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Topic: 24v BOB Thermostat (Read 2540 times) |
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mattias77
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scorpio -98, when it was best they put it to rest!
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24v BOB Thermostat
« on: Jun 3rd, 2010, 1:32pm » |
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The BOB cooling system is not one of the best designs in automotive cooling history. All problems with Ballooned radiators is just one of the symptoms. I’ve figured some years ago when I changed my first radiator that the thermostat was the blame for all this and as I understand it is a general opinion. But there is no “bug fix” for it available or described? One problem as I’ve figure my self is that it is hard to find a simple re routing tubing that will but the thermostat and is by-pass in an more conventional position before the radiator to minimize the constant pressuring from the pump/engine and the steam blasts that mr. Sherlock Holms is concluding are ballooning the narrow vanes. In the absent of that what is the next best thing to do? As I figure like in all automotive applications when you are trying to increase the volumetric efficiency you want an lower operating temperature to lower the volume of the incoming air i.e. make it more dense in the cylinders. In the name of economy the operating temp of the BOB is tremendously hot as many of you have noticed the mechanical problems that follows with that and destroyed looming and etc. So just by change the thermostat from the original hot from about 88C incoming regulating temp to the pump to say 82C(180F) would ease some of the issue of hot outgoing water from the top off the engine. As I remembered normal idling temp on a regular summer day is well past 95C at the position of the top of the engine where the both dash and pcm monitoring temp senders are mounted. So were do you find a thermostat with a 82C opening to a BOB? Good Luck! You will not. As I scanned all possible candidates there is none that I found that exactly matches the Ford BOB thermostat housing with hose mountings. You have to have in mind the AC pump bracket and that more pluming is not what you what in an already crowded engine bay. But just some day ago I stumbled over an candidate that might work and as I investigated it more deapely it seemed to be the direct match that I have searched for all this years. An BMW M10 thermostat with an 80C grading. It was an direct fit with just one simple modification of the by pass hose connection angling. I’ll be adding some pictures soon but it looks all very clean and very straight as it just come of the assembly line from the factory.
So has any one tried this mod? Shouldn’t it be the answer and solution to Mr. Holmes conclusions instead of just replacing the original thermostat with a new one? As for my installation I can only state “So far, so good” and yet I can’t figure any down sides to it except of maybe some minor mileage gph effect. Just scanned the temp yesterday and now the outgoing temp(sensor temp) from the engine seems to be approx. 88 at idle.
So is this the final solution to the BOB cooling problems? Comments!
http://www.motornord.se/system/webshop_showimage.asp?ShopID=54&Produ ktID=71692&HemsideID=256
Best Regards,
Mattias
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Highlander
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Re: 24v BOB Thermostat
« Reply #1 on: Jun 3rd, 2010, 7:14pm » |
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Hello and welcome to the site.
I personally think the thermostat and coolant system are ok, not ideally designed but it works.
I reckon the problem with the ballooning radiators is the radiator manufacture itself.
The 24v radiator is a one off design, only for the 24v.
I have fitted 12v and 16v radiators to 24v's which have suffered ballooned rads (sometimes more than one) and in all cases that has cured the problem, if the thermostat were the problem the other rads would also balloon
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on Oct 17th, 2011, 12:35pm, Simmo wrote:I give up !  Too much for an old boy!  |
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Highlander
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Re: 24v BOB Thermostat
« Reply #3 on: Jun 3rd, 2010, 11:21pm » |
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Its VERY similar 
I was looking at a Mondeo 24v thermostat which is also similar but has a replaceable thermostat.
The only reason I was looking at it was for price, its a fraction of the £110 plus that Ford want for a new 24v one.
What price is the BMW one?
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on Oct 17th, 2011, 12:35pm, Simmo wrote:| I give up ! Too much for an old boy! |
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mattias77
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scorpio -98, when it was best they put it to rest!
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Re: 24v BOB Thermostat
« Reply #4 on: Jun 4th, 2010, 12:48am » |
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I paid 285SEK, about 24GPB. And they are also avaliable in a 71C, 75C and 90C temp so fare as I'ev seen when googleing. So you have the option to have an very alike original temp if you prefere the higher temp for economy...
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Scorpio
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Re: 24v BOB Thermostat
« Reply #5 on: Jun 4th, 2010, 11:39am » |
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Mattias, well done. Thanks for the research and info.
I am going to try this theory. Just purchased an 80C, brand new one for £14
Will fit to one of mine and feedback on any isssues.
For info here are some of the BMW models with the M10:
3 SERIES 316, 316i, 318, 318i, 320i (E21) 75-82
3 SERIES 316i, 1.6, 318i (E30) 82-88
5 SERIES 518 (E12) 74-81
5 SERIES 518i ( E28 ) 81-88
FTH126
Adam
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mattias77
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scorpio -98, when it was best they put it to rest!
