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Cooling fans relay burn out
On returning from a run in heavy traffic Victor Smith could not hear the cooling fans running so checked the engine bay and found the cause. It's a service check many V8 enthusiasts could make to avoid a similar problem.
(Mar 12)

On returning from a run in heavy traffic I was about to back into the garage and noticed I could not hear the cooling fans running. As V8 enthusiasts know when the car is not moving and the twin cooling fans are running they make a very audible roar. So my first check was the water temperature gauge (that was at around 5pm on the dial so the Otter switch would normally have cut in) and then I checked the manual override switch by my left knee as I was reasonably sure I had thrown the switch when held up in a traffic queue. Yes it was still on. So I opened the bonnet and earthed the spade to the Otter switch terminal to earth on one of the bolts of the Otter switch flange - the fans did not come on. So engine off and ignition off.


Brown wire from the fuse box to the cooling fans relay terminal "C1"

Leaning over the offside wing my search worked from the fuse box along the brown wire carrying the power supply to the fans relay and there, on the other end of that wire, I saw the spade connector to the terminal on the underside of the 6RA relay was burnt nearly to a cinder.
I removed the relay and could then see the underside and the terminal was almost hanging from a hole burnt in the base. On inspection the "C1" terminal showed signs of some corrosion, so the likely cause was an increased resistance through that connection which, with the relatively high current drawn to run the twin fans, must have generated a great deal of heat. The relay is rated 12V 20A.

I then went off to my spares bag and found I had a new "6RA" relay so began fitting it until it dawned on me it was a three terminal 6RA and not a four terminal 6RA which I needed to make the replacement. Both relays have "6RA" on the side of the unit, so if you need to buy one do check you get the right one!

Fortunately Brown & Gammons had a four terminal 6RA in stock (part number 142169A replacing 589665).

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Original 6RA cooling fans relay

Three terminal 6RA relay with no "W2" terminal

Once the relay and a new
section of brown wire (7.5 cm long BTW) with insulated spade connectors crimped to each end was replaced it was found the Otter switch (part number BHA5252) also needed replacement.
Crimping is best done with a specialist crimping tool.

So a worthwhile preventative maintenance item is checking the spade connectors at either end of this brown wire. After 35 years preventative replacement is worth considering together with a replacement Otter switch because reliable cooling is essential with a V8 engine in an MGBGTV8 engine bay.

See also a NEWS item on the Otter switch. More
See also manual override switch. V8NOTE389
Where can I get the spares for this safety check?
Several V8 members have been in touch to enquire where they can get a replacement relay and a short brown cable with a spade connector correctly crimped at each end so here are the links to the Brown & Gammons webpage and to Bob Owen's electronics company which can supply a replacement cable. It's important the spade connectors are correctly crimped on this cable.
Replacement 6RA four terminal relay

Visit the online spares catalogue on the Brown & Gammons website where you can buy this item - part no: 142169A at £21.80 plus £4.36 VAT = £26.16 plus post and packaging.
B&G webpage
Price correct in March 2012
Replacement short brown cable - fuse box to relay

Bob Owen is offering to supply a replacement brown cable link with a spade connector correctly crimped at each end, both with plastic protectors at only £3.00 each including carriage and VAT. TE Electronics
Price correct in March 2012
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