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MG MGB Technical - Engine driven cooling fan on rubber bumper?

Hi All,

The temps. in the bay area are beginning to feel like summer, and my 1977 MGB coolant temperature gage agrees.

My question is: Is it possible to put an engine driven radiator fan on my late B?
If yes, as long as the engine is running, the fan will pull air through the radiator - I think this should help.

My current (non-stock) electric puller fan cuts on at 180 F and off at 160 F. (This equates to my temperature gage being at about the 3/4 point when the fan turns on - does this sound correct?)

According to the Moss and Victoria British catalogs, the same water pump is used on 1974 1/2 - 1975 through 1980 MGBs.

My plan is to use the 7 blade plastic fan that was stock on 1975 and 1976 MGBs, Moss P/N 434-340 / Victoria British P/N 10-020. This, plus my stock water pump pully and fan clamping ring V.B. P/N 12-4323, would also be needed, along with longer bolts to clamp the ring and fan to the water pump pully.

My main concern is the spacing distance between the front of the water pump pully & engine to the back of the radiator on the rubber bumper MGBs ..... is this distance larger on the later B's, than the earlier MGBs that used engine driven cooling fans? Would I need to add an additional spacer between the water pump pully and the fan to get the fan closer to the radiator? How closs should the fan be to the radiator? Would I also need to add a shroud?

Thanks in advance for any and all feedback.

Keep cool!

Regards,
Greg

Greg Knodel

Greg-
Yes, you can install an engine-driven fan. However, the distance between the fan and the radiator is so great that it would be useless without a fan shround. Forget about spacers as the distance is far to great to make that a practical proposition. You'll need to custom-fabricate a shroud.

Before going to all that trouble I'd suggest that you flush the entire cooling system with a good engine flush. The rust and crud that's accumulated over the years and acts as insulation is usually the biggest part of the problem with hot-running B Series engines.
Steve S.

And, if you have a CA smog-compliant '77, why pull any additional power from an already disadvantaged engine? Particularly, when the electric fan should suffice if everything else is well with the system. I agree with Steve S. on the best remedy.
Barry Kindig

err.

I am planning on going the other way with my '75 B. The engine-driven fan just doesn't cut it when summer actually hits. (Pullman summer is 80-100 F, but dry)

I am currently running a 190 stat, and my temp gauge stays dead in the center all winter (and creeps above that in the summer). When I ran the 160 stat, it made little difference in the summer, and the car never would heat up come winter.

Your gauge sounds off, 180 should be center or really close to it. The engine-driven fan really doesn't help a lot, it doesn't pull enough air when idling, and isn't needed when at speed (and robs you of power to boot).

Also, the change to electric fans is coupled with a change in rad. location.
http://www.wsu.edu/~aaronpw/MG/SU/index.html shows where the '75 rad is, quite a bit closer to the engine. I am not sure if you could extend the fan to the later location, maybe the bonnet could foul...

As for a shroud, you could make one, but I don't know of any that would just bolt up.
Aaron Whiteman

Greg:

One of our customers requested we instal a separate toggle switch beneath the instrument panel...out of sight but easily within reach. When activated, the toggle switch would throw on the fan motors. When left in the "off" position, the fan motors would activate as normal...through the radiator sensor switch.

This gave them peace of mind during the hot days of summer as they could activate any time they wished. Of course, it helped when their cooling system was flushed and clean and the rest of the engine was tuned properly as well.

Mike Brown,
Seven Shop British.
Mike Brown

Does you overheating problem occur on the highway
only? If so, improving the cooling fans won't help.
Do you have the original twin fans? I find
these sufficient to cool my 79 (should be same
set-up as your 77.)

But the stock fan switch turns on at too high a
temperature -- as you note 3/4 scale, which is
really I think about 200 deg. F or above.
I bought a fan switch from Autozone with a sensor
that fixes to the radiator, and can be set to
turn on at any temperature.

