Bongo Fury

This has been baffling me.

Last week we drove up to Mull, a journey of about 400 miles. Half way there the temp gauge suddenly shot up to about 2 oclock before going back to its normal position (maybe slightly higher). I thought that it would be prudent to stop, and check the coolant when the engine had cooled down. No sign of any in the tank! Topped up with a litre and got it up to its usual level. Got to Oban no problem so checked levels again, no sign of coolant in the tank. Topped up with another litre and got ferry to Mull and drove across the Island. Next day checked levels and hey guess what? No sign of coolant in tank. Added another litre.

Since then the coolant level has remained the same and I managed to get home with the Bongo running well and the temp gauge behaving itself. What could have caused this initial loss of coolant? Did not notice any leaks. Is there a possibility that any damage could have been caused? I think that maybe I should get it to the garage and get the system flushed and checked for leaks. Coolant is still at the same level.

Oh Dont know if it is worth mentioning that we had a new back box fitted a couple of days before?

sounds a bit of a strange one this.the gauge if not modified tells you nothing until the coolant system is going wrong.
you should not be loosing any coolant at all normally,and you should investigate thoroughly.
you say you can not find a leak? get the system pressure tested.this may show your leak.
from your symptoms i would sugest that the rad cap(not the expansion tank cap) is leaking under pressure,the leaking coolant is then falling on to the hot radiator and evaporating off and not being seen.

Oh dear i hope you find the cause out ok
jayne

I hardly dare ask but.......

......do you have a low coolant alarm fitted?

If not, you know what I'm going to say next......

Fingers crossed your motor may be OK

bongonads

That is how mine started and the problem was the rad, fitted a new rad and thermostat and all is now well again, the old rad was clogged, it really does sound like exactly what mine was doing.

As has been said, relying on your unmodified temp gauge to tell you anything useful is getting you nowhere, it will sit at 11 oclock position form about 55 degrees to something like 100 degrees, you can fit a Mason alarm to modify it to tell you what's going on a bit better & give you a settable alarm, or there is a how to on modifying the temp gauge to resensitise it, details on both in the factsheet on coolant & temp alarms in the members area or by doing a search on the forum.
If you've lost that amount of coolant, you need to find out why & acquaint yourself with a bleeding process, you're skating on thin ice IMO.

...I think that maybe I should get it to the garage and get the system flushed and checked for leaks...

Good advice to yourself. You do need to get it checked for leaks... and you need to get it bled ASAP. A flush won't necessarily make a difference, because it depends what the problem is. Your garage can advise once they've identified the problem.