Physics q on oil and water temps....

[JMC 0]

...to run much hotter then before they are rebuilt? If so, how long is it likely to last? The reason I ask is that I had my G60 taken from 1.8 to 1.9 with a recent rebuild (done about 1200 miles so far). Now, it's great fun (don't get me wrong) but the oil temp is about 10 degrees hotter than it was before the rebuild. At the moment, it's not been mapped and is generating about the same power as before, oil pressure seem fine, my oil cooler is getting hot, so that seems to be working alright. Basically though it is running quite a bit hotter. It's not a problem when moving but as soon as I get stuck in traffic my water temp starts to shoot up and sits around 105, which I am not used to, and with hot weather on the way I'd like my mind putting to rest please :D .

[junkie 0]

Mine on 1900 with the turbo as well does the same in traffic, but with the mocal 13 row on when driving sits around 80 degrees.

 

Maybe as its not properly mapped it may be running slightly lean and causing slightly higher temps.

 

Remember its a tuned performance engine so expect higher temps.

[JMC 0]

Cheers Simon. It's not the magnitude of the oil temp as such that bothers me (sits at about 110 on the motorway, as opposed to 100 before the rebuild), it's the fact that the water temp rockets up as soon as I get stuck in traffic. May have to consider a bigger oil cooler now then :? . Maybe where I have the oil cooler isn't the best location (where the old G60 intercooler was), combined with it only being the small 13 row one (about 6 inches long) which means that the new engine is much more work for it.

[vwdeviant 0]

To go to 1900 don't they have to open the bores out? Hence less metal between the combustion and oil/waterways so more heat?

 

Try a fan on the Mocal if you are worried. Wouldn't be too paranoid about oil temp through the MFA as sender's probably a bit inaccurate too!

 

My Valver sits at 108 motorway and 112/4 traffic, but a mate's "dip sender" down the dipstick tune said 102.

[dirtytorque 0]

my oil cooler sits next to my fmic so as to get air in from the front of the car..

an option maybe?!?!?..

[junkie 0]

Mine is mounted vertically, as your looking from the front of the car its to the right of the left hand headlight next to the intercooler behind the grill.

 

The water temp is the same on mine.

[flusted 0]

new thermostat?

[JMC 0]

new thermostat?

 

Don't think they installed a new thermostat when they did the engine - wasn't one on the bill anyway :lol:

[Jim 1]

Maybe worth getting some higher power fans installed in the rad to help bring the temps down? Can you get a lower temp fan switch for your rad perhaps?

[JMC 0]

I've got one of the aftermarket fans from G-werks in there at the moment, wired so it comes on a full power when it is in operation - just wondering whether it is worth fitting a manual override as the fan switch seems to be a bit slow (fan doesn't come on until 100). Of course I could just replace the fan switch :lol:

[CTWG60 0]

I've got one of the aftermarket fans from G-werks in there at the moment, wired so it comes on a full power when it is in operation - just wondering whether it is worth fitting a manual override as the fan switch seems to be a bit slow (fan doesn't come on until 100). Of course I could just replace the fan switch :lol:

 

I'll be fitting a larger capacity engine in the near future and I noticed you have a golf front mount intercooler. I too have a FMIC from a golf G60 and I've bought a new larger radiator that is also from a Golf G60 I can get you the part numbers and dig out the ebay sellers name if you want. It might be running hotter just because there is more friction a the moment due to bedding in of the engine. I'm also thinking of fitting a fan to the oil cooler I have for hot days in motorway queues that would blow with the rad fan for simplicity. :)

[JMC 0]

Cool CTW that would be really useful. I think its definately oil more than water based though - think a bigger oil cooler may be needed, especially if I am making more power. I tried a fan on my cooler and it made everything run hotter :cuckoo: . The fan impeded the ariflow unless it was turning - tookit off and everything cooled down again :D

[CTWG60 0]

Cool CTW that would be really useful. I think its definately oil more than water based though - think a bigger oil cooler may be needed, especially if I am making more power. I tried a fan on my cooler and it made everything run hotter :cuckoo: . The fan impeded the ariflow unless it was turning - tookit off and everything cooled down again :D

 

Interesting what you say about the fan on your oilcooler! Did you fit it to the front or the back? The oil cooler I have is new but from and audi 80 diesel, the great thing is it fit's perfectly into the old G60 intercooler ducting and I've mounted it in that location so a fan at the rear that sucks air through it should be ok! :scratch: As the air pressure differential between the front and the rear of the cooler at that location should be enough to turn the fan during driving I hope.

 

I'll fit it before I fit the new engine and see what happens. The audi 80 diesel had fan assisted oil cooling in a similar location.

