Overheating - help!

[Slybacon]

Thanks for the advice Dave.

If it isn't the stat then I'm not sure what to try next. I suppose I should flush the system but I'm not 100% on how to do this. Do I, put a garden hose into the expansion tank and let it run, keeping the drain hose open? Or is there something else I should try?

[Slybacon]

Okay, removed the water pump to check it out - looks perfect: blades are clean, free running no play in the bearing. So I'm crossing it off my list of possibles.

I reckon that leaves two possiblities (please feel free to correct me): 1. The radiator has a blockage, 2. Their was air in the system before I started restricting the flow. (I'm discounting cracked head/head gasket as I've had no loss of coolant). A third, outside choice is that the thermostat was indeed faulty despite my test. I'll get a new one anyway.

So the plan is to fit a new stat, fill her up with coolant, bleed the system - will give the see-saw including Dave's variation a try - and see what happens.........

[mikeonb4c]

Sly - did the old coolant show any sign of rust in the water, or cloudiness?

Another thought, that I'd need others to comment on in case it's a no-no. For the sake of short term testing, would it do any harm just to put pure water in the system (anti-freeze costs). If, after bleeding, and having done some testing, all seems OK then drain the water (check for clearness of the water as well) and refill with 50/50 water/antifreeze mix. Having just done it once, you should find it easy enough to do again. It it doesn't pass the test, I'd say the radiator has to be flow tested and/or replaced (I wonder if it's possible to find out what the weight of the radiator is when new as it should be possible to tell if its crudded up by the fact it weights more than it should). You'll have saved £20 (or whatever it is) on antifreeze in the meantime.

I believe there is an argument that says antifreeze is important in raising the boiling point and the thermal conductivity of the coolant but I'm not sure it's critical for testing purposes. Wait and see what the experts say to this (start a new thread specifically about this if they don't spot this post and reply).

[Slybacon]

Mike, there was a little cloudiness - not much though.

I like your idea about using water to test the system - if any experts could advise it would be great..

I'm actually hoping (strangely perhaps) that it is the radiator because then it's something I can change and have some confidence that it is fixed. Reading the mega post last April about overheating it seems that new radiators aren't necessarily the cure though!

I may start a new thread if no replies - here's hoping though..........

[mikeonb4c]

Mike, there was a little cloudiness - not much though.

I like your idea about using water to test the system - if any experts could advise it would be great..

I'm actually hoping (strangely perhaps) that it is the radiator because then it's something I can change and have some confidence that it is fixed. Reading the mega post last April about overheating it seems that new radiators aren't necessarily the cure though!

I may start a new thread if no replies - here's hoping though..........

I'm off to bed, but good luck with that. The cloudiness is a bit suspicious perhaps. A part of me just likes the idea of having a new, efficient radiator and thermostat in place if there is any doubt. I wonder if there is a descaler product you could put in with pure water and then check colour when it's drained (hopefully bringing loosened/dissolved crud with it) before refilling with 50/50


Zzzzzzzzzzzzzzzzzzzzzzzzzz - I'm gone

[Aethelric]

The stat was the best bet, I would have bet on it

You can see if the rad is blocked in situ, although its messy. Drain the rad, by removing the bottom hose and collect the coolant. Then put your hand over the stub, get someone to fill up the rad, and then release the flow. You should get a litre in around 2 seconds. (that's what I got with a new rad). If its substantially less then the rad is restricting the coolant flow. The capacity of my new rad was 2.08 Litres BTW.

Are you certain your fans are OK? One of my radiator fans had the blades detached from the rotor! I had no idea until I removed the rad.
Is the scavenger fan working OK. There are posts on here about how to test it. That would account for hot seats and handbrake.

Good luck

Dave

[mikeonb4c]

The stat was the best bet, I would have bet on it

You can see if the rad is blocked in situ, although its messy. Drain the rad, by removing the bottom hose and collect the coolant. Then put your hand over the stub, get someone to fill up the rad, and then release the flow. You should get a litre in around 2 seconds. (that's what I got with a new rad). If its substantially less then the rad is restricting the coolant flow. The capacity of my new rad was 2.08 Litres BTW.

Are you certain your fans are OK? One of my radiator fans had the blades detached from the rotor! I had no idea until I removed the rad.
Is the scavenger fan working OK. There are posts on here about how to test it. That would account for hot seats and handbrake.

Good luck

Dave

What an excellent post Dave

[Slybacon]

I have to agree with Mike - a great and very helpful post Dave - Cheers.

I got a new thermostat today so I'm going to do the test Dave suggested and see if my radiator is choked. If not, I'll put the new stat, coolant in and bleed the system. Then, I'll just see how it goes. If the rad it blocked significantly I'm going to give serious thought to a new one.

I'll report back later...

[Aethelric]

No problem
When the radiator is full, its the time for the first litre out of the rad, obviously it will slow down as it empties.
Dave

[JulianG]

Is the scavenger fan running ? Dont fill it with tap water use de ionise or antifreeze the water ways in a bongo head are small and dont like hard water. Try running it without a stat to see if it cools down.

[Simon Jones]

Filling it up with tap water to do a quick test wont do it any harm. I was advised that by a proper Bongo specialist. There is little point in putting anti-freeze in if its liable to either leak straight out again, or you haven't flushed it out. Fresh tap water will also allow you to judge the cleanliness when you drain it out again.

I've recently replaced all my main hoses with silicone pipes. I used the old one from the bottom rad, cut it in half & fitted at standard Hozelock connector in the end (with assistance from a jubilee clip & glue gun). This meant I could fix the garden hose to the bottom of the rad to reverse flush the system. Depending on what you do with rad & expansion tank caps, and the bleed pipe, you have plenty of places for the 'dirty' water to come out of. You will also get a trickly from the hose on the bottom of the 'stat where it has been disconnected from the rad. I took the 'stat out when I last flushed it out.

I compared a new 'stat to the one I took out in a pan of boiling water. The new one opened at a lower temp & also the disk moved further which would give a much better flow. definitely worth the small cost when you're going to take the time to drain, flush, refill & bleed the system.

Good luck Sly.

[Slybacon]

Thanks folks for the helpful comments.

Tried Dave's rad time test tonight - all seemed fine. Got 2 litres in and the water pure gushed out (as we say here in darkest lanarkshire!) Easily 1 litre in 2 seconds.

So I'm a bit dumbfounded tothe cause of my problem. I'm not sure about the scavenger fan - I'll need to do a test on it.

What is left to do now is back flush (good suggestions Simon), fill her up, bleed the system and test.

I'm sincerely hopin that it was just air but who knows...........?

Oh, and I fitted a new thermostat. Did a wee test today with old and new one - no discernable difference - new one possibly opened a bit quicker though.

Oh well, time for bed ....zzzzzzzzzzzzzzzz

[mayk19]

Sounds simular to my issue, how did you fix it >? How did you know you overheated ?