Blown headgasket

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Radical Racing
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Blown headgasket

Post by Radical Racing »

Took my 121,000 mile immaculate 1989 635 Csi out for a cruise recently and the head gasket blew. Trying to fix it myself but having a terrible time getting the intake manifold off the head. The nuts on the underside of the intake runners are driving me crazy. I have tried every combination of thin wall 12 mm sockets, wobble extensions and universal joint connectors and there are still two nuts in the middle that I cannot get to. So I am thinking I will have to take the head off with the intake manifold still attached. There is a big bundle of wires that come off the firewall and runs through the loom cover. However there is also a bundle of wires that exits from the underside of the fuel injector wiring "loom" that goes under the intake manifold and runs over to the drivers side inner fender and connects to the wiring system there. I cannot see if there is a plug connection hidden somewhere under the intake manifold so it will be easier to move the fuel injection rail/wiring loom out of the way in order to remove the head and intake manifold still attached together. I have been working on this for a month now and my progress has come to a standstill. Any tips or advice would be greatly appreciated.


I checked YouTube and found one video about removing the head from a M30 equipped 5 Series but it was no help in regards to getting the stubborn underside intake manifold nuts off or dealing with the problematic section of the fuel injector wiring bundle.
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Re: Blown headgasket

Post by ron »

Put your location in your profile as requested by admin.

I've removed a few inlet manifolds from '88/'89 cars without any problems.

You need a 12mm/1/2" Snap-on 1/4" drive wobble socket. It is the only tool I could get to fit.

I posted this long ago! Have fun refitting the wave washers.

viewtopic.php?f=2&t=27695&p=199805&hili ... et#p199805
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jps635
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Re: Blown headgasket

Post by jps635 »

I did this just a few weeks ago on a B34. As Ron said I used a 1/4" drive and long extensions with a universal, but taped the universal with masking tape so held an off set, and had my son help guide the socket on from the exhaust side. Take the manifold support bracket and fuel rail off first.

Prior read up suggested the B35 was easier than the B34
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Brucey
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Re: Blown headgasket

Post by Brucey »

clearance to these nuts varies between models because the size/shape of the intake runners is different depending on model.

IIRC I used a 1/2" full hex socket, 1/4" drive, thin walled, with a wobble bar. ISTR that being 'the wrong size' it slipped over the nuts at an angle (unlike a 12mm one) but also that if the manifold was still it its original position (i.e. not pulled away from the head slightly) some of the nuts wouldn't come off the studs. This means that all the nuts have to be loosened and backed off a few turns before some will come off. It also means that if you back off a nut in situ (i.e. with the manifold up against the head still) any socket can get trapped in position.

Thus the procedure for refitting the manifold is to

- slide it over the studs
- leave a 1/4" clearance between the manifold and the head
- fit and start all the lower side nuts/washers
- spin them all on until they are up against the manifold
- move the manifold inwards
- continue tightening all the nuts

disassembly may need to be carried out in a reverse procedure.

On some cars it is easier to remove the head with one or both manifolds still attached. Would weigh a ton with an M30 head though.

cheers
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86_6series
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Re: Blown headgasket

Post by 86_6series »

I used my engine hoist and lifted the head with intake and exhaust attached.
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Re: Blown headgasket

Post by ron »

86_6series wrote: Fri Oct 26, 2018 6:08 pm I used my engine hoist and lifted the head with intake and exhaust attached.
You cannot do that on the later engines. I posted this comment years ago.
Problem with the wiring is the big loom that runs from the
injection loom conduit.This runs along the top of the head
alongside the fuel gallery.The big loom comes out of the bottom
of this conduit and runs down through a gap between the head
and the inlet manifold and goes to the diagnostic socket and
another large multi-pin connector.These are too big to go through
the gap!!
The only way that I can see is to remove the inlet manifold prior
to removing head.
They are ALWAYS rustier than you thought!!!!!!
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'87 M #367
'88 High line.
'10 X5
‘84 Alfasud 1.5 ti
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86_6series
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Re: Blown headgasket

Post by 86_6series »

"You cannot do that on the later engines. I posted this comment years ago."

Didn't know that--thanks. Do you happen to know when the harness route changed?

I had the same problem as RadicalRacing. The exhaust nuts hadn't been touched in

32 years. The rusted nuts made for very difficult 12mm fit. Even tried 11mm forced on

6 point sockets--no go. When I did get the whole unit to the bench, the only

solution that worked for me was plenty of heat--turning the nuts the color of the sun

and using water pump pliers for grip. Very difficult to do on the ground but doable

I guess.

Good luck RadicalRacing-- hope it's less trouble for you.

Bob V
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Brucey
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Re: Blown headgasket

Post by Brucey »

I think the change occurred 6/87 and coincided with the move to the B35 motor. These engines have a different inlet manifold, no CSI, and a few other changes.

Perhaps it is possible to remove the head with the inlet manifold attached, complete with wiring harness?

cheers
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Drew
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Re: Blown headgasket

Post by Drew »

FWIW, and not adding anything new here, just repeating what others have said, I've had success using a 1/4" drive with a UJ and a long extension. So 12mm 1/4" socket, then the UJ, then about 9" of extensions then the 1/4" drive. Never thought of using tape to firm up the UJ and stop it flopping about, good one!

I've previously left the exhaust manifolds on and disconnected the bolts at the connection to the downpipe (3 easy to access nuts as opposed to 12 hard to get at ones made of brass). A crane to lift away helps, but it is possible to lift the head and ex manifold off by hand
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Re: Blown headgasket

Post by ron »

Brucey wrote: Sat Oct 27, 2018 2:33 pm Perhaps it is possible to remove the head with the inlet manifold attached, complete with wiring harness?
Requires removal of pins from multi-plugs. Real PITA to remove and re-fit and requires specialist pin removal tools.
They are ALWAYS rustier than you thought!!!!!!
'85 M #228
'87 M #367
'88 High line.
'10 X5
‘84 Alfasud 1.5 ti
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Brucey
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Re: Blown headgasket

Post by Brucey »

I was wondering if you could get as far as working on the head and manifolds (eg using an engine crane or just laid upside down on a piece of wood) off the engine but still in the engine bay, whilst you enjoy better access to the lower inlet manifold nuts.....? Never done it, but might try that if I have to.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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