[4ePajero]

To drive without a thermostat is not a very good idea, but as long as you drive accordingly.
My Touareg's thermostat failed (in the open state), and I had to drive ±800km with it like that.

Keep your eye on the temp. gauge and don't stress the engine if it runs 'cold' (under normal).

The test should at least tell you more about your problem.

[andrew.ashton]

Can you hear the viscous blowing when it gets hot?
Are you sure the viscous is pulling air through and not installed back to front so it's blowing air back into the radiator? (I have seen it happen)

On the Gen3 you can't fit the OEM viscous back to front - the mounting of the impeller on to the hub is asymmetrical.

[CATS]

Hi CATS,

For interest (and I know that it does not impact the fact that the temperature IS rising) where is the OEM coolant sensor located vs where is the MadMan coolant sensor located?

Taking out the thermostat does not always improve things - if coolant flows too fast through the radiator it can have the same effect as flowing too slowly - i.e.too fast and the efficiency of the radiator drops. But it still worth a try.

Is it an original OEM 2-core aluminium radiator or a 3rd party 3-core copper radiator?

Have you thought about removing your front ARB as test to see if it is airflow related? I know that seems a bit drastic, but desperate times call for desperate measures!

Andrew

Not sure where the different sensors are located but think the Madman one is on the inlet(top) pipe just before it enters the radiator, so probably at its "worst" heat spot.

The radiator is a new one which look similar to the old Mitsu OEM one which it replaced, pretty thin in my opinion , but the old one worked beautifully for 13 years so can't fault it.

I will not remove the ARB bumper. I have had that bumper on for 11 years of ownership before I redid the engine and towed the same Xplorer through many a rough and hot terrain in the past with no hassle, so refuse to believe it is the cause of the overheating since rebuild.

CATS

[CATS]

I only get some overheating when I tow my Xplorer now. Solo I can flog it to death on a hot summers day on an uphill and it goes to about 95degC max. If I hook the Xplorer and climb a hill or drive fast like 120km/h it gently climbs. This weekend it went as high as 116degC on the Madman and just under the red on the dash!!!.
CATS

To be honest, if it remains under 100'C by itself, your DiD seems perfectly fine, it should be within design specs and you should be happy!!

Second observation: besides the fact that you really shouldn't tow your Xplorer at 120kph all the time, it really is normal for any vehicle to get hot when pushed whilst heavy loaded. I think this is fair to expect it to sweat a bit when being pushed in summer.

116'C I wouldn't recommend going higher than 110'C. The risk just becomes too high IMHO

PS That ARB bumper makes me think... It may very well affect your airflow negatively. Why not remove it completely and test then? Or then go even further and put the original bumper and test again (obviously documenting the whole saga here for us). If the bumper is the culprit, it can at least account for the issue and end up with a few strategically placed 40mm holes

If you expect it to remain cool, contemplate fitting a bigger/more efficient radiator. It can't ever run too cold, that is what the thermostat regulates.

Larry

If it remained at 100deg I would probably not see the dash needle move at all and would have been happy. But it does not and the Madman just confirms this, which is the reason why I fitted it.

I hear you that things will get warmer if pushed but the problem is this. Before I did my engine rebuild I have put on 280000kms, 200000km of those myself, 80000km by previous owner, while towing the exact same van over much rougher terrain with never a HINT of overheating. Same driver, same drive style, same tow load etc. Now since the engine rebuild and the replacement of thermostat, Radiator, waterpump, oilpump etc as preventative maintenance measures, I suddenly have an overheating engine after spending a LOT of money on a rebuild! I have also had the ARB probably for the last 11 years, during which it NEVER overheated, and now I have this problem. I dont believe the cause is the ARB bar.

I will fit a bigger radiator if someone will guarantee that it will sort the problem but still believe that by doing that I am just hiding another more sinister problem(like a blown head gasket or cracked head), as the standard radiator has done duty for many years before the rebuild with no hassle at all.

I need to resolve this before my warrantee expires but dont know how to sort it, and neither does the engine rebuilder at this stage.

CATS

PS - Dont worry I dont drive 120km/h with the Xplorer on tow ALL the time

[CATS]

@larry007,

Thermostats already come with an air bleed built in these days.

@CATS,

Two other random thoughts:
1. Is the aircon condenser (radiator) clean and unobstructed (no bent fins) because that is the only supply point of outside air to the engine coolant radiator.
2. I see talk on the Aus Pajero site of high flow thermostats (e.g. here: http://www2.pajeroclub.com.au/forum/sho ... 835&page=3). Such a thermostat will still allow engine to get to and maintain optimum operating temperature, but allows for higher flow as temperature rises vs standard OEM thermostat.

