Puma 2.4 coolant loss, cracked head?

Its taken me a few days to get to this but here goes.

As many people on here are aware I had to replace the head gasket on my 2009 puma when it had 95,000km on the clock.

The symptoms were mainly overheating and some coolant loss. By overheating I mean the thing would go into limp mode going over a speed bump.

We tried absolutely everything we could replace before the head came off, we replaced the thermostat, the fan, nearly all of the hoses, pressure tested the radiator and so on.

Replacing the head big job on these things and there is a lot that needs to come out to access it all so you really want to be sure thats what needs to happen.

I am going to throw the cat amongst the pidgeons here and say that I think a lot of people panic about the puma heat a little too soon especially with the scan gauges. The thermostat is fully open at 94deg so people worry that if the thing reaches 95deg it is too hot but they dont take into account their circumstances.

If you were driving a stock rig out of the showroom then yes maybe you might have some cause for concern but think for a moment about the poor cooling system trying to work its guts out to instantly cool down while you are humping 2.8t+ of truck riding on 35's with 240mm spotlights and a winch blocking the airflow possibly with a larger intercooler amongst all the other accessories we pile onto these things. With all of that working against it it is going to take a while for the cooling system to catch up.

I regularly top out on a hill now into the high 90's, and occasionally the low 100's and yes I do carefully manage the temperature but I always try to keep it under 105 deg. I back off as soon as it starts climbing rapidly which always coincides with going up a hill. The one thing I notice is that once I back off or reach the top of the hill the heat climbs for another couple of minutes, to be expected but I always allow for this.

Quote:

---

Originally Posted by n plus one

I can easily achieve water temps (CWT) well north of 100 degrees if I deliberately boost up my 2.4 at low revs in sixth up a big hill. CHT are typically in the order of 10 degrees higher again when I do this.

---

Be very careful with this, 6th gear in these things is a weak POS and it is very easy to destroy a box by driving under load in 6th. If you destroy 6th you destroy the box which is a minimum $3,500 fix.

The best advise I was ever given is that 6th gear is an overdrive and should only be used on the dead flat once you have reached cursing speed (nothing under 95km/h) and as soon as you need to accelerate up a hill change down to 5th.

Quote:

---

Originally Posted by chook73

The one thing I notice is that once I back off or reach the top of the hill the heat climbs for another couple of minutes, to be expected but I always allow for this.

---

Yep, same experience with temp here.

When we are considering our operating temps, it's also worth noting that the coolant temps on a 2.4 appear to be a complex arrangement based on the cylinder head temp (CHT) sensor and not a simple actual coolant temp. The CHT sensor is a two wire affair and there does not appear to be a separate coolant temp sensor in the system - unlike the 2.2 Puma. Pull your CHT plug and your CHT reading goes awol shortly followed by the CWT which appears to default to the intake air temp (weird eh?). Plug the CHT back in and the CHT value immediately resets whike the CWT climbs back up. This is all based on scanguage readings.

Point being, the coolant temp values we are all talking about may well be a bit disengenuous?

Need to get of my arse and install my Madman coolant temp sensor to get some real data around coolant temps!

I've spoken to several LR independents and considered your comments. In all probability the head is cracked and only exhibits symptoms of coolant loss at full operating temp under load. They can't test the head by replicating the operating temp conditions so that exercise might result in a false negative.

I have a trip to the VHC in early Nov and if the coolant loss symptoms persist on this trip down I'll be left with the unavoidable (yet unsubstantiated) conclusion of a cracked head. If so, off with the old and on with a new head. Just need to find a lazy $6k. :(

Sad thing is, i have no way of testing if the conclusion is correct and the new head was money well spent.

The joys of LR ownership. MLD

That maybe the case, but once the head has bee removed it can be tested for hardness (especially between coolant passages and the cylinder chamber) and can be checked for cracks. As with any alloy head I always check them myself for hardness (compare outer edge hardness as its likely to be ok, to that of close to the cylinder chamber) if it tests ok, I then send them into Head Exchange for checking.

Just as a note, a cylinder head that has soft spots will exhibit these symptoms, all fine when cold but pushes coolant when full operating temp is obtained.

So basically once the head has been removed, it should remove any doubt as to the cause of coolant loss.

Regards
Daz

P.S just as some added info, if you talk with a engine re-conditioner you will find the Ford engine isnt prone to cracking.