2004 Disco - Overheating after head gasket and ALL cooling components replaced
 

My 2004 Disco has 98k miles on it and is running hot after all cooling systems components were replaced. Listed below is what has been done to the vehicle:

New Radiator
Thermostat
Fan Clutch
AC Fan
All cooling hoses and pipes
Water Pump
Head Gasket

I just picked it up and according to my ODB gauge I am running about 217 on average. I can see the two fans running and no coolant is leaking, and I can also not smell any coolant. It is not completely overheating, but I know this is too high an operating temperature. I will be contacting the shop that did all this work (over 3k) but I would like some feedback on what else it could be. Thank you in advance for your help.

What thermostat did they install? Do a block check.

It was an OEM thermostat. I also needed to mention that I use DashCMD as my tool for checking the temp. I realize it may be off a few degrees, but before I was having overheating issues my truck ran in the upper 190's. They did an overnight pressure test and could not find any leaks in the engine. They tried all other componnents first before the head gasket was replaced.

Yeah do tell us which thermostat you are using. How is your engine oil? Is it low by chance or leaking? Just trying to start with the small more obvious things.

Keep us posted on how things turn out.

The oil does drip a little. It had an oil change when the head gasket was replaced. I'm not sure the model of thermostat, but they did tell me it was a land rover brand. In fact before doing the head gasket they told me they tried 5 thermostats as they were convinced that was the issue. The hoses, water pump, radiator were replaced as they showed leaks during the pressure test.

Maybe they didn't bleed it correctly.

That's my bet, too. Probably a very easy fix.

OP just be careful. Like someone else on here said the other day - the temp gauge only has 3 readings; cold, in the middle, and 'it's too late'... Regardless of whether or not you plan to take it back to the guys who couldn't get it right the first time, don't risk overheating it.

If I were you I would switch out your thermostats for this 180 degree TD5 thermostat. Read through various threads on this site alone and you will see how many owners stand behind this thermostat, Myself included. My engine temps went from 212 in city/197 highway down to 197 city and 188 highway and that was just after swapping out my old genuine LR thermostat. THERMOSTAT ASSY DII & FREELANDER 180 DEGREES FAHRENHEIT, PEL500110, RNQ028 - Rovers North - Classic Land Rover Parts

If you decide to order it, wait until you get it than take the time to bleed the cooling system while your swapping out the other thermostat. This way you can make sure the bleeding was done correctly and if you do it yourself you wont have to pay for labor. Various owners myself included have found that if you CAREFULLY pick up the coolant expansion tank and hold it at an angle as high as it will go, it makes the bleeding job easier and pushes more air out of the plastic coolant bleed screw. Be very careful when working around any of those thin plastic cooling pipes because they are notorious for becoming brittle and snapping if you play with them to much. Ive snapped at least 3 pipes on my truck so far.....

Good luck mate and keep us posted.

Was the cap replaced, if it is not hplding preasure your temp will be high because the system is not preasuruzed

I'm riding the inline thermostat high right now. So I would do that and you'll run 188 all the time.

But first make sure they bled the air right. And if you want to try and genuine 180 thermostat.

Disconnect coolant tank carefully when engine cold (don't break anything) and put on top of battrey box or hold it high, (make sure it won't move around if start engine,) fill a little over full line, then loosen bleed screw on T and let it lose coolant till see study stream of coolant, then tighten , (don't over tighten it, or you will break it),
Then start it , let idle a little, now sit inside, and give it little gas , then release pedal, if you hear water fall sound means there is air in heater core, if so, best way to get it out is to park the truck somehow that front of truck is at least a foot higher than back , youCan use ramps under front tires, or find a high curb (and using low gears drive front tires on top of curb),

Put coolant cap back on & tighten, let engine run till hot ,while giving gas now & then till gets hot, then turn off & let it cool down, if you repeat a couple times , and front of truck is raised enough , should get red of all air in heater core , (no more waterfall sound from under dash), and it should run normal temp even with standard thermostat,

Of course lower temp 180 t-stat will bring temp down another few degrees,
Good luck,

Crank the temp all the way up on your AC head unit and find out if the system will blow hot air, i.e. "The heater." This will give you a reference point of air in the coolant system. If it is blowing cold air then you definitely need to bleed the air out of the cooling system. And definitely heed the advice of replacing that OEM Tstat with a soft-spring 180 deg. If the shop used red dex-cool for coolant then you will want to flush that out and use the traditional green fluid with distilled water and a coolant additive. Do all of this yourself so that you know exactly what's going into your vehicle and finally bleed it properly. As long as you have a screwdriver and your OBD or outboard temp Guage you will have no problem. My temp was about 217 also. I did everything mentioned above while replacing fan and clutch and my temps went down 20 degrees. Good luck and get that under control STAT.

Can you explain that, please ?

If a cap does not hold pressure; would that cause overheating ? Or just cause coolant/steam loss and because of that loss, could overheat from lack of coolant ?

Am sure without a cap will not overheat. It will not pass 100C / 212F.
But we have to define a temperature borderline to name it overheat.

I propose defining overheating as over 110C / 230F --->Would that be reasonable ? Is there an already established consensus ?
New cars with idiot pointers tell us nothing, as what is factory 'normal'
If I remember well, the top 'white zone' on Land Rover is 111C

Water under pressure boils at a higher temperature that water not under pressure.

"When the external pressure is:

- less than one atmosphere, the boiling point of the liquid is lower than its normal boiling point.

