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All 6 cylinder base gaskets leak

Well my first rebuild didn't go as well as I had hoped. It runs great, and sounds awesome, but all 6 of the cylinder base gaskets leak.

As part of the rebuild I upgraded to fully finned 3.3L P&Cs from Mahle. During the assembly I used the stock .25mm copper gasket that came with the gasket set that I bought from EBS for my car, and then I used the aluminum shim that goes between the cylinder and the head, as you are suppose to with the fully finned cylinders.


I installed the copper gaskets dry. I also had installed ARP head studs and I used their torque value of 36 ft/lbs with their ARP moly lube on the washers and nuts.


The problem I have is that all 6 cylinder base gaskets leak.


So my question is this : should I have used a thicker copper base gasket with that type of cylinder? Or did I use the right gasket for my application. With the 3.3 fully finned cylinders is there another way that is commonly used to seal the cylinders to a 930 case?


We did not use any form of loctite on the copper gaskets for the following reason : once we placed the cooling tin on the cylinders, the cylinders were quite tight, and we were afraid that if we used loctite that it might harden in some areas before we actually got ready to tighten the head studs, which would have given an improper seal.


As a side note: on my prior 2 rebuilds, not performed by me, the base gaskets also leaked initially, but after the engine was ran for a while, they sealed themselves it seemed. Example: on both rebuilds at my first track event the back of the car would be covered in oil which appeared to have come from the base gasket area. However, after that first track event, I had nothing more than the occasional drop of oil, normally associated with our engines.

Any advice? I've read some of the other posts, regarding cylinder base gasket leaks and it seems like everyone says to tear it down and do it again. Only problem is that I'm not sure what I'd do differently.

Brian


Brian
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Old 08-21-2004, 06:40 PM
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Was the case decked i.e. were the spigots cleaned up and made flat?
-Chris
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Old 08-21-2004, 06:58 PM
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No. But this engine has been apart before and the old copper gaskets weren't ever replaced.

But then again, it leaked, then sealed itself somehow.

Brian
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Old 08-21-2004, 07:01 PM
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Seems unlikely that all six would leak on their own, without some other major thing being wrong. Is your torque wrench properly calibrated?

-Wayne
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Old 08-21-2004, 08:31 PM
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the fully finned cylinders used a rubber o-ring base gasket. i often wondered if they could be used on an earlier case with a copper gasket and still seal.
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Old 08-21-2004, 11:21 PM
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Wayne: Brand new MAC Tool Torque Wrench. It should be calibrated, since this is the first time I've used it.

Thanks John. Stephen Kaspar at Imagine Auto says the same thing. Must use o-ring with the copper gasket.

Brian
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Old 08-22-2004, 04:31 AM
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John : Do you have the part number of the o-ring?
Brian
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Old 08-22-2004, 05:52 AM
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The case spigots probably need to be machined flat.

Did you use a proper torque pattern so that the cylinders did not get cockeyed?
Old 08-22-2004, 08:25 AM
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Curious if you have leaks from above and oil is running down (or being blown from fan) near the base area?
Old 08-22-2004, 02:28 PM
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the o-ring is 999 707 152 40. sounds like you should use the o-ring along with the base gasket. i have a set from a '92 that i'm going to use on my '87 930 engine. i haven't done that particular swap yet, sorry you had to be the guinea pig.
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Old 08-22-2004, 03:20 PM
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RCWaldo : Top of engine is completely dry. Even the tops of the cylinders. So it looks like all of the leakage is occuring on the bottom of the cylinders.

The case is fine, and yes I did follow the torque pattern and specs. This looks like a simple case of not having all of the information regarding the required seals for this particular set of cylinders on an older case.

The engine is out, and disassembled.

