Radiator cold spots?

I was gutted when my 110 overheated again this weekend. Could really use some advice. When I first got it, it ran cool (with the needle never getting up over 1/3 from the left). Then, over the course of a couple days, it climbed until it would reach just into the red - whether idling or working (both easy & hard) - after about 5 minutes, so I parked it and started tinkering.

Here's what I did:
- replaced thermostat, belts, expansion tank cap, hoses, viscous fan clutch, & water pump
- flushed rad & cooling jacket (forward & reverse) with low pressure water
- topped up engine oil and replaced anti-freeze
- looked for HGF symptoms but can't see any
- and other stuff I probably forgot

When it all went back together a couple months ago it ran cooler with the gauge getting only just over 1/2 from the left. That lasted until this weekend when, over the course of a couple short drives, it went exactly back to its old habit.

So, went back on LZ looking for suggestions. Found a couple and tried them: parked on a hill with the expansion tank elevated, opened the cap and let it warm up, looking for bubbles as the tank filled, but only 1 or 2 tiny ones came up.

Then I checked the rad for cold spots. The bottom 1/4 to 1/3 was stone cold and the top was hot, with an even gradient in between. Is that normal?

Can I do anything to check coolant circulation?

Would really appreciate any other suggestions - thanks guys

This is a common problem with Aluminium engines. The coolant creates an electrical circuit between the radiator and the aluminium block which results in white deposits collecting inside the radiator. The cold spots in the radiator is where the white deposits have collected and blocked the radiator. If your radiator is newish you can get it professionally cleaned, otherwise best to change the radiator. Some coolants are better than others for preventing this issue. You can research for best coolants online. davidg

Modern antifreezes have additives to limit such sedimenting but good old fashioned Ethylene Glycol dissolves aluminium over time which settles out of solution. Hence the move to OAT formulated anti freeze in many modern alloy engines. However you should be wary of using OAT in an older engine that has become accustomed to EG as it can cause even more corrosion to take place.

Hey Chris , it does sound like a clogged rad , but when u topped up did you remove the bleed plug on the rad ( the one I was on about when we first met ) ?

sypher said:

when u topped up did you remove the bleed plug on the rad?

Click to expand...

Hey thanks Steve - but there is no plug on my rad.

Quoth the workshop manual: "NOTE: Disconnect bottom hose to drain on radiators without a drain plug." That's ultimately what I had to do. Made a right mess, too.

By the way, :welcome2: to davidg... and thanks!

kavefish said:

Hey thanks Steve - but there is no plug on my rad.

Quoth the workshop manual: "NOTE: Disconnect bottom hose to drain on radiators without a drain plug." That's ultimately what I had to do. Made a right mess, too.

Click to expand...

Hey bud , are you sure now .... on top of rad either the top left or top right corner looking from the front . ( can remember what side its on as its been a while ) .
I can remember topping up your header tank and it didnt take much untill I removed the bleed plug on top of the rad .

sypher said:

]on top of rad either the top left or top right corner looking from the front

Click to expand...

Oh sorry - I thought you meant the drain plug at the bottom. No I only opened the filler plug. I'll go check and see if I can find what you mean...

Edit: Beats me. All I can see is the big filler plug on the very top of the rad. Are we talking about the same thing? IIRC, remember you first filled the reservoir and practically nothing went into the rad. Then you got creative, elevated the reservoir, forced air thru the reservoir opening and down it went into the rad (probably after opening the filler plug). When I did it the other day, I opened the filler plug, opened the reservoir, topped up the reservoir (nothing went into the rad again) and then I topped up the rad directly thru the filler plug. Did I forget something or did I do it right for once?

Nope thats right mate thats the plug I was on about - ( it may of been a case of cronic air lock thats why I mentioned it ) .

Dont forget to replace those ****ty plastic bungs with some decent brass ones with bleed nipples.

MTM - what's this about plastic bungs and bleeder nipples? I don't recall seeing anything like that, but since my new rad hasn't arrived yet (been on order 3 weeks and counting!) there's still time to make improvements.

Probably a daft question, but could you point me in the right direction?

On the 200TDi and 300TDi Radiators, they have a plastic bung on the top to allow you to bleed out any air from the coolant system - but they are rubbish - they break and all the water pours out, so the trick is to replace them with brass items which allow you to bleed the air out whilst the system is hot and pressurised.

Bit I notice yu have a V8, so it might not apply to you.

Ah thanks. It does sound like a useful change. There's a brass bleeder plug on mine, but it doesn't have a bleeder.