Blowing B*&#£y Manifolds

[Katana550]

Hello all,

I am writing again to seek advice on the subject of blowing manifolds

Having sorted out the previous problem with the manifolds (primarily the exhaust) blowing (by the use of two gaskets) I find that the retaining bolts/stud nuts (six bolts on top, four studs beneath) work themselves loose in pretty short order. I went through the whole gasket replacement palaver last weekend and, even though I have regularily tightened the bolts/nuts, it is starting to blow again!!!!

I used locknut (rather an equivalent) this time but that is pretty useless due to the excessive temperatures. I am off to Marshalls on Saturday (tomorrow) to collect some new replacement bolts, studs & nuts but I have no confidence that this will cure the problem.

Can anyone give me some pointers as to how to stop this recurring??? It has never been a problem with motorcycles or the VW beetle so I do not understand why it should be so persistent here.


Many thanks

Tim

[E_T_V]

The problem is usually the opposite one getting the blooming things off. It might be because you are using two gaskets that they "give" much more than the standard setup either that or the manifold is warped or it hasnb't been tightened down enough.

Always put copperslip/grease on the threads when you do them up as you'll thank yourself for doing so a few years down the line!

[talkingcars]

Put a nut on the bolt and fully tighten, add another nut and fully tighten this to procuce a lock nut.

James

[Katana550]

Originally posted by talkingcars
Put a nut on the bolt and fully tighten, add another nut and fully tighten this to procuce a lock nut.

James

Hi ya,

I presume you mean stud and not bolt?

Yep, for the studs that are long enough I tried this but it didn't seem to make much difference.

Tim

[John]

Are you getting your studs in all the way, may be worth putting a tap down the holes to clean the threads out. Also check the threads aren't stripped and use the two nuts locked on the end of the stud to make sure they go all the way down.

[talkingcars]

John is saying turn the stud into a bolt by locking the two nuts at the end of the stud,when the stud is in you can then remove the nuts.

James

[Katana550]

Hi all,

Thanks for the replies but I think someone has got the wrong end of the stick!!

The problem is not getting the studs or bolts in or out; the problem is that when the manifolds are attached to the engine, using the correct procedures and torques the nuts (on the studs) and the bolts work themselves loose.

What would be the best way of stopping this resurring?

Thanks

Tim

[John]

Have you tried shakeproof washers, either spring washers or the star washers. Use a flat washer against the manifold and the spring washer and then the nut or bolt. I can send you some if you give me the size.

[G Force]

Hi Tim.

I think the reason why the manifold is coming loose all the time is probably because of the fact you are using two gaskets. With two gaskets I think there is too much compliance between the head and the manifolds causing the whole thing to come loose eventually. At the end of the day you have to consider why you need to have to fit two gaskets just two stop the manifold blowing. I think you probably have a manifold that is badly warped most likely the exhaust manifold. You can check the mating surfaces of the manifolds with a straight edge to find out if one is warped.

You could carry on trying to persevere with two gaskets, experimenting with the various locking nuts, spring washers etc that are available, there are lots of different types that will work in high temperature applications, but I think you will be lucky if you sort it that way.

You could get a different manifold, use one gasket and the standard bolts, studs, washers and spring washers etc, make sure the steady bars for the inlet manifold are fitted and not stressed unduly and hopefully the job will be sorted.

Cheers Gary

[E_T_V]

If the manifold is warped you can get it skimmed flat again relatively easily. I tend to agree that the two gaskets combined with a warped manifold could allow it to rock/vibrate and loosen its mounting bolts. exhaust manifold bolts are usually a pain to get off rather than come undone by themselves.

[Katana550]

Ok, that all makes sense!!

So, any idea where I could get hold of a new (or as new - i.e. not warped!!) exhaust manifold? How much would one expect to pay?

Thanks

Tim

[John]

Scrappie, shouldn't cost much.

[Rich]

Intresting from experience, the exhaust pipe to manifold connection on the 1.3 consits of a plate on the end of the exhaust, which mates to the manifold. This is held on originally by 3 8mm studs and nuts. I have lost 2 of the studs on mine and replaced them with bolts, only one stud is original (with very little thread left). I changed this a good few months ago, and when I put it back together I used new 8x25 bolts, washers and spring washers in the original holes, and a normal nut and spring washer on the stud that remains.

Had to give it some more attention the other day, when changind the fuel pump as what thought was a slight blow was in fact a "grab hold fo the pipe and move a lot" type thing going on. Turns out the heat had absolutly ruined the spring washers. Seems when hot the "spring" has been lost and made them flat.

Ive put it back again with new spring washers but know it will happen again, had considered using ny-lok nuts, but would imagine the nylon to melt vey easilly. Maybe a tab washer?

Just thought I would mention it, seems spring washers are useless in the heat!!

Rich

[E_T_V]

I'm sure I've said it before but I'll say it again, use plenty of copper grease it'll make it ten times easier to undo in the future.