1.Aircon radiator is clean and unobstructed as it was before engine rebuild.

2.Interesting. I wonder if Mitsu SA will know about this high flow item. Will follow up on this.

I wish I did not replace all these things at once! If I only did the engine and not all the rest I could easily say engine rebuild was at fault. If I later replaced say thermostat alone and had issues I could easily say that is what has led to the problem, but now everything is new and I almost need to start throwing each item out one by one, at a cost, to determine which one is the culprit. Unfortunately my original radiator, waterpump, oilpump, thermostat etc is probably long ago been melted up and doing duty somewhere else.

CATS

[CATS]

remove the thermostat and hook your trailer.

If the temp still rises it's the waterpump
If the temp stays cool then the thermostat is dud (remember to install a new one with bleed nipple on top) - I think you should change it for another original one anyways.

the statement of too fast flowing coolant through the radiator is unfounded. A fully opened thermostat allows full flow and max cooling.

Your cooling system is over engineered. It should be able to tow max weight up and down passes all day long.

Can you hear the viscous blowing when it gets hot?
Are you sure the viscous is pulling air through and not installed back to front so it's blowing air back into the radiator? (I have seen it happen)

I think this will be my next try. Run it without thermostat and see what happens. I will only do this as a test, not long term.

I agree - cooling system worked 150% in the past with no hassles or modifications at all, it should be able to still do this.

Viscous is blowing and is connected right way round, blowing onto engine and sucking air through radiator.

According to Alan Black they have now already replaced thermostat as well as waterpump again with no change in performance. Can it be that the new radiator is at fault? Wonder how I will test for that?

Also a bit worried about the AMC replacement head and the different thickness gaskets that needs fitment on these motors. Can a wrong installation like that not also lead to these symptoms? Can a diesel engine also check for exhaust emissions in the coolant to rule out a minute head crack or gasket leak leading to the overheating?

So far I do not loose any water so the closed system is waorking as it should which to me seem to indicate that it is not gasket or head related, but maybe I am wrong?

CATS
If I do find the culprit, and it is something stupid like an upside down thermostat as replaced by the engine rebuilders I will not be held responsible for my actions!

[larry007]

Cats, this is tough. I also wished that I didn't replace a lot of stuff at once last year, thinking `whilst at it....` you know. Currently you have a gut feeling about this and now the trust is broken as you know what the heat gauge should be doing - I feel you pain!!

You have confirmed that all the following are in order; thermostat, fans, airflow, correct temp reading, water pump, piping. My goodness!! As far as I am concerned only one of two things could possibly be the culprits, either the radiator, or the rebuild. Of these, the easiest should be to look at the radiator. Test or swap it, even with POC member if needed.

And then, in all sincerity, if you can prove all the above and still have overheating issues, then the rebuilder must come to the party.

PS If you experience no water loss I wouldn't be inclined to suspect the head, but am pretty sure I was told by HeadZone that you can have the water tested on a diesel.

[cloyd]

Cats,

A small piddle stream to add to the discussion: Why not borrow an used original radiator from Partshunt? Explain the overheating problem to Martin and ask for a used unit as a test installation with the promise to buy it if it solves the problem.

Cloyd

PS: I agree that by fitting an oversize rad will only hide the problem and not solve it.

[4ePikanini]

start with the cheap stuff. Get a new thermostat. Make sure it is installed correctly.

I still have dad's 3 core radiator. I'm not sure if it's the same between gen2 and gen3. We can do some measurements and check. The 3 core gives extra cooling capacity and extra cooling efficiency.

Do you still have the CATs in your exhaust?

Is the exhaust manifold heat shields in place?

Are the underbody covers in place?

Next time it gets hot, open the windows and turn the heater to max. Does that make a difference?

Remove the thermostat and check the flow out the radiator hose into a bucket at idle. A video would be good but it should be flowing at a substantial rate.

Can we get another gen3 owner to stop by and confirm that all the pipes are connected the right way? Screw ups are easy to make.

Allan Black may done the pump timing on the bench but has the timing been correctly set in the car? See page 10 onwards of attached PDF

Also make sure the tappet clearances are correct.

Sit this out. When you are done the car will be great. I spent 2 years getting my touareg up to scratch and now I'm loving it! The persistance is worth it!

11C.pdf

(1.92 MiB) Downloaded 116 times

[andrew.ashton]

@CATS

Can you remember if the problem started rearing its ugly head before or after you replaced the radiator?
Did you use an OEM radiator or a 3rd party radiator?

(Just wondering if the higher capacity 3rd party radiators really do provide improved cooling vs OEM radiator).