oil temp very high, water temp normal. Any ideas?

[williamp]

Got a problem with my Aston DBS V8, and the forum and two specialists have rtun out of ideas.

Basically, the car has 10 litres of oil and a few more litres of water. Its a lot of fluid to get hot. Usually, the water gets to 70 deg, and the oil about the same on a hot day.

However, my oil gets very high- over 100 degrees indicated. Its not high speed running- just idling in the garage for 10 mins or so. Even on a low speed drive (max 1500 rpm) the oil goes very high.

And we cant figure out why.

-Its not the sensor. New one replaced old, same symptoms
-Its not the gauges: both oil and water gauges recently refurb'd, and swapping the feeds shows the same increase on either dial
-It did have a blockage in the system, but now it has now oil pipes and both new oil coolers. In fact, after an idle in the garage the oil coolers get very hot to the touch.

So, I am certain the oil IS getting hot, rather then something misreading.

-Oil pressure is good throughout- what you'd expect. So oil pump is OK.
-The spark plugs indicate its not running lean

Any ideas?

[Snake the Sniper]

Do the oil coolers have fans? Does the gauge temp come back down when driving?
Oil should be ok up to about 110 or so degress, so it might not be much to worry about.

[Boosted LS1]

I agree, it shouldn't be that hot. Sounds like the oil is doing to much work somewhere and collecting heat. Any sources of extra friction? Has the car had a health check, valve clearances, compression check etc?

[GreenV8S]

Is it over-filled, or perhaps there's some other fault allowing more oil to fall onto the crank than normal? Being whipped up in the crank case puts a huge amount of heat into the oil.

[stevieturbo]

williamp said:

Got a problem with my Aston DBS V8, and the forum and two specialists have rtun out of ideas.

Basically, the car has 10 litres of oil and a few more litres of water. Its a lot of fluid to get hot. Usually, the water gets to 70 deg, and the oil about the same on a hot day.

However, my oil gets very high- over 100 degrees indicated. Its not high speed running- just idling in the garage for 10 mins or so. Even on a low speed drive (max 1500 rpm) the oil goes very high.

And we cant figure out why.

-Its not the sensor. New one replaced old, same symptoms
-Its not the gauges: both oil and water gauges recently refurb'd, and swapping the feeds shows the same increase on either dial
-It did have a blockage in the system, but now it has now oil pipes and both new oil coolers. In fact, after an idle in the garage the oil coolers get very hot to the touch.

So, I am certain the oil IS getting hot, rather then something misreading.

-Oil pressure is good throughout- what you'd expect. So oil pump is OK.
-The spark plugs indicate its not running lean

Any ideas?

Define high, as it isnt very specific.

100degC oil temp is ntohing to worry about...nor is 110....nor is 120 with the correct oil.

[PJ S]

When was the last oil change and what was used - brand and multi-grade type?

[Pumaracing]

GreenV8S said:

Is it over-filled, or perhaps there's some other fault allowing more oil to fall onto the crank than normal? Being whipped up in the crank case puts a huge amount of heat into the oil.

No it doesn't. Get your food mixer out and see how hot you can get a bowl of liquid just by thrashing it with a whisk. Get back to us on that after you've tried it.

[Pumaracing]

williamp said:

Got a problem with my Aston DBS V8, and the forum and two specialists have rtun out of ideas.

Basically, the car has 10 litres of oil and a few more litres of water. Its a lot of fluid to get hot. Usually, the water gets to 70 deg, and the oil about the same on a hot day.

However, my oil gets very high- over 100 degrees indicated. Its not high speed running- just idling in the garage for 10 mins or so. Even on a low speed drive (max 1500 rpm) the oil goes very high.

And we cant figure out why.

-Its not the sensor. New one replaced old, same symptoms
-Its not the gauges: both oil and water gauges recently refurb'd, and swapping the feeds shows the same increase on either dial
-It did have a blockage in the system, but now it has now oil pipes and both new oil coolers. In fact, after an idle in the garage the oil coolers get very hot to the touch.

So, I am certain the oil IS getting hot, rather then something misreading.

-Oil pressure is good throughout- what you'd expect. So oil pump is OK.
-The spark plugs indicate its not running lean

Any ideas?

Yes I have many of them, usually multiple times a day. The first in your case being that you don't have a problem with the oil temp because it should never have been as low as 70C anyway. Oil should be at about 100c or a tad more for best performance so in fact the system is clearly working correctly now but wasn't previously when you were seeing 70c. So either a gauge or thermostat in the oil cooler system was once faulty and now isn't.

If anything you have a problem with the water temp because that should also be much higher than 70c. Usually between 82c and 88c with standard thermostats. Go much lower than that and the fuel mixture will stay too rich because the temp sensor sees the engine as still warming up. That can contribute towards bore wear due to the excess fuel as well as high fuel consumption. I suggest you change the water thermostat and stop worrying about the oil.