If you're running hot on the highway, the problem
is probably the radiator. I've concluded that
the stock 3 row radiator is marginal for the
California climate in summer, especially if the
engine has even mild performance modifications.
Solution may be to recore to a 4 row.
Ronald

Switching on/off around the 3/4 point is as per factory specs. What problem are you trying to solve? It is normal for the temp gauge to hover around the 3/4 point in traffic. If the fan(s) can't cool enough to keep it there in traffic, or if the gauge doesn't get back down to around the N on the open road, then you have other problems generating too much heat and/or not getting rid of it that an engine-driven fan won't solve.
Paul Hunt

Paul do you know the cost of a recore? if you do I would like to know as i run a custom rad and it does not look stock and i would like a stock looking rad.
thanks
Ross

Hi All,

Thanks for the inputs. In response to some of these:

1. My radiator / engine / heater have all been flushed and the anitfreeze / distilled water mixture is a nice shade of green. No rust color visisble. I do this every year in the late spring. I'm also running with water-wetter in the collant. Oh, I'm also running with an oil cooler - call me paranoid.

2. I have recently had a my radiator upgraded to a 4 row - this helped, as my temp gage used to go all the way to the beginning of the red zone.

3. On the freeway, with normal speeds >55 MPH, the car stays about mid-range, but heats up VERY FAST if traffic slows down or stops / or if I get off the freeway. Is it normal? What else can I look at or adjust?

4. I've taken the stock set of electric fans out, completly, and just have the 10" Hayden electric fan mounted on the back of the radiator, pulling air through.

5. I've been running with a 160 F thermostat this year. Last summer, I pulled the thermostat and put in the blanking sleeve. This seemed to only cause warm up time to increase, but once warmed up, the temp. gage climbed up as usual.

6. I have been considering using the extra write that came with the non-stock electric fan, along with a toggle switch so the fan can be turned as I want. And the adjustable temp. sensor also sounds good. Maybe both!

Again, thanks for you inputs!

Regards,
Greg
Greg Knodel

How is the baffle around the radiator? Are you pulling hot air back through the radiator? How hot is your oil cooler getting and is that heat coming back through your radiator?
.

Greg,

Since your car temp is normal on the highway, and only
heats up in traffic, the problem is definitely insufficient air flow
from the fan. The single 10" fan is probably not adequate. For
some reason I think a puller fan is not as good as a pusher.

You might try a single large (12"?) Hayden fan as a pusher
in front of the radiator (if there's room.) But the best solution might
just be the twin stock fans.

Also, for $7.00 you might try a new temperature sender -- these
things are not alway accurate. If you can borrow an infrared
temp. sensing gun, you might check the temp. of the radiator
to see if your gauge is really accurate. Again, midpoint should
be about 180 deg. F.
Ronald

you may wish to revist the oil cooler. if this was a north american spec car, you or the po probably installed it. the factory rb oil coolers were underslung to allow sufficient air to flow through the rubber bumper vents. by placing a cooler in front of the radiator, you may have blocked some air flow

rn.
RN Lipow

ug, that's "revisit"
RN Lipow

Greg,

I found the 10" to be too small, and used a 12" in puller configuration wired to the stock temp sensor in the radiator. The puller is more efficient than the pusher, so just replace the 10" with the 12" in your current configuration. There is plenty of room for the 12".
Paul Konkle

Mike B,
I recently did away with the factory pusher fan (there was only one in place), and installed a puller fan. I too have the desire to place a toggle switch under the dash. I think I would like the option of turning it on manually, but still keep it's automatic function.

My question is, where is the closest place I can splice into the fan control wires. At first glance, I thought I would just do it right where the radiator temp. sensor is. Does anyone have a better (closer route).

So far in the month that the new puller fan has been installed, I have not yet had it come on. The temp gauge has not climbed above 3/4. I am running with a 190 F stat. I sure would like to see how the new fan runs while in place. I tested it before installing so I know it runs.

Cheers,
John '79B
John F

We still don't know what the problem is. When you get the engine up to temp by driving it, then stop in traffic, the temp gauge is *supposed* to go up and the fans are *supposed* to cut in at about 1/2 way between N and the red. Is the problem that the temp keeps rising when the fan is running? Or doesn't drop back to N and the fans cut out? Factory V8s in ambients of 80F-90F may not cut out either, but they should stop it getting into the red at least. RV8s had a huge puller (which is definitely more effective than a pusher) of about 12" or 14". 10" even as a puller is not much bigger than one of the standard fans. Having seen a couple of very slimline, shrouded, spiral blade after-market fans in use I don't think the factory fans are that bad after all, although shrouding them would help. Make sure you have as much voltage as possible getting to the fans, I recently went through an excercise of soldering crimped connectors, replacing the relay and adding local grounds for the fans as well as the loom ground and gained about 2v which has made a significant difference to fan speed and hence cooling.

