overheating - thermostat

Hi guys,

I thought I had the problem fixed NOT

I booked the RR in for an MOT tomorrow morning and thought, I'd give it a trash down the road>
About a 5 mile trip and when back in the drive water was spraying from the expansion cap!
bottom hose from Thermostat was cold

Now I have replaced both, t-stat and expansion cap and even tested the t-stat before fitting it. (was working fine)

I have spent about an hour trying to get all air out of the system - t-stat still does not open.

The weird part is though that when I let it idle for no matter how long - it will not overheat, nor will the t-stat open.

Any ideas

Sounds like it's still air locked.

I assume you have squeezed all the pipes not just opened bleed screw?

Have you tried doing it parked at an angle? The air bleeding that is!

Bromsgrove Defender said:

Sounds like it's still air locked.

I assume you have squeezed all the pipes not just opened bleed screw?

Have you tried doing it parked at an angle? The air bleeding that is!

Click to expand...

I wish there wash a bleed screw on the p38

but yes, I think i've tried all options - even from an angle.

ⓡⓤⓓⓨ;1521816 said:

I wish there wash a bleed screw on the p38

but yes, I think i've tried all options - even from an angle.

Click to expand...

Is there coolant in the top hose?

Have you tried filling it from the top hose and expansion tank at the same time?

Bromsgrove Defender said:

Is there coolant in the top hose?

Have you tried filling it from the top hose and expansion tank at the same time?

Click to expand...

Yes, there is coolant in the top hose, but I have not tried the stereo filling yet

I'm gonna let it go cold and try again. The only issue is that when I leave the exp. cap off, water starts boiling over after a few minutes.
Quite normal I'd say as the system isn't pressurised, but very awkward to get any air out afterwards

ⓡⓤⓓⓨ;1521842 said:

Yes, there is coolant in the top hose, but I have not tried the stereo filling yet

I'm gonna let it go cold and try again. The only issue is that when I leave the exp. cap off, water starts boiling over after a few minutes.
Quite normal I'd say as the system isn't pressurised, but very awkward to get any air out afterwards

Click to expand...

I think if there's coolant in the top hose then the stereo filling wont help. :scratching_chin:

Have you flushed the radiator both directions?

Has it ever had stop leak or similar stuff put in it?

another place to check is the neck of the expansion bottle for hairline cracks. Had that on a Rover car. Always boiling over / spitting out coolant. Discovered the cracks (obviously letting air in when turned off = coolant instantly boiling when not circulating / pressure being maintained. Just a thought.

Water pump?

I've flushed the radiator - perfect flow
Inspected the bottle for hairline cracks - all fine

Waterpump is something I am going to check tomorrow. I have been thinking this myself since a core plug was missing (possibly through ice in block) it is very possible that they have tried to start the engine while frozen and sheared off the impeller......Just a theory

Another thing -- would a faulty water pump only cause it to overheat while driving?

ⓡⓤⓓⓨ;1521998 said:

I've flushed the radiator - perfect flow
Inspected the bottle for hairline cracks - all fine

Waterpump is something I am going to check tomorrow. I have been thinking this myself since a core plug was missing (possibly through ice in block) it is very possible that they have tried to start the engine while frozen and sheared off the impeller......Just a theory

Another thing -- would a faulty water pump only cause it to overheat while driving?

Click to expand...

I would have thought you'd have heard something, but yes possibly, assuming that is you have a standard Viscous Fan then I'm fairly sure it would prevent overheating on tickover.

Bromsgrove Defender said:

I would have thought you'd have heard something, but yes possibly, assuming that is you have a standard Viscous Fan then I'm fairly sure it would prevent overheating on tickover.

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Thanks, I do have the standard viscous fan.

1 more question......would a faulty waterpump also prevent the t-stat from opening?

Stat is not in the head or block I thought on that engine, so hot water not getting to it...

jonbill said:

Stat is not in the head or block I thought on that engine, so hot water not getting to it...

Click to expand...

There is hot water going to it (the hoses do get hot), but maybe it's not enough to open the t-stat......

Hey Rudy,

changed the stat on mine a while ago, bled the system pretty good but wanted to see the stat working before I went out for a spin...took maybe 10-15 mins sitting on idle to open up, so it does need to get pretty well cooked!

JD. said:

Hey Rudy,

changed the stat on mine a while ago, bled the system pretty good but wanted to see the stat working before I went out for a spin...took maybe 10-15 mins sitting on idle to open up, so it does need to get pretty well cooked!

Click to expand...

I've had mine idle for over 30 minutes and nothing

so its been frozen are you sure no other damage was done like cracked head or block?

ovalandrover said:

so its been frozen are you sure no other damage was done like cracked head or block?

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I'm not entirely sure it has been frozen. When I bought it, 1 core plug was missing. I thought it might've been frost, but could well be something else.

I just read in another thread that when the little pipe from the top of the rad freely flows into the exp. tank, the water pump is likely to be ok. I have free flow there....
This does not make it easier..lol

Have read a few times about people drilling holes around the stat to ensure waterflow, didn't like the sound of it myself though.

JD. said:

Have read a few times about people drilling holes around the stat to ensure waterflow, didn't like the sound of it myself though.

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Yes, I have read that too, but like you, I don't like doing that either.
I really like to get to the bottom of the problem instead of masking it!