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Re: 24v BOB Thermostat
« Reply #6 on: Jun 8th, 2010, 4:22pm » |
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OK! Let me know what you get out of it. Mine is still working with no problems and an strange thing is about the reading on the dash gauge. It's still reading like before just in the middle. Had expexted some reading on the lower side but as it has stabilased it's steady like with the original thermostat!??? I'll guess the dash isen't either an precision gauge like the pcm temp.
One thing I made just as an precausion was the little hole instead of the smal "check valv" that the original bob thermostat is fitted with but not the BMW thermostat.
Good Luck!
Best Reards,
Mattias
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-95 24v Estate for fun…
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Highlander
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Re: 24v BOB Thermostat
« Reply #7 on: Jun 8th, 2010, 5:00pm » |
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on Jun 8th, 2010, 4:22pm, mattias77 wrote:| OK! Let me know what you get out of it. Mine is still working with no problems and an strange thing is about the reading on the dash gauge. It's still reading like before just in the middle. Had expexted some reading on the lower side but as it has stabilased it's steady like with the original thermostat!??? I'll guess the dash isen't either an precision gauge like the pcm temp. |
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Does your theory work in practice?
Fitting a lower temperature stat would only achieve letting the coolant through at a reduced temperature on the initial engine warm up.
Once the engine has warmed up (thermostat open constantly) the cooling fans/airflow would then be in control of the engine temperature.
hence why you are seeing the temperature gauge sitting in its normal place?
I have run a 24v with the stat jammed open just to see what effect it would have, which is similar to what you are doing here, my engine temperature rose very slowly initially as you would imagine but once up to temperature the fans were cutting in to control it, it didnt run cooler than normal.
I would expect driving it very carefully at low rpm in a cool outside temperature may have the effect of reducing the engine temperature but I certainly never saw any sign of that with mine.
I have seen 16v's with stuck or missing thermostats running cool but I think the 24v may just be producing too much heat?
Maybe a better solution would be to "fix" the cooling fans to come on quicker to reach your target temperature?
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on Oct 17th, 2011, 12:35pm, Simmo wrote:| I give up ! Too much for an old boy! |
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mattias77
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scorpio -98, when it was best they put it to rest!
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Re: 24v BOB Thermostat
« Reply #8 on: Jun 9th, 2010, 12:11pm » |
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Well none of my experiences is with any guarantees:) I can just state so far so good in my application.
As for the temp regulating the thermostat and its by-pass mixing feature has an direct function to mix the cold water from the cooler matrix with the heated water from the by-pass hose. This is in general the way the engine is regulating the temperature and are keeping it constant, as I reckon. When the water from the cooler matrix isn’t cool enough and the thermostat is fully open and totally blocking the by-pass hose pushing all heated water to the cooler(no mixing) the temps starts to rise and eventually at the 200F or so? the cooling fans “high speed” cuts in and “regulating” the temp. down hopefully. OR?
Yes, if you got an jammed thermostat that’s slightly open you got the long time cooling temp rising and potential overheating when the thermostat isn’t open as much as it should when needed.
As for the 24v cooler I think it’s well dimensioned. It’s quite big with it’s additional 60mm in height or so compeering to the other engine options. And with AC you often have the fans running at low speed to get air flow true the condenser so you’d also get some thru the cooler even at low engine temps. At least the cooler is fare enough up her in the north. At Winter I prefer to have some of it blocked with stiff paper to have more water flow thru the cooler in constant below freezing weather conditions.
/Mattias
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a900one
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Re: 24v BOB Thermostat
« Reply #9 on: Jun 9th, 2010, 5:22pm » |
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All very interesting, but I think its to do with the pressure cap. After just having a balloned rad I checked the cap blow off pressure with a tyre pump that you could set the pressure it cuts off at. Starting at the blow off pressure, it cut out before the cap opened, and the pressure had to go up by .5/.75 of a bar to get it to open. After that it opened every time at the right pressure, I think they stick to the seat. I now open it every few months, fingers crossed.
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Highlander
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Re: 24v BOB Thermostat
« Reply #10 on: Jun 9th, 2010, 5:48pm » |
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I think I can discount the cap too 
on the ones i've swapped to 16v radiators i've retained the 24v cap and never had any further problem.
convinced its the radiators!
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on Oct 17th, 2011, 12:35pm, Simmo wrote:| I give up ! Too much for an old boy! |
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tlundkvi
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Ex. Scorpio 2.9 24V -95
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Re: 24v BOB Thermostat
« Reply #11 on: Jun 9th, 2010, 8:33pm » |
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on Jun 9th, 2010, 5:22pm, a900one wrote:| All very interesting, but I think its to do with the pressure cap. After just having a balloned rad I checked the cap blow off pressure with a tyre pump that you could set the pressure it cuts off at. Starting at the blow off pressure, it cut out before the cap opened, and the pressure had to go up by .5/.75 of a bar to get it to open. After that it opened every time at the right pressure, I think they stick to the seat. I now open it every few months, fingers crossed. |
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I've read somewhere the pressure cap should be renewed every 4 years. I don't know, but I'd suppose it won't make things better if it's not working.
