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Topic: HBC heatsink (Read 1078 times) |
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TonyS
Junior Member
Scorpio Nutter - 12 years
Posts: 96
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HBC heatsink
« on: May 1st, 2004, 3:28pm » |
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Summer is hear (well nearly) and another problem was revealed with my 24v - the HBC was going into thermal runaway as documented.
Pulling it out I noted that the primary heatsink had been modified with the addition of a aluminium fin pop riveted on. Smacks of my favourite bodger who had the car before me as :-
- Attaching a secondary heat sink this way would not work, no thermal path is established!
- The fin actually blocked the air flow over the primary sink!
I'm not sure if the fin is original, a Ford engineering afterthrough or an out right bodge but anyway I wanted a cheap fix so did the following :-
- polished and coated the mating surfaces with thermal paste
- tightly screwed the secondary fin to the primary making sure the two mated flat
- modified the fin by drilling holes to allow air to pass over the primary
So far this has been enough to solve the problem. Does anybody know if the pop riveted fin is of Ford origin?
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1996 Mk4 2.9 24v Estate
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john.n
Full Member
I love my cossie
Posts: 721
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Re: HBC heatsink
« Reply #2 on: May 1st, 2004, 6:48pm » |
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Excuse my ignorance and please explain? How else do we learn! john.n 
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TonyS
Junior Member
Scorpio Nutter - 12 years
Posts: 96
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Re: HBC heatsink
« Reply #3 on: May 1st, 2004, 7:50pm » |
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Ah .. I've the modified one then and the bodge is a bit of Ford engineering in pop riveting the extra heat sink (the fin) onto the cast ali one.
As shown in the pick the extra piece actually blocks the air flow over the existing sink and without facing the interface between the two pieces of metal the thermal conduction will be less than optimal, compensated no doubt by the large surface area. Looking at mine I'd guess most of the heat was being conducted via the pop rivets.
I'd guess this wonderful piece of engineering is a power transistor used to control the blower fan and hence at low fan speeds is generating ~10Watts.
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1996 Mk4 2.9 24v Estate
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admin
Administrator
The Big Boss
Posts: 1410
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Re: HBC heatsink
« Reply #4 on: May 1st, 2004, 8:09pm » |
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Hi Tony,
theres some more info on the HBC via the ac index page at http://www.fordscorpio.co.uk/acindex.htm
the HBC is the achiliies heel of the cc system and provided the most trouble hence the revised fmc "design".
Pete c
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