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O-Ring Cylinder Heads/Blocks - Discussion

DynastyLCD

Well-known member
Joined
May 12, 2006
Messages
761
Location
Harwinton, CT
i was just reading through another thread about a head gasket problems.

background (first mistake): bought a junkyard 6 bolt longblock from a friend, for cheap. longblock, manifolds, radiator, hoses, t/case and trans for $600. i dropped it all in, she ran great. at the time it was: 16g, 680s, VPC/GCC, and all supporting mods. 3 times around the neighborhood, started misfiring pretty bad. took it home, did some diag, found a burnt exhaust valve.

rebuild: honed block, new rings, new bearings, reused rods/pistons, polished the crank, head was machined with all new SS valves, new valve seals, new front case/BSEK, ARPs & a mitsu 4 layer. then swapped 16g with 3052, all else remained same.

my guess at the problem: the mitsu MLS had been torqued before.

ive got about 10k on this thing since i rebuilt it last year. its been pounded daily, just about every day for the past year with 25-30 psi through the 3052. around 5k miles into it, i would start to loose coolant here and there. mainly after hard pulls, or heavy boost. had a cracked intercooler, couldnt make boost really, and the problem never occured again til the intercooler was fixed.

so heres where i stand: ive got this gorgeous stock bottom end that loves getting pummeled. id like to keep it, but im a little nervous about putting another MLS gasket it in it, and having it fail.

called up a reputable machine shop that does a decent amount of 4g63 work. spoke to a good personal friend there. he was explaining to me that o-ringing a cylinder head or block is best paired with a mitsu composite gasket. ive got a few problems with this...

#1: that composite gaskets going to hold up to all that boost, time and time again?
#2: what should i do when i cant use a mitsu composite, say on an engine thats bored more than .020?
#3: does anyone here have expierience with o-ring'ed cylinder heads or blocks?
#4: is it a good idea to o-ring either head or block, then use an MLS gasket?

question 2 applies to my stroker engine that im building. id like to push some dumb boost with that, but again, im worried on sealing issues. i also cant put a factory sized gasket in there, as its already punched out to .030.

please leave some good input here. also, this isnt a cost vs. cost thing. im more interested in results. i dont care if gasket X is cheaper than gasket Y, i just would like to know what seals the best, period.
 

boostedinaz

Well-known member
Joined
Apr 20, 2006
Messages
4,085
Location
Scottsdale, AZ
Here is my thoughts on it.

My first thoughts are that the old motor is a big unknown and that is the cause of your issues. An unknown head and block surface can make for a bad seal. If you're going to go through the work of having it O-ringed might as well just have it machined to the correct finish for the gasket you plan on using. That, in it self, with a good tune should last even under a LOT of boost. Of course that means that all the parts in the system work well together and are correct for the application.

As for doing th O-ring I have never been a fan (never had an Oring motor before so take it with a grain of salt) but here is why. I look at the head gasket as a fuse. If something goes wrong in the motor I would rather replace a head gasket that have to replace a piston or junk a head. A regular style gasket is recommended because it is soft and flexable enough to allow the O-ring to push it up into the machined grove. An MLS is far less forgiving and might proved less of a seal because it can't be pushed into the grove as well.

Just my .02
 

1qkfwd

Well-known member
Joined
Sep 29, 2009
Messages
209
Location
Sun Valley, NV
O-ringing a block is not really needed. My engine is o-ringed and this was done before they came out with all th enew stuff. First off make sure the head and block surface is very straight. Setting the torque on the standard arps up to 100ft/lb helps with an mls. That should hold for a very long time and alot of pressure. It takes alot of pressure to lift the heads on our cars. If you get to that power level then you can step up to L19 head studs and even the felpro permatorque head gasket. That combo without an o-ring block will hold up and in some cases over the 1000hp mark. If your just so stuck on the idea of getting the o-ring done, there has been alot of debate about which is better as for the head or block. Most dsm guys do the head. Like in my case there are a handful that has done the block. A top notch engine builder did mine. Its a cometic mls with a steel o-ring that is recessed more than normal since the steel on steel has less compression than if you where to use a copper ring. He used a silicone system around the cooling and oil passages. He says this combo has held up to some big cubic inch alcohol engines. I offered to get him any other head gastet that will work the best for my engine,and he stated its just how you install it that maters. Another combo that is popular is a composite gasket with a copper ring. Not sure how it holds. There can be some major downsides to doing an o-ring block though. If you have any issues with the head or block, theres a chance you have to go through the o-ring process again. I would see this as a last resort and a little safer on the pocket book.
 

DynastyLCD

Well-known member
Joined
May 12, 2006
Messages
761
Location
Harwinton, CT
your probably right about the surfaces, however, the cylinder head was freshly shaved, and i cleaned up the block myself. the thing that gets me is that it never had a problem until it was rebuilt. i didnt have any coolant loss the whole time when it was together as a longblock. i was still doing 18 - 20 psi thru the 16g, although it didnt make it a long while either. but no signs of leakage through the block or anything. ive seen tons of people run these engines with a resurfaced head, a cookie wheel cleaned block, mitsu MLS and ARPs just fine, no issues, zero coolant loss/push. i even retorqued mine after the first heat cycle. used poly lube, torqued to 90 ft/lbs. i dont know. dosent even loose all that much coolant either, enough to bother me to put another headgasket on it.

about the o-ring material, thats very valuable information. i was planning on doing a copper oring on the cylinder head as thats what i was recommended. i have two cometic 1.6mm MLS HG's to redo both of the engines, i think im just going to re-check all my surfaces for straightness, send the head out for a shave, and call it a day. i didnt even get a quote, but im sure its astronomical, as opposed to the $200 ill spend for having both heads decked/cleaned.
 
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