I'll preface this with saying I've read a bit today, so I apologize for being redundant, and appreciate the help in advance.

My Disco normally runs at 50% on the temp gauge (At first I thought it was a tripped sensor of something because it's been cooler here, there was no smell of coolant/burning, and there was no excessive heat coming from the engine as it sometimes does in the summer. ), but over the last two weeks its been running hotter, hit red a few times, and finally gave me the white smoke today.

The temp gauge comes down when hot air actually blows through my vents (about 40% of the time as of late), but waves back and forth between 50% and over the top of the gauge, and red on occasion.

Temp also tends to drop when on the highway. All but one time.
Earlier this year, I took it to my mechanic because it was running really hot (nothing unusual in the temp gauge) He told me the t-stat wasn't opening... I had the t-stat replaced last Oct, and it was still under warranty, so I took the truck back to the shop that did the original work. They found nothing wring with the t-stat, but found the radiator vent tube was broken and was leaking so much that the expansion tank was almost empty. They replaced the tube, and bled out the system. No further problems.

So far I have checked the fan, it rotates about a quarter of a turn before stopping (Savannah, I think this is what peanut butter is supposed to feel like ). I've felt the temp of the radiator, the whole thing was cool (About 20 min after shutting off).

When I went to check the t-stat, I dropped my pliers, and found a bit of oil leaking when I was under the truck (pics attached).


So my thoughts are:

1. Heater core. She doesn't blow consistent heat. Plus, I have the waterfall sound behind my dash... Not sure if this is related.

2. New radiator. I would think it would be warm to the touch 20 minutes after overheating.

3. Head Gasket work: There are signs of oil leaking from it, and my mechanic said this could be a future problem back in June.

What are your thoughts gents? should I replace the heater core and radiator now, just to throw in $2k towards the headers next week?

 

Oh and yes, I will be purchasing an UltraGauge this week.

 

If you're heatercore was leaking you would have coolant mist on your windshield and coolant soaking your passenger side floorboard. Additionally you'd be able to smell it because coolant is constantly running through the dash. You may want to try back flushing the system for heating problem.

If you're head gaskets havent been replaced they are and will likely be a culprit for you. I'd recommend pressure testing the system. White smoke would indicate coolant mixing with oil. Is your oil milky? When it overheated was coolant boiling in the expansion tank?

Don't let it overheat into the red you are taking a big risk in doing that. When it overheated was it at idle? If not, when? Was this before or after they bled the system?

 

Heat is not stable as you have air in the system and low coolant, or both. Steam won't make as much heat in the core as hot water. If those bubbles under the dash are exhaust gas you could have head gasket leak or cracked block. An exhaust gas in coolant chemical test will confirm what the source of the bubbles is. A coolant pressure test will show where leaks may be.

Radiator could be partially clogged. The cooling tubes run left/right, and sludge makes bottom ones block off. Use an IR themometer point and shoot to measure the temp just after shut down, top to bottom on the fins, looking for 10F difference or less. Mark I palm reader not reliable for this.

Temps dropping on highway (or much higher in town) might also point at the fan clutch, blades for fan, or electric fan.

 

Ok, so no mist on the windshield, and the floorboard is dry.

I let it idle for 15 minutes this morning and oil is not milky. Three tests.

I do not recall coolant boiling in exp tank when it overheated. When idling this am, temp gauge sat at 50% for 10 min, then crept upwards after that. After shutting down I did not hear or smell boiling coolant. I opened the exp tank as soon as I could, and no boiling coolant.

The overheating happened after about 5 min of driving at 25-35 mph. I have not let it idle long enough to see if it would overheat.

System was bled on May 16th.

 

I downloaded an infored app for my phone, it was useless.

The fan clutch and fan were replaced last October as well. Not sure on the electric fan.

I will have it chem tested this week.

 

If you want some help with this problem, send me your number and I'll be glad to walk you thru the steps to take before you start throwing parts at it.

 

Is replacing the head gaskets something that I can do myself, and just have the heads planed at the shop.

Taking my time this weekend, and going step by step using the RAVE is well worth saving $1k+.

Until now, I've only been a brakes, oil, and transmission fluid changer.

Let me know what I'm in for, and if I should just bite the bullet and take it to the shop for full repair.

Thanks again

 

Thanks Mike, just sent.

 

Plenty of real Rover rascals on here have done that and posted the steps, etc. About two weekends under the hood, with machine shop inbetween. $300 ish parts (use new bolts), plus machine shop inbetween. Shop will want the parts, plus machine shop, plus mark up, plus haz mat fee, plus about 12 - 15 hours time.