All,

Searched the forums but couldn’t find the answers so looking for help. I’m a new disco 2 owner and took delivery of the truck a week ago.

Upon delivery of the truck, I hooked up an ultra gauge to monitor temps and they were max 206 deg using the oem 190 deg thermostat. The truck had a SAI SES code on both banks that I was aware of prior to purchasing. After finding a leaky hose to the charcoal canister and a faulty SAI solenoid I finally got rid of the codes for the SAI faults.

However, the truck started suddenly running hot. I noticed the temps while cruising out of my neighborhood were over 220 deg so I turned around back home and parked it. From my research, the SAI system isn’t tied to the cooling system so not sure if the timing of the cooling issue is coincidental or if they are indeed interrelated systems.

I bought a oem 180 deg thermostat to help lower the temps. I parked truck on an incline overnight, removed reservoir and raised it so it’s at the highest position, removed bleed screw on the hoses and proceeded to bleed the system using Peak 50/50 coolant. I added coolant until it was coming out of the bleed screw then put the bleed screw back in and continued to fill the reservoir to the cold fill line.

I started the engine with heater on full blast and let it run for 15 min and temp on the ultragauge was at 195. After tidying everything up I went for a test drive. While cruising the temps were in the 195 deg range however once I got to a stop light and idling the temps started creeping and hit 230 until I started moving again.

Any ideas what to look at next? New fan?

Thanks
Carlo

 

The D2 does not have a valve that lets the coolant into the heater core only when the heater is on. It runs continuously through the heater core. So no need to run the heat inside.

In my book, I would shut that engine off well before 220. More like 212-215 for me and it is stopped.

Pull the lower hose from the radiator and unscrew the cap on the overflow canister. Does it flow well? No real measurement for flow but just an eyeball test of a possible clogged radiator.

 

It would be a good idea to check your bleed.

Do this in the morning when the engine is cold...

Parked on the level, open bleed screw and inspect. If fluid level is not all the way to the top, you have found some trapped air. Eliminate the air pocket by adding coolant directly into the bleed screw hole until full. Replace bleed screw. Drive as normal and note temps.

Check again the next morning and top off if needed.

Repeat until air pockets are displaced completely.

 

Thanks everyone for the suggestions. I will try and report back.

 

I'll throw this out there as well, if you added Peak coolant to a system that still contained OAT, you will likely develop issues. The two do not mix. One theory could be that the truck was full of coolant when you bought it and then consumed it to the point that it started running hot, coincidentally when you fixed the SAI. Then you changed the thermostat but it still needs more bleeding to get the air out. You may want to get a cooling system pressure tester and a hydrocarbon test kit if you do not get the temps back down. Hopefully this is not the case but suddenly overheating after fixing the SAI is a bit troubling.

 

Thanks everyone for the suggestions. I think I found the issues that caused the high temps and have fixed the issues at least it seems that way.

Upon inspection of my reservoir tank this morning it was a bit lower than it was yesterday. Removed the bleed screw on the coolant hoses and coolant was not visible. I believe I had an air pocket that must have been filled once the engine cooled over night. I topped off the system and started squeezing the hoses looking for leaks. I noticed a fine spray of coolant coming from the hose that goes to the top of the coolant reservoir. Tightened the clamp and it appears to have fixed the leak.

Furthermore, a friend suggested to check the fan rotation as I could potentially have a bad fan clutch. I tried to spin the fan with the engine cold and it spun about a 1/4 of a turn at most. But in that 1/4 of a turn I noticed the fan blades were interfering with the fan shroud!

I watched some videos online and saw the shroud should be secured by two screws on the top of the shroud and two screws on the lower part of the shroud. My truck is missing the two screws at the bottom of the shroud and was misaligned causing interference with the fan! The fan shroud misalignment seems to merely be coincidental with fixing of the SAI.

I secured the fan shroud with some spare screws I had laying around and took the truck for a 30 min spin varying the load from idling at stop lights to flooring it up a hill I live on. Temperatures during cruising and stop lights stayed in the 188-195 range. While flooring it up the hill I saw temps of 200 deg which quickly went back down to the mid 190s once I went back to partial throttle.

It seems like my cooling issues have been resolved, but I will continue driving the truck today and monitor temps.
Thank you everyone for the suggestions.

One last thing I noticed on the truck is the drain tube at the top of the coolant reservoir is capped off. The truck has the throttle plate bypass on it. Having the drain tube capped off doesn’t seem part of the throttle plate bypass mod from what I’ve read. Does anyone know why the drain tube would be capped off? See attached pic.

Thanks,
Carlo

 

All Peak coolant? This Peak Coolant has OAT inside - the Euro Vehicle Pink bottle.

 

The capped off tube is the reservoir overflow drain. It's odd that it's capped off but it's easy to leak some coolant out of that pipe when filling up the reservoir and it kind of drips down inside the engine bay, I wish they would have made the tube longer. Perhaps that's why it's capped off? I would uncap it and start the engine and let it warm up while observing it in the driveway just for peace of mind.

Also, I'm just gonna throw this out there as I'm officially a convert- but seriously consider the Inline Thermostat Mod. Forum user Extinct has a really good kit that's well priced and easy to install. When I bought my truck it was running warm for my liking but still OK, I bought a Duralast 180 degree thermostat and installed it while flushing my coolant and and it helped a little bit but it clearly was not a 180 as I was typically in the 190's and up to 210 sometimes when stopped in town. After the mod I'm always between 177-182 regardless of the load condition on the engine. It's fantastic.

 

Thanks I’ll try and see if uncapping that line does anything.

I’ll look up that inline thermostat mod! Thanks for the suggestion.

 

check motor mounts as that often leads to interference with the fan and the shroud..