Ross - the radiator was an 'off the shelf' exchange from Clive Wheatley.

I have an illuminated switch as a manual override so I can see when the fans are running automatically as well - not that I can't hear them when stationary anyway. Wire the switch across the stat contacts.
Paul Hunt

A quick thought here: which way is the fan rotating? About 25% of these beasties came out of the factory wired ar*e about face so:
Going quickly = OK - airflow overcomes fan.
Standing still = OK - fan blows air "wrong way" through rad, but still provides cooling.
Moving slowly in traffic = <BANG> - fan cancels out airflow from movement causing "dead area" in rad and rapid overheating.

Having said that, I changed just about everything (sorry, make that absolutely everything :-( ) in the cooling system of my '77 B, only to find after three years(!) that the connections to the thermo switch were "iffy". The wires to the switch, due to the constant "warmth" provided to them, had hardened, rendering them uncooperative to the crimped on connectors. That meant that occasionally the fan wouldn't cut in! Of course, "occasionally" means "never when you're actually watching for it". Solution: lop off 6 inches of wire and replace.

BTW, my "bog standard" setup now cuts in at 3/4 on the gauge and out at about mid way. I've not had any problems with overheating since fixing my errant wiring.
Tim Cuthill

Let's see ... where to start?

Air baffle in good shape.

I installed the oil cooler and it is hung below the radiator. I have not felt / measured the oil cooler temp when the coolant temp. reads hot.

I might look into a bigger Hayden fan as a puller ... I wonder if I can but the fan and connected wires only?

When I get into stop and go or slow moving traffic, and temp. starts to climb, I'm sure the fan stops the temp. gage from rising any further - and brings it down slightly below the 3/4 point.

I've checked the fan rotation when the car is standing still - it is blowing air in the direction of the engine, (pulling air through the radiator as opposed to blowing engine compartment air towards the front of the car.)

I think the wiring on my "uncalibrated" temperature sensor is okay (it's new, shinny and still flexible) ..... the one thing I do not like, is the sloppy manner in which the radiator fins hold the temperature sensing probe in place, so I also pushed additional metal rods around the probe so it will stay in place better.

I have replaced the temperature sender (the one that screws into the engine, near the thermostat), but by temp. gage read the same as the previous sender. Are there any components (resistors) on the back of the temp. gage that were used to calibrate it to the sender?

Thanks again,
Greg
Greg Knodel

If the fan's stopping the temp from climbing any further after it's cut in then it's doing its job. As far as I can make out, if it's a late B and the gauge doesn't escalate into the "red zone" when things get hot then I think that the old adage about things that are funtioning as designed applies (in pig-latin: "Itno na kudz oyune omen dit").
Tim Cuthill

John:

I don't think there is any other place you can splice in the output wire except downstream from the sensor so you'd have to place this at the front of the car, yes. I can't recall just where we spliced in the feed wire but it was probably into the main white wire coming from the ignition relay, thence into the cockpit to the toggle switch and forward to the front of the car. We wired it so when the ignition is turned off, the fan switch is no longer active of course.

You'll have to do something similar I imagine.

Best regards,

Mike
Mike Brown

Greetings All,

It seems from this thread, and my own frustrating experience the best you can do is get these things to cool a little better than when you started working on the problem. I'm wondering if anyone has tried an aluminum after market type radiator? I've never seen one for an MG, but has anyone fabricated a fit, and how much difference did that make?
Dennis Hill

Dennis-
You can get an all-aluminum radiator from Cambridge Motorsport over in the UK, but they're intended for racing and are wildly expensive. If all you want is greater cooling capacity (such as when running an engine with enhanced power output), simply take your old radiator down to a good radiator shop and have a four-row aluminum core installed. Specify at least 15 fins per inch. You can go up to 1" thicker and it will still fit. While you're at it, have them install a drain petcock to make maintenance easier. I did this and despite that my engine is highly modified, I've never had the engine get overheat or even get dangerously hot, even in F95 weather. It's probably the single wisest investment that I've made in the whole car.
Steve S.

Dennis-
I forgot to mention that the whole conversion cost less than a new stock radiator from an aftermarket supplier.
Steve S.

