Petrol engine manifolds bolt - can't tighten it

Hi

Have just finished fitting a new exhaust manifold to a 2286cc petrol engine.

The manifolds, as you probably know, are both on the same side. There are 5 bolts on the 'top row' - one at each end and one in the middle for the exhaust manifold and two for the inlet manifold.

Below these, there are two bolts that hold both the exhaust AND inet manifolds in place. These bolts have a lozenge-shaped bit of metal on them so that they apply force either side.

Problem is..... I managed to tighten one, but the other one just slips, that is to say the lozenge spins round. The other one is fine, so I am probably missing something really easy.

Good news - at least the engine starts after manifold / carb reassembly and there aren't that many spare nuts left over.

There is a bit of an exhaust leak - what is the torque for tightening the (cast iron) exhaust manifold and the alloy inlet one? Have looked online, to no avail. You'd think it would be easy to find.... I have tightened them to a certain degree but didn't want to strip anything. Leak could also be coming from downpipe (disconnected fan belt so I can feel any leaks by hand).

Any help would be most appreciated. Many thanks in advance.

Sounds like you've stripped a stud - easily done 'cos they tend to rust. The only real answer is to take the manifolds off and replace the stud (worth doing the lot). You can sometimes bodge it with a couple of brass manifold nuts one on top of the other.
Torque setting for inlet to exhaust bolts and manifold assembly to block is 17ftlb. Did you fit a new gasket between the two manifolds?

Hi Oxides

Thanks for the reply. Don't think I've stripped the stud, as I did everything up gradually and not too tight - I have stripped threads in the past and it didn't feel like this. In fact, the bolt felt tight until I started the engine, then it worked loose. You may still be right, but I don't want to take everything off again if there is a simple solution, e.g. I got the bit of metal upside down or something. Do you know the bits to which I am referring?

ps Yes @ gasket. And a new one between manifold and cylinder head.

Don't forget not to fully tighten the two manifolds together until after you have torqued them both up against the head - I did it the other way around first time I did it and couldn't understand why I didn't get a proper seal - Doh!!!

Thanks Ozawaza. I did actually get divine inspiration on this one and left those nuts untightened until the rest was done.

Still stuck on this last bolt though. Needless to say it's the least accessible one.

I like your emoticon. Is this a demonstration of when lap belts actually become useful?

Been a while since I've removed a manifold, but the parts book shows the locking plates to have a raised ring which goes to the outside - would it be a problem if it was the wrong way round? The only other thing I can think of is if the stud is loose in the block.

It's been years since i did a manifold on one of these as well but i do recall having similar problems in the past.
I think it was either something to do with the thread length of the studs being too short or ****e in the head side thread.
I'm trying to think if i had to run a tap down the head threads first or not.
I know it's not much help but it may jog someone elses memory.

It's a bolt that goes into a hole, rather than a nut on a stud.

It went in ok, enough turns before it became tight, but the lozenge-shaped bit of metal won't stay still on the right hand side. Left hand side is ok.

I cleaned all the bolts / studs with a bench-mounted wire brush wheel and lubricated them with copper grease, as is the case with any bolt I have to take out. Even if it's not me that will be taking it out the next time, it makes someone else's life easier if stuff isn't seized.

Have a look at the castings, there's a kind of lug on each that it sits on when its working but they may be snapped off or missing or damaged. I find I have to have a few goes before getting it right....

If it is a bolt it could be bottoming in the hole , take it out and try it with a washer added to shorten it.

Just had a look to see if I could see anything from the photos I took when I put "Flo" back together (wife's landy that I rolled over - but that's another story) and it reminded me that those lozenges are flat on one side and chamfered on the other.... if not put on the right way (flat side towards the engine then it may have the effect of making the bolt longer? if not then perhaps what Blackburn said?????

Regards the emoticon a very good representation of what happened in "Flo"

Aha @ Ozawoza

I did take that bit off to clean it and the bolt, so it's very possible that I put it back on the wrong way round, not realising that each side was a different shape.

Will try tomorrow when I've had less wine. Many thanks + to all others.

You do need some thick washers and split washers too. I forgot the anti rattle washers on mine and it keeps coming undone! Yet another roundtuit for the pile

D

Looked again this morning. The flat side is facing the engine.

Perhaps the title is misleading; i can tighten the bolt (i.e. the thread is ok and the bolt is long enough and the threads in the hole are fine) but the damn lozenge turns round when the bolt reaches a certain tightness.

Thought that there might be something to stop it moving. Will try wedging it then tightening.

harvestmouse said:

Looked again this morning. The flat side is facing the engine.

Perhaps the title is misleading; i can tighten the bolt (i.e. the thread is ok and the bolt is long enough and the threads in the hole are fine) but the damn lozenge turns round when the bolt reaches a certain tightness.

Thought that there might be something to stop it moving. Will try wedging it then tightening.

Click to expand...

bolt's too long (I'm sure this should be a stud and nut, but hey...) Pack it out with a couple of washers between the bolt head and the lozengy thing.

Mine was definitely a bolt not a stud to hold the lozenge in, I do remember one of them being a bit of a bugger to keep on the protruding lugs of the manifold until it was tight enough to grip....kept slipping off when trying to tighten it (right hand one if I remember rightly).... cannot think of anything else apart from add extra washers (don't forget the spring washer) if all threads are OK and correct length bolt used.... note there are two thicknesses of washer according to the parts catalogue, which are used on different fixings, so make sure you are using the "Thick" one

Sounds like it might not just be me being a useless tw-t if you had the same problem. Right hand one as well. Thanks again for all help so far.

I have put a photo of the vehicle in the 'introduce yourself' section, as requested.

OK - bolt is bottoming. Were it me I'd make sure it has the washers in place, and run a tap into the hole to clena out the threads (might be bottoming on crud).

Could alo be someone has fitted a longer bolt somewhere in its lifetime - the dreaded previous owner bugger factor is never a lot of fun to sort out.

ajr

Liking the photo - the matt black looks good...nice clean and simple