MautoK
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| posted on 2/6/09 at 02:32 PM |
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Only slight improvement (overheating)
Following my overheating grief:
The car is back together and I've just taken it around town - about three miles. After about 2 miles the gauge was on the 'O' of
'NORM', i.e. about 2/3. Back at home it was on 'N', so almost into the red and it was making the same boily/gurgly noises as
previously. The fan didn't switch on (thermoswitch in the rad)
The only difference from previous runs is that I propped the trailing edge of the bonnet open about 1/2 inch and that today the ambient is about 10
degC higher. Possibly need to hold it further open...? I want to get an idea of what area of vent I need before cutting holes and ordering grilles or
louvres.
Back home, I took the bonnet off and a fair amount of air/gas came up the small pipe from rad bleed to the header tank 'overflow'. I
haven't yet connected the small port from the 'stat housing to this pipe as I don't have a suitable T-piece yet.
When it settled after a few minutes it took about two litres to brim the cooling system.
I'm now letting it cool down completely and will try again later because so far it's probably just been expelling airlocks.
Time for a cup of tea...
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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Mr Whippy
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| posted on 2/6/09 at 02:39 PM |
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personally I'd take the rocker cover off and give the head a re- torque when its hot. I did this on the Falcons pinto as I suspected it
wasn't tight enough as oil was appearing on the edge of the head gasket at one corner. Simply used the same torque figures as before but since
it was hot the bolts turned quite a bit, they fair slacken off. Never had any problems after that.
To expel air locks, once at running temp, get some oven gloves and squeeze the hoses. That'll pump out the bubbles, though tbh I'm not
convinced that’s the problem as if you’re hearing bubbles moving then they're not trapped and should get vented out the cap. Also if the heater
matrix is hot then they’re can’t be much of an airlock.
[Edited on 2/6/09 by Mr Whippy]
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MautoK
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| posted on 2/6/09 at 03:23 PM |
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Thanks, Mr Whippy,
I've tweaked the head bolts with the engine 'half-hot' and they took about 15 degrees at around 100 ft-lbs. They were all much the
same in feel.
John.
There's no heater - the manifold is looped to the w/pump.
[Edited on 2/6/09 by MautoK]
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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Dangle_kt
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| posted on 2/6/09 at 03:33 PM |
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My logic might be flawed here, but if the gauge is accurate and then the fan should have been cutting in, so either the fan switch is buggered, the
fan isn;t getting power or the thermostat isn't routing water to the rad, thereby bypassing any cooling AND not activating the switch.
Unless I'm missing something?
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MautoK
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| posted on 2/6/09 at 03:54 PM |
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Gauge and sender both from the donor, but the engine wasn't the original for the car. The reading looks reasonable.
The fan did self start when I let the car idle for 10 minutes or so just after fitting the Polo rad. Need to check again.
The fan does work on the manual switch in parallel with the thermoswitch.
Radiator does get hot; thermostat is new (87C); the only way water can go after the 'stat is to the radiator coz the little stub is blocked
off.
quote:
Originally posted by Dangle_kt
My logic might be flawed here, but if the gauge is accurate and then the fan should have been cutting in, so either the fan switch is buggered, the
fan isn;t getting power or the thermostat isn't routing water to the rad, thereby bypassing any cooling AND not activating the switch.
Unless I'm missing something?
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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mark chandler
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| posted on 2/6/09 at 04:47 PM |
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Missing off small pipes at the top of the engine is a fatal mistake!
These invariably are placed so that steam can bubble off to the catch tank or radiator header as only a very small volume of water, the little pipes
worth is displaced before the steam can vent.
Without the main hose has to vent so let’s say 1/2 litre of water may have to move first. You may have stumbled upon the issue.
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omega0684
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| posted on 2/6/09 at 05:27 PM |
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quote:
the only way water can go after the 'stat is to the radiator coz the little stub is blocked off.
thats the rad expansion pipe, it needs to be route to the header tank!
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MautoK
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| posted on 2/6/09 at 05:40 PM |
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Mark,
I intend to connect it, but haven't got a T-piece at the moment. It's always been capped - as removed from the donor.
