Fans cause engine to die

Post cries for help here if your topic fits no other thread in this category.

Moderators: theelanman, GeoffSmith, Sy V, Elanlover, muley, Enright, algirdas, nitroman, clemo, Specky, dapinky, Dave Eds, Nige, DaveT

Fans cause engine to die

Postby Simon_P » Sun 18.03.2018, 14:48

Just recently and about 1000 miles after an engine rebuild.
Symptoms:
When the fans come on either from engine temperature or A/C the engine dies, the fan relay drops out and the engine pics up relay cuts in again engine dies etc.

Thankfully it has only happened when I've been stationary and I have have been able to switch it off.

I've looked at the fan wiring diagram and can't see how the fan would interfere with the engine. I'm going to check for loose earth's over the weekend.

So does anyone have any similar experience or better knowledge of the wiring that can explain what might be causing this.?
Simon_P
God
 
Posts: 924
Joined: Fri 06.08.2004, 12:33
Location: Kent UK

Re: Fans cause engine to die

Postby Saltire » Sun 18.03.2018, 15:00

Simon, I haven’t got the wiring diagrams in front of me at present, but I seem to recall that the connection from the cooling fan relay to the switch (and thereby to Earth) passes through the ECMHC connector, which also carries wires from the ECU. Is it perhaps possible that a fault at that connector is causing the ECU to short to Earth when the fan switch triggers?

Just a vague memory from an old codger, so could be well wide of the mark, but that’s where I might start.
Jonathan

S2 no 512, BRG, magnolia interior, last of four UK S2 to this spec
User avatar
Saltire
God
 
Posts: 776
Joined: Sun 05.04.2015, 22:27
Location: Left foot in Wiltshire, right foot in Gloucestershire, heart in Sutherland

Re: Fans cause engine to die

Postby GeoffSmith » Sun 18.03.2018, 15:12

Possibly an earthing issue causing sensor readings to go awol. I would check the fan earth wrt battery negative or connect a jump lead from the battery to the fan earth.
Calypso Red S2 #417

USB ElanScan interfaces - Sorry, currently unavailable.
User avatar
GeoffSmith
Kitty Fiddler
 
Posts: 13983
Joined: Fri 03.02.2006, 21:57
Location: S2#417 in Tytherington, Gloucestershire

Re: Fans cause engine to die

Postby lotusflasherman » Sun 18.03.2018, 20:43

Idle speed is controlled by the ECM and should be aware when the A/C is switched on and adjusts the Idle Air Control Valve to increase idle before energising the a/c compressor. It does the same for power steering and should react to demands on the alternator.
For the SE the voltages that should be supplied to the ECM are shown on EMK4 Page 6 so you can check with a digital voltmeter - for the S2 I haven't a clue what page but the principle is the same .. :lol: Over to you Geoff :poke:

(I'd put my money on a multi-pin connector problem)
Phil

Leave me alone, I think I know what I'm doing.
Cars: Subaru Forester 2.5XTN, Eclat Riviera & brace of Pacific Blue SE's.... and now an Elan+2S !
User avatar
lotusflasherman
God
 
Posts: 2101
Joined: Fri 05.09.2008, 00:14
Location: Hadleigh, 15m west of Ipswich or 800 miles south (Cap d'Agde)

Re: Fans cause engine to die

Postby HJ2 » Sun 18.03.2018, 21:09

Yeah, Check all the main bond straps between engine components, alternator, startermotor and chassis first. They can make just enough contact, but when the current goes up when the fans switch on, it all breaks down :shock:
If you always do what you always did, you always get what you always got
User avatar
HJ2
God
 
Posts: 3527
Joined: Fri 06.06.2008, 10:54
Location: Delft, the Netherlands

Re: Fans cause engine to die

Postby Simon_P » Fri 11.05.2018, 23:41

Working through it logically....
A/C request causes revs to rise
Grounded fan temp switch to test function
Check main cable connections OK but condemned battery as 11.6 v
Checked and cleaned ECMHC plug/socket.
Check other plug/ sockets.
Checked earth bonding straps all OK
Checked front member bonding strap to fan wiring sockets - high raeistance
Traced fan earth wire to connection on front member (as per diagram).... Loose screw!

Thanks for all the suggestions.
Geoff 10/10.
Simon_P
God
 
Posts: 924
Joined: Fri 06.08.2004, 12:33
Location: Kent UK

Re: Fans cause engine to die

Postby GeoffSmith » Sat 12.05.2018, 06:26

I know I talk BOLLECKS most of the time, but sometimes, very occasionally…
Calypso Red S2 #417

USB ElanScan interfaces - Sorry, currently unavailable.
User avatar
GeoffSmith
Kitty Fiddler
 
Posts: 13983
Joined: Fri 03.02.2006, 21:57
Location: S2#417 in Tytherington, Gloucestershire

Re: Fans cause engine to die

Postby Giniw » Sat 12.05.2018, 20:49

:-D
User avatar
Giniw
God
 
Posts: 975
Joined: Sat 21.04.2012, 20:46
Location: France

Re: Fans cause engine to die

Postby Rambo » Sat 12.05.2018, 21:03

GeoffSmith wrote:I know I talk BOLLECKS all of the time, but sometimes, very occasionally I speak some sense…


:twisted:
User avatar
Rambo
Swivel-hips
 
Posts: 6136
Joined: Wed 24.12.2003, 00:37
Location: Embra

Re: Fans cause engine to die

Postby HJ2 » Sat 12.05.2018, 21:57

I hope i’m still here to whitness it :-D
If you always do what you always did, you always get what you always got
User avatar
HJ2
God
 
Posts: 3527
Joined: Fri 06.06.2008, 10:54
Location: Delft, the Netherlands


Return to Miscellaneous Problems - Need Help!

Who is online

Users browsing this forum: No registered users and 1 guest