Snapped bolt...

rockdemon

rockdemon

Administrator
Staff member
Hi guys,

The bolt that holds the inlet manifold on - the long one at the very front near number 1 cylinder has snapped - question is hold much pressure is this waterway under? If put together without that bolt is it likely to hold, or should i attempt to drill the centre and use an easy out extractor on it ?

Thanks for any advice....

Rich.
 
Hello Rich,

I wouldn't take any chances,...the bolt would have to come out and a new one would have to go in.

Ron.
 
rockdemon said:
Hi guys,

The bolt that holds the inlet manifold on - the long one at the very front near number 1 cylinder has snapped - question is hold much pressure is this waterway under? If put together without that bolt is it likely to hold, or should i attempt to drill the centre and use an easy out extractor on it ?

Thanks for any advice....

Rich.
Click to expand...

Hi Rich

Hmmm.. nasty one.

You are trying to drill out a very hard bolt from a soft aluminium head. :shock:

As Ron says though, not worth the risk.

Personally I do not think that it will seal at all without that bolt at full capacity, and if it leaks, it can leak coolant from underneath the manifold gasket, straight into your engine.

Take a lot of time to get the hole central, then warm the head up with a hot air gun, or similar, prior to using the bolt extractor.

Best of luck with it

Richard

Just a thought - it might be worth considering taking the head to an engineering shop.
 
Don't use easyouts, if the bolt was tight enough that it snapped when you tried to remove it, then the easyout will just snap in the bolt, and you wont be able to drill the broken bit out. Centre drill the remains of the bolt gradually increasing the bit size until you either get to the stage where the thread just peels out, or the whole of the bolt has been drilled away, in which case you'll need to helicoil the hole. The water jacket will leak without that bolt fitted.

If there's enough of the bolt left showing you may get it out with heat and molegrips.
 
When I had the top bolt/stud shear on the V8 water pump,it was a swine to get at and remove,but got there in the end!
If you cannot access it with an external gripping stud extractor and have to use,a screw in type,1st grind the top as smooth as poss,then using a center punch make a nice dent in the middle,starting with the smallest HSS drill bit 1-2 mm,and a slow speed at first, drill down as straight as poss at least an inch,then progressively bigger drill bits till you can get a substantial extractor tapped in,or the rest just comes out easily
I used a std gas blow lamp to heat the area to help ease it out!!
Good luck,have fun! :)
 
ok... So worst fears confirmed... the bolt had rusted through so i guess the jacket was leaking anyway. So... I'll have a go at drilling it out small bits first to large bits... I guess if i make a mess i always have 2 spare sd1 heads that i was saving for later.

If i decide to go down that root is there anything more to it than replacing the entirety of both heads with the parts from the sd1 engine? Do i keep the rockers pushrods etc from the sd1? Do i use the same gaskets for valley etc? Of course this assumes the 40 year old head bolts come out first try...

Thanks,

rich.


P.s. Please tell me owning a p6 isnt always this much hard work! I need reminding!
 
Rockdemon, P6 ownership can on occasion include suffering and tribulation, but bolts snap on all old machines, not just those from Solihull. Patience is the key to this particular conundrum. Experience of a snapped water pump bolt has taught me that you MUST drill accurately into the broken bolt or you'll just make things even worse. Ideally you want the drill to be in a guide, ensuring that you are always drilling directly into the broken bolt.
Forgive me if I'm being dim, but have you removed the P6 heads from the engine, or are they still in place? Your SD1 heads will swap on using the same type of valley gasket and seals. The pushrods are the same. The SD1 heads should be marginally better than the P6 heads, and I would have thought would make for a worthwhile swap. The valve seats will be harder and more suitable for unleaded fuel. I think the valves themselves might be marginally larger. Can't remember all the differences between the two types of head, but I know people who tune the V8 for more power are scornful of the P6 heads and prefer SD1 or later heads.
Good luck, keep a cool head, stop for regular tea breaks, I reckon lots of chocolate HobNobs help make light work of such jobs. :)
 
rockdemon wrote,..
If i decide to go down that root is there anything more to it than replacing the entirety of both heads with the parts from the sd1 engine? Do i keep the rockers pushrods etc from the sd1? Do i use the same gaskets for valley etc?
Click to expand...

