Mongo

Ok where do I start; not the best news to receive for the holiday season, but things happen. I've made the decision to rebuild my 944's engine which has suffered a piston ring failure in cylinder #3.

I have a couple questions below which I'm gonna need assistance in answering from those who have experience with 944 motor overhauls.


1) Assuming my bores after 130,000 miles are not out of round and are still in spec, I will re-ring the pistons and replace my engine's rod bearings. To re-ring the pistons, can I drop the oil pan and push the pistons through the top of the motor after the cylinder head is removed?

2) Is there a Porsche-specified tool required to re-ring Porsche pistons?

3) What are some other good "While You're At It" things I should replace and/or upgrade while I am working on the motor internally?

Below is a list of things that have already been done to my motor so we can rule out replacement for now. These have all been done within the past 10,000 miles:

- Water Pump
- Timing Belt and Balance Shaft Belt
- Timing Belt and Balance Shaft Belt Rollers
- Oil Cooler Seals
- Radiator
- Cooling System Hoses
- Engine Temperature Sensors and Fan Switch
- Thermostat
- Rebuilt Cylinder Head
- Oil Separator

What is currently on my replacement list:

- Piston Rings
- Rod Bearings
- Rear Upper Balance Shaft Seal
- Throttle Position Switch (Mine is working but as a safe thought I have a brand new one sitting in a drawer next to my leg here)


Any thoughts, suggestions and recommendations are appreciated.

At the same time, this thread will contain pictures as I perform the tear down hour by hour.

Wish me luck and let the replies roll...

Russian Rocket

Well, good luck and get some band aids for those knuckles

Porsche-O-Phile

Bore, sleeve, 3.0L crank. 'nuff said.

Mongo

Teardown of the top end and pulling the cylinder head starts this weekend. We will be using a micrometer on the cylinder bores to check and see if they are in spec. If they aren't, I will be making another purchase: a short block to overhaul, which I will put my cylinder head on. This motor will then be swapped into my car.

Mongo

Sorry man, I am limited to under $1,500. I can't build a $5,000 engine. Nevertheless I didn't say that it isn't a wet dream of mine

Scootin159

1) The pistons will just push out the top of the bores once the head is removed.
2) None I know of
3) While they likely won't need it, as long as you're pulling the oil pan it may be worth replacing the main bearings. Also may want to look into some simple oil-management upgrades (i.e. oil pan baffles, crank scraper, etc.)

SamGrant951

Oil pan baffle $45: look down on page (bit past halfway)

http://www.goingsuperfast.com/for944turbo.html

(Lindsey sells them as well)

Jfrahm

If you broke a ring and scuffed a bore, the block is toast. Not worth boring or sleeving. NA shortblocks are cheap, a lot cheaper than oversized pistons even.

-Joel.

marky522

Maybey I overlooked it but i didnt see main bearings in your list, I dont believe there is a Porsche special tool to do rings there pretty straight forward,

Mark

Mongo

main bearings aren't on the list. The crankshaft is not coming out of the car.

The DareDevil

3.0? Take it to 3.4!

marky522

Crankshaft doesnt have to come out to do mains, its definately a good while your in thre thing to do.

Mark

Mongo

does anyone know if there's a high chance that after 130,000 miles my bores may be out of round too??

joseph mitro

my bores were fine after 126K, mic'd by the machine shop. they did not even hone the cylinders because it all was within spec.

i installed the rings using a $5 ring spreader from autozone, and used the ring compressor that cost all of $10 as well. pretty easy, but make sure you install the rings in the correct orientation. the ring packages should have a diagram about that.

EDIT - if you're going to this trouble, i would consider dropping the lower crankcase half and removing the crank for polishing and balancing and replacing the main bearings.. also, look for some forged OEM rods if you don't have them already. i got lucky and found a set of forged rods for $50 on ebay, perfectly good set

Jakerx

hey andy

after 138k miles my bores were completely fine. i had them checked of course and they were within spec. all i had to do was replace piston rings and go from there on my engine rebuild two summers ago. i went through this same process. if you need any help along the way you know how to reach me bud. take care.