Has anyone Surface Machined a 300TDi head?

[Tank]

My 300TDi head is warped 0.13mm, 0.05mm over the limit, I know that you are supposed to "discard" (L/R loves that word) the head if it is warped more than 0.08mm and I know the head surface is heat treated (hardened). But I do not have the funds to buy a new head.
So has anybody had their 300TDi head shaved and reused it, if so are there any problems, Yet, has anyone had a failure of head or gasket after doing above procedure.
What's involved in getting the head "re hardened", can it be done, what's the word on this, any info will be most appreciated, Regards Frank.

[d2dave]

Frank,
Can't help with an answer at present but I took the head off my wife's fairlane yesterday. It is in the shop being machined. When I pick it up tomorrow I will ask them if they have ever done one.

Dave.

[Bush65]

I have had 300Tdi heads skimmed.

Overheating events cause the heads to develop soft areas, and then they can't hold bolt clamping loads, leading to head gasket failure.

Shops that do heat treatment of steel parts can heat treat the 300Tdi head. Get hardness tested and look for variations over the head to determine if it has developed soft areas. These shops usually have metallurgists that can give you advise.

If it hasn't had a bad overheating and hasn't been blowing gaskets, I wouldn't worry about heat treating unless it has soft areas.

Edit: Metalert in Carrington (Newcastle suburb) are heat treaters that have experience heat treating 300tdi heads.

[spudboy]

Had mine done 3 or 4 years ago after an overheat episode. Don't know how much was taken off - I didn't think to ask. No problems since though.

That's a fair way off the max spec. If it was only .09 or .10 you might be happier chancing it.

[Tank]

Had mine done 3 or 4 years ago after an overheat episode. Don't know how much was taken off - I didn't think to ask. No problems since though.

That's a fair way off the max spec. If it was only .09 or .10 you might be happier chancing it.
0.13mm is only 6 thou, 0.006", I'm hoping that I'll be able to get away with it, any idea of what a new bare head is worth or a good straight secondhand one is worth, Regards Frank.

[Disco_owner]

0.13mm is only 6 thou, 0.006", I'm hoping that I'll be able to get away with it, any idea of what a new bare head is worth or a good straight secondhand one is worth, Regards Frank.

Frank ,Give Triumph rover spares a call in the morning and they can tell you how much a good 2nd hand head is worth:cool: I presume that the replacement 2nd hand head would been vaccume tested and tested for soft spots , but you can certainly ask.

[alien]

Had a look here to get some ideas on prices.

Land Rover parts - CYLINDER HEAD PARTS (http://www.roverparts.com.au/cylinder_head_parts1?b=1)

(Just took 5thou off a TD5 head,told hardining is 7thou on these, no overheating problems.)

Cheers.

[Waxenwane]

I have heard of one that has had several millimeters taken off :eek:.........apparently it was a mistake and the engine reputedly goes like stink. No names.

[isuzurover]

I have heard of one that has had several millimeters taken off :eek:.........apparently it was a mistake and the engine reputedly goes like stink. No names.

Don't see how it would improve performance - the head is flat. Though it would move the injector closer to the piston.
https://www.aulro.com/afvb/

Btw Tank - turner lists a genuine bare head for GBP295. But I would take John's (Bush65) advice.

[Waxenwane]

Don't see how it would improve performance - the head is flat. Though it would move the injector closer to the piston.
http://turner-engineering.co.uk/storemaker/images/300TDI_head_bare.jpg

Btw Tank - turner lists a genuine bare head for GBP295. But I would take John's (Bush65) advice.

I would have thought the increased cylinder pressures will enhance performance. As I said I heard about this from someone who saw it.

[isuzurover]

I would have thought the increased cylinder pressures will enhance performance. As I said I heard about this from someone who saw it.

That was my point - there will be no increase in cylinder pressure. In a domed head engine - sure, but in a flat head engine, compression ratio remains unchanged.

[Tank]

The combustion chamber is in the piston, so you would have to reduce it's volume to increase compression ratio (I assume that is what you are talking about) or increase the bore diameter to increase the swept volume.
Thanks all for the info and advice, the head is being machined and the valves adjusted (machined) to be the correct height above the pistons for proper clearance, Regards Frank.

[87County]

The combustion chamber is in the piston, so you would have to reduce it's volume to increase compression ratio (I assume that is what you are talking about) or increase the bore diameter to increase the swept volume.
Thanks all for the info and advice, the head is being machined and the valves adjusted (machined) to be the correct height above the pistons for proper clearance, Regards Frank.

I'm told by the experts that what is being done (setting the valves back to clear the piston) is correct and that as it is a "flat head" that there is no concern re about the theoretical increase in ratio that you mention

[Waxenwane]

That was my point - there will be no increase in cylinder pressure. In a domed head engine - sure, but in a flat head engine, compression ratio remains unchanged.

Makes sense, but if the valves are not recessed as well surely there is some increase?

[PAT303]

I'd be more concerned about the pistons deadheading on the head,you could do it but a thicker gasket would be needed.Back in the day I used to take 1/8'' off 2.25 heads to get them to go but they were low comp engines so they needed it. Pat

[LOVEMYRANGIE]

Where did my other post go???????
Pat, the head face is flat. No matter how much you take off, the piston will never come into contact with the head face.
The valves however are a different story. By reducing the headface thickness, the valves will come closer to the crown so basically you need to recut the valve seats by the same amount to maintain valve to crown clearance.
Using a thicker head gasket is only to increase clearance for piston protrusion, not headfacing. This will have an adverse effect on CR.
The only time piston protrusion will change is from new pistons and/or decking the block.
As there is no volume in the head and with the small channel between the valves, you will not get any CR change by skimming as the piston carries the chamber volume.

Cheers

andrew.

[d2dave]

Where did my other post go???????
Pat, the head face is flat. No matter how much you take off, the piston will never come into contact with the head face.
The valves however are a different story. By reducing the headface thickness, the valves will come closer to the crown so basically you need to recut the valve seats by the same amount to maintain valve to crown clearance.
Using a thicker head gasket is only to increase clearance for piston protrusion, not headfacing. This will have an adverse effect on CR.
The only time piston protrusion will change is from new pistons and/or decking the block.
As there is no volume in the head and with the small channel between the valves, you will not get any CR change by skimming as the piston carries the chamber volume.

Cheers

andrew.

Andrew you are spot here.
Being a retired spanner you have saved me a lot of typing.

Dave.