84 esprit cooling fan sensor problems
Discussion
my cooling fans only operate when air conditioning is on, this is the only time the two wires on the sensor on metal cooling hose housing lights up on a test light, and operates fans, does this mean that sensor is bad, and if so where is a good parts outlet. i also noticed the fan on the engine cover never powers up, i tested wires with ac on etc and no power, where does this fan receive its signal from. thanks for any and all advice. thanks Rod Mathews
grooveshack26 said:
my cooling fans only operate when air conditioning is on, this is the only time the two wires on the sensor on metal cooling hose housing lights up on a test light, and operates fans, does this mean that sensor is bad, and if so where is a good parts outlet. i also noticed the fan on the engine cover never powers up, i tested wires with ac on etc and no power, where does this fan receive its signal from. thanks for any and all advice. thanks Rod Mathews
Rod,
You may have a bad 'Otter' switch (named for a company which once, but no longer manufactured them)on your fan circuit. This can be tested by using a multimeter w/ aligator leads. Hook up to either side of the 'Otter' switch and check for continuity, cold there should be none, hot there should.
So far as the engine bay cooling fan is concerned, this is governed by a 'T'stat (located under the cover) and a timer (Black box attached to the ignition box cover) + the two relays adjacent to it. Finally, the switch which sticks out of the ignition box is the master switch to insure the fan doesn't operate when the cover is lifted.
Swap relays with known good ones, disassemble the 'T'stat and clean the bi-metal contact. Then using a Bic lighter, hold it about 4" under the metal contacts and if it doesn't trip, gently bend the metal until it does (this is a trial and error type of adjustment), check master switch for continuity, check plug on bulkhead for power. If all else fails, it's most likely the timer unit which may be repairable, but probably easier to replace unless you are good at soldering/desoldering IC components from a board. Happy Motoring! ...Jim'85TE
>> Edited by lotusguy on Thursday 20th May 05:28
Fan on engine cover?? I don't have one.(???) Bought my 87 turbo esprit last year & I couldn't be happier. It does not overheat, runs strong, etc. Years ago, I thought I saw a picture of a Guigiaro type with a fan beneath the engine cover, but when I bought my esprit, no fan??? I looked good underneath the cover and could not find any bracket or hole indicating a missing fan, so I ignored the issue & forgot about it. Should the 87 esprit have the fan? Does it only operate after shutting off engine to cool turbo? Anyone with advice/knowledge?
judgea said:
Fan on engine cover?? I don't have one.(???) Bought my 87 turbo esprit last year & I couldn't be happier. It does not overheat, runs strong, etc. Years ago, I thought I saw a picture of a Guigiaro type with a fan beneath the engine cover, but when I bought my esprit, no fan??? I looked good underneath the cover and could not find any bracket or hole indicating a missing fan, so I ignored the issue & forgot about it. Should the 87 esprit have the fan? Does it only operate after shutting off engine to cool turbo? Anyone with advice/knowledge?
Hi,
The fan is called the Engine Bay Cooling Fan. It was used on the carb'd turbos and it's sole purpose is to draw cool air over the carbs and vent the Engine Bay, preventing carburettor vapor lock. It exhausts out the LR wheelwell after being directed down over the turbo and exhaust manifold. It works only on engine shutdown and then only when the bay temps are sufficient to energize the 'T'stat.
The fan is governed by a bi-metal 'T'stat and/or a 15 min. IC timer to prevent battery drain. If the engine cools sufficiently to de-energize the bi-metal 'T'stat, the fan turns off. If the engine heat remains high, after 15 min. the timer cuts it out regardless. There is also a dead switch mounted in, and protruding from, the ignition box which prevents the current flowing to the fan if the engine cover is raised.
Despite it being overly complex, and the fact that the bi-metal 'T'stat often requires adjustment due to it's contacts pitting, or metal fatigue in the contact (simply requires some bending to make it work again), it's a pretty robust and efficient means of avoiding vapor lock. It was used in all the carb Turbo models until the Bosche EFI was introduced in 1986. Happy Motoring! ...Jim'85TE
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