Tomorrow I'm going to order :
Top end gasket set
The head gaskets that go on top of the cylinders - I'm not going to re-use the brand new ones that I just pulled off
Copper base gaskets
The 999-707-152-4 o-rings.
And a set of nuts and washers

What else do I need to order, what am I missing? We're gonna try to turn this around and have the engine back in the car by next weekend since I have an event coming up in 3 weeks (Sept 10). If we can get it done by next weekend, that will give me time to break it in, take it to the dyno for a tune, and be ready to roll.

Brian
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Old 08-22-2004, 03:38 PM
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Seal the base gaskets with Curil T. No oring is necessary.
Curil T is non hardening and will seal the cylinders even considering they are constantly moving. Curil T is an Elring product available from many sources including Supertec Performance.

In a perfect world, cut a groove inside the spigot and install an oring there. In lieu complete disassembly and machining, Curil T is the answer.

At Supertec, we warranty engines against leaking for 2 years. This is one of the reasons we can offer this warranty.

Question: Did you say the heads were torqued to 36 lb.
This seems very high. We would only recommend these high numbers for 500 plus horse power turbos but these kinds of number are excessive for most engines.
Are you certain that was not the torque number for the rod bolts?
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Old 08-22-2004, 07:58 PM
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The APR box that my head studs came in says 36 ft/lbs using their moly lube, and 42 ft/lbs with straight oil.

I didn't use Curil T because once I put my cooling tin in place the cylinders were tight. I was afraid I might make things worse by putting the Curil T in there when I wasn't quite ready to torque the heads yet.

Anyway, its torn down. o-rings will be ordered tomorrow.

And yes, this Turbo engine will be pushing 500+ HP.

Brian
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Old 08-22-2004, 08:04 PM
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Because the Curil T is non hardening there is no time constraint when assembly is delayed.
If the cylinders are not grooved for an oring the oring will make matters worse.
Are the cylinders grooved for an oring?
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Old 08-22-2004, 08:20 PM
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'90s 930 fully finned cylinders come with an o-ring groove.
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Old 08-22-2004, 10:00 PM
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Just grooving the cyl base is no guarantee either. The 993RS went to a groove in the block and a groove in the cyl. base.

I went one step further on my 993RS as Henry suggested. Curil T
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Old 08-24-2004, 01:46 PM
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Quote:
Originally posted by john walker's workshop
'90s 930 fully finned cylinders come with an o-ring groove.
Sorry - I didn't catch this in your first post - thanks for clarifying John. The o-ring is there for a reason - did the cylinders you have not come with the groove? More details, perhaps on exactly which cylinders they are?

-Wayne
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Old 08-24-2004, 02:45 PM
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The cylinders I have do have the groove. They are brand new Mahle cylinders and Pistons, that are made just like the ones on the 91-94 turbo except they don't have the drilled and tapped hole for the knock sensors. We reinstalled the cylinders last night with the o-rings in the grooves, along with some curil-T, and we also treated the copper base gaskets with K&W Copper Coat.

Hope this answers the questions.

For 930 owners - if you are upgrading to Fully Finned Cylinders from Mahle, make sure you use the 999-707-152-40 o-rings with them, if the cylinders have the o-ring groove cut ino the bottom of the cylinder.

Mahle says they aren't required, but if you look at how the copper gasket fits agains the base of the cylinder, you will see that there is not alot there for it to "grab" onto. I'd say use the o-rings. Unfornately I didn't know this and its costing me about another $500 to get another gasket kit, head gaskets for those cylinders, etc.

AND, these cylinders require a 1mm head gasket as well. basically a 1mm shim that sits on top of the cylinder (stainless steel I think).

Brian
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Last edited by briankeithsmith; 08-26-2004 at 05:15 AM..
Old 08-25-2004, 06:18 AM
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I ordered 98mm 3.2L cylinders from EBS as part of a 3.4L turbo upgrade. The cylinders will fit into the stock case. Do I need o-rings since the cylinders are considered fully finned? Right now, I am just planning on the copper gaskets.
Old 08-25-2004, 06:49 PM
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only if there's an o-ring groove cut into the bottom of the cylinder.
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Old 08-25-2004, 06:57 PM
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