advice on cylinder head skim

Guys , this weekend I am changing my head gasket on my Landrover and have a couple of questions .
Background: I own a disco 1 300 tdi 1997 , T reg , with 125k on the clock .
Whitest towing caravan or when on a long journey 60 miles + the Landy over heats and has to be refilled with water . Last week towing caravan 80 mile journey driving with care , no more than 50 mph over heated 6 times each time refilled with water . Spoke to local garage with symptoms and they confirmed/ agreed the head gasket is on its way out .
Ordered new gasket and bits / extra tools needed.
My questions are :
1 . Garage advised me to have head skimmed ( £40) . Do I " really " need to do this or is it just good practice ?
2. Will I need to take valves out to have head skimmed? Or can I leave them in ?
If I need to take them out might as well have the valves lapped , however that adds time and a bit more expense and hassle .
ANY ADVICE WOULD BE FANTASTIC, no matter how small .

Thanks in advance for any advice .

Could just as easily be a blocked radiator matrix or faulty thermostat. Shotgun parts replacement is rarely cheap OR effective...

Flushed radiator ( took it completely out and put hose through it , the day after I got home ) . Took the thermostat out , road side , after it overheated the forth time on the way home , symptoms continued. Took out for run to the tip the next day , mainly uphill , overheated . Temp guage went from just under half to just under red twice . Had 20 bags of weeds in back , so not to heavy , but engine working slightly harder than empty car .

But does ALL of the rad get hot, if yes get a garage to do a hydrocarbon sniff test of the coolant expansion tank to confirm a blown gasket / cracked head etc...

Thinking about that , looked for sniff test kit on flea bay ( £29) , could be cheaper at garage . Mind you white smoke ( not steam ) does come out of expansion tank when you take top off , which smells a bit exhausty .

That does sound a bit like a gasket issue. Some people just do a gasket,some skim no matter what.... I look at the TDI as a long lasting rebuildable motor - Check the head for flat,skim only if necessary,have the valves out and lap if needed.Changing the valve stem seals at the same time will help with oil consumption too.

Or stick some K-Seal in it Head gasket went on my old Ford Explorer - got quoted a couple of grand to fix (4litre V6 on gas). Cured it and ran for years after with no problems!

Bad news.......It's a Tdi, it has overheated a number of times, it WILL most likely have blown the gasket and probably warped the head in the process.
To resurface the head, (only possible if warpage is minimal), you will need to remove all 8 valves as the combustion chambers are in the piston tops and valves sit proud of head surface.
Replace the head using a Victor Rienz MLMS head gasket, I have had great success with them.
Also a new set of head bolts is a good investment and can help save future failure.

I have a 300tdi head in the store at home. I'm not there at the moment, but I'm almost certain that the valves do NOT sit proud of the surface. Injectors iirc do, but not the valves.

We're not talking much space at all, but they do not protrude.

In fact, I'm certain of this, as I removed the plugs and injectors for storage, as then the head sits flat. As to if it can be skimmed with them in place is another matter, but they do not protrude.

Did a few 300 TDI in the last year, one was from a farmer high up on the mountains. So no maintenance at all.
IT was constantly overheating and so the head should be warped.
After checking the head was perfectly straight but he wanted a new one.
I ordered one from Paddocks, installed it and the disco is still on the road. working hard every day with a 3.5 ton trailer on the hitch, only short distances mostly in low gears.

regards

It will almost certainly be the head gasket and it needs to be checked for flatness, they can only take a bit off with skimming but at least needs checking. Valves need to come out and may as well get it pressure checked while you're on. Do it once, do it right is my motto. Also worth checking the rad, a flush doesn't mean it's ok. Also check P gasket, in fact I would change it anyway while the engine is stripped down.

Thanks for everyone's advice , changed the head gasket last weekend .....had to buy a few tools that I didn't have eg : angle guage , however took me two days to strip , lap all valves etc etc etc , and rebuild . So far so good been out today for a trip ( 50 miles) no problems . Was unsure at the start if I could do it , however kept myself VERY VERY organised Eg : each group of nuts and bolts that came out got put in food bag and label on bag telling me where they had come from , and bolts pushed through cardboard in order they came out .
Saved myself a fortune .