300TDi inspection results

In article , Austin Shackles writes

Hi Austin

Landrover say you cannot (should not) skim a Tdi head.

I skim every one that comes in and have never had a problem.

As a matter of coarse a three hole gasket is fitted. You will struggle to find a main dealer that sells anything else.

If the valves have been hitting the pistons on a regular basis you would of heard a strange popping noise from the air intake.

When you check the timing belt it is worth removing the camshaft sprocket and making sure the locating pin on the cam has not broken which would cause the valve timing to move.

It is unusual for a tdi head gasket to blow between cylinders 2 and 3 normally they blow from number 4 to a pushrod hole or straight out the back of the block. blowing between 2 and 3 might point to it getting a little hot before it blew.

Hope this helps

General disclaimer - I haven't had one of these motors apart but I'm a mechanic and I do a lot of diesel repair work.

Well you've measured it the right way, and it's outside spec so machining it is going to be necessary. If you lop .008" off then you're going to want a gasket that's .008" thicker than the existing one. I'm not sure if they're available but I'd go for a laminated steel gasket if I could - reasons for this follow. The alloy head expands at a different rate to the steel block and as a result frets on the gasket - the laminated steel gaskets are much less prone to this, do not need re-torquing and I have never seen one give trouble on a motor I have fitted them to (mostly Toyota diesels).

Dunno if they all do that, but if it pressure tests okay I wouldn't be overly concerned about it - plenty of other alloy heads do this sort of thing with no ill effects.

They almost look like it might have been overfuelling at some time but don't look serious - I'd ignore them.

Carbon build up on the valves through lot's of slow running, that then knocks itself off on the piston is a possibility - I see it all the time on diesels. Is it just a "show" of touching or has it actually left an impression in the crown of the piston?

Really close. That's why you'll need a thicker gasket if you remove any material from the head.

It's cheap insurance - I'd do it as a matter of course. I'd also pull the valves, give them a quick reface (or lap depending on the gear you've got) and reassemble with new stem seals.

ACR want GBP 261 for a remanufactured head (or 309 for a stage 1 flowed one). Depending on what you'll end up paying for machining, crack & pressure testing it may make sense to spring for one of these (guaranteed, and you know exactly what you've got).

Good luck, if you need any more info email me and I'll do some asking around - unmunge my address as per the signature.

Austin Shackles wrote in news: snipped-for-privacy@4ax.com:

I'd seriously suggest taking it to a specialist "just in case", but that's based on my Pug experiences! As I recall, there are some cracks in an ali head that can be welded -- if necessary. In Inverness we have Auto-Head Recon. Excellent people and always very busy. I'd give "the other place" a miss...

Derry

On or around Wed, 28 Jul 2004 20:11:00 +0100, marc enlightened us thusly:

hmmm.

I figured as much, same applies to the peugeot/citroen ones I've had experience of.

I don't think it's regular. each piston is marked, but not recently.

noted, ta.

from what I can deduce, it overheated terminally. I'm amazed it's not in worse condition. Father has a habit of not watching gauges... It does look as though it might have been blowing slightly from #4 as you describe, but the main damage is in the middle, which could of course be warping due to overheating. this engine has, for ages, been losing coolant *very* slowly, such that you top it up about every month or 2. It's not, however, had a habit of overheating, even with low coolant.

On or around Thu, 29 Jul 2004 09:30:39 +1200, EMB enlightened us thusly:

that's worth knowing. By the time it gets tested properly, etc...

and since it's already got the 3-hole gasket, there are no thicker ones (from stock, anyway) to be had.

Book say the tolerance for head flatness is 0.01mm which is pretty damned fine.

provided the rings are OK (no way of telling without stripping it much more than I want to at the moment) it looks to only need the head looking at.

On or around Wed, 28 Jul 2004 16:44:56 +0100, Austin Shackles enlightened us thusly:

and a picture of one of the pistons, showing valve marks...

Hargreaves in Carmarthen might be able to help. Though I don't always agree with their opinions.

On or around Thu, 29 Jul 2004 09:30:39 +1200, EMB enlightened us thusly:

been talking to 'em, they reckon a warped and cooked 300 head is most likely to be scrap, and offered a brand new built-up one with new valves and springs for 381 plus vat (the 261 is plus vat as well), so one is currently on order, along with a few gaskets and such and a timing belt.

I've been meaning to check on the belt for a while, so now's a good opportunity.

On or around Thu, 29 Jul 2004 18:16 +0100 (BST), snipped-for-privacy@4x4cymru.spamtrapped.co.uk (Niamh Holding) enlightened us thusly:

following a chat with ACR's bloke, I've gone for a new one.

's not that silly, really, and is new and guaranteed. He reckons that after you cook it, the head metal isn't ever the same again, and by the account I had, this one was well cooked.

new head a bit more pricey, but still... should be OK for plenty more miles afterwards.

Well we the engine one of ours we'd do the same.

One would hope so :)

And he's right - the ally was heat treated to harden it after casting, and it's just been heat treated back to soft again - more than likely it'll just move all over the place and blow another gasket (I missed the original reference to how hot it had been). If you ever want to re-use an alloy head that's been hot ask the machinist who skims it to do a hardness test for you.

Not much help to you, but this is a Td5 when the piston starts touching the valves properly (collapsed big end bearing):

Just out of interest, does the Tdi piston actually have an offset piston bowl, or is a trick of the camera?

On or around Thu, 29 Jul 2004 23:06:08 +0100, "Martin Lewis" enlightened us thusly:

they are offset. I'll get the hoover on 'em to suck the dust out, I reckon, before I reassemble it.