Need to drop engine after rebuild

[911pcars]

Originally Posted by polizei

Hey guys,

I recently completed a top end rebuild and turbo conversion on my '87 Carrera. Once I got to driving the car, I found that it was going through 10 quarts of oil over 2,500 miles.

I ruled out the turbo as there is no trace of oil in the charge pipe going to the TB. There is a leak between the cam towers and the heads, but it only leaves a very small amount of oil on the garage floor after sitting overnight. I believe the leak is caused by a poor sealant, so that will be resolved when we drop the engine. My friend who is doing most of the engine work believes either the rings have not seated or there's a problem with the valve stems.

It smokes slightly to moderately at times on idle. It smokes VERY heavily through the first three gears after it sits overnight. My friend drove behind me on his motorcycle and said at speed it smokes slightly while cruising, and he said he could definitely smell it. It smokes moderately on engine deceleration.

A couple things come to mind as to what the problem may be. We didn't measure the thickness of the cylinder walls, so perhaps one or more cylinders are out of spec. We used a ball hone as opposed to a diamond hone on the Mahle cylinders. What are the measurements I should be seeing for an in-spec 97mm Mahle cylinder? Is it advisable to send the cylinders out to be measured and re-honed? Does anyone know of any shops near Eastern Pennsylvania that are reputable?

What should I be looking for as we tear the engine down?

As usual, thanks for your help guys.

I would have advised conducting a compression test to confirm the rings are not sealing. If you're into the tear-down stage, you'll have to measure and inspect to determine the most likely cause.

Sherwood

[les_garten]

Originally Posted by mb911

yeah tend to agree. Mine almost could use a scavange pump as the oil sump can't keep up at idle. What do you guys think though are the turbo seals now shot or can he get by with just the pump?

Mine fogged the Freakin' neighborhood so bad, that Mosquito's were dropping out of the air at 10,000 feet and neighbors literally showed up to see if the house was on fire. I put the restrictor back in and pretty quickly, no smoke ever again.

[polizei]

Originally Posted by les_garten

Mine fogged the Freakin' neighborhood so bad, that Mosquito's were dropping out of the air at 10,000 feet and neighbors literally showed up to see if the house was on fire. I put the restrictor back in and pretty quickly, no smoke ever again.

Ben, thanks for thinking ahead for me! Les, so you didn't have to replace the turbo seals?

[polizei]

Originally Posted by 930gt-40r

If your rings are not bad and your plugs look fine, you need this part and plumb it back into the breather cap at the top of the motor since your oil tank has no provision for a turbo oil return.

Where is a good place to buy one?

[les_garten]

Originally Posted by polizei

Ben, thanks for thinking ahead for me! Les, so you didn't have to replace the turbo seals?

No, once the flow was restricted, no issue at all. I have heard it may take a little while for the seals to re-situate themselves. It was a few drives for me. Hope that helps...

[polizei]

I can't seem to find the Tilton 40-524-1 model for sale anywhere. Will the 40-524 model do the job? Does this substitute for the oil scavenge pump that sits downstream of the turbo oil return on the stock 930? What will be involved with installing this?

[jbrinkley]

when I thought about this, alot, I was going to go with westech. here http://www.scavengepump.com/faqs.shtml

I hadn't decided yea or nay on a catch tank or just plumb it inline with the drain and return straight to the tank, (top)
First thought was to mount it inside the bumper, inline, and return to the top through the breather hose.
I didn't have oil issues though so I didn't bother.

[EPorsche]

Any updates?