Thanks Steve, that sounds like exactly what I'm looking for. I should mention I have a 69B and it's not really modified, nor does it actually overheat, it just runs too hot for my taste. I'd like to get it to run in the 180 degree range. I converted to an electric fan which helped, but it seems than on a hot day, it still likes to get a little hot. I'm wondering what year you did this on.
Dennis Hill

Well,

This weekend I installed variable thermostat (so electric fan would come on at 160 to 210 degrees F, depending on the setting of the adjustment screw.)

I inserted the temperature sensing probe just below the top inlet to the radiator, as recommended.

At first I set the adjustment to full clockwise setting, and the plan was to turn the adjustment screw counter-clockwise until fan came on, after the thermostat opened, and the radiator began to get warm -then it is calibrated, per the instruction page.

What actually happened was the fan came on at the same time the radiator began to get warm.

This means the electric fan would run continously to maintain the temperature, rather than shutting on and off, the the radiator fins, in contact with the temperature sensing probe changed temperature. This does not make sense to me.

Maybe the temp. sensing probe is too close the the radiator inlet? What is the general consensus on the proper location for this probe, in the radiator?

As always, thankls in advnace for your feedback.

Greg
Greg Knodel

Greg,
Hmm, that sure doesn't sound right. If you have the adjust turned fully CW and that's the maximum setting, then it should come in near 210 F right? I'm pretty sure that the radiator isn't reaching this temp as it first warms up. I used one of these controls successfully on a vehicle for 5 or 6 years and never had a problem setting it; the probe was installed amongst the fins near the top outlet like yours. My guess is that the variable T-stat is defective. You could try running the screw back and forth energetically through its full range and see if this makes any difference when you try it again.

Best, Joe

Joe Ullman

Hi Joe,

I'll try that, and if I can take it out of the circuit, I will use ohm meter to ensure the resistance varies as the adjusment is turned. Usually, these should be reliable - buit every oce in a while .....

Thanks,
Greg
Greg Knodel

Greg,
I'm not sure that the resistance should vary with the adjustment screw. Is your controller some kind of solid state device? Even if it is, I doubt that you'd see a resistance change at the leads. If the resistance changed at the leads, you'd see a change in motor speed, not the pickup point. If your controller is mechanical, the screw may change something else physical inside the mechanism. Then, you may need a thermometer and pan of water to determine if the screw is functional in changing the pickup point. Just a thought.

Joe
Joe Ullman

Joe,

I would call it solid state. My understanding is the variable resistor is in the same circuit with the temperature sensing probe. The temperature sensing probe changes resistance with temperature change, and the variable resistor is supposed to change the resistance, so the fan activates (relay closes) at the desired temperature (or resistance.)

I'll verify it this weekend.

Thanks,
Greg
Greg Knodel

Greg,
Okay, your controller is different inside than the one I used successfully for years, but the function is the same.
I still think the only thing you'll see on those two leads is open or closed, on or off, or is that what you said? My suggestion was to use the pan of water and thermostat to see if the screw would change the point where the contacts closed.
I tried out my first B in San Jose about 35 years ago; drove it through the woods on a sunny day up to Loma Prieta and back.

Joe
Joe Ullman

Hello All,

I just discovered something that I'm sure everyone but me knew. I've been fighting this running too hot problem for years. Never gave a thought to the fact early on I discovered a thermostat for a 350 Chevy fits an MG fine. I've been using them ever since (lets face it they are easy to obtain). Well guess what, on a fluke, I ordered one for an MG and thought, gee that's a small opening. That's right it was flowing too much water. My hot problem is gone completely. I just thought someone else might be doing this, so I though I would mention it.
Dennis Hill

Gregg - very unlikely. Even if solid-state the output of the thermo switch will be either 'closed' to operate either the relay or fans, or 'open' to switch them off. I have never heard of a continuously variable cooling fan (which isn't to say ...) and a relay contact is only ever open or closed, nothing in between.
Paul Hunt

Has anyone thought about the water pump? I've heard some of the newer ones don't puch the water around as effectively as the older units.

Check out your pump. With the larger radiator and the electric fan, water wetter, etc. you should be running way cool.

Good luck and let us know what happens.

Luis
Luis

Luis's comment reminds me of someone who found that an 18V pump would fit an 18G? but shift much less water. Or was it the other way round?
Paul Hunt

I think Luis is talking about the infamous Quinton-Hazell water pumps. They have an aluminum body and a cheezy bent sheetmetal steel impeller instead of a proper cast iron closed impeller. Also, the aluminum and steel in contact with a water solution guarantees galvanic corrosion will take place. They last about 3 years, and then self-destruct. They cannot be rebuilt either. I hadn't thought to ask Greg about the pump. Good catch, Luis!
Paul Konkle

What's a good method to determine if the water pump is working proberly? Then again, it's easy to change, right?
Greg Knodel

Yay for the home team, I suppose.

