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8 & 10 cyl Bristol cars From Type 407 onwards

overheating problems? Ha!

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Old 01-05-20, 08:58 PM
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Default overheating problems? Ha!

All big block engined hybrids like Bristols and Jensens overheat. No wonder, put a large cast iron motor in a confined space designed for looks rather than functionality and put in a radiator designed to just about handle things when the car is new and you should not be surprised to run into problems a few years down the road. All of these cars were not engineered to last (Bentleys were). look at them as fashion items for their well to do owners who'd exchange them after an average of 2 to 3 years.
The big myth about cooling is aluminium radiators. Been there done that. Aluminium rads do not cool better than their similarly sized steel friends.
They're just much more expensive. But.. they are lighter. makes sense for a racing or sports application but less so for a cruiser like a Bristol.
Simply get a large core modern steel radiator and spend part of the money saved by not getting a custom ally one on a set of high performance fans.Our cars were built when fan technology was in the stone age of fan technology.
Lastly, play around with your ignition timing. Originally Chrysler recommended something in the region of 5degrees initial advance. My Bristol runs at 13 initial and noticeably cooler than at say 10 degrees. Somehow each engine seems to be a bit different here. Since making these amendments I can sit in traffic for ages at 90 degrees. No sweat.
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Old 03-05-20, 06:39 AM
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Quote:
Originally Posted by paul robert View Post
All big block engined hybrids like Bristols and Jensens overheat. No wonder, put a large cast iron motor in a confined space designed for looks rather than functionality and put in a radiator designed to just about handle things when the car is new and you should not be surprised to run into problems a few years down the road. All of these cars were not engineered to last
Given the percentage of all Bristols manufactured which still exist, it would be fair to say they were certainly not engineered not to last.

Have many Bristol V8 owners experienced overheating problems? I don't recall seeing many discussions about overheating in the past.
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Old 03-05-20, 07:13 AM
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Looking at the fans on my V8 Bristol I have been struck by how well designed they are. Maybe something to do with a legacy of aerodynamic knowledge in the company, but the twin electric fans are built into a little cowling which I think is a component only found on Bristol cars in that period. I have seen very poorly arranged fans on other classic cars of the period, but the way the Bristol fans are mounted in a cowling seems very well designed, and this carries the pressurised cool air efficiently to the radiator core.

I may have missed something but I not familiar with steel-cored radiators. The 'old' material was brass (or even copper !). It is true that brass is a better heat conductor than aluminium, but cooling has much more to do with surface area and the ability to turn over both the coolant and the air near the cooling surfaces, than the conductivity of the metal. The modern OEM industry uses plastic end tanks and aluminium cores. In this context aluminium is used because it is cheaper than brass. The external surfaces of the core have all sorts of clever little methods to 'turbulate', i.e. mix up, the air on the outside of the core, so as to maximise the heating of the air and cooling of the surface. There are similar structures on the inside of the surfaces to maximise the contact between surface and coolant.

If you can install a complete modern OEM radiator of a suitable size, this will give a very good result, but it is difficult to find the right size. The best alternative is a custom made aluminium radiator, where the maker is using a modern aluminum core material, possibly modifying cores taken from modern OEM radiators.
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Old 04-05-20, 12:42 AM
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There are off-the-shelf radiators from US manufacturers which will fit, with fans and shroud.
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Old 04-05-20, 05:20 PM
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Mmmmmm...

Bristols didn't overheat when they were new and shouldn't do if they are looked after. A radiator recore is relatively inexpensive and has taken the 410 up the Atlas Mountains and through a good deal of Europe and up the Stelvio without any issues on that score.

My maintenance schedule does however include a very regular cooling system flush out and refill.

I back Thors comment re the two shrouded little fans - which are indeed (or in my case were) remarkably effective. I think I'm right in saying that Bristols broke new ground for the whole Automotive industry on that score when they introduced electric fans on the 407 and, incidentally put Kenlowes on the map.

But beware, in my case I say "were" because I discovered quite a few years ago that the brushes on mine were worn down to the bone and in imminent danger of failure. I spoke to Kenlowes, who incidentally remembered that Bristols did them a great favour by going with them all those years ago, but they weren't able to help with replacements and anyway nowadays recommend the use of one large pusher fan as opposed to two small ones. So that is what the 410 now carries, but it made little if any difference as to how effectively the cooling system operated. But does, I hope, introduce an element of reliability in far flung parts.

Roger
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Old 06-05-20, 12:42 PM
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Quote:
Originally Posted by Thor View Post
Looking at the fans on my V8 Bristol I have been struck by how well designed they are. Maybe something to do with a legacy of aerodynamic knowledge in the company, but the twin electric fans are built into a little cowling which I think is a component only found on Bristol cars in that period. I have seen very poorly arranged fans on other classic cars of the period, but the way the Bristol fans are mounted in a cowling seems very well designed, and this carries the pressurised cool air efficiently to the radiator core.

Thor, I'm not convinced the design was that great. That "little cowling" has the fans sitting six inches away from the radiator, and sat in slow moving or stationary traffic there is no air pressurisation effect - one is entirely reliant on the fans alone.

Having fans force air at the radiator is different to forcing air through the radiator, as modern surface mounter fans will do. I found that once an AC condenser had been mounted in front of the 411 radiator, the original fans no longer maintained a safe engine temperature. However, there were a number of gaps for the air to go through, rather than go through the path of higher resistance - through the condenser then the radiator.

As a relevant aside, I changed the radiator on a Mercedes ML430 at the weekend - pig of a job, not least because it also provides cooling for the transmission and the power steering - it was interesting to see what lengths Mercedes went to, to stop air going around the radiator.
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Old 06-05-20, 02:54 PM
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Modern flush-mounted puller fans will be hugely more efficient - the draught behind the radiator from a pair of new original-style fans is pretty feeble.
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Old 06-05-20, 11:12 PM
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Philip I couldnt agree more. My 411 started with factory fans and in the australian summer the car got so hot you couldnt use it. These fans were replaced with 2 larger fans at the front of the radiator to little or no improvement. These were in turn moved to the back of the radiator which improved things some what.Finally I installed a set of AU Falcon fans fully enclosing the entire back area of the radiator and sealed so that the fans could only draw air through the radiator. The results were spectacular the car now runs so cold I have had to fit a higher temp thermostat. Yes the original Bristol set up may have been fine in the UK but not in hot climates.

NB the rush of air through the radiator into the engine bay is remarkable
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Old 13-05-20, 03:02 AM
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Peter, have you got your fans on a thermo switch?
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Old 13-05-20, 02:28 PM
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I think the set up designed by Bristol was a lot better than many other systems on cars on the market at the time. Most production cars still had engine driven fans in the 1960s and 70s. I think in those days there was still an expectation that a car would not be stationary, with the engine running, for a long time. The Bristol fans were probably just not big enough for Australian summer weather. Forming a plenum for the fans to pressurise (or de-pressurise) is the key to really good performance, as other posts have pointed out.
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Old 14-05-20, 08:47 AM
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kevin

I use the original switch mounted in the top of the radiator. Its common to early series E Type Jags and works well
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