Head removal

[Robm100]

Hi all I'm getting to the critical stage of disconnecting sensors and wiring from around the head in order to remove it but have trouble knowing what I need to disconnect and what some of the sensors are. Would anyone know what I need to disconnect or have pictures/knowledge of what to do. Any help massively appreciated.

[Tuga2112]

if you click the "manuals" link. you get directed to pinky's website which hosts both the workshop and the parts manuals.

both those togehter should give you a compreensive list of parts and procedures to complete the work.

i have removed the head soo many years ago that i cannot remmeber any of the sensors. but curious to know if your taking out both head turbo and intake in one piece, or separating them before taking the head out.

the intake is quite a challenge to remove. and theres a few things back there attached that you want to ideally undo before pulling up.
namely the fuel lines and any wiring that may catch up (thinkign about the positive cable that connects to the alternator. )

now that im thinkign about it. to name a few sensors and other bits, you would be looking for
- idle air control
- secondary throthle (vacum line)
- CAS
- Air temp sensor
- MAP sensor (i woudl advise both vacum line and electrical line)
- TPS
- throtle cable
- HT Leads
- coolant temperature switch (at the thersmostat)
- boost sensor
- engine grounds (2 on the side of the boost sensor)
- injector wires

this is by no means a complete list. just a few of the stuff that comes to mind from memory, that happens to be in the area and i would say consider them as a minimum, and not the "whole"

[Robm100]

Along with my dad, we've removed the turbo (absolute pain) surprisingly only 2 snapped bolts which by some of the stories I've heard is very good going. But we're leaving the intake manifold on, as you say it's fiddle to say the least. The turbo has been sent off to have a full rebuild too.

What we're planning is to crack the head off by hand then use the engine crane we have to hold the head whilst we check around for any pipes/connectors we may have missed. For a 34 year old car it's surprising the amount of sensors there are.

[Tuga2112]

What we're planning is to crack the head off by hand then use the engine crane we have to hold the head whilst we check around for any pipes/connectors we may have missed. For a 34 year old car it's surprising the amount of sensors there are.

not really that surprising to be honest.
the widespread use of electronics in automotive industry started in the 80s. The m100 was ahead of its time by quite a bit, but when you look at its engine electrics side. its not very different in amount of sensors to other cars of the same vintage.

[Simon_P]

The studs on the turbo are designed not to come undone - that's why they snapped.

Clear instructions in the manual. For preference I would remove the plenum and the inlet only six or so bolts and so much easier particularly on reassembly

[Tuga2112]

For preference I would remove the plenum and the inlet only six or so bolts and so much easier particularly on reassembly

this is the first time we agree on something

worth noting. it is only a few bolts. but they are a pig to access,
I did remove the intake plenum when i did mine, and had to remove it again when the IAC valve bolts rusted in place. it wasnt any easier the second time.

[dapinky]

I go the other way, and remove the exhaust manifold, with the turbo attached to it, and leave the inlet side intact..... removal of the exhaust means that you have to remove the studs from the head to get the clearance to separate the parts, but it isn't hard to do.

[Tuga2112]

i also did that, and would recomend it.
tbh i done it many years ago (with a considerable amount of help from pinky) and my skill, knowledge, familiarity, toolkit and confidence around an engine has changed a lot with the years, but it i was to do it again, i would definitely remove the same parts and do as much pre-emptive fixes as possible while im there (AKA freeing up any rusty bolts, like the IAC valve).

[RonR]

I did the head removal in one piece using a crane which wasn't too bad, BUT if you put it back as an assembly be careful when lowering the head onto the new head gasket, the dowels don't stick up much and it's easy to damage the gasket or ding the head on a dowel.

Something I've not seen much discussed in the 'While you're in there' department is freeing up the secondary throttle spindles. Mine were really stiff with carbon build-up and needed lots of carb cleaner and working to & fro to get them to move freely.

Oh, and don't forget to check / attach the Knock sensor wiring before fitting the head.

[jamherber]

Thanks for all the info so far (I'm Rob's father so this is a joint project and a steep learning curve!).

We have the turbo and exhaust manifold off, cam belt off and have printed a copy of the workshop manual.

One of the turbo nuts was so rusted that it sheared off part of the stud (hopefully pic attached) but we'd decided to have the turbo rebuilt anyway whilst it was off so they will be replacing all 4 of these studs as they need to machine the face

We were hoping to lift the head off with the inlet still attached but at the moment we are struggling to disconnect all of the sensors under this (currently stuck with a blue sensor and also the fuel pipes). Good to know that we have to disconnect each injector individually (I'm much more used to working on the K series in my Elise were there is just one connector for the whole fuel rail electrics)

Once we eventually get the head off (hopefully this coming weekend), its going for a skim, valve seat re-cut and new valve stem oil seals. Whilst it's away we will strip down and clean all the tappets and free up everything we can see (as per recommendations above). Also considering sending off the injectors to be cleaned and checked over.

[Robm100]

Hi everyone, we managed to get the head off today but noticed there's only 2 dowels locating the head (I've attached the photos) is this normal?

Also the secondary throttle seems free and isn't sticking but there's slight side to side movement? Is this expected and normal?

Edit:photos attached are too big to upload, I'll try shrink them but hope my explanation is of some use!

