qwerty
Club Retro Rides Member
Posts: 2,410
Club RR Member Number: 52
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Cooling system woes.qwerty
@qwerty
Club Retro Rides Member 52
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Jul 21, 2016 12:42:53 GMT
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Polo cooling system is starting to try me.
A few weeks back it started getting warm while driving so I replaced: Coolant Thermostat Thermostat Housing Fan switch Blue temp switch.
Then the temp guage stopped working. On Monday I replaced the guage and took it for a drive. Initially it started to get a bit warm (100) and then suddenly it dropped and sat at 80 for the rest of the day. I was happy, I thought it had all worked.
Alas no! Took it out last night and it started getting warm again. Got it home and opened the bleed valve on the heater matrix, with the heater on full warm, thinking I might have an airlock. Nothing came out unless you revved the engine and the fan didn't kick in.
At this point I went in the house and sulked (through the medium of pizza).
So my thoughts are
A) I have an airlock somewhere B) The radiator is still silted up rendering the switch innop. (Fan kicks in when you bridge the connections) C) Switch is knackered (from ECP, so possible) D) A combination of the above E) HGF despite no evidence of oil and water mixing.
What are peoples views? What else should I check? Water pump? Whats the best way to burp the system? Originally I opened the bleed screw left the expansion cap off and let it idle for a while. I've read I should re try that but at a fast idle (1.5-2k). Anyway to test the fan switch?
Tom
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Jul 21, 2016 14:35:18 GMT
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I changed the rad on my 190e a few weeks back. I just let it idle with the cap off. Let it get up to temp and top it up as you go. Any air will make it's way out the header tank. Could also massage the pipes to help it along.
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1993 Mercedes-Benz 190e LE in Azzuro Blue.
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Jul 21, 2016 14:46:11 GMT
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It could well be the head gasket on its way,my G40 has been running hot for the last 4 months,although the fan was kicking in,and with the odd misfire on startup in a morning.it finally let go last week,number one cylinder was steam cleaned.stripped it,fresh gaskets,head skimmed and I'm building it all up later.worth flushing the rad with a hose first but a compression test came back good on mine right up to the end.
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qwerty
Club Retro Rides Member
Posts: 2,410
Club RR Member Number: 52
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Cooling system woes.qwerty
@qwerty
Club Retro Rides Member 52
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Jul 21, 2016 16:25:21 GMT
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I might give it a good flush and then if that doesn't work a compression test.
Dunno if its worth replacing the AAU headgasket or just replace the engine with something a bit more peppy.
Tom
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ChasR
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Cooling system woes.ChasR
@chasr
Club Retro Rides Member 170
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Jul 21, 2016 22:34:55 GMT
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I never trust aftermarket sensors. On my 944 the switch cut it in the high 90s and not low 90s as the genuine part I bought later did.
However, I doubt they are causing your issues. I do have a few questions of my own though.
-What brand of thermostat did you fit? Did the thermostat you remove have a jiggle pin in it? -have you opened the bleed screw without the engine running? Where in relation to the header tank in terms of height is the bleed screw? -Are your heaters hot?
I personally reckon you have an air lock. Having the wrong thermostat despite them "all being the same" will cause you issues IME and a fluctuating reading; it did with my 944 when I went from a First Line 'stat to a BEHR item. The 106 was the same but it did stay cool.
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qwerty
Club Retro Rides Member
Posts: 2,410
Club RR Member Number: 52
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Cooling system woes.qwerty
@qwerty
Club Retro Rides Member 52
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ChasRThe thermostat is a "genuine quality" one from VW heritage although I can't remember the specific brand. I don't beleive the old one had a jiggle pin The bleed screw is in the scuttle a couple of inches higher than the expansion bottle. I have had the bleed screw out without the engine running, mainly because I dropped it and lost it and had to wait for a replacement. They do indeed get hot, infact I whack them on hot to get a bit of heat out of the engine. Tom
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ChasR
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Cooling system woes.ChasR
@chasr
Club Retro Rides Member 170
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If the bleed nipple is higher than the neck of the expansion bottle you'll never get the air out as the water will "level" out. In this case I only see you as having a few choices. -Use a pressure bleeder to pressurise the system and remove the excess air. This has worked very well for me on a couple of cars, and I only used a bike pump and an inner tube attached onto the expansion tank so as to do this! -Park the car on an incline so that the header tank is higher than the bleed nipple. Brim the header tank right up to the filling neck and then use the bleed screw with the car not running initially. -Raise the header tank if it is easy to do so, thus giving the engine a healthy head of water etc. You could do this in the Renault Espaces and Pug 205s, as the header tank was designed to have this happen. -Finally if the above does not work you'll have to get a "funnel" onto your header tank so as to artificially raise the level of the water like below:
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Last Edit: Jul 22, 2016 8:07:18 GMT by ChasR
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i also don't like to trust cheapie sensors ...infact cheapie anything
water pump might be going ?
i always bleed mine like this....run it up with the cap off , top it up while its running and wait until the fan turns on , it may bubble but then settles , turn off and let it cool down and check the level then cap on and its fine
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91 golf g60, 89 golf 16v , 88 polo breadvan
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ChasR
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Cooling system woes.ChasR
@chasr
Club Retro Rides Member 170
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Jul 22, 2016 11:24:55 GMT
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i also don't like to trust cheapie sensors ...infact cheapie anything water pump might be going ? i always bleed mine like this....run it up with the cap off , top it up while its running and wait until the fan turns on , it may bubble but then settles , turn off and let it cool down and check the level then cap on and its fine If the pipes or component (heater matrix being the main one) are higher than the header tank, which it sounds like in this example, that will not work. On a self bleeding system on a car then it is not a problem.
