Yet more overheating !!!

My 110 Hi-Cap 300 TDI conversion landy keeps over heating.... I have seen a lot of similar threads and have already followed much of the advice but I'm still garaged and summer's coming.


Before you ask. The power and heater are working great! Water is flowing into the expansion tank and I have replaced the following;

• Pump
• Hoses
• Expansion tank cap
• Thermostat x3 times including genuine land rover
• Radiator (bearmach)
• Temp Gauge and Sender
• Viscous Fan with Electric Fan

I am not loosing coolant, and the system is not over pressurizing.

This is the agro section.
If take out the Thermostat the truck stays around 40 - 80 at load and the radiator is evenly hot all over. But as soon as I put the Thermostat back in the temp goes up to 100 and the rad is cold, and so is the top hose.

As soon as I pump it (the top hose) a few times it heats up along with the rad but quickly cools down until I pump it again but the engines stays hot.
I take out the Thermostat and again no problems, I have tested it (the thermostat) and it works. I have also tried every method listed to bleed it. What's up!!
..

So removing the thermostat fixes the problem? Sounds like problem is thermostat...

Having replaced it that many times, and tested it, it doesn't seem possible that the stat itself is causing the problem. Are you sure you are installing it correctly? Is it possible that corrosion inside the housing could prevent it from opening properly?

When you are refilling the system, where are you filling from? All caps off, radiator till it overflows then apply cap, thermostat till it overflows then apply cap, then expansion take to appropriate level is how I have done mine in the past with no problems

first off, is your temp gauge and sensor matched and working?

ie, did they both come from the donor and they worked fine in that?

those lil infrared laser heat guns are about a tenner and can double check. (i should start selling them as i mention them so much)

and it's polite to stick a post in introduce yourself

Thanks for the reply, regarding the temp gauge it was a matched kit sender and gauge brand new. thanks for the tip to introduce my self.

Regarding the thermostat I don't see what in the housing could restrict it and I have refilled it about six time now, even up hill. It seems like when it opens it pushes an airlock into the radiator or there is just not enough flow through it.

explain how you are bleeding it

also since it's a conversion.. i assume it has been plumbed in ok, etc.

it was fine when I got it, mostly.
In any case I have filled from the expansion tank with rad cap and therm housing open. once it over flowed from the Rad cap I closed it and kept filling till water came out of the therm housing. I then topped up the expansion tank, closed it and pumped air from the top hose filling the therm housing until it was overflowing. I then ran it and topped up from the therm housing a few more times leaving the expansion tank firmly closed.

Also to note the car was running in the upper 90 before I started all of this swapping and upgrading. I though that the conversion put the rad to far from the fan so I installed an electric one.

But now I don't see why the rad would not heat evenly with the thermostat in and would work perfectly without it?

sounds like the stat isn't opening. hopefully it's just an airlock.

try exp cap off and heat on full hot and let it idle for a bit

OK this is my plan for today, I still think it is and airlock so I'm going to take out the valve (ball bearing) in the thermostat to allow some coolant to move through when it is closed.

Result!! the car takes a bit longer to warm up but now my radiator is hot all over and no more airlock.... Runs now between 80-90

My cooling mods Fan and New Radiator

To remove the airlock issues I drilled out the thermostat valve

well done mate

I was just going to tell you to drill a tiny hole into the stat when I read the last post.

I always drill a very the hole on all the stats for BMW engines, it won't affect the cycling and guarantees to be air lock free.