Strange at least to me cooling system issue, although temps are normal I appear to be losing coolant after driving for several hours.
About 1/2 inch loss after 2 or so hours of driving
Coolant loss appears to from the expansion bottle overflow line.
I am verifying this with a rag wrapped around the line a tire wrapped to capture any coolant from there.

Status

• System holds pressure
• While driving temps between 188 and 194 - 1600 to 2300 rpm 20 to 55 Mph
• Idle at traffic light 197 to 201 depending on how much stop and go drops as soon as rpm increases
• Will reach 201 after highway run at traffic light drops immediately once moving
• Hoses remain soft at 194 -197 degs
• System has pressure in the morning normal pfft noise
• No air at bleed screw
• Engine Warm up appears to be normal not excessively fast
• No misfires or codes
• Heater is blowing hot hard to judge how hot though

I have replaced the rad cap this am and need to go for drive to eliminate that as the issue.

Suggestions ?

Update

This was a head gasket issue when starting disassembly I found the following sure signs:



Sorry about the fussy images

Milkshake in but only just starting PCV was also milk shaked
Coolant was good - no signs of oil
oIl has not been drained as of this post but dip stick is clear

 

Did this start by overheating or how did you notice it was low ?
My 03 and previous 04 liked being at a certain level on the expansion tank.
For example if I filled tank say to hot top line it wouid bleed itself out until it reached its happy level

 

My 03 is always below the hot line on the tank even if coolant is hot. Always been like that for over a year

 

@redwhitekat No overheat at all.

Mine has liked being at the line, but a clogged heater core or rad could cause normal to be too high. At least the heater core is easy to bypass to test if a bit nippy to drive around that way.

 

Well fueled up getting ready for a day trip with the club tomorrow, went for a 20 minute drive mix of hi-way and a hill climb home. Speeds between 50 and 90 mph numerous stops 1 to 5 minutes, needed to work the Hi/low CDL before the trip so very slow speed and stopped for about 5 to 6 minutes temps never passed 197 which normal for my disco when stopped for a while.

This was with the new rad cap, rag was dry when I stopped in the driveway.
Expansion bottle level was just above the mold line when hot, 1/8 of an inch or so.
Heater blows constantly hot

With luck it was just the cap.

If the water pump is going and weeping will the system hold pressure ?
There is no fluid underneath but could it be a small enough amount to not be seen ?

 

The OEM style plastic reservoirs are famous for seeping at the seem on the tank.

 

@Best4x4 thanks for the reminder to check the tank, it appears to good.

Level is good after 2 hours so far it is looking like the cap was faulty, I will report back with the results after tomorrow's run.

 

Hi Richard,

I have my old reservoir, T-joint and various hoses which I kept when I changed my engine this year. Let me know if you would to use them to check the system out. I will be back from the States on Monday evening. Have an uneventful trip on Sunday.

 

@acg Thanks Andrew with luck it was just the rad cap, I should know either when I reach Chilliwack or before heading out for home.

So far tonight level has held.

 

No joy not just a rad cap, good news once the cooling system hits it's new level it stops losing coolant from the overflow hose.

The new hot full seems to be at the expansion tank seam or a bit below.

• Heater still blows hot
• No misfires at 140 KM driven today
• Temp range 188.6 to 201.2
• Running at 2100 or so rpm 188.6
• Sitting for 5 minute no movement at idle peaks at 201 then drops right back to 194 and stays there
• hoses remain soft

Things to check:

• radiator return line and exit hole at the expansion tank to make sure there is no blockage.
• Exhaust gas test - although this does not really present as a head gasket leak, I need to make sure
• Rad cap is quite tight to get on cold is this normal

Any other suggestions ?