Does your water temp move at all on track?

[shimmy]

Any unexpected high temps on track at WOT always points to HG failure between cylinders if said temps then fall quickly when slowing. Most HG failures blow into coolant or oil system which is easy to diagnose. E46 M nearly always between cylinders. Less easy to spot and can remain minor until complete fire ring failure shows itself with a noteable miss-fire.

Any problems like this an I'd have a cylinder leak down test, NOT compression test.

Alex, why does cylinder to cylinder leak cause higher temps at full throttle then?

[shane@mbtech]

Alex, why does cylinder to cylinder leak cause higher temps at full throttle then?

Full wot will create more heat, the heat and subsequent Movement/expansion of the head/block IMO then highlights the hg slight failure, the increase in cyl temps due to the cyl to cyl then IMO accelerates the issue further

These are all just theories, Each part only has to be minute to create overheating issues

Once it's got too hot once then I feel damage is already done, ticking timebomb then.

Try the basics first, forget your fan, it's got fuck all to do with it, unless it overheated whilst stationary at an earlier date.

We had a similar problem on a big powered Evo
It left us and several big tuners scratching our heads.
We looked at it from a very basic angle, tried a thermostat as it was basic diagnosis and it fixed it.

Said tuner had done all kinds of things to remedy it, as they built the engine from scratch, the problems started soon after. They even wire rung the head
A preventative measure that masked rather than cured.
Same fault happened again.

We replaced stat and problem fixed.

[funtime]

Lawsy & Shimmy - agree with your theories, not sure about Alex's case, but my fluctuation in water temp does not follow high oil temp. My water temp is moving about without the oil going over 100, (only 1-2mm left and right of the centre of the gauge in normal driving) so I've been advised to change the thermostat first.

As soon as I have done so i'll report back - good thing is I'll know as soon as I've done it whether it's fixed the problem as it shouldn't move at all. (or so I've been told)

Fingers crossed

[shane@mbtech]

Lawsy & Shimmy - agree with your theories, not sure about Alex's case, but my fluctuation in water temp does not follow high oil temp. My water temp is moving about without the oil going over 100, (only 1-2mm left and right of the centre of the gauge in normal driving) so I've been advised to change the thermostat first.

As soon as I have done so i'll report back - good thing is I'll know as soon as I've done it whether it's fixed the problem as it shouldn't move at all. (or so I've been told)

Fingers crossed

Yours dropping below also, does sound like a stat issue

Hope it's a simple fix for you.

[AlexGTT]

Lawsy & Shimmy - agree with your theories, not sure about Alex's case, but my fluctuation in water temp does not follow high oil temp. My water temp is moving about without the oil going over 100, (only 1-2mm left and right of the centre of the gauge in normal driving) so I've been advised to change the thermostat first.

As soon as I have done so i'll report back - good thing is I'll know as soon as I've done it whether it's fixed the problem as it shouldn't move at all. (or so I've been told)

Fingers crossed

Mine wasn't a case. Not had HG probs with mine..................yet!

Shim, any transfer of compression to another cylinder before it's ready for that particular cycle will cause heat issues. Then add combustion to that other cylinder as well (ignition from the cylinder that's lost the compression across the gasket) and you are effectively getting pre-ignition. If that is happening durring the up stroke of the next door piston.......................well, you can imagine the rest:bigcry: with the engine turning at 133 revs/second @ WOT.

[glendog74]

Mine wasn't a case. Not had HG probs with mine..................yet!

Do pay attention Alex - Funtime is referring to 'alexk' who has posted earlier in this very thread... :whistle:

Clearly you haven't been spending enough time on this forum lately! :hahaha:

[AlexGTT]

Do pay attention Alex - Funtime is referring to 'alexk' who has posted earlier in this very thread... :whistle:

Clearly you haven't been spending enough time on this forum lately! :hahaha:

Sorry Sir. Must try harder.:smt075 Feckin' hell, sounds like every school report I ever got.:hahaha: Things never change.

[alexk]

thermostat analysis

Today I found the time to remove my thermostat and do a comparison to the new one.
I am reminding that I had an overheating problem at the track.
I was also experiencing a drop in water temp after a fast run (i.e. highway with 200km/h and then backing off, the water temp would drop... and then after a while will go back to the middle).

I changed the viscus fan sometime ago as mine was dead.
This solved the overheating problem but clearly the thermostat was faulty too.

I ran a few tests using the traditional method of a an old pot and hot water.

1st test, put boiling water inside.
The new thermostat is on the right on all pics.
It opened faster but also opened wider.
You can see there is a difference of 2mm.


Then I quickly pulled them out for a pic.
Again the difference is massive.


I let them cool down and then did a 2nd test.
The result was similar.


3rd test
I started putting cold water inside.
The old thermostat didn't close fast enough (that explains my water temp dropping when backing off).


I am confident my temp issues will be totally resolved with the new thermostat.
My recommendation is if someone has overheating issues to change the viscus fan and thermostat.

Last but not least, a picture of my helper 'Pipis'.

[shimmy]

Very interesting Alex, great test and nice pussy :thumbs:


I have my M stat fitted now so my temps are rising slower than before but no test yet of overheating issue, need 23oC + for that

[Bounce]

I bet you can boil an egg to perfection Alex.:thumbs::thumbs::hahaha:

[magnust]

...
I am reminding that I had an overheating problem at the track.

...

I changed the viscus fan sometime ago as mine was dead.
This solved the overheating problem but clearly the thermostat was faulty too.

VERY interested on how it was behaving at the track before and after changing the fan "thingy"! A bit surprised the fan would be involved in cooling the engine at speed on the track.

[alexk]

VERY interested on how it was behaving at the track before and after changing the fan "thingy"! A bit surprised the fan would be involved in cooling the engine at speed on the track.

It is a very tight track where you do 5 corners doing 60-65 (2nd gear).

[magnust]

It is a very tight track where you do 5 corners doing 60-65 (2nd gear).

Ah! Thx!

[shane@mbtech]

It is a very tight track where you do 5 corners doing 60-65 (2nd gear).

The Viscous pulls air through the rad from outside the car. When you are travelling at say 15mph, the air pushing through the rad is far greater than your viscous can pull it through.

Viscous only works when stationary or crawling in traffic.

[alexk]

The Viscous pulls air through the rad from outside the car. When you are travelling at say 15mph, the air pushing through the rad is far greater than your viscous can pull it through.

Viscous only works when stationary or crawling in traffic.

You theory is correct mate.
However, I have seen many times in Greece (with temps above 40C) BMWs having overheating issues when driving up a hill/mountain on 2nd or 3rd gear (40-80km/h) which were caused only by the faulty viscus fan.

You will notice the sound of the fan on a very hot day when accelerating on 2nd gear for example.