- equal to one atmosphere, the boiling point of a liquid is called the normal boiling point.

- greater than one atmosphere, the boiling point of the liquid is greater than its normal boiling point."

And yes, it would keep steam from escaping as well...

We all know fifth grade boiling points.

It is about overheating; which is not the same.

Well if it's such common knowledge to even a 5th grader then why are you asking those '5th grader' questions questions in the post previous to my last? Most people don't get snarky when people offer them helpful advice and suggestions. I'm sorry you're having a bad day.

Put in the 180 degree thermostat now.
If you don't do that - you are absolutely asking for trouble.
This is the middle of the summer.

Just do this.
Don't question it. Do it.

Made the BIGGEST DIFFERENCE on my D2.
You will drop 10 to 20 degrees.

If you refuse this advice - you deserve to overheat. Sorry but... that's the truth.

Drowssap and June8200 are correct. Everything has to be leak-proof and air-tight for a pressurized cooling system, such as that of the Discovery to work properly. I had a tiny pin-hole crack in the neck of my expansion tank which is the same thing as a faulty cap in this case. Even though the loss of coolant was so unremarkable that I could not even find the source of the leak without having to pressure test, my vehicle began running hotter and would have over-heated had I not known there was a problem.

Updated Information
 

Hello all,

I was mistaken regarding the thermostat, it is not an OEM, but the NAPA 180 degree thermostat. The part number is NBH 34723. Since this is a 180 degree thermostat, should I still purchase the Land Rover 180 degree thermostat that was recommended in this thread?

AK, the inline thermostat mod will take you an hour and cost about the same as an OEM thermostat. Really does improve your engine temps and it is all upside for the rest of the life of the truck.

But if you want to stick with the original setup then in hot climates the gurus recommend the 180 soft spring thermostat, which is designed for diesels. This is the one.

you probably want to check it with a digital thermometer to see when it is opening

Napa thermostat is made in China Junk.

Get the land rover 180 degree.

People put in Motorad 180 degree and those are junk too.

Sorry but you need to pony up $80 for the right genuine part.

Your engine is not worth holding out for $80f for the correct thermostat.

Just stay home from going out on the town for a week or two.
That will pay for it.

Or do the inline mod and your thermostats will cost between eight dollars (cheapie--stay away) and 11 dollars (tops!). Sorry. Broken record... but it really is a great mod.

The only way a cap not sealing causes overheating, is allowing the water in the mix to reach boiling point and escaping, therefore coolant level goes down and overheating occurs. If you do run without a cap,(unless you use waterless coolant like EVANS Coolant) once your temp reaches boiling point of water, it will escape and overheat.
Waterless coolants actually recommend drilling very small hole in radiator cap, because boiling point is 375* and you want the water to escape and replace with more coolant until system is totally waterless.

Easiest thing to do is start with ordering the 180 TD5 thermostat. Bleed the system and evaluate the results. It is critical that you find the source of the high temps and correct them ASAP.

What kind of coolant are you using? What color is it?

Thank you all for the feedback. I have ordered the suggested 180 thermostat, and will bleed the system and install the new one. The current coolant is the green from NAPA. What brand do you suggest I replace it with?

Brand of coolant is not as important, just use any conventional green coolant,
Bleeding system completely out of air is the real key,

I think the concern was whether you were using red/orange coolant (dexcool), which can thicken and sludge... especially when you switch coolants from red/orange to green.

more important is that the dexcool is never allowed to mix with air. It then starts solidifying which is were your real problems come from.

Thank you!!
 

The new 180 thermostat seems to have worked. My truck is running about 10 degrees cooler on average. I will keep an eye on the temp with the DashCMD app, but I think this worked!!! Thank you all for the recommendations of using the thermostat. It is amazing that a more expensive after market part that claimed to be 180 degrees did not work.

Congrats!

THat is often the case, but I still get the cheap stuff anyway. HAHA

Charlie, does that mean you are using the Motorad Tstat? That's what I have since it was the only item available,locally, when I did my last cooling system upgrade. I'm sure the LR gray would get my temps a few degrees lower but this cheapo is close to spec

No, I did the inline thermostat mod so I am using a ten dollar Chevy thermostat. I'm also using the cheapie MAF (amazon, 40 bucks... has worked fine for almost two years), allmakes window regulator, etc. But the one thing that I would always buy OEM is the thermostat, and I would get the soft spring gray one I linked earlier in this thread. I'm obviously NOT a purist but I have replaced my own head gaskets twice and the second round, I am pretty sure, was due to a stuck Motorad thermostat (with the stock hose setup... prior to the inline mod). Everyone says the Motorad thermostats are junk and I don't believe that, but I got a bad one and the fix is no fun. For similar reasons I won't eat take out chicken, but that's another story.

I trust Rovers North took care of you and was very friendly? In any case we may never know exactly why your temps were at their previous level. Assuming you replaced the thermostat with the grey 180 TD5 and assuming that while you were swapping them out you also did a good bleed on the cooling system. The high temps could have indeed been the thermostat and they could have been the cause of air in the cooling system. Either way test out the cooling system. Warm up the truck, take her for a good long drive through city traffic then turn the AC on full blast and idle the truck for a little while and WATCH THOSE ENGINE TEMPS LIKE A HAWK! If your cooling system is in good shape now and there are no other issues than with your new thermostat you should be getting around 197-205 under the above circumstances and around 188 on the highway.

Good luck and Im happy its working out for you so far. Keep us posted.