I have fixed a 106 GTi because the last owner though the HG was going as a result (I bled the car an hour after I bought it at a service station!), and my BMW refused to bleed via this method (an E36 323i). When we owned our old 205 my mate simply filled it up with the cap off and ran it, wondering why the temperature would not come down. With it done as outline in my above post it always kept its cool.
You do wonder why everyone doesn't just fit a self bleeding system but packaging tends to be the main argument.EDIT - The header tank looks like the highest point in the shots I've seen of a MkIIF engine bay. In which case it "should" have bled itself via the manual's instructions or as per steveo3002 's guide if nothing else.
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Last Edit: Jul 22, 2016 13:10:58 GMT by ChasR
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qwerty
Club Retro Rides Member
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Club RR Member Number: 52
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Cooling system woes.qwerty
@qwerty
Club Retro Rides Member 52
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Jul 22, 2016 11:56:57 GMT
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Thank you for the advice. Based on it my belt and braces approach is going to be.
Drain coolant. Flush radiator thoroughly with hose. Replace radiator switch with genuine or genuine quality replacement. Replace temp sensor incase its giving guage false readings Fill coolant system whilst car is on ramps and raise the expansion bottle slightly while doing this. (should be enough slack in the pipes) Run it at fast idle for 10-15 minutes with bleed screw open, expansion cap off and heater set to hot.
Sound like a decent plan?
Tom
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ChasR
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Cooling system woes.ChasR
@chasr
Club Retro Rides Member 170
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Jul 22, 2016 12:45:33 GMT
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Thank you for the advice. Based on it my belt and braces approach is going to be. Drain coolant. Flush radiator thoroughly with hose. Replace radiator switch with genuine or genuine quality replacement. Replace temp sensor incase its giving guage false readings Fill coolant system whilst car is on ramps and raise the expansion bottle slightly while doing this. (should be enough slack in the pipes) Run it at fast idle for 10-15 minutes with bleed screw open, expansion cap off and heater set to hot. Sound like a decent plan? Tom Before anything I'd just raise the expansion bottle, and open the bleed screw with the car not running. Wait for the air to come out and then replace it as the coolant is still coming out. If nothing else it should remove one potential issue out of the line of issues. Then I'd consider changing the sensor. Do you still have the old switches? As said, I'd simply bleed the system first as above before spending your money and/or replacing things . P.S do you have a shot of the bleed screw in the engine bay. I cannot seem to find it from the photos/info I've seen regarding the Polo MkIIF. A sill Q, but is the bleed off hose going to the header tank clean, and did you have the heater on Hot when it was topped up?
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Last Edit: Jul 22, 2016 13:08:50 GMT by ChasR
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qwerty
Club Retro Rides Member
Posts: 2,410
Club RR Member Number: 52
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Cooling system woes.qwerty
@qwerty
Club Retro Rides Member 52
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Jul 22, 2016 13:42:21 GMT
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I'll try and get a picture tonight ChasR thanks for all the advice so far. The bleed screw is on the heater matrix which is in the plenum under the windscreen. Tom
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qwerty
Club Retro Rides Member
Posts: 2,410
Club RR Member Number: 52
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Cooling system woes.qwerty
@qwerty
Club Retro Rides Member 52
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Jul 22, 2016 17:06:03 GMT
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Photo of expansion tank and the bleed screw is in white in the background. Tried to get the best picture I could to show it in context. Tom
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Jul 22, 2016 19:13:43 GMT
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ive had one of those polos over 10 years ,they're not hard to bleed at all
my bet is the plastic impeler blades have come off....got a spare engine here and the water pump had near all its blades gone
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91 golf g60, 89 golf 16v , 88 polo breadvan
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qwerty
Club Retro Rides Member
Posts: 2,410
Club RR Member Number: 52
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Cooling system woes.qwerty
@qwerty
Club Retro Rides Member 52
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Jul 22, 2016 20:44:05 GMT
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ive had one of those polos over 10 years ,they're not hard to bleed at all my bet is the plastic impeler blades have come off....got a spare engine here and the water pump had near all its blades gone You may well be right. Guess I'll have to download the haynes manual again and see how big a job it is.
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Fungus
Part of things
Posts: 960
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Jul 22, 2016 23:32:36 GMT
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I've changed the coolant atleast once in all 12 of my Polo's and never had to do anything more than run the car with the heater on full, with the heater matrix bleed screw undone until no air comes out.
I would suspect a worn water pump (I once removed one with no impellers left at all).
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stealthstylz
Club Retro Rides Member
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Cooling system woes.stealthstylz
@stealthstylz
Club Retro Rides Member 174
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My old one did similar and that was the waterpump. Did that and the head gasket in less than 2 hours.
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might as well fit a cambelt if youre pulling the pump...isnt too bad to do if the allen bolts don't round off
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91 golf g60, 89 golf 16v , 88 polo breadvan
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ChasR
RR Helper
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Cooling system woes.ChasR
@chasr
Club Retro Rides Member 170
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Have you made much progress with this since last time? Was it your water pump in the end?
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qwerty
Club Retro Rides Member
Posts: 2,410
Club RR Member Number: 52
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Cooling system woes.qwerty
@qwerty
Club Retro Rides Member 52
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I'm just on replacing the radiator and re bleeding it due to an unfortunate incident.
If this doesn't work I'm going to change the water pump.
*Edit* replaced the radiator. Got up to temp, thermostat opened, fan didn't kick in.
Either a dodgy switch and/or a water pump.
Tom
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Last Edit: Aug 4, 2016 6:05:14 GMT by qwerty
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