Dave Baker
Puma Race Engines

[williamp]

last oil change was approximately 8 miles ago, and a few miles before that when I changed the sensor.

Thanks for the input, but all the other Aston V8 engines dont run 100 deg oil tmep- about 70-80 deg for both is normal. Hence my concern (the gauge, for example is "max" at 120 deg, with the middle at 70 deg). These enignes are known to be opver-cooled, and often its a real struggle to get heat into the oil in the colder months.

[stevieturbo]

williamp said:

last oil change was approximately 8 miles ago, and a few miles before that when I changed the sensor.

Thanks for the input, but all the other Aston V8 engines dont run 100 deg oil tmep- about 70-80 deg for both is normal. Hence my concern (the gauge, for example is "max" at 120 deg, with the middle at 70 deg). These enignes are known to be opver-cooled, and often its a real struggle to get heat into the oil in the colder months.

That must be one pretty unique engine then. No other engine runs oil so cool, and certainly not cooler than the water used for the cooling system.

Might be worth putting a proper temperature gauge onto it instead of whatever you are using at present.
And where is that temperature sensor located ?

[Boosted LS1]

When I had a big winged sump on my rover the oil took absolutely ages to get up to temp and would run cool simply because of the sheer volume. I had to fit a cooler with a stat in it and use less oil.

[tristancliffe]

Your oil temp is fine. Worry when it hits 130 (semi-synthetic) or 150 (fully synthetic).

Your water temp is a bit low though. See if you can get it closer to 80 or 90 (but obviously so that it won't overheat when stationary on rad fans).

[InRong Ghia]

With all that work done, did someone add an oil thermostat as well? It is a common item to use with an oil cooler, but sounds like it is not there as standard.

This would of course stop the oil from being cooled until it was considered to be at "working temperature" for oil. On my Citroen, the default is for the gauges for oil and water to be at the same level, but the oil is a higher temperature (gauge has a longer range).

[annodomini2]

If this was running hot, there are two things which can cause this and are probably the same problem, either the oil cooler isn't working correctly or something is causing a restriction in the system.

Have the oil cooler(s) been flushed when the oil was changed?

[williamp]

No thermostat added.

The pipes and both oil coolers are brand new.

[annodomini2]

williamp said:

No thermostat added.

The pipes and both oil coolers are brand new.

Airlock in the oil cooler?

[Pigeon]

Pumaracing said:

GreenV8S said:

Is it over-filled, or perhaps there's some other fault allowing more oil to fall onto the crank than normal? Being whipped up in the crank case puts a huge amount of heat into the oil.

No it doesn't. Get your food mixer out and see how hot you can get a bowl of liquid just by thrashing it with a whisk. Get back to us on that after you've tried it.

It's OK, old Joule did that in 1845. We already know it works.

[GreenV8S]

Pumaracing said:

No it doesn't. Get your food mixer out and see how hot you can get a bowl of liquid just by thrashing it with a whisk. Get back to us on that after you've tried it.

No experimented with it myself but I'm told that when it goes wrong it can go very wrong. The oil mist in the typical crank case is so thin that it doesn't absorb much power (still enough to justify knife-edging and scrapers etc if you're after every last scrap), but get a few litres of liquid being bashed about and frothed up and the power involved starts to become significant. It's also self-promoting since the oil is less inclined to settle out as it gets hotter and bashed into smaller droplets.

[Boosted LS1]

Pigeon said:

Pumaracing said:

GreenV8S said:

Is it over-filled, or perhaps there's some other fault allowing more oil to fall onto the crank than normal? Being whipped up in the crank case puts a huge amount of heat into the oil.

No it doesn't. Get your food mixer out and see how hot you can get a bowl of liquid just by thrashing it with a whisk. Get back to us on that after you've tried it.

It's OK, old Joule did that in 1845. We already know it works.

Is that in your kitchen chap

[ScumSoft]

Hi.

I would suggest that maybe dirty jets in the carburettor(s) This would make the fuel/air mixture to become lean and coz the engine to become to hot..
Oil`s viscosity suffers from to much heat, and would not give enough protection and lubrication when hotter than 110 degrees Celcius.. (Except for very expensive synthetic oils) so be very careful not run the engine when oil temperature is more than 100 Degrees Celcius.
Check for dirt or other debris in the carburator, make sure you have a max of 10 micron fuel filter(mounted after the fuel pump)

A carburator does have an Idle Jet, slow Jet, and Full speed Jet.. When the slow jet is clogged, the car "behaves" like normal but it is like you need to give it a little more "pedal" to get a response,(thats all)BUT the engine gets less fuel than it should have and that will cause it to become hot..

Just a suggestion, thats all..

Regards