Hello Rich,

Pushrods, lifters, rocker assemblies and tin valley gaskets are identical for all Rover V8 engines from 3.5 to 4.6 litres.

Ron.
 
the heads are still attached on both engines... The one that has the rusted through bolt would've been left as is except that the water feed to the manifold was a different size.we tried taking that off but the bolt sheared on that... So we went for changing the inlet manifold.... Wish i'd ordered a new pipe instead now.... Live and learn i guess:) i'll try the drilling technique first. If that goes wrong i'll swap the heads. Just wasnt planning on doing that till later.

Thanks for alll the great advice as always...
 
If it's snapped off flush or slightly proud and you have access to a mig welder, place a nut over it with a hole size the same as the bolt and weld into the nut so the stud/bold is fused to the nut. The heat has the effect of loosening the seizure and the weld ensures the shrinkage of the bolt as it cools resulting in a freed-up bolt and relief all round.

Alternatively, warm it up with a heat gun, apply plenty of a good penetrating oil, repeat and gently, with a bit of swearing (optional), it should come out.
 
I dont have a welder unfortunately... In the week i'll get myself a blowtorch and some hss drill bits and see how i go...

Thanks all, rich.
 
Try to get left hand bits and work up incrementally to the size of the extractor. you may get lucky and have it come out on the drill bit.
 
I had this before whist refitting heads and managed to get it out with and easy out, although the bolt had been out and cleaned.

Where I have been removing these bolts and they have been tight and then snapped it is very difficult/impossible to do it DIY without causeing damage to the alloy.

If you are going to drill make up a plate. which you can attach using atleast two of the other bolts. this will be a good guide and prevent slipping etc.

if there is any of the bolt showing. take off the head. soak in wd40 for a day, bit of heat, more wd40 and then put the remenat in a metal vice. tighten full and then give the head a sharp twist and you might get lucky. I have successfully used this with exhaust manifold bolts. If it is very stiff you can gradually tighten and loosen the bolt until it is free.

Colin
 
If you can get PB Blaster spray over there in the UK, then I would recommend using that. It works better than WD40 in my opinion. Since I have started using PB blaster spray I have not broken a bolt since. Touch wood, touch wood!

There are a stack of left hand drill bits for sale on Ebay. I first saw them at one of the parts stores in the US, a few years ago. Having broken easy outs in the past, I think that left hand drill bits are a better way to go.

James.
 
ordered some left hand drill bits yesterday off amazon so we'll soon see!

I've been using the 3 in 1 penetrant spray - is PB blaster a similar thing?

Thanks all,

Rich
 
Well I've managed to dril about 3/4" into the bolt so far before my drill's battery ran out last night with the left handed drill bits!

Pleased I didn't manage to ruin anything yet!

Rich.
 
Oh dear :(

Are you using the standard P6 carbs?

If so, you may need to richen up the needles a bit.

Richard
 
yep - it's an 'oh dear' moment, but got to be pragmatic and get on with it for my sanity. the previous owner said it might have sd1 heads on already and when i dismantled the carbs they had none standard needles so i think the carbs i have are probably already set up correctly! Suck it and see i guess!


is there anythinh i should be careful of when changing the heads?

Thanks

rich
 
Hello Rich,

The spark plugs will be an easy give-a-way as to whether or not the current heads are off an SD1. P6B heads used short reach plugs with 12.5mm of thread depth, later heads all use long reach plugs with 19mm of thread depth.

Be sure to use an anti seize lubricant on the bolts or similar and tin gaskets if you wish to keep your current compression ratio or go with composites which have improved sealing but will cost about 0.6 in terms of reduced compression. There is also the lifter pre load which will no longer be within spec if you use composites with 14 bolt heads. The heads can always be skimmed to give them the same spec as 10 bolt heads, then you can have your cake and eat it too,...improved sealing with composite gaskets, the compression ratio does not change nor does the lifter preload.

Are you going to fit all new rocker assemblies while your at it...and new timing set and maybe a camshaft too or just go with the heads?

Ron.
 
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