Thread: 300TDI - What else to replace while changing the headgasket?

Originally Posted by ScottW

I bought a cheap Disco1 with a blown headgasket and I'm after some input from those with more knowledge on the subject than I.
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I gave it a compression test as I pulled it down and got 2 cylinders in the 420 range, one in the 'barely moved the needle' range and one snapped glowplug that is seized into the head. I could hear it huffing on the rear cylinder when it idled, so there were no surprises here and the compression check just confirmed the problem.

The car blew a fair bit of smoke. The turbo was full of oil, and I poured about 200ml of oil out of the intercooler, but once I pulled the hoses off the turbo and intake, wiped the oil out of the turbo and revved it a few times there wasn't any new oil coming out of the turbo, so I think it was all coming through the crank case ventilation (more on this later). The turbo spins as you would expect, but has zero movement in the shaft, either side movement or endplay.

I pulled the head today and the sure enough the headgasket was blown through and huffing straight into the crankcase through the pushrod hole. All the coolant passages were intact, so no milkshake and the cooling system still pressurised as it should. I pulled the breather off the rocker cover while it was running and it was huffing air and oil out of the hole fairly solidly, which matches the thought behind where all the oil in the turbo was coming from. It also blew the dipstick out once while I was increasing the revs to spool the turbo and clearing the oil out of the turbo.

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I'm pretty new to the 300TDI (I've had a few V8 RR's and an Isuzu County), so does anyone know if that head gasket is aftermarket? To me it looks much fresher than 29 years and 250,000km, so I'm thinking it's been replaced before.

The head has the Land Rover casting so I'm assuming it's the original head.
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My plan was to throw a brand new head on it as even though I don't think it overheated this time, who knows why the headgasket was replaced before (assuming it was). Is there any reason to try use the original head when a new one is fairly cheap?

Which is the best place to get a new head and gasket set from? Are there different manufacturers or do they all come from the one place? I'm on the Gold Coast so I figure I'll be getting it shipped to me.

I'll replace the timing belt while I'm stuffing around with it. My father has a brand new Gates kit sitting on his shelf that never made it onto his old 300TDI Disco 5-6 years ago.

What else should I be replacing while I'm at it? My list so far is:
Head
timing belt
Water pump
glow plugs
turbo oil drain (I killed it trying to remove it)
serpentine belts

Another thing that was noted is the injector pump had diesel on it, like droplets starting to form. Is it usual for these to leak a little and can it be fixed DIY, or is it a refurb type thing?

Turners do fantastic heads, but maybe costs these days may be too much...

Mike at Britrest has a few tips on the pump...

If its got a lot of kms on it, I would be looking at the bottom end bearings, etc... When I did the clutch in mine at 370k, I asked the mate same question... As we were removing the engine anyhow, we checked the bottom end bearings and found them worn so it was a good called to check/replace

I would just check that the head is straight and pop in a new gasket. That is how they blow and it does not hurt anything usually.

No point spending good money if you are leaving the bottom end as is.

Use new bolts. Torque as per the book. Do the timing belt stuff and water pump.

Originally Posted by Red90

I would just check that the head is straight and pop in a new gasket. That is how they blow and it does not hurt anything usually.

No point spending good money if you are leaving the bottom end as is.

Use new bolts. Torque as per the book. Do the timing belt stuff and water pump.

Fair enough. I've done some reading and seems just the gasket is good enough.

But, which gasket? There are composite and MLS. There seems to be a split as to which is better. I'm leaning towards the composite as MLS are usually best suited to cases where the head is skimmed dead flat again.

I prefer the elring composite gasket for the TDI,more forgiving than the MLS.
I would get the head hardness tested and checked for warpage, they can be machined if only slightly warped.

Elring composite.

- Measure piston protrusion and use correct thickness.
- Lap valves and change valve seals.

If head is warped, replace. Don’t machine.

Originally Posted by Red90

Elring composite.

- Measure piston protrusion and use correct thickness.
- Lap valves and change valve seals.

If head is warped, replace. Don’t machine.

Absolutely no issues giving them a light skim if required.

You don’t understand. When they warp, they warp again when heated. Every time.