Torquing 300TDI head bolts 5 Nm more.

Hi Guys,

I know some purists will say follow OEM specs but I wanted to tighten my 300tdi head a bit more...question is how much is too much and at which torque stage.

I have installed the thickest head gasket (no holes) lowering the compression ratio a bit and have re-bored the block 40 thou more, I would like to push a bit more boost.

So LR manual torque sequence is as follows:

1. All bolts to 40 Nm following sequence
2. All bolts 60 deg following first sequence
3. All bolts 60 deg following first sequence
4. 20 deg on selected bolts different sequence

I would like to pull the head bolts another 5 Nm on the 1st pull...so 45 Nm at stage 1. These bolts are not stretch bolts will/should hold up, has anyone does this?

Thanks and Cheers.

Barbados said:

Hi Guys,

I know some purists will say follow OEM specs but I wanted to tighten my 300tdi head a bit more...question is how much is too much and at which torque stage.

I have installed the thickest head gasket (no holes) lowering the compression ratio a bit and have re-bored the block 40 thou more, I would like to push a bit more boost.

So LR manual torque sequence is as follows:

1. All bolts to 40 Nm following sequence
2. All bolts 60 deg following first sequence
3. All bolts 60 deg following first sequence
4. 20 deg on selected bolts different sequence

I would like to pull the head bolts another 5 Nm on the 1st pull...so 45 Nm at stage 1. These bolts are not stretch bolts will/should hold up, has anyone does this?

Thanks and Cheers.

Click to expand...

They are stretch bolts and the extra 5 nm will make little difference other than starting the angle tightening a tad later. Stick to factory torques and make sure the initial 40 nm is gone over several times in sequence before starting angle tightening.

Thanks warmers..... thought they said these are not stretch bolts...they are bolts whcih can be reused up to 5 times.

The BMW stretch bolts can't be reused since they stretch when first installed and have to discarded when doing any head removal. I don't doubt your guys here, I know the Landys have their differences and always learning something new.

So you don't think 5 Nm more will make a tad difference in a tighter head gasket seal?

Cheers.

BTW I was going to reuse the original head bolts, seems as though it's the first time the head came off....

We've just done the HG on my 300tdi last weekend. Skimmed head and a 1.5mm gasket. We actually reused my headbolts as they were new ones fitted last year 1st time i changed the HG because it was blowing at the back.
Anyway back on topic, when we tighted up the head with a snapon digital torque wrench we over tightened by 5nm or more on most of them as its bloody hard to be so exact.
But hey ho she runs beautifully and mine runs a fair amount of boost.
Soon we'll be fitting a boost pin and new rad to keep it cool.

Hope that helps your question...

an extra 5nm wont hurt but isnt going to help either, the extra 20 degrees was added later after the 2 x 60 degrees to give it extra nip, they are stretch bolts , you can reuse them as long as they havent stretched there was a measurement for the bolts to check
as wammers said the first 40nm needs doing at least twice as center bolts will be slack by the time you finish the outer bolts

Hi Taylonm, thanks for the reply.
Why are you pulling off the head a second time? The head gasket I have is the 0 hole 1.69mm thick, the thickest one. How much boost are you running? I will be running a VGT/VNT so wanted to make a tighter seal for added boost. Happy yours running well so far, keep an eye on your EGT.

Cheers.

jamesmartin said:

an extra 5nm wont hurt but isnt going to help either, the extra 20 degrees was added later after the 2 x 60 degrees to give it extra nip, they are stretch bolts , you can reuse them as long as they havent stretched there was a measurement for the bolts to check
as wammers said the first 40nm needs doing at least twice as center bolts will be slack by the time you finish the outer bolts

Click to expand...

Hi James, I will pull the 40Nm twice to ensure that they got the full 40Nm torque, I normally let the first pull sit for half hour or so and then pull them again. The bolts do have specific lengths, I can measure them, but I wonder what the cut off tolerance will be, if its exact and how accurately they were made.

Cheers.

