My project LR3 seems to have an overheating issue.

The instrument gauge says normal but temps raise above 220 with my scan tool into the ODBII port before I shut it down.

From my understanding normal temp is in the area of 206-212

Today I removed the thermostat out of the housing to see if it made any changes but it did not.

Any ideas.

 

How far above 220? 200 is not odd and within spec. If you removed the t-stat then it should be running cooler though.

 

It's not running cooler without the thermostat.

It take about the same amount of time to get up to operating temp.

Today I waiting until it got to 212 then I put the heater one. After a minute I still was not getting any heat. So I know I have a flow problem.

The LR3 does not seem to have a gate that opens the coolant to go to the heater core so coolant flows through the heater core at all times. Is this correct?

Also I'm the LR3 came with green coolant and the original radiator so there is a possibility that the radiator may not flow as well as new if it was not flushed properly when switching from orange to green coolant.

 

Correct, its a constant flow core.

And true, if the coolant flush was not done properly you could have some blockage.

Its odd its not running cooler with no t-stat. The t-stat, like most, is variable and it regular coolant from the radiator which is MUCH cooler than engine temps. With no t-stat to regulate the radiator will flow 100% causing the engine to overcool. You may have much larger issues besides some blockage.

 

Doesn't the LR3 use ORANGE coolant? You might try doing a coolant flush, as someone might have screwed that up in the past and caused a blockage (excessive air maybe?). It doesn't matter if you pull out the the thermostat if your lines aren't flowing properly. Also, if coolant isn't circulating in your radiator, it doesn't matter how fast your fans are running, as no flow means no cooling. Flushing the lines is a pretty simple thing, especially compared to newer cars. Might as well switch back to the ORANGE coolant while you're at it, as it's the recommended coolant and I don't trust the previous owner didn't use whatever cheapest **** green coolant they could find.

If flushing it doesn't help, you have bigger problems, like actual corrosion/deposits in the radiator or engine channels, reducing thermal transfer.

 

Yep, thanks guys.

My next plan of action are to remove the hoses for the inflow and outflow of the heater core and see if I can get flow just using a long hose and funnel with gravity. If that does not work I'll use a garden hose. I figure it is clogged I can't really do any more damage with the garden hose.

I'll then do the same with the radiator.

I need to spend more time right now on my P38 getting it ready to sell....so hopefully I'll get to this in a couple of weeks.

Thanks again for the input

 

Well, happy to report the LR3 is running cool again.

I flushed all the lines and there did not seem to be any blockage.

Replaced the pump, thermostat, belts and radiator. Yes I threw a bunch of parts at the problem but with 130,000 miles I figured it was good preventive maintenance.

One thing to note. After flushing the coolant, new pump and new radiator I tried to run it without the thermostat installed. This still ran hot. My guess it does not allow the coolant to flow properly.

My guess it was the radiator. Very dirty between it and the condenser. Maybe it could have been flushed and cleaned but a new one is a good piece of mine.

 

Sounds like radiator was clogged if it was still hot with a new pump and you were able to flush water through the hoses and engine block. Good thing you didn’t run it much before fixing the problem.

I would avoid using a garden hose to flush a block. Spending money on distilled water, even for flushing is worthwhile.

 

Yep, I just used distilled water and a long hose with a funnel to let gravity do the work of flushing.

The more I think about it, the thermostat could have been the problem and only needed about a $40 new thermostat.

The big thing I learned was you can't run it without the thermostat in the housing.

 

Why do you believe it was the thermostat? I read through the symptoms and come up with a different diagnosis.

When the thermostat was removed the engine continued to overheat, which indicates no coolant circulation. Diagnosis would be clog in system or failed pump. A failed thermostat, once removed, would have resulted in overcooling.

Once the pump was replaced that ruled out the pump, leaving only a clog. Replacing the hoses and flushing the block narrowed the blockage down to the radiator. I’m not one to encourage changing parts “because it needed it”, but refreshing the cooling system around 100k miles is good maintenance. A standard cooling system refresh wouldn’t include a radiator, but yours was definitely faulty and it was necessary.