After about 3-4 months of the engine swap 2years ago, there was a telltail miss at idle. Sometimes a black cloud of smoke when flooring the pedal at about 30 mph. Suffered through blackend 02 sensors, check engine lights and smelly exhaust. The intake gasket leaked, it seems the bolt for cylinder #1 had stripped. It did originally torque down. Through some heat cycles the manifold separated a little. Just in the last 5,000 miles the idle became really bad, the spark plugs would get sooty in just 1,000 miles. This engine had about 100 of the bolt holes helicoiled while it was apart, it seems this one bolt was torqued once to often.

Now it idles like a sewing maching, can't even tell it is running. After all of that, it was something so simple. Tried the propane test a number of times over the last several months and never got an inkling of a leak.

Now I'll drop in a new 02 sensor, may need a new cat too, will wait until emissions testing in Jan. to see if the cat will need to be replaced but a sensor for sure.

What a relief, it had become like a hobby, some hours to kill, open the hood and replace this wait a week and repeat the process and try that.

Just need some more tools or another car. Wife wants me to have another car.

Thanks to all for there suggestions.

DanR 94 964 287,000 miles (53,000 on the new engine)

760T ran rich. O2 sensor fouled, so did converter. Brushed sensor tip with wire brush and put propane torch flame through each of its three slits until sensor tip glowed red and flame burned clean. Sensor still works like new after 12 years. I did change converter.

How did you fix the stripped bolt hole?

When I did the head gasket on my car, I noticed that exact hole was a little messed up and asked the shop to Helicoil it but they said they could't get a kit locally as it was 7 mm. They did have a tap to clean the threads and I was super careful starting the bolt straight when I put it back together.

Its OK as of today.
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'96 965, 16" wheels, Michelin Pilot Sports, rear 18mm bar + Koni, 204HP cams, 128K. Put 200K on '85 745 TD.

Yeah, that 7mm size is a pain. Had to remove the PS pump to make room. Maybe the most common size on the engine too.
I went back to the shop that did the original work for me, the guy gave me his kit to take home. It is a father and son shop and very friendly. The only codes that ever appeared was the 212, for the 02 sensor.

I am thinking of ordering a kit just to have.

Awhile back you had mentioned the intake gasket as my sore of trouble. You nailed that one.

DanR 94 964 287,000 miles (53,000 on the new engine)



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DanR

I wonder why you couldn’t pick up the manifold leak earlier. Good information, thanks for sharing the fix.

Now the big question, what is the next car going to be?
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Tom F. Three Bricks, maintain two more.

Good to hear DanR-,hope it stays running well for a long time. Vacuum leaks are hard to get your thumb on it seams--Had two main air leaks on mine ,you helped me find last week--worked great for a couple of days -the gass mileage got back to 26 then it fell off again-I'm thinking I have a vacuum leak in the dash now--I blocked off the lines coming from the vacuum block under the hood on the drivers side and started replacing lines one at a time till the trouble came back--it was the one to the inside of the car which controls the servo's-not good.
Hope it runs well
Poolman

Are you talking about the line thats on the exhaust side of the intake manifold? It's connected to the manifold by a rubber nipple, and the line runs to the firewall, into a 1 way valve, and out down the firewall and through it.

I've been looking in the chilton books and on the net and don't know what that line is. The nipple is cracked so i put high temp tape on it till I can find a new one.

The end result is i'm gettin almost no boost, once i go past about 1 o'clock on the guage it backs off to 11 o'clock and the rpm's still go up but the turbo doesn't engage it seems. It also won't rev past 4k i don't think. When lettin off the gas it upshifts, but takes longer than it should i'm thinking.