Well after all the time I made to install the head, I am so ****ed. I cleaned the head with carb cleaner and a slight go over with 800 grit sand paper then air dry it. I chased every head bolt hole on the block, measured each for depth, cleaned and air dry them. I then cleaned and vacuumed the block deck, not a speck of anything left on it. I had the bolts soaking in diesel, wire brushed and inspected the threads, ready for action.

Was enjoying cutting and opening the head gasket, no hole 1.66 mm thick and manufactured March 2015. I flipped on its right side upM, a set of frigging, ugly rust spots appeared on the cylinder 2 and 3 sealing rings, I just could not believing what I was seeing. I was so looking forward to cranking down the head and start fitting up the rockers etc. I was disappointed and flabbergasted, ****ed to say the least.

The head gasket was kept safe in my landy with all the other parts in the back which is in my garage, no water nothing, sealed tight in its original wrapper. I dont know if the local supplier will have one and if they will do a replacement, that will add to my frustration. You guys in the UK and surroundings be happy for getting parts easy and cheap.

If you know anyone visiting here soon let me know, in fact there are tons of Brits who arrive here daily on Virgin and BA, dont know why I dont establish some connections I might have to get mad, jump on a flight and go get me parts and head back here.

BTW, my highest piston protrusion is .03175, rounded off to .032" which is .8128 mm. My head gasket is 1.66 mm so .8472 difference. I would be relatively close by the time the head is cranked down on the block, wish I knew what the crush thickness is on average.

Sigh....

.

Barbados said:

Well after all the time I made to install the head, I am so ****ed. I cleaned the head with carb cleaner and a slight go over with 800 grit sand paper then air dry it. I chased every head bolt hole on the block, measured each for depth, cleaned and air dry them. I then cleaned and vacuumed the block deck, not a speck of anything left on it. I had the bolts soaking in diesel, wire brushed and inspected the threads, ready for action.

Was enjoying cutting and opening the head gasket, no hole 1.66 mm thick and manufactured March 2015. I flipped on its right side upM, a set of frigging, ugly rust spots appeared on the cylinder 2 and 3 sealing rings, I just could not believing what I was seeing. I was so looking forward to cranking down the head and start fitting up the rockers etc. I was disappointed and flabbergasted, ****ed to say the least.

The head gasket was kept safe in my landy with all the other parts in the back which is in my garage, no water nothing, sealed tight in its original wrapper. I dont know if the local supplier will have one and if they will do a replacement, that will add to my frustration. You guys in the UK and surroundings be happy for getting parts easy and cheap.

If you know anyone visiting here soon let me know, in fact there are tons of Brits who arrive here daily on Virgin and BA, dont know why I dont establish some connections I might have to get mad, jump on a flight and go get me parts and head back here.

BTW, my highest piston protrusion is .03175, rounded off to .032" which is .8128 mm. My head gasket is 1.66 mm so .8472 difference. I would be relatively close by the time the head is cranked down on the block, wish I knew what the crush thickness is on average.

Sigh....

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i wouldnt worry about the gasket rust spots

jamesmartin said:

i wouldnt worry about the gasket rust spots

Click to expand...

James, never seeing this before and being a perfectionist with engine building and stuff like this, it's bugging me.

I am concerned with sealing and if it will continue to rust since the engine will probably be sitting on the stand for another month or two. Worried about it rusting the block as well sitting there. If I was going to run it the engine soon, I would feel better but it will be there for a while yet......what you think?

Thanks for the reply.

Barbados said:

James, never seeing this before and being a perfectionist with engine building and stuff like this, it's bugging me.

I am concerned with sealing and if it will continue to rust since the engine will probably be sitting on the stand for another month or two. Worried about it rusting the block as well sitting there. If I was going to run it the engine soon, I would feel better but it will be there for a while yet......what you think?

Thanks for the reply.

Click to expand...

it wont rust once its clamped down but bores need to be well oiled if its a fresh surface, and turned over to ensure oil is spread

It's a fresh rebore + 40 thou, new pistons, rings, bearings, complete head job etc...and I use an expensive anti rust lube lol Lucas oil stabilizer..works well during engine rebuilding.

Just want it to be a perfect engine that will last a good couple of years.
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