OK guys I am almost sure this is a water pump issue. This has been happening for awhile with both 180 and 195 (verified correct) t-stats. Basically the coolant just ain't movin. When the head is ready to overheat the radiator is full of cold (literally I can open the drain cock and cold water comes out). It acts like air in the system but that's not it, it will come back to a rise and fall exchange with the reservoir but it can't hold it, eventually it just boils it over again. I flushed the system just this week and verified there's no clogs, the radiator flows with no leaks also, got plenty of antifreeze in it but no dice.

The water pump is one of these 4D56 types that are undoubtedly China made now, a little more than a year old. The only thing that could have stressed it is the belt a little too tight but I doubt that was it. What makes me just about certain it's not making enough pressure is that I switched from the 195 t-stat back to the 180 and it was fine for awhile, although a bit hotter than normal, but not boiling over. Then one day it started doing it, boiling over again, and it just clearly lost pressure.

Thankfully I can rule out the head gasket since it's clear water ain't flowing through the radiator (and that too). Also thankfully I've never actually hit the red line overheating and really never let it get to the upper white line which is 260?

So my conclusion is that it has to be the pump unless you guys can think of anything else but you know and I know about China, there's a bad egg in every dozen and the fact that it fails just outside of a year seems to confirm that. So that's why I ask the guru if there's any other options but the $80 one from GB. I am going to add an intercooler so that should help relieve the heat of the turbo.

Run it without the t-stat first. The impeller would have rusted off. If you did like most cheap asses do and put water only and not spring $12 each gallon x 2 for antifreeze, than no wonder why it rusted off. But I doubt youre a cheap ass. Everything made in china sucks ass. pull the belt off and spin the pump. Does it have a slight bit of tension as you turn it? It should

mikewarme wrote:Run it without the t-stat first. The impeller would have rusted off. If you did like most cheap asses do and put water only and not spring $12 each gallon x 2 for antifreeze, than no wonder why it rusted off. But I doubt youre a cheap ass. Everything made in china sucks ass. pull the belt off and spin the pump. Does it have a slight bit of tension as you turn it? It should

Sierra antifreeze, 20-60% 16$/gal. The impeller ain't rusted off but it ain't workin right. I will get to pulling it apart but we're in the middle of winter today up here. There's just no other explanation for the coolant not moving that I can figure. Not real excited about draining it again only to find out it's still got the problem until I have a solution. I put the 195 t-stat back in there because I know it's fully open at 200 and I'm sure the 180 was working too. But I will get down to the brass taxes on it. Rockauto has the other Pajero pump but I couldn't find this one: http://cgi.ebay.co.uk/Mitsubishi-L200-Shogun-Pajero-4d56-Water-Pump-Brand-New-/120502227061?cmd=ViewItem&pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1c0e7e1075

Well no BFD after all. Mike was right, just a t-stat problem. I retested both the 180 and the 195 and the 195 didn't fully open until 210 so it was shot. The 180 did open properly but it wasn't the right t-stat, it was the gasser and a little bit offset of center. That's the only explanation I have for why it failed and why I thought it wasn't the t-stat.

But I drove it 90 miles today to pick up 40gal of VO and it was fine. I will go with the 195 t-stat as it runs better on it, with an intercooler it should work out well.