4200 Thermostat

CatmanV2

CatmanV2

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Folks

Anyone know what temperature these are meant to open at? I used the opportunity of the leak test after replacing the header to fire my thermometer at the radiator top hose while the car came up to temp.

The temperatures climbed what seemed rather gradually, until the ultraguage was indicating near a **** it 90C, the infra red was only reporting 70C. There didn't seem to be much of a leap either.

On the road, it drops to about 72 on the motorway, but will cheerfully hit 99 in traffic...

Thoughts?

C
 
Zep

Zep

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Is the top hose the return from the rad? Is so should be a bit lower. The fact that an IR thermometer reads surface temp will also have a small effect. I'll measure mine over the next couple of days and let you know.
 
CatmanV2

CatmanV2

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Cheers. I guess it might be the return. Very close to the 'stat. Would they put the stat on the return?

C
 
drewf

drewf

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Zep said:
Is the top hose the return from the rad? Is so should be a bit lower. The fact that an IR thermometer reads surface temp will also have a small effect. I'll measure mine over the next couple of days and let you know.
Click to expand...

CatmanV2 said:
Cheers. I guess it might be the return. Very close to the 'stat. Would they put the stat on the return?

C
Click to expand...

The top hose is never going to be the return... Hot in at the top, cold out at the bottom; that's how every rad works, as far as I know.

The stat is on the return line in loads of cars. Have a quick Google at how 'easy' it is to replace a stat on a Freelander, then wonder wtf were they thinking!
 
CatmanV2

CatmanV2

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drewf said:
The top hose is never going to be the return... Hot in at the top, cold out at the bottom; that's how every rad works, as far as I know.

The stat is on the return line in loads of cars. Have a quick Google at how 'easy' it is to replace a stat on a Freelander, then wonder wtf were they thinking!
Click to expand...


Well, Zep is an air conditioning man, so he may have been confused ;)

Hmm. Sensible place to put a stat, indeed
C
 
drewf

drewf

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Good point, I'd forgotten Zep lives in a different world.

6-8 hours to replace the Freelander stat. Top design, that..
 
Zep

Zep

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drewf said:
The top hose is never going to be the return... Hot in at the top, cold out at the bottom; that's how every rad works, as far as I know.

The stat is on the return line in loads of cars. Have a quick Google at how 'easy' it is to replace a stat on a Freelander, then wonder wtf were they thinking!
Click to expand...

Its got a pump on it so the altitude of the connections is largely irrelevant in my experience (unless the medium inside is evaporating or condensing in which case you are right). Now, having looked at the radiator diagram the top hose goes to the thermostat and the hose from the engine goes to the bottom.... I will be back in about 20 mins....
 
CatmanV2

CatmanV2

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Zep said:
Its got a pump on it so the altitude of the connections is largely irrelevant in my experience (unless the medium inside is evaporating or condensing in which case you are right). Now, having looked at the radiator diagram the top hose goes to the thermostat and the hose from the engine goes to the bottom.... I will be back in about 20 mins....
Click to expand...

I could have told you that. In fact I sort of did....

C
 
Zep

Zep

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You did! I was just checking again before checking my temps.

For my money the bottom hose gets hot first, so the stat is on the return.

To answer your original question - the temp sensor is in the pump this might explain why we read colder temps at cruise, it's measuring the return water temp which will always be colder than the engine. The difference between the IR and the temp sender is probably because rubber is a good thermal insulator and so the external surface temp is not a true reflection of the temp of the contents.
 
Zep

Zep

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As an aside, I picked this up from the machinist today...

9bf321144c31735e215adafe38e3556d.jpg
 
conaero

conaero

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Zep said:
As an aside, I picked this up from the machinist today...

9bf321144c31735e215adafe38e3556d.jpg
Click to expand...

Very nice mate!

Just to confirm our earlier conversation, there is only one wire to the 4200 oil pressure sender, where you have a second wire from GOK
 
Zep

Zep

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I traced it out, it was not connected, just tucked into the loom on the left hand side. Someone might have been using it to confirm there was pressure - I did ask them to check it out when I bought it.

My car now only has one wire too
 
Zep

Zep

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It's pretty much the same as yours, 90 in traffic and low speed, a bit above the 70 line at cruise (about 75ish if I was to guess). Slightly above 90 after 5 laps of brunty. Always has been like this, was going to change the stat at some point, but anyone I've ever asked has exactly the same thing.
 
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