MGA Forum

This may be a bit disturbing. I have now had multiple cases of replacement plastic fan blades that have broken. This is Moss Motors part number 434-332, replacement part for original 6-blade steel fan on 1962-1967 MGB. It is also sold as a "modern" replacement part for the MGA steel fan. It is "similar to" the OEM plastic fan for later model MGB (but may not be exactly the same structural configuration).

Date Miles
07/20/77 150,000 Purchased used MGA
09/25/95 220,000 Broken steel fan blade (220,000 miles) Install a used one.
05/06/15 445,038 Install plastic fan, Encinitas CA.
07/16/15 455,667 Plastic fan failed 2-blades, Weaverville CA. (10,630 mi)

08/15/15 458,719 Second new plastic fan installed, Hillsboro OR.

04/12/16 479,540 Repair radiator #1 damaged by plastic fan broken blade, Matoon IL. (20,821 mi)

05/13/16 482,369 Repair radiator #2 damaged by plastic fan broken blade, Raleigh NC. Install steel fan

One month to the day from the last broken blade and radiator repair. Exactly the same damage to the radiator, but at the top this time. The blade fracture is much different. Prior blade breaks (three of those) occurred at the thin base of the blade. This time the wide flange of the hub is breaking up. It appears to be stress cracks originating near the leading edge of the blade root. In the picture you can see one blade gone and another on opposite side about to let loose. I assess this as typical 1970's engineering trying to make everything as cheap as possible without regard to strength or quality. Pretty obvious (to me as an engineer) that the plastic is not thick enough to have sufficient strength to handle long term stress.

Now I want to know if anyone else has encountered failure of the same part number replacement plastic cooling fan. I have had them last 10K and 20K miles, but so far two or two have broken, and no keeper. Perhaps no one else has driven this many miles on one of these plastic fans. But if you have more than 10,000 miles on one and it has or has not broken, I would like to know about it.

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Barney Gaylord - 1958 MGA with an attitude - https://MGAguru.com - barneymg@mgaguru.com - Ph: 630-946-3841
(Please email me direct, do not leave a PM on the public server).

I recently installed the 7-blade plastic fan (from Moss, I assume they are all the same?), and thought it seemed a bit "skimpy".
But I figured all was well as had not heard of failures.
Now this!
It seems a better choice of material would be some type of fiber-reinforced resin, or hi-strength engineering resin.
I would pay more for one much less likely to explode!

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Dave

Barney,
We have not had any complaints on this fan. Have you told anyone here of the issue you are having?

Thanks,

Shawn

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Shawn Carlberg
Marketing Manager
Moss Motors
shawn@mossmotors.com
1973 MG Midget

Not yet but I was about to send a note to Moss. With the first blade failures (at root of the blades) I gave it the benefit of the doubt, thinking the blade tips may have contacted the metal fan shroud. in years past I have had a metal fan contact the steel shroud with failure of an engine mount. That chewed up the shroud some, but no significant damage to the steel fan (which I continued to use for many years on).

Since the second blade failure I have removed the fan shroud. But this latest breakage involves failure of the hub, and two blades on opposite sides of the hub. I was wondering about the material, if perhaps OEM parts for MGB may have been made with Fiber Reinforced Plastic (generally good for structural parts). These replacement parts seem to be plain plastic, no reinforcing fiber that I can see.

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Barney Gaylord - 1958 MGA with an attitude - https://MGAguru.com - barneymg@mgaguru.com - Ph: 630-946-3841
(Please email me direct, do not leave a PM on the public server).

Barney,
I have run this to the top of our list to look at. We have had 0 failures reported to us. We are gonna cut one apart and look at it.

Can you send us any or all of your broken ones?

Shawn

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Shawn Carlberg
Marketing Manager
Moss Motors
shawn@mossmotors.com
1973 MG Midget

107K on a '79 MGB with dealer installed A/C from new.
1 bad water pump and a broken (cracked) metal pulley behind the aluminum fan spacer but fan never failed.
75% of the miles were interstate (high fan RPM)

Wonder who the supplier was for those fans and what the difference is in material? - mine was off-white.