Edit:

[Simon_P]

Yes, only 2 tubular dowels. - have you found the parts manual? Good diagrams if you are trying to work out how things come apart or go together.

The secondary throttle isn't a precision instrument, it's just to block 4 ports - It needs a bit of play (not like the throttle body). Notice where the vacuum chamber is you need to reconnect it when you put it back.

[jamherber]

So the head dowels came out with the head which is going off for skimming so they will need removing. There seems to be a high chance of them being damaged on removal (stuck tight) but the usual suppliers aren't listing replacements (part number A100E6318S).

Any ideas?

[Tuga2112]

just a warning. this is just a couple of guesses. i dont have hands on experience on skimming heads, i have been lucky that both times i changed the gaskets in cars there was no damage to the heads
the suggestions are just my train of thought if i was in your position.

i dont know how your company does the skimming, but i cant see reason why a manually operated milling machine wouldnt be able to skim around the dowels ?

have you tried heat to remove the dowels ?
also can take very precise measurments of them and ask nicely someone wiuth a lathe or milling machine to make new ones

[jamherber]

just a warning. this is just a couple of guesses. i dont have hands on experience on skimming heads, i have been lucky that both times i changed the gaskets in cars there was no damage to the heads
the suggestions are just my train of thought if i was in your position.

i dont know how your company does the skimming, but i cant see reason why a manually operated milling machine wouldnt be able to skim around the dowels ?

have you tried heat to remove the dowels ?
also can take very precise measurments of them and ask nicely someone wiuth a lathe or milling machine to make new ones

I'm using a guy who has worked magic on various K series head for me over the years. I'm from an engineering background so know that dowels definitely need to come out. I'm sure Rog (the guy doing the head) will be able to remove and re-instate them but also know that he'll ask me if replacements are available as this would be much easier and save considerable time/cost.

Below is picture of the cause of the HGF - it will probably need welding before the skim.

head failure mode.jpg

[Tuga2112]

heres my ignorance coming through.

isn't that a sleeve replacement scenario ?

as far as skimming the head. have you tried to use a nylon rust removal brush on a drill to clean the crap ?
onse its clean you can put a straight edge on it to find out if it warped or not.

something like this, they wont cut tghouth the metal but all the gunk, gasket remains and rust will come out. giving you a pretty good surface to check
https://www.amazon.com/Abrasive-Filamen ... B0CJJWZFP4

[jamherber]

heres my ignorance coming through.

isn't that a sleeve replacement scenario ?

as far as skimming the head. have you tried to use a nylon rust removal brush on a drill to clean the crap ?
onse its clean you can put a straight edge on it to find out if it warped or not.

something like this, they wont cut tghouth the metal but all the gunk, gasket remains and rust will come out. giving you a pretty good surface to check
https://www.amazon.com/Abrasive-Filamen ... B0CJJWZFP4

The circled area is a recess in the face of the head where the gasket sealing ring fits so depending on it's depth, it will either need welding and then a light skim of the head or if it's not very deep, a skim to take off enough material to get to the bottom of it. Either way the head will need machining. We haven't cleaned up the head as Rog will give it a full chemical clean before starting work on it.

[dapinky]

Joao, the dowels need to come out, otherwise the head can't be clamped down to hold it steady enough to prevent warp.... and it is done with a fly mill.

The dowels can be removed with a hammer and chisel, and are a common enough part that your recon guy should be able to source.

Have you looked at the Workshop Manual for info on head skimming? - it tells you how much material it is permissible to remove before the head becomes a large paperweight with no automotive use. It is worth printing off the relevant page(s) for your machinist, as it is easy to remove too much when trying to remove warp and taking it too low - the head actually accepts quite a large (comparatively) bow before it doesn't seal, so no need to go 100% flat.

As a 'future information' thing, I always use stamps to mark the outside of the head with the amount that has been removed - it may help me (or someone else) in the future to decide if the head can be skimmed again or not (or if it will need a MLS gasket).... mine simply says "15thou skim, 07/2007" or similar.

[jamherber]

Joao, the dowels need to come out, otherwise the head can't be clamped down to hold it steady enough to prevent warp.... and it is done with a fly mill.

The dowels can be removed with a hammer and chisel, and are a common enough part that your recon guy should be able to source.

Have you looked at the Workshop Manual for info on head skimming? - it tells you how much material it is permissible to remove before the head becomes a large paperweight with no automotive use. It is worth printing off the relevant page(s) for your machinist, as it is easy to remove too much when trying to remove warp and taking it too low - the head actually accepts quite a large (comparatively) bow before it doesn't seal, so no need to go 100% flat.

As a 'future information' thing, I always use stamps to mark the outside of the head with the amount that has been removed - it may help me (or someone else) in the future to decide if the head can be skimmed again or not (or if it will need a MLS gasket).... mine simply says "15thou skim, 07/2007" or similar.

Great advise there - will print and include that part of manual for the machinist. Rog does indeed stamp up heads he's previously done for me with this information.

[Simon_P]

There's a long oilway which has a pressure relief valve in it the welch plug is an unusual size 16mm? I have a packet of them if you need one.

The head looks pretty good should clean up. Unlikely that valves will need more than lapping.

The valve stem seals often come the wrong size - too big, should be a tight fit that you have to tap on - if you get good ones can you note the part number