MN (2.5hp) High Engine Temperature Thermostat Modification

[SEJ GLX-R]

My MN has been running high engine temps, at between 95 - 105 degrees but not overheating (boiling). As we know, there are a few threads on over heating MN Tritons here, here and running temps here but I didn't want to loose this in one of those threads so I started this one.


I have been watching my engine temps on the ScangaugeII like a hawk for a long while now which goes back to when the car had about 10,000kms on it. The original coolant went a brown colour very early on. I did a full flush, cleared all the coolant out (not just drain the radiator) and put in some nice new (non genuine) coolant in. After that I noticed the engine temps were higher than before, between (95 - 105). Thinking I had an air lock in it I tried everything to get the air out with no success. I put up with it for a little bit and thought maybe it is due to the non genuine coolant so did a full flush on it yet again using genuine coolant with no improvement.


Thinking about it more and more I came to the conclusion the thermostat was faulty as the engine temp was always between 95 -105 no matter what the outside temp was. I had driven it in over 40 degree temps and down to single figures with the frost warning on, still high engine temps.


I bought a new thermostat to fit and noticed that it didn't have an air bleed hole in it. This got me thinking again about an air lock behind the thermostat.
Today, I finally pulled out the thermostat and sat the old and new ones in a pot of water and brought it up to temp......... surprise surprise, they both operate at the correct temp (82 degrees) Which means it was an air lock all along.


Now to the modification part.

- Remove the thermostat from the engine, (under the power steering pump with 3x 12mm head bolts)
- Check the operation it a pot of water to ensure the thermostat is fine,
- Drill a 1/8" hole as close to the seal as possible,
- Refit the thermostat with the hole right at the top,
- Refill your coolant,
- Test drive your Triton,
- Check, check and recheck for leaks,


During my 50km test drive up some long hills, I am happy to report that my engine temps now range from 86 - 94 not 95 -105 The funny thing is the temp gauge has always sat in the exact same place, right in the middle.



Please note:- I did this for high engine temps, NOT overheating, and it worked for me. If your Triton overheats (boils) take it to the dealer, this will not help that.

[Homer]

Good post mate there's been a few people chasing lower engine temps. This could possibly help them.

[fraz91]

I've noticed after every coolant change the dealership does, it tends to run a little hotter for a while (verified by Torque OBD app and engine fan). After a couple of good runs or off-road adventures though, it tends to settle down. Might have to look at doing this the next time if it doesn't work.

Great write-up though

[snowman]

nice work Sej.

[Tony]

Nice work and yes all thermostats should "ideally" have a bleed hole although once open should burp the air lock out with the heater tap open etc..

a side note...... You dont want them running much cooler than 82c, as temp sensor 2 (The one the scan tools see) plays a big part in the ECU functions including emission control.

[GLRkenny]

Good to hear it worked sej, I used to do it to all my commodores too, when both my cars get their coolant changed I will do this for sure, is the seal just an I ring type or will I need gaskets?

[SEJ GLX-R]

........ is the seal just an I ring type or will I need gaskets?

It's just an O-ring

[srb]

Just wanted to thank SEJ for posting this mod. I have always thought that mine ran a little hotter than most MN's (Ultragauge measured) Well I did this the other day and can confirm that it works a treat! I have notice about a 8- 10 degree drop in max temps. I Would always see 95- 105 degrees no matter what the ambient temp. So did this little mod and now I don't see it get past 93 max around town it's at 85- 89 So it seems mine had an air lock since new. I had mentioned my higher than normal temps to my dealer and they were going to change my fan and thermostat at the 30k service but they didn't get time and said to bring it back. No need to worry now.

Hay CD if your listening... This could be your problem too?

[Cowboy Dave]

If I'm listening? Sheesh. This one is possibly beyond me... I don't seem to get quite as hot as you. I did get a little excited when I saw the Tridon thermostat described as a high flow... Not sure if that would help. Might buy one, drill the hole and get it changed over next service.

I spent today modifying the plate that runs from the bash plate to the front of the bull bar. I cut two big rectangles out and then riveted in two sets of forward facing vents/scoops with a view to channeling more air in towards the transmission cooler and intercooler. If it doesn't look too crap when the paint is finished I might even post a photo tomorrow.

[SEJ GLX-R]

Just wanted to thank SEJ for posting this mod. I have always thought that mine ran a little hotter than most MN's (Ultragauge measured) Well I did this the other day and can confirm that it works a treat! I have notice about a 8- 10 degree drop in max temps.

No worries I'm glad to hear it worked for you too

[killa]

..

[Calblitzen]

Has anyone tried the waterless coolant. (http://liquidintelligence115.com.au/) NBo water, therefore no steam and low pressure. Appears radiator cap can be removed whilst the car is hot.

[Longranger1]

Has anyone tried the waterless coolant. (http://liquidintelligence115.com.au/) NBo water, therefore no steam and low pressure. Appears radiator cap can be removed whilst the car is hot.

Looks like interesting stuff. Thanks for posting.

[killa]

..

[Calblitzen]

Has anyone tried the waterless coolant. (http://liquidintelligence115.com.au/) NBo water, therefore no steam and low pressure. Appears radiator cap can be removed whilst the car is hot.

