Cooling issues - am I missing something?

[Vernon]

Hi
Got a DG 1.9 petrol, end of last year the temp gauge was reading all over the place, traced it to sender. Replaced sender but the gauge reading high, fans not coming on even tho it sits on drive ticking over. Tested fans,Ok. Changed sender again, fan & thermostat. Fan still not coming on even tho the pipes & rad are red hot. Gauge still reading 3/4 across.
Am I missing something? Air lock somewhere even tho there's no air coming out of bleeding valve on rad?

[RogerT]

Where your temp gauge sits, seems to vary with different temp gauge sensors. There's a fairly current thread about it here http://forum.club8090.co.uk/viewtopic.php?f=39&t=137325" onclick="window.open(this.href);return false;

Tested my fan last night after changing my radiator. The neighbours must have loved me, 20 odd mins of medium revs to get the fan on, maybe more. The needle sat in its usual place for a good ten mins or more before the rad got hot enough to trigger the fan, and the fan only ran for seconds at a time.

So I think your needle position concerns should be separate from your worries about your fan.

The fan is a simple electrical circuit, and as long as you've got a working sensor on the van, you should be good to go. I note you say you've tested the fan, I take it this was by pulling the plug off the sensor on the radiator and bridging the live and earth?

Sometimes new sensors can be duds, I don't know if anyone has tested theirs by taking the new sensor and putting it on the plug, then dipping it on boiling water?

As for the temp Gauge, it does sound as though changing the sensor stopped it being erratic, and I wonder if it's position now is just it's new normal? As long as you're not overheating, got no leaks, dalek cap functions properly, and you have that top up tank behind the number plate (don't scoff, I didn't have one when he bought my van and didn't realise I should have one for a couple of years. Just thought it was a bit of a pain that the dalek cap was peeing water onto the ground whenever it got hot). Info in the wiki here
http://wiki.club8090.co.uk/index.php/Ma ... ing_System" onclick="window.open(this.href);return false;

Let us know how you get on/come back with more questions...

[Oldiebut goodie]

I know that mine is a diesel but my gauge read high for a while after changing engine until all of a sudden it behaved more normally around the led mark. I have assumed that it "burped" an airlock as it has been fine since.
I would suggest investing in a cheapo infra-red thermometer ( a couple of £ on ebay) to check around the engine, pipes, rad etc just to reassure (or not) yourself as to the actual temps that you are feeling. Then you can consider whether the fan should be coming on or not and possible problems with the switch.
I find that with heaters anything over about 100 deg. my hand is no good as a guide. 120 deg feels the same as 100.

[rockthebus]

I know that mine is a diesel but my gauge read high for a while after changing engine until all of a sudden it behaved more normally around the led mark. I have assumed that it "burped" an airlock as it has been fine since.
I would suggest investing in a cheapo infra-red thermometer ( a couple of £ on ebay) to check around the engine, pipes, rad etc just to reassure (or not) yourself as to the actual temps that you are feeling. Then you can consider whether the fan should be coming on or not and possible problems with the switch.
I find that with heaters anything over about 100 deg. my hand is no good as a guide. 120 deg feels the same as 100.

I bought one of the ir temp gauges. Do you know what this is for?




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[Oldiebut goodie]

Looks like a list of how well various surfaces emit the heat signal in the infrared spectrum. Presumably you could use it to correct the error in readings from the various surfaces.

[rockthebus]

Looks like a list of how well various surfaces emit the heat signal in the infrared spectrum. Presumably you could use it to correct the error in readings from the various surfaces.

That makes sense. Thanks

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[Vernon]

Thanks for the info.
Yes I did test the fan by putting a link in the plug so we know that's ok.
I shall read this again in the morning and work through it, I have a temp meter with a thermocouple lead on it so I will tape or tie it to somewhere to check temp, don't know why I didn't think of that,probably frustration

[Vernon]

I also think it's not over heating as I've got no leaks anywhere and the dalek cap isnt passing water, maybe I'm a little over worried as we're driving nearly 400 miles in her next weekend
Night all

[Vernon]

Well after going through everything you suggested I'm a lot happier now. Even tho the gauge is reading 2/3 across the fan kicks in and out. I stuck my thermocouple to the rad near the fan switch and the fan came on about 78C, obviously cooled down then went off. Like you say Oldiebut Goodie a good run on our holidays and maybe a good burp will settle it down.
Thanks for all your advice, I'm a lot less worried now

[Mr Bean]

My sensor went open circuit and when I replaced it (JK) the needle finished up further across when the engine was at running temperature but everything else was spot on as far as I could determine.
Having spent about ten years in temperature controls and Instrumentation in an earlier life I just assumed that the new sensor is a bit out of spec from new.
The recent hot spell confirmed this as the fan did cut in and out as expected when sitting in traffic for extended periods of time.
CS