Thread: REVISIT COOLANT EXPELLED FROM EXPANSION TANK. PROBABLE CAUSE

Hi Guys,
I think I have an expensive problem. After just completing (at least I completed it) a trip of around 9,000km from Urunga to Adelaide, to have a rear tail shaft replaced after the centre support bearing bracket broke near Yunta in SA, up through the Flinders to Innaminka then inland QLD to Bowen & back home also inland, I have to face up to a problem that developed early in the piece.

When driving with the caravan attached at around 90 to 95kph after a few hours coolant blows out of the radiator cap on the expansion tank. If I drive at 80 to 85kph no coolant is expelled. If there happens to be long pulls up hills at the 80 to 85kph coolant will be expelled. So this problem occurs while under load. Prior to the trip I could drive all day unloaded at 100 to (rarely? 110kph with no problem.

I have replaced 3 radiator caps with the same result. Radiator is not blocked from the outside & no signs of contamination of the coolant & coolant seems to flow freely through the expansion tank. No indications of excess temperature rise either by the temp gauge or "feel" of the engine heat under the bonnet. Please... no snipes about "feel", it's a sense after being in, under & around vehicles for a very long time.

I am not experienced with these engines & information I have received suggests this could be an indication of early stages of head gasket failure. The suggestion has also been made that it is not viable to replace head gaskets but to replace the whole engine. I come from a different age & this seems a little extreme although I can understand that there are often run on problems that can arise. It is a 2007 D3, 220,000km, belts & oil pump replaced, coolant distribution plastic junction replaced with billet item. Coolant changed a couple of times since I've had it.

Any & all constructive feed back & suggestions will be welcome.

Regards, Wayne

Hi Guys, A brief recap. I have a 2006 D3 2.7D. We went for an extended trip & after a few hours driving towing the caravan coolant would be expelled from the coolant expansion tank. No signs of excess heat, no high temp gauge, no limp mode. Quite worrying. The car could be driven all day without the van & no problem at all so issue only under load. First enquiries while on the trip in South Australia indicated this could be the first signs of a blown head gasket & the consequent result being to replace the engine !!! I'm still having difficulty with that. Subsequent enquiries & valuable information gained from this site indicated the same.
I tried just about everything including radiator & thermostat & a few caps replacement, diagnosis including testing for coolant in exhaust or combustion gas in coolant etc. Problem persisted.
I was looking down the barrel of replacing the motor & had a conversation regarding this with the guys at MR Automotive, Redcliffe. QLD. They told me they have had problems with aftermarket coolant expansion tanks & no longer use them & suggested a test I do. I did the test which was to get the engine hot & see if I could lift the radiator cap slightly off the thread & he said it would take a fair pull. I managed to get the cap to jump one thread. I figured a young guy on the tools full time would have a grip something like mine was 25 or 30 years ago when on the tools so I elected to purchase an OEM coolant expansion tank.
The day it arrived I installed the tank, bled the coolant system & hooked up the caravan & took it for a drive of around 100 km. The drive was mostly uphill with ambient temperatures at 40 on the steepest part & around 37 the rest. I drove as hard as I was capable or game to & when finally stopped with great trepidation I opened the bonnet & checked & there was absolutely no coolant expelled. I had to look a couple of times & then go back later & look again after I'd had a beer. The car had expelled coolant previously on a part of this same run on a much cooler day.
It appears the material of the aftermarket & cheaper expansion tank must have a different expansion rate & under heat & pressure will allow the cap to jump a thread which will reduce the boiling point & allow coolant to escape via the thread rather than the pressure release valve allowing pressure only to escape & then redraw when cooling.
At this time I feel the problem is resolved & will be completely satisfied when I've done a thousand or so km.

Hopefully this may be of assistance to someone in a similar situation to at least try. Apologies for the length but tried to cover in as much detail but briefly. Feel free to contact me if you would like more info or clarification.

I must make special mention to MR Automotive at Redcliffe QLD, very helpful, courteous & knowledgeable & also do a thorough engine change over if necessary at very competitive rate.
Also, British Off Road, Sunshine Coast QLD. Also very helpful & knowledgeable. They have a completely reconditioned 2.7D motor for exchange & also do a supply & fit also at an attractive price for a fully recon motor.
All 4X4 at Kotara NSW also do engine swaps & include comprehensive set up including new belts. None of the above simply slot a replacement motor in, they do comprehensive checks to protect themselves & the purchaser.

I hope I'm inside the guidelines with this. Regards, Wayne