 

EDIT

 

big golf g60 rad part no. b 191 121 253 AL

 

ebay contact for this as VW no longer have stock is felgenhaus_co_uk.

[JMC 0]

Mine was a rear mounted fan, but I found it just impeded the flow of air when it wasn't running. I had it mounted in the same place as you. To improve airflow I cut loads of small (12mm diameter) holes in the wheel arch liner behind the cooler. No idea whether it made any difference, but basic air flow tells me it hasn't done any harm. Thanks for the details on the rad :D

[boost monkey 0]

:salute: keep goingwith the science mods Jon!

 

Will email thos docs soon, still a bit hectic i'm afraid! :?

[CTWG60 0]

Mine was a rear mounted fan, but I found it just impeded the flow of air when it wasn't running. I had it mounted in the same place as you. To improve airflow I cut loads of small (12mm diameter) holes in the wheel arch liner behind the cooler. No idea whether it made any difference, but basic air flow tells me it hasn't done any harm. Thanks for the details on the rad :D

 

Hmmm! Maybe I won't bother then. Maybe a stupid question but was it mounted to suck air through the cooler?

[JMC 0]

Yes it was mate, lol. Maybe better in your case, all down to the individual fan design I suppose. I did a back to back comparison on the motorway driving under standard conditions to figure my temp differences out.

[JMC 0]

I know that will have put most of you off, but hopefully some fellow science geeks can answer this. Been keeping an eye on water and oil temps on my G60 since the rebuild. I've noticed that the water temp comes up quickly to 90, while the oil temp rises a lot slower, but ends up finally at a higher value.

 

I have a mocal oil cooler which I thought were thermostatically controlled and therefore not going via the cooler all the time. Surely this should speed up the oil temp rise, while mine seems to be rising slowly. Also, anyone know what temp the mocal plates switch over - my cooler is warm when the mfa read 70 degreess for the oil temp? Any thoughts on this (or a healthy scientific discussion of what is going on) welcome :D

[boost monkey 0]

I would say:

 

Oil has a larger density and therefore will take longer to heat up, but when hot would take longer to cool down even though it gets thinner with temperature it is still a more viscous fluid than the coolant.

 

hth,

 

Jon.

 

p.s. # rho rho rho your pressure vessel, laminarly down the fluid with negligible-surface-roughness #.... catchy?

[Toad 0]

I believe that the Mocal plates don't entirely cut the oil supply off to the radiator, just restrict it. Otherwise you'd suddenly get half a litre of cold viscous oil in the engine when the stat opened, and any air in the system after fitting the mocal would also go straight in and cause seizure.

 

I don't like the idea of completely removing the oil-water cooler, they help the engine warm up evenly and quickly enough, plus if your mocal is working well and the oil temps have been brought down then they might actually remove a little heat from the water.

[JMC 0]

I would say:

 

Oil has a larger density and therefore will take longer to heat up, but when hot would take longer to cool down even though it gets thinner with temperature it is still a more viscous fluid than the coolant.

 

hth,

 

Jon.

 

p.s. # rho rho rho your pressure vessel, laminarly down the fluid with negligible-surface-roughness #.... catchy?

 

Ah, but the thermal capacity of water is greater than that of oil, so it should take longer to heat up and cool down (but obviosuly the cooling down method is different and will have an effect). And yes, very catchy :lol:

 

I believe that the Mocal plates don't entirely cut the oil supply off to the radiator, just restrict it. Otherwise you'd suddenly get half a litre of cold viscous oil in the engine when the stat opened, and any air in the system after fitting the mocal would also go straight in and cause seizure.

 

That makes sense Toad - hadn't thought about the thermal and viscous shock of suddenly having a litre of cold oil join the system. That would explain why it is warm even after a short journey, and why it is relatively slow to warm up - the rad being slightly open all the time would provide constant cooling. Am I right in thinking then that the water rad is not used until it is up to temp, or does the water system work the same way, providing slight cooling until up to temp when the stat opens fully?

 

Times like this I realise, how little I actually know.

[boost monkey 0]

This is true Jonathan, thermal conductivity is measured in W/mKand to be honest I haven't done a great deal of work in it (avoided this question today!) but would be interesting to see data for both G12 coolant with a water base and also engine oil...

 

which engine oil do you use as it should have a different conductivity depending on it's viscosity/

[JMC 0]

Specific heat capacity of ethylene glycol based coolants are about 20% less than pure water from what I can gather in standard concentraton ranges. Oil wise I use Synta Silver (so a 10w40 semi sythetic) and I should think oilman will have that sort of info. Gut feeling - the water based coolant will still have a highe specific heat capacity than the oil, but I will have a dig round and find out....

[boost monkey 0]

:salute: this is where the fun begins!