Eric

I purchased and installed a moss plastic fan in July of 2015. I have just a tick under 10,000 miles(9,953 miles) on it since.
I took a quick look at it this evening. One blade i observed has on it what appears to be what looks like a scratch? The scratch is deep enough to catch the tip of my finger nail on it but the other side of the blade is clean.
Full disclosure, when i installed the blade, the fan shroud was close enough to catch the tips of the blades and shave off 1/8 inch.
I didn't take the blade off of car to inspect it fully so it may contain fractures that i didn't see.

My radiator has been fixed (again), and a (used) early MGB steel fan installed (like I ran for a decade before). I will send what is left of the latest broken plastic fan back to Moss. It really is a bit of a mess. Fortunate that we found the broken off blade for forensics. Another blade is "caught in the act" about to part company in similar manner. Light yellow parts of the fracture appear to be long term creeping stress cracks, while the more ragged whiter parts appear to be more instant fracture at time of final break.

As far as I can tell, there is no sign of any reinforcing fiber in the plastic. A club friend here in Raleigh was just chatting about an original MGB plastic fan on his car that was rubbing on a bolt after air conditioner installation. That blade did not fracture, and he claims it is still in use, but he did say it had clear signs of reinforcing fibers sticking out at the abraded spot.

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Barney Gaylord - 1958 MGA with an attitude - https://MGAguru.com - barneymg@mgaguru.com - Ph: 630-946-3841
(Please email me direct, do not leave a PM on the public server).

Shawn
On 5/4/2016 I called Kelvin Dodd and reported a blade failure on the seven blade plastic fan. The fan was purchased 11/6/2012. The fan failed in April 2016 at 28,601 miles.

Barney, as you have had multiple failures could it be the shroud is causing resonance at the blade tips, eventually leading to blade fatigue root failure? Aircraft jet engine compressor fan blades spring to mind.

Keeping an eye on my 7-blade asymmetric fan. Nothing like your mileage and all is well so far. 26 degrees the other day and still cant get the temp above 175.

Steve

Dropped a blade off the steel fan on the way to Whistler a few years back. Wife held the fan steady against a lamp post so I could cut off an opposite side blade. Picked up a good used one from a restoration shop in Calgory, great people there. I won't mention the blown head gasket, that's another story. Got to be ready for anything out there!! Marvin,ct

Tough luck...I've had my plastic fan for over 10 years now and no problems. The reason for the plastic one is the steel stock one threw a blade?? What a noise that made. I would say another plastic one would be a good bet, but if you have a steel one coming stick to that.

Plastic ages and often become brittle with time, so replacing old factory plastic fans is a good plan - hopefully they won't find any structural or material deficits in these repro fans.

I wouldn't be too fast to toss out an original steel MG fan, though. They are pretty rugged and last many years

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Bill Spohn www.rhodo.citymax.com/carstuff.html
Current: 1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1957 Jamaican MGA (200 bhp)1965 1971 Jensen Interceptor (350 bhp)
2009 Pontiac Solstice GXP Coupe (375 bhp)
2007 BMW Z4M coupe (340 bhp)
Recent: 1969 MGC roadster (175 bhp),Jensen CV8 (375 bhp),
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
North Vancouver BC

I just replaced my steel fan with a yellow plastic one. (Moss)
I inspected and found a tiny crack starting on the steel one.
The car is a '59 with 73+K miles on it.
Hell, I'm afraid to trust any of them now!

C'mon Moss...get cookin' on a proper reinforced plastic model, and offer a nice discount for folks returning their old plastic one, if bought from you.
You know you want to...

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Dave

FWIW, my thinking is just the opposite. While we've had a couple of recent reports of breakage of the reproduction yellow plastic fans, I'm not aware of any reports of failure of OE plastic fans. There are reports, however, of OE metal fans breaking and throwing blades through the radiator or bonnet.

I'd be interested in knowing if anyone has especienced breakage of the OE yellow plastic fans...

Dick

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Errabundi Saepe, Semper Certi
(Often wrong, but always certain)