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MG MGB GT V8 Factory Originals Technical - Cooling Problems

I have read articles and heard of cooling/overheating problems encountered with V8 conversions.
I have recently converted a '79 "B". I have utilised the standard twin electric fans, an aluminium race radiator (which is larger than the standard radiator), RV8 extractors though the inner fenders/guards, an oil cooler and have used a reputable coolant in the radiator. The vehicle runs just over normal mostly but rises rapidly in traffic or if I drive hard (On the track). Are there any particular types/brands of coolant or other remedies/solutions that I could also look at, or have I covered all bases??

Kim Porter.
Kim Porter

If you haven't already, read the V8 archive thread called:
I finally did something right cooling-wise
Making sure you force all the air through the rad by fashioning some duct work, as well as having a fan shroud (as the thread states) should help on the track, as far as idling, search for "water wetter" as there is a thread which lists percentages of water, coolant and water wetter which might help, also, someone said they use a motorcycle (suzuki?) fan on their oil cooler. And of course, make sure your engine is well tuned.

jimt
jimt

Kim
The RV8 exhaust system alone is sufficient to keep the heat under control however the temperature will rise until the fans cut in - so you might want to follow the advice in the original V8 notes by fitting a handraulic switch to the fans.
RW

Yes - it works in ambient 40 degrees still
Roger

Roger
What switch is it that you are refering to? Could you give me the URL of the V8 notes your are referring to, please
Marc

Marc - the precise origin of the notes escapes me but there were three or four little booklets put out when the Factory V8 was new and had been properly evaluated on the road. Mine are in Hampshire - will come back to you next week - this particular mod is a must - illuminated switch on the dash to control the fans -light tells you fans are running - goes out when the heat switch takes over.
RW
Roger

If the temperature rises rapidly from normal when stuck in traffic, and the fans have cut in and are running, then fitting a manual override switch to the fans is superfluous. With electric fans a rise from 'normal' is, well, normal since the fan cut-in point is usually a few degrees above the stat setting to stop the two fighting each other. On a factory car the cut-in point is about mid-way between N and the red. Factory cars were always marginal, I have had mine idling on the border of the red in very (for the UK) high ambients with no ill effects than a little rough running. Since then I have bought an SU fan stat which cuts-in a degree or two lower. But the major difference came about as a result of plotting the voltage-drops through the circuit - I was losing about 3v or so at the fans. Cleaning up all the connections, replacing the fan relay (which was getting very hot) and running additional grounds to the mounting bracket of each fan got rid of most of this, and has made a noticeable difference to the speed of the fans and the rate of cooling once they cut in.

Personally I have my override switch and light wired so the light comes on whenever the fans are powered - regardless of whether this is from the fan stat or the override switch. Not sure what Roger's "light tells you fans are running - goes out when the heat switch takes over" means.
Paul Hunt

Kim,

Exhaust coating (not wrap) is readily available in US. In UK ceramic coating is available at a price, Louvres in Bonnet and Water Wetter all no extra weight. Then change the twin fans and if you can fit them small puller fans + shrouds but add weight.

Paul
Paul

One thing you might want to do is use electric puller fans. There is some serious surgery to be done if you want to install a big ol' 12" or 14" puller fan approximately concentric with the water pump, at least if your motor and rad are in the stock locations and you have the stock-type water pump.

But it's easy if you use smaller fans on the sides. All I did was buy four 8" electric fans from JEGS: two are pullers and two are pushers. The pullers are mounted on an aluminum cowling that I had made up at a sheet metal place. It holds the fans just above the sway bar. You have to measure pretty carefully, but there is indeed room for them below and on either side of the water pump pulley. The pushers are mounted to the core about where the stock yellow fans blew (I never found that the stock fans were able to actually push air through the core, and they drew a huge amount of current). The pushers are connected to a 200 on/ 175 off Painless Wiring switch screwed into a bung I had soldered into the top tank of the rad, and the circuit has a manual override switch. I also had an aluminum tray fab'd that seals the bottom of the rad to the back of the (stock) front valance. I have not bothered to seal the top of the radiator to the hood, on the theory that the engine bay could probably use a little cool air. Anyway all this seems to work well. The body (CB) is stock, and the car has a 4.2L with block-hugger headers (ceramic'd). The rad hangs down 2" deeper than stock, and I had a 4-tube core installed in it. No hood vents or oil cooler. The four fans draw 28 amps collectively (!) so just to be safe I had the alternator upgraded to 75 amps. Although I don't often run with all four spinning. The car runs at N until it gets into traffic, at which point it runs a little north of there unless the pushers are manually switched on first, in which case it will stay at N. I had initially tried a flex-fan driven off the water pump, which was reasonably effective, except that one day it decided to flex into the back of my radiator, which was an expensive PITA to fix so I switched to the electrics. Everything is relayed and on nice fat wires.

