Thread: Coolant loss worry

Originally Posted by Morry948

A nice warm day here so took it for a drive out over the some hills, accelerating hard to get it working nice and hard

Aftermarket temp gauge ( placed in the top bung of the radiator ) got to 92-93*c after a few hills, and that was going up the hills hard at 100-110Kph. Temp dropped backed down gradually to 82-85*c and stayed there all the way back into town

Just checked the coolant level....hasnt lost a drop...

Those 92-93 values, was that with A/C on?
What kind of ambient temps on the day?

For comparison:
Mine barely moves irrespective of ambient conditions, except when it's 10°C or so outside.
Once up to operating temps mine just sits at about 83°C (give or take 1-2°C).
On those frozen 0-10°C mornings we've had recently, it struggles on the freeway drive to work to hit 80°C.

I replaced my thermostat with an 88°C Tridon which opens up a bit more than the original Waxstat at the start of winter too.
The original waxstat type barely opened much at 88(just millimeter or so to allow a trickle through) where the Tridon was at least 5mm open and obviously flowing much better.
Adding freshly boiled water the difference in opening rates is visibly marked between the two. Tridon opens up instantly and wider, Waxstat with a much slower response and after a few mins sitting in the boiled water tub(ie. water at about 95+ C) its still hardly opened, maybe a 2mm gap. Tridon's gap is at least double, more like triple or more. I'm seeing this as better flow(when needed).

With the old waxtsat thermo:
Last summer on the two or three occasions I used the air con(hot 35°C days on gravel roads) I was getting >95°C on an easy, flat run and even the slightest incline would see it run up to >100C with the A/C on.
Same conditions with the A/C off would see it drop to around the high 80's .. so it was the only way I could manage the coolant temps on any drives. The highest temp I saw at one point was 105°C after one long medium speed climb up to the crest. Once backed off(with A/C still on) on the long down slope now, it came back to about 95°C 5mins later as we hit the bottom of the downhill run.
All this time EGTs were within safe temps between 500-600C as I wasn't lugging the engine in any way.

So far on the two or three days we've recently had at or above 30°C I ran the A/C to see if the coolant temp still climbs and as yet I haven't seen more than about 87°C .. but have yet to tax the engine up and down any inclines either.
But I reckon that Tridon thermostat has dropped the easy running with A/C on drive from about 95-ish down to 87-ish(give or take).

When I got my Tridon thermostat, of got both the 88 I'm using now, and a 78° version too just in case.

For the sake of clarity with respect to the temps I'm getting, I feel confident that they're pretty accurate.
1. I used my IR temp gun to measure the temps of the head at various points, and the thermostat housing too. Heads definitely have hotter spots, thermo housing is spot on with temp gauge readings.
2. on a few occasions I've totally botched(rushed) the bleed method and not bled the coolant properly, and have got high 90's temps on my easy run to work. Never yet past 100 with air locks in the cooling system(run to work isn't that long), but with that, I'm confident that my temp gauge is working fine.

And after all this time watching the temps at these various times, only the one time did the dash temp gauge move off it's 'just under halfway mark' which was on this long run up the hill with the A/C on when my added temp gauge hit 105°C ... and my pants started smelling really bad!

Originally Posted by AK83

Those 92-93 values, was that with A/C on?
What kind of ambient temps on the day?

No Aircon - in fact the condenser has actually been removed

Temp was about 35*c

I might try a lower temp thermostat and see if that makes a difference

I have just had my head gaskets replaced on my D2a V8, I also have all new hoses, thermostat, water pump, idler pullies and tensioner, serpentine belt, and radiator fitted also a new viscus fan was fitted last year But I am still getting high temps at low speed or when I pull up at the lights.
At cruising speed the system works perfectly
I have absolutely NO coolant leaks or any coolant loss at all but the engine is still getting up to 115C at times.
If I put the truck into Park and give her a few revs the will engine cool down.
I wonder if the belt is slipping on the drive pulley for the water pump and low revs?

Its not getting hot around town, only when pushed hard up hill ( so far ). Sits under 80*c around town

When I am just cruising at 100 it is sitting around the 83-85*c mark

Originally Posted by Morry948

....

Also, there appears to be 2 sensors on the thermo housing, so which is which ?

Attachment 130299

There are 2 sensors, one is the coolant temp gauge, the other effects a switch electronically to turn the aircon off if the system overheating (obviously inoperative since your aircon has been removed)

Have you checked your "P" gasket (above the alternator) and your water pump for leaks ??

- any leak will evaporate quite quickly due to engine heat but there should be a coolant deposit (greenish white) where it has leaked

- can you smell coolant after you stop ?

- if the cabin heater has been bypassed there will be a reason (like it was leaking)

Originally Posted by 87County

Have you checked your "P" gasket (above the alternator) and your water pump for leaks ?? Yep

- any leak will evaporate quite quickly due to engine heat but there should be a coolant deposit (greenish white) where it has leaked. Nothing

- can you smell coolant after you stop ? Nope

- if the cabin heater has been bypassed there will be a reason (like it was leaking) ..who knows why it was disconnected...much like the air-con....grrr

Just strange that this time it got nice and hot but no coolant loss...

funny this convo came back. i drove 200km yesterday from wellington dam back to perth. was in the low to mid 20s driving around the 100kmh mark back. EGT got to about 620 at its highest. usually around 450 to 550 mark. coolant went to 90C when i got to the 620 (very briefly) stayed mostly on 87 and 88C all the way. my sensor is on top of head in the spare bung there. all in all, the car behaved faultlessly. oil pressure gauge still has occasional erratic readings. but sits usually on the 54psi mark whilst cruising and when warm drops down to 28psi when at idle. did some nice muddy 4wd tracks and some steep rutted sections in all-terrain tyres. there were some sections where we aborted as it got too crazy to attempt with our set-ups. but generally speaking we never got into any trouble, went over all obstacles. my d1 and a mate with a d2 td5 vehicle.

Originally Posted by Fausto79

... oil pressure gauge still has occasional erratic readings. but sits usually on the 54psi mark whilst cruising and when warm drops down to 28psi when at idle. ...

For the occasional errant oil pressure readings, I'd first look at the earthing for the sender unit and or the connection on the unit and cable.
Is your sender unit the large-ish grey body VDO type with the M4 sized nut for clamping the wire connector? (I think the VDO part No. could be 360.002)

I get some weird spikes every now and then, not common, usually noticed in the logs..

I was getting similar oil pressure readings as yours(60-ish at 2000RPM and 28 at idle) when I had the full synth Penrite 15W50.
Only last week or so I changed, but used semi synth as that's all I could get from my local store, so I thought what difference would it make.
Oil press now down to low 50's at 2000RPM and 22 at idle now!

All pressures recorded at 'operating temp' not cold.


@ trout: I'm slowly getting a D2 V8 going too, and the reason it's a slow process for me is the overheating issues(that caused it's previous owners to abandon it).
But my issues are the exact opposite to yours.
At idle, it won't get hot, or hardly gets hot. Longest test I've tried yet has been 90mins at idle, where it usually reaches about high 80's(as per the thermostat). No leaks in this test.
Drive it when it's got close to operating temps tho, and I've seen 129°C on the nanocom and an OBD scanner, and clouds of steam .. but no actual coolant loss.
Obvious culprit on this one is likely a head gasket, but then again it could be a more serious issue like cracked water gallery into a liner or something.
Hope yours isn't too serious.
Does your electric fan(for A/C) come on at about low 90-ish. Can't remember the exact temp, but just a bit over 90°C on mine, and switches it on.