Well, I am fairly optimistic that my on-going rev-limit cut in problem (ecu sets the rev limit to 5500rpm)seems to have been fixed. The bits checked/replaced were (in order)
Spark plugs
Wheel speed sensor
Vacuum hose
Coil pack & plug leads.
I had to take the Exige on a 250 mile round trip today and the problem never occured once - so fingers crossed!
During this trip, I got stuck in a mega traffic jam on the A34 (road closed due to a vehicle fire). As I sat there in the baking sunshine, I watched the temperature guage going up, up, up, thinking that the fan would cut in at some point, but no! As the guage read 116 - 118 I decided to pull to the side of the road and switch off before it boiled over. It ran fine after I had let it cool off and I checked the fuse to see whether it had blown, but it seems fine, so I assume fan motor has packed up - is this an easy to replace item or a clam off job?
Also while crawling in this traffic jam I noticed a new noise! A distinct knocking from the rear nearside but only at very low speed. You don’t notice it at speed. Any ideas what this might be?
Oh well, it will be back to my friendly local Lotus specialist next week!!
Yes the rad fan is a clam off job i’m affraid. 118 is seriously hot, all of my fingers are crossed for you as I have known head gaskets fail at a lot less than that before.
The knocking could be a drive shaft CV joint. Did the knocking increase with road speed?
Hmm, what symptoms should I look out for re HGF? It ran fine afterwards with the temp at a steady mid-high 70’s and the coolant level in the expansion tank was normal when I got home. I’m off to the Nurburgring in three weeks so the last thing I want is for it to fail while over there
The knocking noise was only noticeable at crawling speeds, it seemed to disappear when the speed increased.
Thanks!
Neal.
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[quote=SeanB]Hi Neal,
Yes the rad fan is a clam off job i’m affraid. 118 is seriously hot, all of my fingers are crossed for you as I have known head gaskets fail at a lot less than that before.
The knocking could be a drive shaft CV joint. Did the knocking increase with road speed? [/quote]
Yeah I agree it doesn’t sound like your HG has gone, I just wanted to state that in my own experiance HG’s have failed due to overheating at a lot less than that.
How close are you to Dudley in the Midlands. We have a device we can screw onto your header tank that measures any combustables that are in your coolant. It takes 5 mins and is obviosulsy free of charge and would put your mind at ease.
Thanks for the offer Sean, I am in Bicester, Oxfordshire so about 70 miles from Dudley. I am going to book it into my local Lotus specialist to get the fan fixed/replaced and will ask if he can do any checks re possible HGF. I checked it again yesterday and the expansion tank level has dropped a bit from where it normally sits, but seems okay. I also checked the oil filler cap which appears clean (no sign of mayo!), so hopefully I have been lucky!
The fact that you pulled over at 118 should prevent a head gasket going in the future, in my experience a HGF as a secondary failure was 95% of the time caused because the engine really did get cooked (ie rad failure and then driven with no coolant)
Fingers crossed you should be OK. While it’s in the garage it may be worth having a manual override fitted? You can also force the fans to full speed manually by switching on the Cir Con if you have it.
Fan override is a good idea, that way if you know you are going to be stationary for a while, you can get the fans on early to avoid having to play catch up when they eventually switch themselves on at 100ish.
I know its a race car, but I have my rad fans set to come on at 90 degrees.
Elise parts do an override kit (I have never used this).
Looking at the wiring diagram’s it looks like you could bypass the fan relay by putting a switch between the BN/BG wires. This would need some 30A cabling and a 30A switch as the fan load is 25A.
A better solution is to provide a separate switched earth to the US wire going into the relay. (Note: This wire does feed into pin 57 of the engine ECU that provides a low current earth to switch the fan on.)