It took me about a day to rig this, and someone with any skill at all could do it in half the time. If anyone wants a picture I can take one.
David

I solved all my cooling problems with 1 16" puller, 3000 cfm. Yes, it involves cutting out the valance in front of the radiator & moving the radiator forward untill it touches the slam panel, but it is a one time fix. The factory fans are marginal at best, less than as they age. A 30 amp relay is a necessity, as is a manual override switch, & indicator light. I use an adjustible fan stat to turn the fan on, it has a capillary tube which can be inserted in a hose, or clipped to the radiator fins.

Ducting the radiator is a help, as is a front spoiler, but the spoiler only works when you are moving.

I would never use the thermal wrap on headers (again). It holds heat very well, & will cause block hugger headers to crack at the 4 way joint. It also collects moisture & will rust mild steel headers of any design.

I do recommend ceramic coating of headers. There are several brands available, all seem to be the same except for the advertising. Mine are coated in silver(chrome look) and after 40,000 miles, look just like the day they were installed. No discoloration at all, substantial under hood heat reduction.
Jim

Jim,
What brand of fan are you using?

Al
Al Wulf

Paul,
My V8 went back on the road last weekend, in time for the good weather up here in Blackpool

I've got louvres, rv8 style manifolds, wrapped with the same stuff TVR use on their system, and water wetter, but is still got very hot on idle when I parked it to simulate a traffic jam.

I've got one large shrouded pusher fan, and a variable thermostat switch, my brother bought me a digital wine tester for Xmas (the wine's never in the bottle long enough to test in our house, but the probe fits nicely between the radiator fins), and it reads up to 100c in 1/10 degrees,Normal on the temp gauge is 80c, fan cuts in at 85c on the lowest setting, the car runs at about 82c on the road, the Hot equates to about 100c, didnt dare let it run to this temp. but at 95c the fan is still running, and the temp is still rising very slowly . Clearly I need to move more air, what about small puller fans behind the radiator, of extractor fans under the louvers?

Mike Barnfather
Michael barnfather

Jim at what temperature did you set the thermostat switch for the fan to come on? mine is set at 182 deg. it comes on for about 2 min and goes off at about 175 deg. when the fan comes on the temp. gauge pointer is about half way between N and H.
Romney.
romney

David,
Please send some of those pictures my way. I was thinking about the same type pf set-up a few weeks back..
Larry Embrey

This is all getting very technical! I fitted a
simple over-ride switch to my factory car. Have never had the fans come on automatically - if you watch the
temp guage in traffic snarl-ups and turn the fans on when it is coming up to hot you should get the cooling you need before the water gets too hot.
J M SWIRE

The fans should comne on automatically significantly before the gauge gets to 'hot'. If you have never seen yours come on automatically I would test your thermo switch urgently. What happens when someone else has charge of your car, like at an MOT station?
Paul Hunt

Thanks for that Paul - appreciate your concern. Of course the fans come on OK
when it is left ticking over etc as on the last MOT, maybe I did not phrase it right!
I once had a Daimler V8 which always boiled over (till I had the rad rebuilt) and it made me a bit paranoid about overheating.
As you know it can get hot even in the Midlands if you're stuck on the M6 in a jam on a hot day! Fitting the over-ride means that the fans can be turned on at will before the need arises so I now tend to use them in traffic quite a lot. As a point of interest I wonder if our friends in Australia and/or California et al bother with anti-freeze. As I understand this increases the boiling point.
Cheers - Martin
J M SWIRE

Yes, here in the land of cactus we use anti-freeze for the increased boiling point and are as likely to call it coolant as anti-freeze because nothing ever freezes here. I have switched to a weaker mixer with two-thirds water even though the boiling point is lowered because the heat transfer is improved. Another reason to use coolant/anti-freeze is that it has improved anti-corrosion properties over plain water, which is even more important when using an aluminum motor.
George Champion

Ah yes, the dreaded M6. 3 months of travelling from Solihull to Telford and back was enough for me. I also have a manual override courtesy of a PO, the only time I have really needed it was after the bottom hose ruptured and I had to get home with a temporary repair courtesy of the AA. I had been to Liverpool and yes, you guessed it, got stuck on the M6. Keeping the fans running full time kept the temp at 'N' which significantly reduces the pressure in the system thus taking the stress off the repair. 50% antifreeze is vital in the V8 for its anti-corrosion properties.
Paul Hunt

Since buying a factory v8 completely refurbished 18 months ago I have been reading a lot of the postings, particularly on the overheating issue. Having boiled in Guildford last summer I have followed someone's advice from here and removed a strip of the bonnet seal in front of the windscreen. On Good Friday I was stuck near Stonehenge for 45 minutes in a traffic jam, and with the manual override switch being used, and the fan on, the temperature guage did not move above 'N', but previously it would have done so very readily! The same applied on the way back on Tuesday in the vicinity of Chicklade, I think that this move was the best piece of cheap advice!!
Peter Velati

Water Wetter also has beneficial properties for these engines, according to website.

