Exhaust Manifold-to Head Fitting

[DrSarty 90 1 Cars]

This is actually regarding the removal and refitting of my Maniflow manifold, which I'm having to do because of a noticable blow where the manifold meets the head, but I guess my question could apply to the fitting of any manifold.

 

Without going into why it has a blow other than to say I was a d*ck when I had all the space and access in the world fitting it originally to the head when the head was off (opportunity wasted ), then here's my question.

 

Apart from fitting new, original Pug studs, flat-faced nuts, a new gasket and fitting the studs first, then can anyone recommend any of the following or indeed something else:

 

1) Using 2 gaskets (current 1 mth old one plus brand new one)?

2) Using a thickish washer between each nut face and the manifold surface?

3) Using any sealing, paste type gasket product/compound to help get the seal once and for all (i.e. belt & braces)?

 

I appreciate it shouldn't be necessary to do anything other than use a new gasket and evenly, correctly torqued bolts, but I've cocked this up once and want to make sure it seals this time round, when I'm doing it in the much more confined space when the head's on the engine in the car.

 

Hope someone can advise.

 

Thanks

 

Richie

Edited March 4, 2007 by DrSarty

[Richie-Van-GTi 71 2 Cars]

having just fit 2 magnex mani's in the last 2 weeks I found the use of washers is essential otherwise the nuts tighten onto the unthreaded shank of the stud before making a good contact with base plate. This was with new studs on both times. Im sure original studs have less of an unthreaded part however and shouldnt have thisissue. But i would definatley use spring washers just to be sure.

Dont use 2 gaskets if one of them is old and you've already had a blow.

Seen a lot of folks reccomend RTV sealent but I have no experience of it.

[DrSarty 90 1 Cars]

I would definatley use spring washers just to be sure.

Seen a lot of folks reccomend RTV sealent but I have no experience of it.

 

Thanks for the educated reply - no substitute for experience eh!

 

I figured the washers would be a good idea, but hadn't thought of spring washers - top tip.

 

As for using RTV which I believe to the layman is common silicon sealant, anyone got experience, advice, warning or a different recommendation please?

 

Rich

[david932 0]

never done a gasket on this engine but as a mechanic i have done many others in the past.

 

firstly you should make sure both surfaces are completely clean with no trace of old gaskets. also i would use brake cleaner or a similar cleaning substance on both surface.

 

washers are a good idea as it evens out the clamping force.

 

as for silicon or rtv i wouldn't advise it as it's not suitable for manifold temp and pressures

 

doing the above should seal perfectly

 

hope this helps

[hengti 2]

would sealants withstand the temperatures?

 

apart from being sure that the surfaces are v clean, i'd make sure the studs are actually tight as they can work loose. took my mani off in the week; i think the washers were spring washers too - hadn't really noticed it before. i've also always finger tightened the nuts and then tightened them working out from the inner pipes - not sure if there's much merit in doing that though.

 

you'll also need to check nut tightness after a week or so as they'll need nipping up.

 

 

ed. beaten to it

Edited March 4, 2007 by hengti

[DamirGTI 342]

I use sealent (high temp. resistant "Permatex" gasket sealent) on exhaust gaskets , but onley when i'm fitting old ones

[petert 586]

I recommend Loctite Copper Maxx silastic with no gaskets. It's specifically designed for the job, is rated to 320 deg C, is lamda sensor savvy and seals up to 6mm!

[Rippthrough 98]

I recommend Loctite Copper Maxx silastic with no gaskets. It's specifically designed for the job, is rated to 320 deg C, is lamda sensor savvy and seals up to 6mm!

 

 

Known as loctite 5920 over here for those trying to find it

[Mikey S 29 1 Cars]

what type of nuts are you using? you would be better off using the squashed ended nuts as they bite into the manifold studs alot better than normal nuts.

 

another idea would be to put a straight edge on the manifold face itself as if its warped slightly it will cause the gaskets to fail more rapidly.

[DrSarty 90 1 Cars]

So, and perhaps to PeterT primarily, the 64pence question:

 

I have a new gasket, but instead would you recommend using the Loctite 5920 stuff alone (plus the spring washers ofcourse) i.e. NO gasket? The 5920's around £26.

 

Rich

[tom_m 0]

where are you getting that price? i'm sure i got two tubes of the stuff from halfrauds for less than that!

 

the last manifold i fitted a put a thin layer of 5920 on either side of the gaskets and they are still going strong.

 

on my magnex manifold which destroyed the last set of gaskets i put in it i've used purely 5290 and no gaskets and it too is still going strong

[petert 586]

I use the 5920 with no gaskets and have never had any problems. It depends a lot on how rigid the Manilfow faces are, but given the rather ambitious claims of the product, I'd give it a go gasketless.

[skeggyrik 3]

The £26 is for a 300ml GooGun canister of the stuff.

 

It's about £7 for a 80ml "toothpaste tube" of the stuff

 

https://www.burtonpower.com/default.aspx?de...004&PSet=98

 

4th down.

 

cheaper than gasket?

[DrSarty 90 1 Cars]

The £26 is for a 300ml GooGun canister of the stuff.

 

It's about £7 for a 80ml "toothpaste tube" of the stuff

 

https://www.burtonpower.com/default.aspx?de...004&PSet=98

 

4th down.

 

cheaper than gasket?

 

Thanks for that - order placed for one x skin flint tube from Burtons. Will follow advice and remove maniflow manifold (looking fwd to that - NOT), all traces of old gasket, old nuts and studs, then reface both surfaces and refit with this wondergoo, new studs, spring washers and nuts. That should fix it!

 

Rich

[lagonda 42]

I'm not so sure about recommending spring washers. My experience of these is that they tend to fracture with the heat when used on an exhaust manifold. The new nuts that I got from pugspares are plated & have one-way teeth on a wider shoulder than the 13mm head, thus spreading the load & locking as well. Seem to be doing a good job so far, indeed hardly any of them needed retightening.

Would also strongly recommend you check your manifold with a straight edge.

[taylorspug 7]

Another one for checking the manifold with a straight edge, ive seen some in the past (MX5 turbo springs to mind) that were so warped it was a wonder you couldnt see daylight through the gap, let alone stop it leaking!