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mattias77
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scorpio -98, when it was best they put it to rest!
Posts: 10
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Re: 24v BOB Thermostat
« Reply #12 on: Jun 9th, 2010, 10:01pm » |
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What is the acutal value of the relase pressure of the cap? I cant read it from the cap as it's usually stated on other more normal cars that I have come across... 120KPa? 1.2bar? Above values mentioned seem to low? Or? I have to try it out with my hand pump with pressure gauge....
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te_ess
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Re: 24v BOB Thermostat
« Reply #13 on: Dec 20th, 2010, 9:29pm » |
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Hi all,
just read your mod about the Thermostat.
are you still happy with the mod? i'm quite interested also, because i have to redo my 24v rad soon.
@highlander: what is necessary to mod the 24V to use a 16V or 12V radiator?
are any side-effects known? what do i have to look at, besides that they need to have the Auto-fluid-cooler fitted ? anything else needed to be modded?
greetings
Torsten
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mattias77
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scorpio -98, when it was best they put it to rest!
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Re: 24v BOB Thermostat
« Reply #14 on: Dec 20th, 2010, 11:12pm » |
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on Dec 20th, 2010, 9:29pm, te_ess wrote:Hi all,
just read your mod about the Thermostat.
are you still happy with the mod? i'm quite interested also, because i have to redo my 24v rad soon.
@highlander: what is necessary to mod the 24V to use a 16V or 12V radiator?
are any side-effects known? what do i have to look at, besides that they need to have the Auto-fluid-cooler fitted ? anything else needed to be modded?
Yes! Now its full winter outside with about -10 to -20deg. No problems so far but temp is very slow rising to normal temp in this weather. Im planing to place a pice of paper board infront of the radiator and see if it helps. I'll guess it would have been better to chosen an slightly higher temp when driveing in coled server
/mattias
greetings
Torsten
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te_ess
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Re: 24v BOB Thermostat
« Reply #15 on: Dec 21st, 2010, 8:19am » |
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Hi Mattias,
thanks for the answer.. maybe I should hunt for something closer to the original 88 C then.. hmm, i drive the Scorpio only from April to October, so it might not be a big deal
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Highlander
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Re: 24v BOB Thermostat
« Reply #16 on: Dec 21st, 2010, 10:26am » |
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on Dec 20th, 2010, 9:29pm, te_ess wrote:@highlander: what is necessary to mod the 24V to use a 16V or 12V radiator?
are any side-effects known? what do i have to look at, besides that they need to have the Auto-fluid-cooler fitted ? anything else needed to be modded? |
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just the coolant header tank
http://www.fordscorpio.co.uk/cgi-bin/yabb/YaBB.pl?board=admin;action=dis play;num=1286379380
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on Oct 17th, 2011, 12:35pm, Simmo wrote:| I give up ! Too much for an old boy! |
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Dave2302
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2006 Mercedes S55 AMG, Retired Barefoot Waterskier
Posts: 1119
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Re: 24v BOB Thermostat
« Reply #17 on: Jan 3rd, 2011, 5:34pm » |
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Hey Fellas,
Check these out.............
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=350356900499&am p;ssPageName=STRK:MEWAX:IT
Cheaper than a "new" 24V balloon LOL
Gonna fit one on my 24V Rally Puma
There is also a mod to the water pump to prevent rad ballooning, although like Stuart says, once I fitted an auto 16V rad to my Cossie Estate it never had a problem
Cheers Dave
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Dave "The 'ol Bear" ex Footer !
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gozz
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Re: 24v BOB Thermostat
« Reply #18 on: Jan 3rd, 2011, 8:39pm » |
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Dave.
Would it not be tricky for the average Scorpite to fit a Mk3 rad with no auto cooler as well ?
GOZZ.
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Dave2302
Senior Member
2006 Mercedes S55 AMG, Retired Barefoot Waterskier
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Re: 24v BOB Thermostat
« Reply #19 on: Jan 4th, 2011, 11:26am » |
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Gozz,
I thought those ally ones had a cooler listed as auto ??
Will have a look again, not necessary for me cos Puma's Manual !!
Oh yeah it appears there is no cooler in the pic but......
Even so, it's not hard, a bit of pipe re routing and use a large tranny oil cooler kit, around £45.
These are better than the stock radiators oil cooler and the extra one put together, they come with all brackets fittings etc etc, take about 1/2 hr to fit
I put one on my Scorpio Estate because I used to tow with it and the stock set up IS NOT up to the job
Cheers Dave
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Dave "The 'ol Bear" ex Footer !
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