V8 engine temperature - running very cool!

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MikeV8SE

MikeV8SE

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Right guys, was driving along the M4 down to Wiltshire today for a spot of beating and noticed that the engine was running really cool.

Now, I should say that it did get up to temperature before (it tends to sit halfway in normal conditions, just below half if it's cool outside, say sub 10'C) but at around 60mph the temperature dropped right down to just below the first mark on the gauge and stayed there for the whole motorway journey.

Is this normal? Or a sign of something minor (dodgy thermostat?) or something major (anything else!)? I would say that it was cool outside, I would guess hovering around 5'C, and damp too with a layer of fog.

Would you say this is normal? Oh, was also running on LPG, which should make it run hotter I'd have thought?

Cheers!
 
i had the same....check the Stat......it my not be working also some have summer stats in them. i changed mine for a higher temp stat and all was OK
 
Thermostat stuck open.

I've just had to change mine due to my new engine running too cold and the faulty stat was brand new. After changing it, it's closer to normal temp, but it's still running a little cool so i've removed my viscous fan now too.
 
redarrow007 said:
i had the same....check the Stat......it my not be working also some have summer stats in them. i changed mine for a higher temp stat and all was OK
Click to expand...

Thanks - what degree stat did you go for in the end?

renton500 said:
Thermostat stuck open.

I've just had to change mine due to my new engine running too cold and the faulty stat was brand new. After changing it, it's closer to normal temp, but it's still running a little cool so i've removed my viscous fan now too.
Click to expand...

Did you try sticking the stat in warm water to check it? Also, do you have to drain the system to change the stat?

kieronf said:
Faulty stat or viscous coupling failure. Check that you can stop fan with rolled up paper.
Click to expand...

Will that not damage the fan blades?

Cheers guys! :)
 
From cold, the viscous coupling should allow free rotation of the fan blades. If the coupling has failed, and is 'driven' from cold, the engine will not warm up. Simple test on a cold engine is to see if a rolled up newspaper can hold the blades. If your paper is chewed - your viscous coupling is shot
 
kieronf said:
From cold, the viscous coupling should allow free rotation of the fan blades. If the coupling has failed, and is 'driven' from cold, the engine will not warm up. Simple test on a cold engine is to see if a rolled up newspaper can hold the blades. If your paper is chewed - your viscous coupling is shot
Click to expand...

OK, so if I go start the car now (been stood for 4 hours outside) then should the fan rotate and be easily stopped, or not rotate at all?
 
thermostat sticking slightly open will cause this, the viscous unit should draw strongly when first start up from cold and quickly stop driving after a minute or so, no mater what the temp is the needle should be at half way on the gauge with out removing viscous units etcetera
 
OK, with the engine switched off the fan spins reasonably freely in both directions. Bit of resistance, which I believe is normal, but all looks fine.

Started the engine up and left it for a minute or so, stuck a rolled up newspaper in it and the fan stopped with ease.

So next step is to check/replace the thermostat I guess. Do you need to drain down the system to do this?

What stat do I need, I've seen 74, 82 and 88 degree ones for the V8 readily available? Mine is a late model soft-dash Classic V8 auto if that makes any difference. Will be used all winter but also on a trip to Morocco next year, will the same thermostat be suitable for both uses?

Cheers!
 
MikeV8SE said:
Did you try sticking the stat in warm water to check it? Also, do you have to drain the system to change the stat?
Click to expand...

No, didn't test it cos they're only cheap so just put another new one in. I did drain the system from the bottom hose to try and avoid getting too much coolant on top of the valley gasket and on the dizzy and make a mess, but you could prob just undo the top hose at the rad end, empty that out, then take the other end of the hose off, then remove the stat housing. It would be a bit more messy, but would mean you wouldn't have to use so much new coolant. Depends if you want to do replace your coolant at the same time I guess :)
 
Hope this sorts it for you.... I am still on about a 1/3 way up on engine temp which takes about 15 mins to get there. Problem I have is getting the housing bolts out as they are well and truly tight. Think I have a new 88 stat ready to go in.
 
fett said:
88 degree one for the uk , not sure about on your desert trip- depends how hot it gets there.
Click to expand...

Cheers Fett, what are the other two rated ones for then, hotter climates?

Morocco will be approx 32-38'C mostly - so hot but not insane.
 
For what it's worth, Morocco is a popular destination for Portuguese offroad fans and I've never heard of anyone replacing the stat to go down there. Assuming that the same stat is fitted to the RRs that were sold here (which I'm 99.99% sure), you shouldn't have any problems.
 
To be honest, in theory, the stats should not need to be changed. Its only really when the coolant system is marginal in terms of its efficiency that you'd need to do it.

I got a near new rad fitted in m bobtail before fitting the disco serp engine and a new viscous unit.. Engine takes only about 5 minutes to get to temp, then stays there...regardless of whether its just on idle, driving like a granny on a sunday afternoon drive, or thrashing the nuts off it foot hard to the floor (which was fun).
It highlighted to me just how bad the old rad and viscous unit n coolant system in general was in the old engine...even before I had the problems with it.
I'm seriously considering fitting a new rad to the silver daily driver RRC asap, even though I've not ever had overheating problems with it.
 
fett said:
thats ok for uk, but the other stats are listed becuse they are for overseas markets, like saudie for example
Click to expand...

Yep true. But what I'm sayin is if the coolant system isn't doin what it should do, fitting a stat with cooler opening temperature means the engine runs cooler. The engine temp is gonna be higher than ambient temperature, so running different rated stats on a std engine isn't really always the answer. Yes, difference between ambient and engine is gonna be less in Saudi, n greater in UK this time of year....but ya engine SHOULD be running at about the stat opening temperature. If it aint you got problems
Racers do it cos they're running engines that could potentially overheat very quick otherwise... In a std road engine ya shouldn't need to...though I appreciate LR might suggest it cos they know the V8 has a pretty fookin marginal coolant system compared to other engine systems, even when new! lol
 
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