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oil thermostatic valve


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Hello all.

I suspect that I may have a stuck (closed) oil cooler themostat, and I wonder what the correct opening temperature might be, so that I can test it.

Also by way of experiment, is it safe to run with it removed?...

It is a 1997 300TdiDef. 78,000 mls.

Many thanks.

and best regards.

Howard.

2X300TdiDef.

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workshop manual doesn't give any opening/closing temps for that thermostat, as for running with it removed the oil may not get to the right temp or may get too hot & overheat.

sure I've a used but working spare oil stat in my garage, will go have a look.

it's the same on the TD/200 & 300Tdi engines ERC5923

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Found my old stat, it has

G 910529 & 74C stamped on the body

I'm thinking the 74C is the operating temp 74 degrees Centigrade.

same as this one ERC5923

Many thanks Ralph. Good man as ever...

I have fitted a thermometer to the exit pipe of the rad- Oil cooler, and on the 220mile round trip that I made today the max. Temp. 'found' (have to stop to check) was 67c. Out of intererst I am going to fit a second thermometer to the inlet side to find out what that is.

The problem is: I can cruise 'all day' at 50/55 mph, and the oil warning will NOT come on the next time the engine idles.

If, I cruise at 60 Mph: the oil warning DOES come on at next idle.

If I then slow down to 50 ish, for 10 mins. or so, then the oil light will stay 'out' as is normal.

The engine sounds great with normal power, and no water over heating.

I will fit an oil gauge when I can, and find the oil pressure for sure.

It's been like this for a 'few' months, but with mainly local motoring, it does not happen.

Duckhams' semi synthetic 15/40, 80,000 miles, 'sounds as sweet as a nut'.

Maybe the plastic bodied oil pressure has 'gone high with age'? let's hope so!

All thoughts, and observations warmly recieved....

Howard.

Isle of Skye.

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check the idle revs too [750 to 800rpm] I had a flicking oil pressure light & idle, raised the idle revs to nearer 800 & that stopped the light flickering.got to be worth a try, if it still flickers then replace the pressure switch.

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check the idle revs too [750 to 800rpm] I had a flicking oil pressure light & idle, raised the idle revs to nearer 800 & that stopped the light flickering.got to be worth a try, if it still flickers then replace the pressure switch.

Be nice to think so eh.

Will report back when my VOLVO AWD. Rear wheel bearing is done, and I get a chance at the LR. Had to buy a hydraulic press today for that job, they wanted £450 for hub assby! So bought a press for half that.

Best regards.

Howard.

PS. I can spell Thermostat if I try hard enough.

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  • 2 weeks later...
didn't notice the missing letter till you mentioned it :lol:

I fitted an oil pressure gauge today, in place of the oil pressure switch.

Ambient temp. +10c. On start up, 40psi on tick over. 60psi when revved up.

When warmed up after 30min. drive, 20psi on tick over, 50 psi when revved.

Seemed the same after 50 min.

This doesn't seem too bad to me, what is anybody else getting please?

The old switch has a translucent cap on it's body, that seems half full of oil! so that can't be good, I will 'lash out' on a new one.

Thanks in advance.

Howard.

2X300TdiDef.

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25 psi to 55 psi :)

Edit: That is assuming Ralph meant kgf/cm2, otherwise he meant some unit I've not got in my converter app here.

Thanks Retro---

Yes he had me going for a bit with that cm3... Must be thankfull to Ralph though, probably wrong in the LR book, not a standard SI unit anyway!!

For the folks at home: 1kgf/cm2=14.223 psi.

BUT what I realy wanted to know was the pressure the oil switch tripped at, I feel sure these figs. are for the normal oil pressure range(25-55).

No one go to bed yet.

Howard.

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Thanks Retro---

Yes he had me going for a bit with that cm3... Must be thankfull to Ralph though, probably wrong in the LR book, not a standard SI unit anyway!!

For the folks at home: 1kgf/cm2=14.223 psi.

BUT what I realy wanted to know was the pressure the oil switch tripped at, I feel sure these figs. are for the normal oil pressure range(25-55).

No one go to bed yet.

Howard.

Books correct cm2 see above ^^^^ my fault eye to finger trouble :lol:

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the normal switch will trip at something like 3-5psi on most cars usually.

Our A4 is a bit odd in that its switch trips at 14psi, however only the turbo models got the 14psi switch, the cooking spec models got the 5psi switch.

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the normal switch will trip at something like 3-5psi on most cars usually.

Our A4 is a bit odd in that its switch trips at 14psi, however only the turbo models got the 14psi switch, the cooking spec models got the 5psi switch.

Arrrr, thanks a lot Aragorn, for that. I should be ok with a hot oil pressure in the teens then.

I seemed to recall that it was fairly low, but needed some re-assurance.

Been on the web and phone today, and it was a bit hard to find them actualy in stock.

Thanks again.

Howard.

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you been shopping for a thermostat then ?

cos my old one which works is sat here doing nothing.

Hi Ralph.

I dont think I will need another one now, as the oil temps seem ok.

I am going to fit thermometers to both the inlet and outlet of the oil cooler though, and take some records, and report back here for the pleasure of my soulmates.

It looks to be the pressure switch, which is nice. However it started when I fitted a new oil cooler/rad. And so it mislead me.

I suspect that the idea is that the oil cooler is always 'in-use', when the engine reaches 'normal' temps. But is not used in freezing conditions, I will find out.

Many thanks for your help.

Howard.

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  • 2 years later...

I'm in the process of changing the o ring and i noticed there are 2 washers sitting between the spring and the bulb and there doesn't seem to be any mention of them in the parts catalogue and diagram. I've never had any oil temp pressure problems but am curious to know why they're there.

post-22390-0-84249600-1330429887_thumb.jpg

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That's how they come, you need at least one for the t/stat to close and no, as far as I could make out they aremn't mentioned in any parts list ?? (although I don't have Microcat up and running yet)

I changed mine five or so months ago as it had jammed open and as a consequence i couldn't get the coolant up to operating temps unless I went for a 25km minimum drive during winter.

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