Thread: Coolant Loss - Engine Overheating

Originally Posted by Sol

Yep, seems like a common issue but of course I didn’t know that until it happened and read the numerous posts. Preventative seems to be the way to go if you’re on a long trip, especially towing.

MR Auto are sending one today and hopefully fitted and fixed in a day or two.

Praying there’s no further issues or over-cooked motor.

Which leads to the question/s I've been meaning to ask

1 - is it worth fitting a low coolant alarm as per recommended for D2, or does the D4 already have a similar feature built in along with a coolant temperature gauge that actually works (unlike the D2)?

2 - I usually don't connect up my GAP tool around town, and haven't actually worked out if it provides an equivalent warning?

It has a low coolant warning for the bottle level and if for any reason you need to top up coolant that’s the warning to find out what’s leaking ASAP. It is easy also to see the main culprit part in the valley and see if any coolant residue is around.

Lifting the bonnet during road trips for a look and smell is the go. The bottle is well placed to eyeball the level in an instant.

No automotive coolant temperature probe works once out of coolant. So D2 vs D4 comparison is moot.

D2 gauge works fine - IF - coolant isn’t lost (and engine is just overheating)

D4 has a low coolant sensor, warning on dash etc. and works very well.

I got a ‘low coolant’ message on the dash and then ‘engine overheating’, at which point I pulled over promptly! As others have said, the leak is very obvious once you remove the engine cover, looking under the throttle body from the passenger side. You can smell it too.

Originally Posted by Tombie

No automotive coolant temperature probe works once out of coolant. So D2 vs D4 comparison is moot.

D2 gauge works fine - IF - coolant isn’t lost (and engine is just overheating)

D4 has a low coolant sensor, warning on dash etc. and works very well.

Mike, we will have to agree to disagree.
In my D2a, I routinely had my Evo set on instrument mode with the coolant alarm set at 105 C for normal driving, and occassionally 110 C when I knew it could get a bit warmish, but I would be keeping an eye on it.
The LR gauge wouldn't move until over 115 C, and even though I know from Blknight that the TD5 is designed to operate at up to 120 C, only a 5 degree differential is too close to expensive for my liking.

Originally Posted by Tombie

No automotive coolant temperature probe works once out of coolant. So D2 vs D4 comparison is moot.

D2 gauge works fine - IF - coolant isn’t lost (and engine is just overheating)

D4 has a low coolant sensor, warning on dash etc. and works very well.

Mike, we will have to agree to disagree.
In my D2a, I routinely had my Evo set on instrument mode with the coolant alarm set at 105 C for normal driving, and occasionally 110 C when I knew it could get a bit warmish, but I would be keeping an eye on it.
The LR gauge wouldn't move until over 115 C, and even though I know from Blknight that the TD5 is designed to operate at up to 120 C, only a 5 degree differential is too close to potentially expensive for my liking.

Originally Posted by gavinwibrow

Mike, we will have to agree to disagree.
In my D2a, I routinely had my Evo set on instrument mode with the coolant alarm set at 105 C for normal driving, and occassionally 110 C when I knew it could get a bit warmish, but I would be keeping an eye on it.
The LR gauge wouldn't move until over 115 C, and even though I know from Blknight that the TD5 is designed to operate at up to 120 C, only a 5 degree differential is too close to expensive for my liking.

And it doesn’t have to. Normalised gauges are in almost everything now.
5c is a lot in an engine. Remember a pin hole that drops pressure reduces BPt back towards 100c.

Seperate the 2 situations and this is what you have.

1) Overheating.
2) Sudden loss of coolant

1) can be fan failure, hard work under load in excessive heat etc.
the ECU and engine can easily deal with this. Fuel cut occurs in alternating cylinders and the engine protects itself.
Running at 115c won’t hurt it. For comparison in summer I’ve had EL falcon 6s running at 118c without a problem. It was in the workshop manual this was a normal range temp.

2) Sudden loss of coolant.
No immersion based sensor can read temperature once not immersed. Guess what else can’t happen - engine protection strategy can’t work because it doesn’t know it’s hot.
The D4 has a slightly better factory set up, it looks for coolant level drop. First warning. What it won’t sense is complete fluid loss as a temperature increase - submerged probes only work submerged remember.

Low coolant warning SHOULD mean “Cut load and Pull over as soon as safe.” Not keep driving watching temperature gauge.

Originally Posted by gavinwibrow

Mike, we will have to agree to disagree.
In my D2a, I routinely had my Evo set on instrument mode with the coolant alarm set at 105 C for normal driving, and occasionally 110 C when I knew it could get a bit warmish, but I would be keeping an eye on it.
The LR gauge wouldn't move until over 115 C, and even though I know from Blknight that the TD5 is designed to operate at up to 120 C, only a 5 degree differential is too close to potentially expensive for my liking.

You can watch the temp on a GAP11D if you really want to be sure. The fan doesn't even start to partially lock until 107 and the gauge only moves at 117 on the D4, at which point it jumps to just below the top. The fan is fully locked at about 115. Low coolant is a completely different kettle of fish to over heating, as Tombie said. Easy to reduce load and increase engine speed by dropping down a gear or two if it gets hot but loss of coolant destroys the engine very quickly, which is why you need to the low coolant alarm, which the D4 has.

Unfortunately at the moment my low coolant warning works too well and is intermittently activating with full coolant level. I will have to try to find out what is wrong I guess, so that if it does lose coolant I will know about it.

Re the plastic housing, I replaced mine with an alloy version when they did the two manifolds. I think it should be replaced at least with the timing belts, if not at lower mileage and 7 years of age perhaps.