Funny thing Paul H., I did install the old WP unit from my '77 18V on my '69 GH (being el cheapo), the bloody thing fit! Sure enough, it did run hot until I finally bought a new correct pump (cast iron). I was thinking the 18V WP must have been bad, I now see it was designed for a specific application.

Good luck, Greg. I seriously hope you find a solution.

Luis
Luis

Anyone know a USA source for cast iron waterpumps for 72-74 18V and 18GB thru GK
65-71 engines? All replacement I have recently seen are aluminum. Clifton
Clifton Gordon

Clifton-
I believe that World Wide Auto Parts up in Madison, Wisconsin is still remanufacturing the cast iron water pumps. If they are, you'll need to send them your old cast iron pump as a core exchange. They have a website at http://www.mailbag.com/users/nosimport/

Yes, all of those bad things that people say about the aluminum-body pumps (less pumping capacity, corrosion, unrebuildable) are true. In addition, there's one other thing: due to their El Cheapo stamped-sheetmetal impellers they cavitate at high rpm. "Cavitate" means that they form bubbles in the coolant, much like the propeller of a ship at high speed. Not the way to go if you choose to install a camshaft that shifts the power output to a higher RPM (Piper 270, Piper 285)!
Steve S.

I believe that all of the responses on this thread are focusing on the cooling system. Last year, I was having over-heating issues on my TR3. After fooling around with the cooling system for a month, I correctly adjusted the ignition timing, and it ran much cooler.

I'm not suggesting that this particular issue is due to poor ignition timing, but I'm surprised that no one has suggested looking at these other "non-cooling system" possibilities.

CH
Chet Harter

Thanks Steve. I already had Worldwide Imports bookmarked. I didn't notice any reference
to rebuilding water pumps but I'll email them and see what they say. Joe Curto also rebuilds
water pumps and sells some repair kits. Only problem is I have two cars and only one cast
iron water pump. On the 68 the QH? pump keeps the engine cool even though it has a Mike
Brown modified head. I recently rebuilt the 74 and the cast iron pump had noisy bearings so
I installed a QH pump and the engine does run a slight bit higher temperature than before the
rebuild, just above the normal mark. Radiator was recored about 3 years ago and prior to the
rebuild I had it cleaned and a drain plug installed.

I'm going to Import Carlisle next month so I'll be looking for a couple of rebuildable cast iron
water pumps.

Regards, Clifton
Clifton Gordon

Hi Everyone,

I took a week's "vacation" to get a buch of work accomplished around the house ......... I'm making headway.

Anyway, I got started on my water pump job late this afternoon:

The new water pump and old water pump are quite a bit different in appearence and weight! The new must be cast iron, and the old is aluminum.
The portion of the pump that protrudes into the engine is also different in appearence - old has metal fins, and new has what I would term as molded inlets or something like that.

I'm keeping my fingers crossed that I will be driving a much cooler car by noon tomorrow.

Thanks to O'Connor Classic Cars in Santa Clara - they shipped the good water pump, based on everything I've seen from you guys.

Keep you posted.

Regards,
Greg
Greg Knodel

I finished the water pump installation today. The weather is on the cool side (58), so I can't give it the worst case test today - but, it seems to take the engine longer to warm up - is that a good sign?

Also, I figured out the variable resistor on my ajustable thermostat had to be turned fully counter-clockwise to start the calibration procedure, as fully clockwise setting allows the fan to turn on as soon as the engine therostat opens. Now I've adjusted it so it comes on at the half-way point on the temp. gage, and it turns off just below the mid-point range.

Well, here's hoping the weather will be warmer tomorrow.

Thanks,
Greg
Greg Knodel

Since the stat should be closed during warm-up it shouldn't take any longer, but different ambients will give different results, as will bonnet up and bonnet down, driving style, or just idling.
Paul Hunt

I thank everyone for their help and feedback.
My '77B runs very nice now at mid-point on the temp. gage.

The key was the cast iron water pump.

My next subject will probably concern passing the California smog test, this coming August.

Thanks again!
Greg
Greg Knodel

This thread was discussed between 01/04/2002 and 20/04/2002

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