Overheating?

[mcgc0]

Made it down here to the French alps. Ok on the autoroute at a constant cruising speed @ 150kph, but a couple of concerns;

- the moment I slow down and there is a queue or slow traffic the oil temp rockets to close, or on, the 2nd marker (above half way), this followed by constant dipping of low revs and engine cut out. Having to coast using the handbrake allowing me to keep the accelerator depressed to 2k revs just to keep the engine alight.

- less of an issue right now, but there is on the autoroute when hot occasional miss fire or just a bit lumpy acceleration if I floor the throttle by any degree. Me thinks maybe a dodgy injector cable/line?

Any ideas? Oil level is good and checked but can't figure out the overheating and engine cut out.

 

[Dekker]

Have you checked the oil cooler infront on the right hand wheel arch? Is the fan coming on? Is the thermostat working OK? Is there anything blocking the oil cooler air flow?
That's what I'd check. With the oil temp at 9 o/c the fan should be running. Remember it is also a 2 speed fan and it starts at the lower speed.

David.

 

[andrew_churcher]

Mate - just wondering if you have observed it start to come back to the half way mark once its approached the 2nd line. Mine was going above the 2nd line when i first bought it and when checked they found the temp sensor needed replacing (2nd speed fan wasnt coming on to bring the temp down in traffic). I have noticed now that as it approaches that second line it does level out and drop back to the midway position.

 

[ray stobbs]

if i was doing 150k 85 ish down a motor way my temp would not get past the seven o clock mark with all that air passing through it even in high temps do you see the temp gauge go up to eightish then the stat opens and down it comes to seven

 

[mcgc0]

David, Andrew, thanks for the prompt help. Good points and something to check first thing. Will manage things a bit gently on the way back. The two fan speed thing isn't seperate connectors on the cooler by any chance - meaning I can whip off the arch sheild and look for bad connectors?

Marcus

 

[mcgc0]

I do see in driving today the gauge climb then drop back when the stat/cooler kicks in. However, 10 minutes later its back up to nearly on the 10 o'clock line...

 

[Dekker]

ORIGINAL: mcgc0

I do see in driving today the gauge climb then drop back when the stat/cooler kicks in. However, 10 minutes later its back up to nearly on the 10 o'clock line...

The next place to look is the air cooling.
Is the curtain on the rear spoiler broken?
Is the spoiler extending at 50 mph?. Try the cabin switch and make sure it goes up and do a run to see if the oil temp is cooler.
Is the fan belt at the correct tension?
Is the fan OK any damage visible?

 

[RLambert]

It's going to be to do with the front cooler. For a start, is it getting hot? If it is then check the fan, I think you can unplug the temp sensor in the topof the cooler and it will stay on all the time.

 

[gregmarshall]

Also the Oil cooler fan is controlled from the AC climate control unit... is your AC , heat/cooling all OK?

 

[PMMatthews]

Some thoughts which may only help you eliminate possible issues, and give you further headaches, but here goes.

Is it running hotter than usual when you're up to speed on the autoroute? If so, then it sounds like the spoiler, and oil thermostat points might be valid. These wouldn't account for an engine that is only running hot when you slowdown though, IMHO. Other possible issues could be an air leak on the inlet manifold side, or air mass sensor(?) issue, leading to the engine running a lean mixture / hot.

If the hot and lumpy running only starts when you slowdown, then the oil cooler fan point starts to seem more valid.

Something else to check quickly would be the coils and ignition triggers for signs of heat damage. I had recurring problems with this (which, I hate to say, only got worse over time), which was eventually traced to an incorrectly routed ignition lead as the cause! The symptoms matched your description - the lead would cause the coils and/or ignition triggers to slowly burnout. Other occasions when this caused a problem were in the rain, when water eventually caused arcing of the errant lead, and major misfire / stalling issues until I gave the car chance to cool down.

Sorry if this just muddies the waters for you. Good luck in getting back (and at your friendly local independent), if you're not yet home.

 

[mcgc0]

Thanks all.

The last couple of days here it seems to be much more normal in running temp but learning in slow traffic to switch up the spoiler (it's flipping hot here!). Spoiler and spoiler curtain all working good. AC working fab - now that I've read the drivers manual and got settings optimized.

It seems then the main issue is long continuous speed journeys. Intermittent misfire when adding some pedal juice and rapidly rising oil temp when slowing right down in traffic queue or stationary idling - engine gives up and cuts out.

All the suggestions above seem valid and I guess I need to eliminate one by one. I will check the temp sensors/cooler and also get the coils and HT leads checked over and replaced. Driving back tomorrow so hopefully no or less weekend traffic slowing things up.

Cheers again...

 

[andrew_churcher]

man - its not what u need on holiday though is it. The missus patience for "its a 20yr old classic....sometimes these things happen" is generally short in my household!!! haha [][]

 

[mcgc0]

Thankfully the wife and kids are flying back a few days later... 8 hour solo driving stint ahead of me tomorrow.

 

[gregmarshall]

As I said on the phone Marcus, the overheating is probably a red herring. Check the ISV and it's problematic electrical connection, plus diz-caps and rotors...

 

[mcgc0]

Cheers Greg. Checked ISV and associated pipeware and me thinks I might have overfilled with oil while away as all seemed very oily inside. Cleaned all parts up, breather pipes, air box and mass air flow meter of any oily residue. Next was rotor arm clean up and the replacement of one of them. Dizzy caps looked ok with LT spring-loaded carbon contact looking good. Took it out for a spin and it seemed fine. A longer run this weekend will confirm.

For high oil temp concerns I found a neat article on bridging the cooler relay contacts for high speed fan switch on and have these going into a switch in the cabin. This allows manual switch-on before any unnerving temp rise to mega hot...

 

[Dekker]

Well you shouldn't have any problem checking the oil if it's getting hot well at least not have to wait long.

It must be overheating otherwise you wouldn't get the symptoms of sudden erratic tickover and cutting out with very low oil pressure.
If you say previously that the oil temp starts to drop when temp at 9 o/c but then starts to climb again, the fan is kicking on, whether it is staying on or the cooler air ways between the fins are blocked you will only find when you take the wing liner off and check it out.
The oil thermostat appears to be working otherwise the hot oil wouldn't reach the cooler and activate the fan.
Taking the temperature of the 2 pipes that lead to and from the cooler should give a good indication of how good the circuit is. The greater the temp difference etc.
By using the switch to turn the cooler fan on full speed, will tell you which area is the culprit. Oil cooling or air cooling.

I hope you'll keep us informed as to what you eventually find out is the culprit Marcus, but in the meantime safe drive home.

 

[mcgc0]

Cheers Dekker, Back home now from what was a clear run all the way - no slow or stationary traffic with no oil temp higher than 9 on the gauge.

Like you said it's the covers off and a check of the fan speeds and temps and a clean of any dirt from the cooler fins. Have a pink ticket for next weekend so will poke around - needs to be the Saturday as the Sunday it's Chelsea Autolegends for the day...