Author Topic: Head torque levels (also, anything to do to improve flow while heads off?) (Read 2699 times)

papercutout · « **on:** January 04, 2009, 02:20:06 PM »

As my head gasket is on its way out (first noticed a little milkiness in the oil a while back, when I was changing the sump, thought I'd accidently got a drop or 2 of water in there), but it got a little worse. Then the other day I checked my radiator, and *eek* the level was down quite a lot, and I'd previously noticed a lovely sweet burning smell I now know is the smell of burning antifreeze!

So I dropped my mate a text and said its on the way out, fancy giving me a hand? He was fine, he said yeah, thats good, so off I go with a list of parts to order:

headgasket set
headbolt set
oil filter
antifreeze
spark plugs
manifold studs and nuts
thermostat

I also want/need:
sump gasket and some studs and nuts as some of the sump bolt holes are stripped. Will sort that myself, should be easy enough!
I've got a replacement backbox arriving too, some cheap stainless jobbie as my present (1 mid box, and straight pipe) is considered illegal by the cops. Sounds fabulous though!

Can anyone see anything missing from the list?

Just got some prices, the headgasket set I knew would be expensive, but they want �165.76, and thats discounted! (about $240.82) My mate MIGHT be able to get it cheaper, will see.

So, saturday just been and gone I drove the 50 minutes to see him (never been there before, found the house first time, given away by his E30 325i outside!) and parked up, he was getting dressed when I arrived (11am), lazy git

Then we started removing everything, in the lovely -2 celsius weather we had on sat morning, with a miny fan heater between us sitting in the engine bay! It was suprisingly easy, no mis-haps, no skinned knuckles, just cold feet and hands! Marked the cams up, removed them by removing a timing chain wheel. Kept it all safe, in his garage. The head will be skimmed this week. Fortunately everything is in great conditon! Almost disappointing though, as I wanted the car faster after putting it all together

So, does anyone know the head torque levels for the M42? And the torque levels for all the other bits above that too?

Is there anything to do to improve car performance while the head is off? Any porting, grinding, smoothing, etc etc to do? I'd love to do this properly and stroke it, but just don't have the money. Not even to buy some nicer cams for it!

Few photo's to make life interesting for you! (including an important question)

With the rocker cover and intake removed:

M42 mit twin dells

:

All off and 'cleaner':

And the question; we accidently dropped the chain tensioner bolt thingy, and were wondering if this is all there is to it? Its obviously fairly important, so I'm coming to you guys, the experts and asking if I'm missing anything!

Thanks!

So: chain tensioner?
toque levels?

Nomadic · « **Reply #1 on:** January 04, 2009, 03:42:56 PM »

Not sure about the tensioner... mine didn't come apart like that. When was it last replaced? That looks like the old style tensioner to me....

Quote

headgasket set I knew would be expensive, but they want �165.76, and thats discounted! (about $240.82)

A headgasket set in the US runs about US$120. If they are really that $$$ in the UK I see a business opportunity... are you sure that's not a engine gasket kit?

Quote

Is there anything to do to improve car performance while the head is off? Any porting, grinding, smoothing, etc etc to do? I'd love to do this properly and stroke it, but just don't have the money

Has the timing chain been replaced? What kind of mileage is on the motor? I'd be looking at the timing chain, rails and sprockets before thinking about head-mods. (or side drafts ; -) How did those Cam sprockets look? Have you checked the timing rails.... bent valves don't make the m42s any faster..... and neither does a cat delete for that matter.

My understanding is there aren't any easy HP mods beyond a MarkD chip. m42's were pretty well sorted from the factory. MotorMetric has an interesting (wacky) intake manifold for the m42... but it is $$$$.

