creaking noise

Clutch slave cylinder hose can leak

Gearbox shift-selector seal can leak

DME relay can fail

Steering rack can leak

Steering tie-rod rubber boots can crack

A/C condenser and oil cooler fan resistors can fail

A/C evaporator can leak

Cooling fan hub bearing can fail

Flywheel rear-main-seal can leak

Engine valve covers can leak oil (Compression test)

Was the underbody panel removed?

Check spoiler going up and down (look at gears—-they can break on the part that rotates up and down)

Shifter bushings and fasteners can have issues

Third brake light bulbs can go out

Vacuum distribution port can collapse

Sunroof seals can fade (difficult to replace)

Sunroof cables can have issues. Little plastic part that pulls down wind deflector can break.

Door-stop mounts can break on A-pillars

Rubber steering wheel airbag mount bushings can weaken, causing the horn to blow unexpectedly or when left signal is turned on, or turning left

Cars that sit can develop problems with congealing brake fluid (white wax material)

• Speedometer, odometer, and/or tripmeter gears can break
• Exterior mirror-bolt trim-caps can be missing
• Windscreen wiper-blade rubber-buffer can be missing
• Windscreen and rear window rubber/plastic trim cracks and breaks. Worse, the window trim plastic is molded to the window, and when it breaks, the fix is to replace the window. The rubber trim that goes around circumference has a felt-like surface, which will creak when it wears out

Front bumper around air vents check for rust

Look for smoke coming from wheel arches (failed cover and oil being burnt on heat exchangers)

Oil temperature gauge

Inside of brake discs scoring

Were suspension bushings replaced?

Electric windows

Seat height adjusters

Exhaust heat shields and silencer welds subject to rust

All ac vents blowing cold and hot air

Bearing in ac controls for ac sensor squealing (little sensor in HVAC control to the left)

Gap between front bumper to hood

Leaky rack and pinion steering gear

Belt between two spark plug distributors can wear

Limited slip can go at 45 unless a motorsport

 

All sage advice. That said, it's a 26-year-old car and will need some work.

 

I agree.
Enjoy the new car.
Don't be too wigged out about the list of potential faults above.
Most are true for ANY 25 year old car.

 

I wouldn't get a compression/LD on a 55K 993 that's running fine, and it's really not true that a 993 that isn't driven frequently will have bad LD numbers. Bad LD numbers in this scenario can come from carbon buildup on the backs of the valves and seats that doesn't get burned off from spirited driving. Just sitting doesn't cause this.

OP if you're buying if from a long-term owner, the key question will be asking about oil consumption. That will tell you, not an LD, about valve guide health.

 

Thanks to everyone for all the very helpful tips. I fully expect that the car will need some work as its 25 years old. I'm not expecting perfection. Just would rather not have a 10k engine out rebuild right after I get it home. Regarding oil consumption current owner states it burns no oil between oil changes. He adds zero BUT he only drives about 500-750 miles a year. PPI was ok. Needs front brakes and rotors they are at 4/32 and the pilot sport tires from 2013 are timed out but only have a few thousand miles on them. Just had major service oil, filters, fuel check valve plugs new rotor and distributors. Has had front windshield done including repair of very small bubble at cowl. The car is a survivor basically 100% bone stock. No modifications. Original everything other than consumables which I find very appealing and plan to keep it that way. Will be picking it up at the end of the month. Will update this thread with the obligatory pictures or it didn't happen post. Thanks again to everyone for their input.

 

Sounds good with the PPI.
Stock is fine but ditch the factory suspension. PSS10s and RS sways make the car WAY more fun, not to mention it looks better.

 

Another Approach to Mechanic / PPI
Ask Mechanic to Sign for DE Tech Inspection.
Hand him the Form - with a Pen !
Sign here please
TJ

 

I do not agree, and haven't seen evidence of this.

Please cite/link examples demonstrating this behavior.

 

Personal experience..when i was a kid, I'd go hunting for cars to fix up with dad. Cars that were sitting always had poor leakdown numbers. Seals would dry up and get brittle 'cause oil doesn't move around to keep everything lubed up. This causes air to escape through all the different mating surfaces within the motor. This phenomenon is more pronounced on a high performance motors from Porsche. It is designed to be driven, and driven alot & hard. Hence all the evidence of post on oil leaks on the various forums. If there is an oil leak, air can leak from the same place. Hence it will likely have poor leakdown.

BTW, one might notice that during the pandemic, planes are flying around with no people. While there are many reasons for this (legal, economic, political), one is also scientific. A plane cannot sit in a hangar for too long. It will begin to fail the conditions it was designed for. Seals dry up, fluids leak, and it will no longer be acceptable to fly it. Either it will then need to be pickled (ie prepared for long term storage) or be flown regardless of passenger or cargo. The science behind this and our cars is the same.

Another classic and somewhat extreme engineering example is the SR71 blackbird. It was designed to be flown in specific conditions..one of which was not sitting on the tarmac. Literally, stuff would start to leak while landing..though this was primarily due to air pressure and temps given the extreme conditions it was designed for. Pilots literally had to come up with creative ways to park the plane to avoid losing control on the ground due to fuel leaks.

3/4 edit: Saw this posting of a 30+ yr old sitting 911 with 'good' leakdown according to the poster. Not sure what the numbers are, but some anecdotal evidence that sitting does not always equate to poor leakdown.
http://forums.pelicanparts.com/porsc...ortomatic.html