2015 Pajero Sport 2.5d (4D56T) engine overheating puzzle

[GlenC]

I have a puzzling overheating issue with my 2015 Pajero Sport (2.5d, 4D56T engine with 250k km on the clock) that I'm hoping one of you gurus could have some suggestions on!

I've been experiencing overheating but always managed to pull over before I got to the red (usually at the last line before red on the temp gauge). The mechanic was adamant a small hole in the radiator was the issue (which he showed me and was on a corner bend so not repairable). Replaced radiator and thermostat but problem persisted. Compression test was good, carbon test was good. No sign of oil in water nor water in oil. I am not losing any coolant so high confidence the head isn't cracked. Replaced cap with 127psi original from Mitsubishi but still the problem persists, manifesting itself by the expansion tank filling up as coolant expands but radiator not drawing it back in (eventually overflowing). Every morning I transfer coolant from the expansion tank back to the radiator (200ml to 1 litre, depending on distance driven). When opening the radiator cap in the morning before starting the engine, pressure releases and bubbles are visible in the expansion tank. What I noticed yesterday after taking it to another Mitsubishi agent was after he opened the radiator cap when the engine was still at operating temp, it did draw coolant back into the radiator as it cooled. He suggests it's likely only 1 of 2 (or both!) options. The head gasket leaking at the intake side, and/ or the water pump leaking somehow. Has anyone else experienced similar or have any brilliant thoughts? Quoted minimum 16k to do the gasket I am hoping for a bit more certainty about what the problem is. Computer doesn't indicate any error codes either by the way.
Sorry for the manuscript but I figured it's better to provide as much info as possible.

Thank you! Here's holding thumbs

[Albertus Viljoen]

Hello Glen

Albertus Viljoen here from Bloemfontein. I purchased a 2016 2.5D Pajero Sport last year with 93 000 km on the clock. Car is in a top condition, no problems on commute to work and in the city exc. Had engine checked out just after purchase and my regular mechanic was very impressed with the engine. 88 km into my first trip to Cape Town, the exact same thing happens to me as mentioned in your post. Pull over and switch off engine before heat gauge reaches the red line, coolant pushed out of reservoir. Towed back to BFN. My regular mechanic does pressure test on cylinder head, no problem, engine output, no problem, no water in the oil. They suspect it is a faulty radiotor cap or thermostat. They replace both. One month later, 220 km into my trip same thing happens, I again make sure that I switch off the engine timely. Local mechanic cannot diagnose the problem, I go to the John Williams branch in BFN. They do a diagnostic test on the vehicle, quickly quote me R 14 000 for a new head gasket. I wait four weeks for the gasket to arrive, they inform me that the part is still outstanding, but that I should bring the car in, they want to do an EGR bypass. I lose patience and demand my refund, as I had already paid for the long awaited head gasket. At this point in time I am considering selling the vehicle as I am unable to find any solution for this puzzling problem. As a last resort I phone the Namaque Garage (Vanrhynsdorp Mitsubishi Branch) as my father had always purchased his Colt bakkies from them. The head mechanic immediately refers me to Mitsitech performance in Alberton JHB. I make contact with Tiaan Venter and Arnold Venter from Mitsitech. Vehicle is picked up in BFN by them. They do a thorough diagnostic test on the vehicle. At one stage they pick up the problem at 320 km! Cylinder head is warped, they also see that John Williams replaced the incorrect radiator cap in BFN! Cylinder head is replaced. They replace the radiator cap and issue me an extra one to keep as a spare. I have now done 20 000 km on the open road since the repair and not looked back. I would definitely recommend Tiaan Venter and the team from Mitsitech.

Tiaan Venter - (076) 402-0053

I hope this can help.

Kind Regards

Albertus Viljoen

[Pierre77@Pajero]

Hi Glen & Albertus

I have been driving for two years now with the exact symtoms given by Glen. I manage the situation by stopping every +- 150-200km and then releasing the pressure from the radiator and blowing back the coolant from the reservoir. Since there is no loss of water and no other issues picked up during yearly services and no "logical" explanations from mechanics ( I visited a few), I just carried on frustrated but loving the vehicle..

Thanks to you guys I have spoken to Tiaan and explained your comments and my history. Funny enough, the first thing Tiaan told me was to get a Mitsubishi radiator cap for my vehicle VIN. (I realised and mentioned it to him, that I had two previous mechanics change the radiator caps but it was not from Mitsubishi linked to the VIN) Tiaan said that is probably why the coolant is not sucked back into the system.

Well, I have ordered two caps today (if it solves the problem I'll have a back-up) for R500 each. If not, a visit to Tiaan is next.

I'll give feedback.

Regards

[rajeev]

Hi bud, did you ever resolve the issue as i am facing the exact symptoms on a 2014 model?

[GlenC]

Hello forum members

Apologies, I thought I had updated this post but it must have been somewhere else! The joys of old age!

Someone recommended that I speak with Mitsubishi head office directly (not just an agent), to assess whether the engine was part of a recall, which it was! Mitsubishi agents in Pinetown performed an inspection and sent the report to head office. Despite me having not used agents for the servicing after 100k km's, the mechanic (as he claims) managed to champion Mitsubishi replacing the engine as part of their recall. This cost me nothing - sully covered by Mitsubishi. It is an import engine that they fitted (according to the serial number), but it's still a brand new engine and cost me nothing.