I drilled a 3mm hole in the 'stat so any air should find its way to the top hose and thence to the bleed which goes to the header tank.
I just fired it up again, stationary with bonnet off, header tank brimmed:
6:02 Start
6:06 'Stat housing hot
6:08 Gauge at mid point
6:09 Top of rad hot
6:11 Bottom of rad hot
Gauge at top of 'norm' band
6:12 Fan switched on via thermoswitch
6:15 Fan still on, gauge still at top of 'norm' band
Switched engine off, then left ign on - fan continues
6:17 Header tank dropped about 1 inch
6:18 Thermoswitch turns fan off
Water level then gradually dropped to 'max'.
While running, once hot, there as a steady stream of bubbles along the pipe from the rad bleed to the header tank and some water was expelled due to
expansion.
After switching off the hoses were:
Top: Hot
Bottom: Warm
Manifold -> pump: Hot
Rad bleed -> Header tank: Hot
Header tank -> Bottom hose: Cool
The header tank level gradually dropped to the 'max' level.
BTW, the exhaust tailpipe is sooty, so shouldn't be overheating due to weak mixture.
While driving there is a hint of pinking (while the engine was warming up) suggestive of the ignition being a little over-advanced.
John.
quote:
Originally posted by mark chandler
Missing off small pipes at the top of the engine is a fatal mistake!
These invariably are placed so that steam can bubble off to the catch tank or radiator header as only a very small volume of water, the little pipes
worth is displaced before the steam can vent.
Without the main hose has to vent so let’s say 1/2 litre of water may have to move first. You may have stumbled upon the issue.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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martinq357
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| posted on 2/6/09 at 05:59 PM |
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I've a similar set up on my Cat (inc. Polo Rad).
The Rad Bleed is feeding the header tank and the Header tank filler goes to the T in the bottom hose.
The only difference is I have the loop from the heater to water pump blocked off. Capped at the WP end and a central heating brass bleed valve at the
manifold end - this I found useful for extra 'bleeding'.
I did fit a lower temp thermal switch to the Rad. I figured as it was half way down (the Tiger Rad had the switch at the top) it ought to be a lower
temp. Mine came from GSF and was 88degs on - 79degs off, low I know, but it works well.
HTH
Martin.
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MautoK
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| posted on 2/6/09 at 06:15 PM |
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Martin,
The thermoswitch does operate a little higher than I'd like, but it'll do for now.
A while back, I did try pinching the manifold-to-pump hose using a G-cramp and a couple of pieces of wood but it didn't seem to make any
difference. In a 'normal' setup with a heater, you want all the heat you can get going to the heater itself - if I had one it would be
excellent! The reason for blocking it was in case the impedance of that loop was too low and inhibiting flow around the main (radiator) circuit, but
that didn't seem to be so. Maybe try that again.
I'm not entirely sure whether the engine is producing excess heat (causing the cooling system to struggle) or whether the cooling system is not
capable of dispersing 'normal' heat output and thus causing the engine to overheat. 
Thanks, Martin.
John.
quote:
Originally posted by martinq357
I've a similar set up on my Cat (inc. Polo Rad).
The Rad Bleed is feeding the header tank and the Header tank filler goes to the T in the bottom hose. Same
The only difference is I have the loop from the heater to water pump blocked off. Capped at the WP end and a central heating brass bleed valve at the
manifold end - this I found useful for extra 'bleeding'.
I did fit a lower temp thermal switch to the Rad. I figured as it was half way down (the Tiger Rad had the switch at the top) it ought to be a lower
temp. Mine came from GSF and was 88degs on - 79degs off, low I know, but it works well.
HTH
Martin.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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MautoK
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| posted on 2/6/09 at 06:24 PM |
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Hi Alex,
It's only the small stub on the 'stat housing not connected. I have a couple of inches of hose plugged with a drill bit currently - If I
disturb the drillbit I get water, not air.
The bleed port at the top of the rad goes to the 'overflow' on the header tank.
I'd been hoping to work out what size of bonnet vents I need then order vents + 8mm T-piece in one hit.
