I've never seen those 0-rings leak. Ever. And I've done a few myself. And I've seen worse oxidation than yours has.

My advice at this point? You're a plumber. Drill and tap those two holes to the nearest larger NPT thread size. Install plugs. Bypass the coolant entirely. It'* purpose is to keep the throttle plate butterfly from freezing in the open position. That is the only risk. I don't think many of us have to worry about that. If you're willing, it'* an option.

Other than that, I'm suspecting a cracked or warped supercharger or lower intake manifold.

What was the purpose of removing the supercharger?

Thank you Will. I'll seriously consider that.

I heard about this board from the honorable Padgett Peterson.

You guys are really helpful and quick. I'll be hanging around. But below, is the actual reason why I posted here (L67swap.com is way too slow, and Reatta.net doesn't have many that know the L67 in -depth

http://forums.aaca.org/showflat.php?Cat=&Number=361222&page=0&view=collap sed&sb=5&o=&fpart=8#Post373229[/url]

That'* a very long topic, and I'm trying to catch up with over 100 posts. Can you summarize?

Apologies. I do respect you, with over 29k posts . You sir, are smart.

I have an '89 LN3 (the pre Series 1 motor with "Fuel Injection." For a long time, I've been thinking that it'* really similar to the Series 1 N/A motor, which is really similar to the Series 1 L67. So, why not swap the special L67 parts onto the LN3? I've consulted with a few different gentleman that have swapped out the entire motors, and another that has a custom turbo setup on his LN3. Everything'* bolted together. Ryan of GMtuners.com is doing the ECM programming (using the stock '89 ECM). I've had it running but not quite right. My tuner sent another ECM chip/memcal/EPROM, but in the meantime, I developed this leak. The car hasn't been driven with this problem.

Take it as putting '95 SSEi parts onto the LN3 in an '89 Bonne

Again, thank you.

The first thing I'd suspect is that some coolant ports in the heads might not mate up to the LIM, and you heat-warped it. Maybe not, but maybe.

Something in your setup is different than stock to cause that leak.

Please keep in mind that the rods, pistons, and rings are not the same in your LN3 when compared to an L67. Neither is the trans by a long shot. Durability will become a key issue. The L67 also got a beefier set of axles. And a different torque converter.

For the time being, I assume you have the correct throttle body (bore size matches the SC inlet) and that you have the paper gasket installed for it?

Your 0-rings should NOT leak if installed correctly. That'* never happened before. I have to go on the assumption that you have a leak elsewhere, and it might not be the o-rings. It might very well be the head/LIM mating.

Which heads and valvetrain did you use?

http://members.aol.com/fastreatta/sc13.jpg[img]

Above are the LN3 intake-to-head gaskets on top of the L67'*. They do line up properly. We concluded that the extra, round port is the integrated PCV. Hard to explain, but I made my own PCV system.

I couldn't figure out the leak myself. The intake manifold and */C, unless they were worked on at some point, came bolted together from the factory and there shouldn't be any conflict.

I do understand the differences between the LN3 and L67 internals. Long term durability will not be the same. But, 3800s are good motors, and mine'* pretty darn tight still. I've discussed it with the turbo guy (doing 260-280 hp out of an LN3) and he hasn't had issues with his engine or transaxle, yet. He does have 125k miles on his car and has had the setup since about 100k.

Swapping the engine would have been better, but at least on paper, would be a lot more intensive. 4T60e or 4T60e-HD is a much better choice over my existing 4T60(h) but then you get into PCMs and stuff...another, worse mess in itself. I won't push it too hard and have a really good local tranny mechanic.

I'm using the LN3 heads. Harmonic balancer, injectors, fuel rail, crankshaft PS, MAF, IAC, throttle body, */C (obviously), intake manifold, tensioner assembly, and some stuff I can't think of at the moment are from the L67 and bolted to the LN3.

I was also wondering about the intake manifold-to-head gaskets leaking, but not possible when I can see and feel coolant leaking out of the manifold-to-*/C gasket. The head/manifold gasket and areas are dry. Used a new gasket there and torqued to spec (8 ft/lbs).

Yes, paper gasket used between the */C and throttle body.[/img]

A turbo application will not suffer from the low-end torque hammer the SC will provide you with. Totally different in terms of durability.

Your torque spec is WAY low. This may be your problem.

http://www.bonnevilleclub.com/forum/...e=article&k=18

I noticed the same Felpro issue a week ago:

http://www.bonnevilleclub.com/forum/...836&highlight=

But I have not observed any coolant leak issues. So my guess is that the gasket isn't the issue.

He torqued his fasteners for the SC to LIM at less than half the spec.

The torque spec page, if I'm reading right, says to torque the */C to manifold bolts to 19 ft/lbs. That'* what I did, or so I did the GM FSM suggestion of 19-22. How did I torque it to half spec?