heliolps2

Hello fellow 951 enthusiasts,

I wanted to share an update on my 951. I had considered selling the car but hesitated due to an oil consumption issue. According to the owner's manual, 1 to 1.5 liters per 1000 kilometers (650 Miles) is considered normal. My 951 was consuming 1 quart every 450 miles, which felt excessive compared to my base 944, which only uses half a quart every 3000 miles. I didn't feel right selling the car with this concern unresolved.

The last time I owned a 944 Turbo was in 1990, and since then, I've mainly had air-cooled Porsches. I wasn't expecting the manual to suggest such oil consumption was normal. Initially, the car used 1 quart every 250 miles with Mobil 1 15w50. On Chris's recommendation at IMA Motorwerks, I switched to Valvoline 20w50, which brought it within the manual's spec. The previous owner had a modified oil pan with a flap for racing, with no oil level sensor because of that, I was always checking the oil.

Despite no visible blue smoke on startup or hard acceleration, no oil leaks, and no oil in the coolant, the car still seemed to be burning oil. I noticed soot around the exhaust, possibly from running rich. The throttle response was also a bit sluggish compared to my 964 Turbo, though the car takes off like a rocket once the turbo spools up. I'm was curious if this is just a characteristic of these engines or if there's something more.


Here’s what I found after some investigation:
I thoroughly inspected the engine with a flashlight and endoscope—no external leaks.
I checked the intercooler pipes and air intake for the turbo and all the hoses. There was only a faint smear of oil, no liquid. No signs of turbo bearing issues, as the boost feels solid.
I pulled the spark plugs (Bosch WR7DC) after 1300 miles. They seemed coked up, covered in oil.
A leak-down test showed 4-6% across all cylinders, with no significant leakage. The compression test read 140 psi, with cylinder No.4 at 135 psi, which had the most carbon deposits. My guess was valve stem seals, replaced back in February, might be the issue since everything else seemed fine. I tried and piston soak and flushed the engine but with no success However, the oil consumption worsened a little over time without visible smoke or leaks.

In June I decided to take the engine apart After further inspection, I found the valve guides were worn out, particularly on cylinder No.4. I had them replaced, along with Inconel exhaust valves from Lindsey Racing. I also found blow-by on the cylinders, so I decided to replace the piston rings with Porsche factory rings $$, which took 2 months to arrive from Germany. and install ACL HP rod bearings while I had the oil pan off. The cylinders had no scoring, Thank God ! The K27.8 turbo was rebuilt with a new turbine wheel and shaft, and I also replaced the motor mounts with Porsche Factory units and the AOS. I even installed a 4-degree advanced timing keyway on the cam. And a new old stock 951 oil pan with a oil level sensor, and alternator and head studs.

With a fresh head, new rings, a rebuilt turbo, and a new AOS, I hope this resolves the oil consumption issue. Did I miss anything?

For the break-in, I'm using Driven BR50 break-in oil. I started the car on Sunday, July 28, 2024, and I'm pleased to report that it fired up without issues. I've driven about 50 miles so far.

I will update with the oil consumption in a few months. I will post pictures soon. Looking forward to hearing your thoughts and any advice you might have on the break in.

heliolps2

Nochrome

Your cars oil use does seem excessive. My car goes thru a quart of oil every 1200 miles. I do notice some oil in the charge pipes, but no smoke. I'm also planning to do the Turbo, AOS and maybe valve seals. Just need to fit it in with all my other projects.

tone3721

Yeah, they eat oil. Especially the turbo cars. Never kept track of the burn rate. If you don't have leaks, just top it off as needed. IIRC I burned more than usual when I broke it in. Was a long time ago now.

944M3

For what it’s worth, I have a a resealed engine, rebuilt head and rebuilt turbo from Evergreen. I have a catch-can. My car burns no oil, as far as I’ve noticed anyway.

Turbodan

I also have a rebuilt head, resealed engine and seem to be using no oil, so far.

heliolps2

"Hey everyone, I completed the engine rebuild last week and have since put 190 miles on it using Joe Gibbs Driven oil BR 50. Then, I ran 500 miles with Driven XP4 15w50—didn't burn a drop. I'm currently on my second round of XP4 at 300 miles, and still no oil consumption. I'll be changing the oil again in the next 200 miles and switching to Valvoline 20w50 VR1. So far, all the hard work and investment have really paid off!" Hopefully the rings have seated in correctly. I'll be sharing my compression numbers soon

tone3721

Oh yeah, the Joe Gibbs oil is what we used. Now that I've thought about it for a while. It did go away after break in.