Viton O-Rings
 

Hi,

I'm currently reassembling my 3.3 turbo due to some pretty bad oil leaks at the cylinder bases. I'm assuming that these were caused by replacing the previous Mahle cylinders with Perfect Bore cylinders which I just realized have a groove at the base of the barrel.

I've read a few threads and have been told by one person that I can use viton o-rings to correct this problem.

Where can I find this type of o-ring and does anyone now what the size would be for my application. I'm currently running 98mm P/Cs...

Best Regards,

Todd

A groove on the base of the cylinder is 3.6 base seals replacing the copper of the 88 turbo.
Bruce

Can you reuse the copper base gaskets on the 3.3 liter engines?

sorry to go op topic.

Fred

Viton is an elastomer that has high resistance to heat-related degradation and thats all we use when the option is available.

I've not seen the PB 98mm cylinders with O-rings so I cannot tell you anything, however if I had the measurements, I have sources for those things. Every cylinder that I've used has provisions for the normal flat base gaskets so I'd need to see what you have.

Remember, O-rings generally require a matching groove in both sealing surfaces to be effective.

I would not overlook the role of loose heads as you do the forensics here to prevent a recurrence. Many aftermarket headstuds do an inadequate job of holding clamping pressure and that allows the whole assembly to leak.

Hey Steve,

Thanks for the feedback. The barrels actually have grooves on the top and base. I had grooves machined into the top of the barrels to accommodate Ni Resist rings. The grooves in the base of the cylinders were already there; however, the surface that mats up to the base of the barrel is flat. The measurements of the groove looks to be approximately 1/16in x 1/16in.

This was my first engine dis-assembly and when it came time for reassembly, I didn't pay attention to the groove in the base of the barrel. Needless to say, once I finally got the engine back in the car it leaked like a faucet and definitely not drivable at all.

I was actually considering filling the groove with some type of silicon sealant but wasn't sure if it would stand up to the heat of the engine. I'm not that experienced with these things so I thought I'd start asking questions questions in hopes of coming up with viable solution to my problem.

http://i69.photobucket.com/albums/i4.../PB_Barrel.jpg

Could you show a photo without the base gasket?

When a friend discovered his RSR cylinders had upper sealing surfaces with grooves in them, and the diameter was not a common one (meaning, the replacement gaskets are rather expensive), a friend who works in Navistar diesel engine design mentioned that they use a graphite packing material. So that's another consideration.

I'm not saying the Viton solution is not a good choice. Just mentioning other types of sealing used in this sort of application.

Hey Kevin,

Thanks for the information. At this point, I'm open to solution that makes sense and that will work...

Best Regards,

Todd

Hey Dave, I'll pull one of the Cylinders and take a snapshot and post....

Better snapshot of what I'm referring too...

Dimensions of the space that I need to have filled with some type of o-ring is Groove Height = 1/8in X Groove Width = 3/16in

Would need to have an ID = 4 1/8in

Not sure if this is significant but the surface of the case is flat with no groove, so I'm not sure if that's relevant or not.

http://i69.photobucket.com/albums/i4...6/000_0005.jpg

Well, looks like I'm not going with the Viton o-ring solution. Talked to Loren Beggs over at 911 Design and he's going to shave the existing barrels and then fabricate a set of aluminum adapters for me....

Thanks to those of you who offered suggestions to my problem.

Best Regards,

Todd

I take it you got these cylinders used from another source. Did you check the deck height with the new cylinders before final assembly?

Hey Dave, yes to both. Picked them up from a gentleman over in the UK, who used them once in one of his race cars.

When I received them, I had them professionally checked out by a professional builder and gave me his blessings. Had all measurements done, including cylinder bore measurements as well.

Best Regards,

Todd

Got a hold of the Viton o-rings. The plan is to install with the oem gaskets and not apply any type of sealant.

Is this a recommended strategy or should I use any sealant to make sure there are no leaks?

Best Regards,

Jitters

Did you check with Perfect Bore?