Cold bottom hose.

[weebrian]

Even after a long run, my bottom hose stays cold. Not being that mechanically minded, what is this likely to be symptomatic of?

Vehicle is a V6 with LPG and the temperature gauge always sits at about 11 o'clock when warmed up. I have been losing a small amount of coolant, about a cupful over a 300 mile journey, in the last few weeks on a few occasions and have put this down to a weeping joint.
Heater works fine and engine runs as it always has done.

[Velocette]

Even after a long run, my bottom hose stays cold. Not being that mechanically minded, what is this likely to be symptomatic of?

Vehicle is a V6 with LPG and the temperature gauge always sits at about 11 o'clock when warmed up. I have been losing a small amount of coolant, about a cupful over a 300 mile journey, in the last few weeks on a few occasions and have put this down to a weeping joint.
Heater works fine and engine runs as it always has done.

On an unmodified Bongo 11 Oclock just means "warmed up and not dangerously overheated". As soon as it moves up off 11:00 it means trouble.

Will leave it to the V6 owners to comment further.

[Simon Jones]

I've got a TM2 sensor fitted to the pipe as it exits the thermostat housing on its way to the bottom of the radiator. On a recent 100 mile trip to Exeter is barely got above 20 degrees C, so the temp at the rad will be a lot cooler. Only time it will get warm which is when the 'stat opens somewhere above 80 degrees C which will be about he same point the fans will come on. In other words: it's working exactly as it is supposed to .

Your leak is likely to be any one (or more) of the following:

- Radiator where the core joins the plastic end caps
- Pin hole in one of the rubber hoses
- Pin hole in one of the metal pipes
- Leak at point where metal pipe meets rubber hose
- Poor seal on the radiator or expansion tank cap
- Leak in front or rear heater matrix

[francophile1947]

Mine was a 2.5TD and I never had a hot bottom hose, unless I was really hammering it. During normal running my bottom hose was always cold, as the heater rads seemed to provide sufficient cooling for the thermostat not to open.

[weebrian]

Thanks for the replies guys. I've got a 200 mile trip on Friday so will see what happens then. A good run down the M54 should give it a chance to warm up if it's going to.

I'm just a bit paranoid over the potential cooling system problems that I seem to read about here all the time that the slightest variation from the norm gets me worrying. Although the LCA gives me some level of comfort, I still have nightmares about having to replace the heads !

[Simon Jones]

Thing to bear in mind is that a blat down the motorway will result in a much greater flow of cool air over the radiator and engine than getting stuck in a traffic jam for 10 minutes. If you want to check everything is working, once you've got off the motorway, pull over and let the engine idle for 10 to 15 minutes until the fans kick in, then you'll feel some warmth in the bottom hose.

[mikeonb4c]

Thanks for the replies guys. I've got a 200 mile trip on Friday so will see what happens then. A good run down the M54 should give it a chance to warm up if it's going to.

I'm just a bit paranoid over the potential cooling system problems that I seem to read about here all the time that the slightest variation from the norm gets me worrying. Although the LCA gives me some level of comfort, I still have nightmares about having to replace the heads !

Don't hear of many v6 Bongos having problems, though avoiding an overheard is always a good idea. Is the v6 an all alloy engine? If so I wonder if it doesn't succomb like the diesel to blocked system due to rust when anti-freeze/inhibitor not changed regularly?

[weebrian]

Panic over! Just hammered it up and down a few hills and then left it running on the drive for about 15 minutes. Bottom hose and radiator red hot. Obviously no problem, just a highly efficient radiator.

[teenmal]

It would probably be worthwhile having a wee look at the thermostat.

[Simon Jones]

The thermostat is behaving correctly as it must be opening to allow the bottom hose to get hot. By all means fit a new genuine Mazda 'stat as it will perform better than an old one. I've just changed mine & tested them both in a pan of boiling water. A new one will open sooner, wider & stay open for longer as can clearly be seen here just after they were removed from the water:

[teenmal]

The thermostat is behaving correctly as it must be opening to allow the bottom hose to get hot. By all means fit a new genuine Mazda 'stat as it will perform better than an old one. I've just changed mine & tested them both in a pan of boiling water. A new one will open sooner, wider & stay open for longer as can clearly be seen here just after they were removed from the water:

I was actually thinking it might not be Closing properly,it would be worth checking as it would save a wee bit of cash on fuel if that is the case.

Cheers.

[francophile1947]

I was actually thinking it might not be Closing properly,it would be worth checking as it would save a wee bit of cash on fuel if that is the case.

Cheers.

If it was not closing properly, the bottom hose would get hot as water would be circulating through it.