Cheers,
John.
quote:
Originally posted by omega0684
quote:
the only way water can go after the 'stat is to the radiator coz the little stub is blocked off.
thats the rad expansion pipe, it needs to be route to the header tank!
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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Andy D
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| posted on 2/6/09 at 06:33 PM |
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Something that worked on my car, if you haven't allready done it, is to blank off the gaps around the radiator. This forces the air to go
through the rad, rather than around it.. 
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MautoK
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| posted on 2/6/09 at 07:50 PM |
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Hi Andy,
Yes, a few people have suggested that and I'll be making up some baffles in the next day or so.
However, it still seems to get too hot just sitting there, bonnet off & nosecone open.
John.
quote:
Originally posted by Andy D
Something that worked on my car, if you haven't allready done it, is to blank off the gaps around the radiator. This forces the air to go
through the rad, rather than around it..
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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omega0684
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| posted on 2/6/09 at 07:53 PM |
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john
What are the actual temps the car is running at?
Alex
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MautoK
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| posted on 2/6/09 at 08:05 PM |
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Alex,
I just fitted a new 87 degC 'stat but I don't know what temp it's actually getting to as the gauge is just the regular Sierra unit
with a big 'NORM' band and a red blob at the hot end.
After the initial warm-up, it gets to mid-scale, stays there a few minutes then goes right up to the hot end of 'NORM'. It's better
than it was a week or so back, when it went into the red...
I don't know the characteristics of the thermoswitch but, as above, it does switch on and off even if a few degrees higher than one might
wish.
John.
quote:
Originally posted by omega0684
john
What are the actual temps the car is running at?
Alex
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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blakep82
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| posted on 2/6/09 at 08:15 PM |
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new pressure cap....
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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mr henderson
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| posted on 2/6/09 at 08:37 PM |
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Back to basics time
Symptom- Heat created in engine not sucessfully disposed of by radiator
Possible causes-
Too much heat being produced (engine fault)
Heat not being transferred to radiator (circulation fault)
Heat not able to escape from radiator (airflow fault) or (temperature too low for effective heat transfer due to incorrect pressurisation,
(Blake's suggestion))
Try looking at the problem in these terms, it might help
John
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MautoK
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| posted on 2/6/09 at 10:52 PM |
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Mr H,
Nothing beats reducing a problem to its basic elements.
I've been tring to think along these lines.
I think water circulation is OK - can feel the warm front progress around the cooling system from a cool start & the rad gets good and hot
('stat is new 87 degC).
The (new Polo) radiator itself should be more than adequate for a standard 100 bhp Pinto as it is reputedly capable of cooling a 200bhp+ engine.
Air flow is an issue. I need to build some baffles around the rad to persuade more air though it rather than the gaps and cut bonnet vents to get hot
air out. (But idling, stationary, with the bonnet off and nosecone tilted it still overheats)
Lastly, the heat source. This has to be the primary culprit. Although I haven't touched the crank/rods/pistons, I have cleaned it up, fitted a
new cam belt and new valve stem seals; shortened the sump and pick-up. Head gasket replaced in the past week; adjusted valve clearances. Carb and
distributor untouched; hopefully fitted the standard box of electronics correctly.
When driving the car it feels fine, there's no sluggishness that you tend to get with over-retard or weak mixture...
Cheers,
John.
quote:
Originally posted by mr henderson
Back to basics time
Symptom- Heat created in engine not sucessfully disposed of by radiator
Possible causes-
Too much heat being produced (engine fault)
Heat not being transferred to radiator (circulation fault)
Heat not able to escape from radiator (airflow fault) or (temperature too low for effective heat transfer due to incorrect pressurisation,
(Blake's suggestion))
Try looking at the problem in these terms, it might help
John
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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scoop
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| posted on 3/6/09 at 03:54 PM |
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Go and get a ruddy t piece and re-plumb john. You wont need the one that taps into your lower rad pipe.
I am so confident that it will cure your problems
Steve
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gottabedone
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| posted on 3/6/09 at 04:52 PM |
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If you're driving the car and think that it's getting too hot then either hard wire the fan that you have or get a larger one from a donor
and wire it in full time (especially if you have the space to put one in behind the radiator)
Steve
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