Cheers

nomad · « **Reply #2 on:** January 04, 2009, 04:11:46 PM »

From the Haynes Manual

Torque wrench settings Nm
Timing chain tensioner plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Timing belt tensioner bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Camshaft sprocket-to-camshaft bolt
M10 and M30 engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
M20 and M40 engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Flange to camshaft (M30 engine) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Timing chain or belt covers-to-engine
M6 bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
M8 bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
M10 (bolt size) bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Crankshaft pulley bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Crankshaft hub bolt or nut
M10 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
M20 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410
M30 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 440
M40 engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
Cylinder head bolts*
M10 four-cylinder engine
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Stage 2 (wait 15 minutes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Angle-tighten an additional 33�
Stage 3 (engine at normal operating temperature) . . . . . . . . . . . . . Angle-tighten an additional 25�
M20 six-cylinder engine with hex-head bolts
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Stage 2 (wait 15 minutes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Stage 3 (engine at normal operating temperature) . . . . . . . . . . . . . Angle-tighten an additional 25�
M20 six-cylinder engine with Torx-head bolts
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Angle-tighten an additional 90�
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Angle-tighten an additional 90�
M30 six-cylinder engine (up to and including 1987 model year)
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Stage 2 (wait 15 minutes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Angle-tighten an additional 33�
Stage 3 (engine at normal operating temperature) . . . . . . . . . . . . . Angle-tighten an additional 33�
M30 six-cylinder engine (from 1988 model year)
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Stage 2 (wait 20 minutes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Stage 3 (engine at normal operating temperature) . . . . . . . . . . . . . Angle-tighten an additional 35�
M40 four-cylinder engine
Stage 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Stage 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Angle-tighten an additional 90�
Stage 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Angle-tighten an additional 90�
Intake manifold-to-cylinder head bolts
M8 bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
M7 bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
M6 bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Exhaust manifold-to-cylinder head nuts
M6 nut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
M7 nut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Flywheel/driveplate bolts
Manual transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Automatic transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Intermediate shaft sprocket bolt (M20 engines) . . . . . . . . . . . . . . . . . . . 60
Sump-to-block bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 to 11
Oil pump bolts (except M40 engines) . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Oil pump sprocket bolts (M10 and M30 engines) . . . . . . . . . . . . . . . . . 10
Oil pump cover plate-to-engine front end cover (M40 engines) . . . . . . . 9
Front end cover-to-engine bolts (M20 and M40 engines)
M6 bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
M8 bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Crankshaft rear oil seal retainer-to-block bolts
M6 bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
M8 bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
* BMW recommend that the cylinder head bolts are renewed as a matter of course.

xwill112x · « **Reply #3 on:** January 04, 2009, 04:21:24 PM »

Quote from: papercutout;64062

And the question; we accidently dropped the chain tensioner bolt thingy, and were wondering if this is all there is to it? Its obviously fairly important, so I'm coming to you guys, the experts and asking if I'm missing anything!

thats the old style tensioner.
its all there, but while your doing all this, i highly recomend changing the tensioner and dropping the oil pan to look for loose bolts. its like 66$ for the lower oil pan gasket and timing chain tensioner at bavauto.com

just be careful unspringing them all the way, its a PITA to get them back together.

those are just my tips/recomendations.

as for the head, double check everything, if your not certain its right, check it.

good luck!

papercutout · « **Reply #4 on:** January 04, 2009, 04:54:54 PM »

I'll be changing the oil etc anyway, so dropping the sump (oil pan), and I'm ordering a replacement gasket for it anyway. NEEDING to build a guard for it, this is my 3rd sump!

Remember guys, I'm in the UK, so any US specific recommendations don't really work for me, bar getting a new chain tensioner!

UK iS's didn't have CAT's as standard, and I'm minus 1 midbox anyway, it FELT like it added a little torque if anyones interested (I had 2 midboxes, one just after the downpipe, the other just after the join. I removed the 2nd to keep backpressure).

Problem atm, is the car and engine is almost an hour away, with the head probably already at a machining shop so I can't go checking anything. The engine conversion was owned by someone who was apparently hugely anal, and I'm willing to bet the chain etc was done then, it sounds really good. Lots of people say these engines sound tappety, mines quiet and smooth typically. Oh and around 100'000 miles.

I've a cheaper headgasket kit btw, that was the price for the official german ones. The ones from GSF (german swedish french) are $100.

I'll sort a new tensioner and get everything sorted, thanks a lot guys! (and maybe find a 318iS haynes manual!)

Froos · « **Reply #5 on:** January 04, 2009, 05:23:34 PM »

If the head is off I would get the valves out, get them cleaned, checked and and anglecut, than regrind them into the valve seats. That should restore some of the power. Also you could drop the pan and take out the pistons. Check and clean them and get a set of new piston rings. This should also give you the opportunity to balance pistons and conrods.