engine shuts down

Hi Guys,

hows you all doing. I have a H66W, 4G18, GDI engine pajero io, SWB.

I always maintain it regularly (service) using only OEM parts which I import from Japan. 

Imported this vehicle from japan when it had 49,000 KM on the odo, 2 years ago. I've now clocked 91,000 KM. The only issues I had was a faulty engine control relay (boy that bugger threw off alot of codes) and a fauly transfer case switch, which I was able to sort out.

My last service was 3 months ago, and that included;

. Oil change (I dont use syntatic. I use mineral oil that can be used on both LPG and diesel engines, 10W40. I live in a tropical country)

. Oil filter change - OEM filter imported from Japan

. Spark plugs - OEM imported from japan

. Transmission fluid flush

. Air filter - OEM

. Sprayed CRC GDI intake cleaner into the trottle body to clean the intake

. Cleaned the trottle body with CRC trottle body cleaner

. Cleaned the MAS using CRC Mass airflow sensor cleaner

. Changed Diff and transfer case fluids.

. coolant topup

Besides the transmission and diff oil change....the rest are standard service procedures that I carry out every time I do a service. Usually its every 2 months but due to the COVID-19 pendemic, parts are slow to arrive when imported.

Anyway, I now have an issue, which Im hoping someone here might have come accross. This started 2 days ago. What happenes is that after driving around for over an hour (I drive with the air con on since its so freaking hot here), the vehicle just shuts off. Especially when its in idle (When i dont have my feet on the excelerator pedal). When I start it back on...it just starts up straight away without any hint of a struggle. but then does it again after 5 to 10 minutes. After the vehicle cools down, it runs normal again.

There is no check engine light at all. the temp guage doesnt go way above halfway, so I dont know if its an overheating issue. I havent really found time to do a proper diagnosis.

One thing ive noticed yesterday night is that the top radiator hose is so hot you cant even wrap your hands around it, when the engine reached operating temp. however the lower hose can be very easily touched coz the temp is like....warm. Ive also notice  a section between the engine head and block, just were the top radiator hose connects to the engine block, has some wet marks. I had a feel and smell and its definately coolent, not oil.

Like I said, I still need to do proper diagnosis. Im realy tied up at work, so Ill fins some time this weekend to really check.

Would appreciate some starting reference points that I could start looking from.

cheers.