O-Ringing an inlet manifold gasket.

[30psi 4agte]

Over the years i have always had trouble getting the inlet manifold to seal to the head.
I have tried various gasket types but have had no luck.

The material gaskets I.E paper / cardboard types just cant hold the boost i run and usually split and blow straight out.

The geniunie gaskets have provided the best seal but it usually doesnt take long before they leak.They dont blow out because they are steel but they do leak on boost as there is a black oily/ fuel film that is evident around the manifold where it meets the head to give a clear indication there is a leak present.

Like i have said above this is only a leak on boost when the pressure is so great it forces out between the manifold and the head.There is no leak at idle or under vacum conditions and it doesnt effect the engines idle and smoothness, its just when the boost is turned up to 2 bar i just cant achieve a 100% seal. ( which shits me. -- lost boost = lost HP )


Now the manifold has been machined and is perfectly flat. I had thought that there could be some runout it the actual head surface ( where the manifold bolts too.) So when i prepped this head i took the time and actually machined this surface. This was a pain in the arse to set up in the mill but i thought that 2 perfectly machined surfaces and a new gasket should hold the boost in !!! so i did it.
Well to my surprise after a short time of running on the car there are signs of leakage !! not as much as usual but enough. Considering i had to pull the manifold off to do some MAJOR modifications to it to stop the cracking that continuely occurs ( this ones a whole another thread !) i thought id try something alittle different to see if i could get this thing to seal once and for all !!

So i have decided to O-ring the std toyota gasket with some wire. What i actually have done is to use 2 gaskets and sandwich a stainless steel o-ring ( read .51mm electric guitar string) between the 2 gaskets.
This will effectivley fill the squash groove with wire so that it cant actually compress and in theroy will provide a thin but hard surface for the alloy manifold to bite into providing a better seal.

The way i have done it is as follows.
I measured the gasket thickness with a micrometer and then the raised ring section of the gasket, so i could calculate how thick the wire i should use should be.
I did this because i wanted the gasket to hold the o-ring in the squash groove.
A wire that was too thick would not sit in the groove correctly and would also space the gaskets apart slightly when placed back to back with the o-ring between.
A wire that was too thin would let the gaskets sit perfectly back to back but would allow the o-ring to float around in between. So the wire thickness had to be spot on to allow the gaskets to sit back to back and allow the o-ring to fit snugly in between.



The o-ring fits between the raised section of the gasket.




The o-ring was lightly held in place with some loctite 401 (super glue) on assemlby but will be held in place by the groove on either side of the gasket when installed.



This photo shows one of the o-rings held in place with the locktite. The other gasket will sit on top of this one and effectively sandwich the o-ring inside keeping it in place.
This should hopefuly fix the prob !!
Will keep you guys posted as to how it works. If everything goes ok it could be a good fix to highly boosted 4age's with manifold leaks

[oldcorollas]

looks good

you could also try O-rings (Viton) or a machined teflon seal... in fact, you could machine the head or manifold to accept the teflon/viton in a groove.
it should have very high pressure tolerance ie,
http://www.pspglobal.com/prop-high-pressure.html

heck, or you could cut a manifold gasket out of teflon sheet itself not too exxy and won't blow out...

other point, the standard gaskets are designed to crush to give a good seal, so by fitting the wire, you are removing some of that crush... a thinner wire might be fine, as when the gaskets crush halfway the wire is contacted?

[30psi 4agte]

hey stu.

Yeah the teflon idea sounds good and i have thought of machining both the head and manifold to accept o-ring as this is the best possible fix for the prob but it would mean removal of the head to do it !
So i thought id try this setup first to see how it goes.

I know about the gasket being designed to crush but decided to try a different plan attack with almost no crush hoping that the solid gasket would get a good bite into both alloy surfaces giving a good seal.

As my favourite saying goes...... Time will tell

[fixeruperer]

hehe this has crossed my mind, i have a found some pretty good gasket paper that can be used as diaphram material its woven inside and is made of a rubbery compound that can pretty much take anything and for now is holding well.

with the wire between 2 gaskets you could possibly stress the manifold flange were the bolts go threw because the main contact is on that wire, what sucks about 4a manfolds is the contact area on the ports, i believe if you can get more surface area contact on the ports its "should" seal.
if i were rich as id love to machine reciever groove on the manifold and place a rubber oring on each or the ports then the gasket around the oring to take up the miner differance and to seal.
trial and error i spoze . few down few to go

[30psi 4agte]

h
with the wire between 2 gaskets you could possibly stress the manifold flange were the bolts go threw because the main contact is on that wire,
trial and error i spoze . few down few to go

This one of the few down sides i thought of too. But the gap is less than .6mm (.3mm each side) so it should be ok.

[oldcorollas]

bah, a bit of crushable material around the outer to give a bit of support?

i checked PTFE sheet price..

at RS component$, 1.6x300x600 = $230
they are always exxy,

plenty of places do cut to size work...

[30psi 4agte]

yeah i have just started thinking along those lines.

Mabe an little rubber o-ring around each bolt to take up some space or a copper washer
hmmmmmmmmmm ???????????

[fixeruperer]

if the rubber o-ring isnt held into place it will squish out or eventuly squish flat.
if u had a washer the same thickness as the o-ring it should support it and the lil bit of extra thickness from 2 gaskets should put more pressure on the port to seal but the differance would wont to be minute.
but it would be nice to make an outer gaket as oldschool said beucase it would look alot nicer.

[30psi 4agte]

I looked at a couple of options. the first was copper washers which were .5mm thick and were too thick and would not provide enough crush for the o-ring to even bite into the head / manifold.
the second were also .5mm thick but were fibreous washers. These may crush enough but .2mm to big for the raised lip on the gasket which is .3mm high.It would be good if i could find this type of washer that was .3mm thick to start with, but you have to remember we are talking about feeler gauge thicknesses here !!
i decided to go with just the gaskets as the difference is .3mm each side ( less than the thickness of a coke can ) this is measured without any form of crush from the gasket.
By the time the gasket is in place and the manifold tensioned up im sure the gasket will crush atleast .1- .15 mm and the rest isnt worrying about. It will prob be the bit that actually bites into the alloy manifold and ends up being flush.

[fixeruperer]

you can also buy sheets of tin/steal shim "paper" comes in any thickness you want.

[30psi 4agte]

bah, a bit of crushable material around the outer to give a bit of support?

i checked PTFE sheet price..

at RS component$, 1.6x300x600 = $230
they are always exxy,

plenty of places do cut to size work...

do you have a link to that teflon sheet stu ??


EDIT: found it

[allencr]

I'd look at a brace/s & spreading the load on the bolts/studs first.

[Matt-AE86]

Just use RTV. When i had my 16v 4AGE turbo'd I RTV'd the intake to the head and when i went to take it off, it didnt want to come off thats how well it sealed

[30psi 4agte]

I'd look at a brace/s & spreading the load on the bolts/studs first.

Braces arnt a fix i already use them. here is a pic of the extent i have gone to in that area.
I have been looking into other types of possible gaskets too. Ie the teflon OC is talking about and possibly urethane .

RTV just snt gonna cut the mustard in my situation .

[oldcorollas]

if you have space on the manifold, i would suggest getting an appropriate depth and width groove cut, and then using Viton or silicon O-rings... neither shulod be affected by the heat, but the viton are a bit strnger i think (feel harder).... then you don't even need gasket at all... then again, there is not much space there...
oh and machining groove could be a pain in the butt