Looks like interesting stuff. Thanks for posting.

Not cheap stuff I think about $40 a litre (maybe wrong), however it lasts the life of the vehicle.

[Mattstruck]

Mine is running same temps as your was Sej.

Tell me, do you lose much coolant pulling it apart?

Do you need to buy any coolant or just top up with water?

Any photos?

[SEJ GLX-R]

Mine is running same temps as your was Sej.

Tell me, do you lose much coolant pulling it apart?

Do you need to buy any coolant or just top up with water?

Any photos?

You will lose a fair bit of coolant Matt, I drained my radiator into a clean container and re-used it but you will still lose a couple of liters when the thermostat comes out.

Grab a 5 liter bottle and that will give you plenty spare for top-ups.

No pics sorry. My plan for the thread was to have pictures but it was too hard to take any showing anything important so I didn't put then on.

[Mattstruck]

Okeley dokely.
I'll put it on the to do list

[Kegsy]

List is gettin longer schmuck...

[rodeddy]

hi guys,
I'm about to do this mod.. Just checking, when i undo the 3 bolts holding the thermostat housing on, that the rubber O ring seal which is attached to the thermostat itself, is the only seal / gasket required? As when i look at the housing it looks like when i undo the 3 mounting bolts, not only will the thermostat housing come of, but the plate it is attached to, looks like a spacer plate, has a normal gasket to where it is attached to the main water outlet, will also come loose and need replacement?
any info appreciated.
cheers, Rod

My MN has been running high engine temps, at between 95 - 105 degrees but not overheating (boiling). As we know, there are a few threads on over heating MN Tritons here, here and running temps here but I didn't want to loose this in one of those threads so I started this one.


I have been watching my engine temps on the ScangaugeII like a hawk for a long while now which goes back to when the car had about 10,000kms on it. The original coolant went a brown colour very early on. I did a full flush, cleared all the coolant out (not just drain the radiator) and put in some nice new (non genuine) coolant in. After that I noticed the engine temps were higher than before, between (95 - 105). Thinking I had an air lock in it I tried everything to get the air out with no success. I put up with it for a little bit and thought maybe it is due to the non genuine coolant so did a full flush on it yet again using genuine coolant with no improvement.


Thinking about it more and more I came to the conclusion the thermostat was faulty as the engine temp was always between 95 -105 no matter what the outside temp was. I had driven it in over 40 degree temps and down to single figures with the frost warning on, still high engine temps.


I bought a new thermostat to fit and noticed that it didn't have an air bleed hole in it. This got me thinking again about an air lock behind the thermostat.
Today, I finally pulled out the thermostat and sat the old and new ones in a pot of water and brought it up to temp......... surprise surprise, they both operate at the correct temp (82 degrees) Which means it was an air lock all along.


Now to the modification part.

- Remove the thermostat from the engine, (under the power steering pump with 3x 12mm head bolts)
- Check the operation it a pot of water to ensure the thermostat is fine,
- Drill a 1/8" hole as close to the seal as possible,
- Refit the thermostat with the hole right at the top,
- Refill your coolant,
- Test drive your Triton,
- Check, check and recheck for leaks,


During my 50km test drive up some long hills, I am happy to report that my engine temps now range from 86 - 94 not 95 -105 The funny thing is the temp gauge has always sat in the exact same place, right in the middle.



Please note:- I did this for high engine temps, NOT overheating, and it worked for me. If your Triton overheats (boils) take it to the dealer, this will not help that.

[rodeddy]

hi guys,
I'm about to do this mod.. Just checking, when i undo the 3 bolts holding the thermostat housing on, that the rubber O ring seal which is attached to the thermostat itself, is the only seal / gasket required? As when i look at the housing it looks like when i undo the 3 mounting bolts, not only will the thermostat housing come of, but the plate it is attached to, looks like a spacer plate, has a normal gasket to where it is attached to the main water outlet, will also come loose and need replacement?
any info appreciated.
cheers, Rod

[Cowboy Dave]

Are you doing it twice?

The bloke who posted up about this mod is away for the weekend on the robe trip so he won't answer til next week, if he answers at all.

I haven't done the job but I bought the thermostat. I was also able to source a gasket from an auto shop somewhere which purported to be a gasket for the thermostat.

[Glock40sw]

G'day.
A photo of where to drill the hole would be good.
Thanks.

[GLRkenny]

G'day.
A photo of where to drill the hole would be good.
Thanks.

Hole has to be to the top


And the oring should be the only seal req'd, from memory the plate(housing) behind has more bolts to hold it in

[rodeddy]

hi ....... I'm on nightshift and a little brain dead and don't really know how i managed that ... lol

thanks for the info. I simply bought a new thermostat, drilled the hole and fit next week on my days off.

cheers for the info..

Are you doing it twice?

The bloke who posted up about this mod is away for the weekend on the robe trip so he won't answer til next week, if he answers at all.

I haven't done the job but I bought the thermostat. I was also able to source a gasket from an auto shop somewhere which purported to be a gasket for the thermostat.