Peter which part of Woking as I'm a Knaphill resident.

Paul
Paul

Paul,
What is the website for water wetter?
Lyle
Lyle Jacobson

Lyle,

WaterWetter is made by Red Line.

http://www.redlineoil.com/
Carl

Peter,

Does removing the bonnet seal, or at least a piece of it, really help? I just can't imagine that any significant amount of air is going to escape. But heck, I'll try it ... will rip it off tomorrow morning!!!
Terrence

Rover/Buick/any other alloy engine for that matter requires corrosion inhibitor in the coolant to avoid er, corrosion !! Most anti-freeze contains an inhibitor, but glycol based anti-freeze is only half as effective as plain water at pulling heat from the engine. This is a problem for modified Mini's with it's tiny rad as well as for MG V8.

So, in both my Mini and my V8 I run de-mineralised water (no salts), mixed with the minimum anti-freeze I can get away with (about 25%) and water-wetter. Both vehicles have standard rads and fans, although Mini is a late one with auxilary electric fan as well as engine driven one. Both have oil coolers, and both have manual fan over-rides. The MG's uses the now redundant O/D switch on the steering column, which is easy to reach. Neither suffer major cooling problems, have just had a good thrash around Cadwell Park on a track day in the Mini without a problem.

I am using the "green" water-wetter from Redline, it's advertised for Diesel engines, but my engine builder says it seems to last a bit better than the "red" one. I believe it has a corrosion inhibitor so maybe those in warmer climates can use it without anti-freeze, but check with Redline first. A 15oz bottle will treat 10 to 15 gallons so do all your cars, or buy a bottle between friends. This will help if the cooling is marginal but will not fix an underlying problem like an undersized or clogged rad.

I'm investigating shrouding the standard "yellow" fans with sections cut from 11"-12" plant pots, don't laugh, their round, slightly tapered, can be cut it to shape easily and are very cheap !!

Removing scuttle edge seal ?? It's a nice idea, and many modified Mini's run with the back edge of the bonnet raised to allow hot air to escape, but I'm not convinced.

Phil.

Phil Hill

Phil,

Obviously all those years watching Blue Peter has paid off. What a good idea. I'll be interested in your final solution, with summer and traffic jam time approaching.

Paul
Paul

Paul

Yes, a bit of lateral thinking going on after a couple of beers. I'm kind of resigned to buying some proper fans, like a pair of 8 or 9 inch Pacets but I want to give this a go first. I'd read all sorts of threads about making "omega" shape bit of ali or tin to shroud the fans with, so I started thinking about ventilation ducts and stuff, then saw some of the wife's house plants and thought hmmmm. Only reason I haven't done it yet is she hasn't got any pots big enough....... I feel a trip to the garden centre coming on !!

Phil.
Phil Hill

The reason I made my shrouds shaped like the Greek letter omega Ù was because the stock fans barely clear the panel below them. I expect you will find the same obstacle, but you can always cut the panel away. Also note that one frame rail comes from the factory bent over to clear one fan and that is another indication how little clearance there is.

My shrouds made a big difference in redirecting the airflow through the radiator, but not as much as replacing both fans with an after market fan. The biggest problem with shrouding the stock fans is that one of them extends past the side of the radiator and with no resistance; more air passes through there than through the rest of the radiator.

Best to you though, maybe you will find the perfect size plastic shroud material. Be sure to post your results for the benefit of the rest of us.
George Champion

Did it really boil, Peter? Several years ago I got stuck in traffic after a motorway sprint in ambients of 90+. The needle reached the red but still didn't boil, got a bit rough though. Air temps have been much lower over Easter even with the sun.

That seal is there to stop any engine fumes getting into the cabin via the airvent, but I did discuss with a Californian factory V8 owner some years ago the possibility of modifying the hinges to allow the back edge of the bonnet to be 'jacked up' from inside the car when needed. I've also considered a flap inside the airvent to allow heat *out* of the engine compartment simultaneously sealing off the cabin.
Paul Hunt

This thread was discussed between 20/03/2002 and 11/04/2002

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