This is a 12-valve 6G72, and it was the infamous oil burning problem that was being addressed here. Mileage at the time of repair was 284,326 km (177,703 miles). I'd like to thank ManyBrews for pointing out the fact that the problem is caused by the valve guides rather than the valve seals. It took about 4.5 hours to remove the cylinder heads, and even more effort to remove the REALLY hardened valve seals. One mistake was rushing it though, and not draining the block before hand.

Anyhow, here's a list of items that were replaced during the process. All parts are OEM unless otherwise specified:

- Intake and exhaust valves
- Intake and exhaust valve guides
- All gaskets (purchased a complete gasket overhaul kit)
- Crankshaft sprocket
- Injector insulators
- PCV valve
- Timing belt
- Timing belt tensioner
- Serpentine belt
- Power steering belt
- AC compressor belt
- Spark plugs
- Thermostat
- Radiator cap
- Upper and lower radiator hoses
- Engine mounts
- Engine oil (Motorcraft Synthetic Blend 10W-30) and filter (Hyundai 26300-35503)
- Mitsubishi Pre-Mixed Super Long Life Coolant (70/30)

The bad news is the cylinder heads were covered in heavy varnish, which I attribute to the poor quality engine oil that was used, sourced from the UAE. I've kept a record of all the oils I've used in this engine, and the one used the most was Gulf Max 20W-50. This oil used to turn pitch black within 1,000 km (625 miles) of use. Never again. At the moment I'm running Motorcraft Synthetic Blend 10W-30 for 8,000 km (5,000 miles), when I will add some Marvel Mystery Ooil and drain the oil at the 10,000 km (6,250 mile) mark. That should clean up all the dust, sprays, etc. used during the process. That point on, I'm going to be using nothing but French-sourced Mobil 1 0W-40 for 15-20,000 km (10-12,500 miles). A used oil analysis will be part of the process, inevitably. The heads were put in a cleaning tank to remove all the varnish and thankfully came out looking great.

Good news is, the spark plugs and injectors were very clean - thanks to a small dose of Marvel Mystery Oil and TC-W3 (which I recently switched to).

After 3 days of work the engine's pulled back together, and the distributor was adjusted with a timing light. She now runs like an absolute dream, and I'm really glad I put in the time and money into this project. This was $800 well spent.

The injector insulators had literally turned to hard plastic, just as the valve seals, and the crankshaft seal was the same. There was some oil on the old timing belt as a result and it took a whole can of CRC Freeze Off to remove the crankshaft sprocket. Needless to say, I replaced it as well, whilst replacing the crankshaft seal. I cannot beleive the dealership never even bothered to replace the crankshaft seal, ever. Suppose if you want something done right, you do it yourself.

 

 

it appears your passenger side exhaust manifold is cracked.

 

Well spotted! Yes, that was replaced...although I left the cover as is.

 

I have an 03 Montero and both manifolds cracked around 90k miles. I've put 10k on since then. I just gotta bite the bullet and spend the grand to replace em.