Checking that an oil cooler is working properly

[Pan Pan Pan]

Has anyone out there fitted an oil cooler, or had to check that is working properly?
I have had an oil cooler on the 7 for some time (it is the type that uses a sandwich plate between the external oil pump on the crossflow, and the oil filter) but every time I check it for temp, it always feels cool compared to the coolant radiator directly behind it. Nor do the pipes to and from the pump to the oil radiator, ever feel hot Only warm, and that could just be radiated heat from the nearby engine block.
I wondered if the system has an air lock, and whether removing one of the pipes from the oil rad, and feeding fresh engine oil down it, before quickly re connecting it, would push out / reduce an air lock, or how the system might be bled to make sure it is as full of oil as it should be?
Also it seems that the oil cooler sandwich plate contains a thermostat which might not be working, or that does not ever open until the oil is very (too) hot?
So if anyone out there has any experience with external oil coolers, and advice on how to make sure it is doing what it is supposed to do, it would be very much appreciated.

[Peanut Gallery]

I used to drive a Citreon GS Club, air cooled with an oil cooler. The oil was only pushed through the cooler when the engine was up to temp, but when the thermostat opened you knew full well it was open. Oil does take a little longer to heat up, so I would simply say get the engine right up to operating temperature, then check temps.

If you are feeling brave, blocking the radiator for airflow would raise the engine temp above the oil thermostat level, opening that up, and you would definitely feel the hot oil then.

(In other news, I knew oil was being pushed through the oil cooler, as only about half of the oil stayed in the oil cooer, the rest dribbled out, so the oil cooler was working when you use more oil than petrol)

[Evoluzione]

Fit an oil temp gauge.
You can't have an airlock on an oil line, it pressurises to circa 8bar which will force any air out.

[gazza285]

The sump is hanging out in the breeze, and the Crossflow isn't really known for cooking its oil, are you sure you need a cooler anyway?

[the_stoat]

As above start monitoring the temperature to see where you are. You may not need the cooler and even the slight thermostat bypass could cause it to be over cooled. I gave up trying to use an air to oil cooler on my Westfield as even with a thermostat as unless on track, which was the reason for fitting, the oil was always too cold on the road. I fitted an oil water heat exchanger, Laminova, and everything was back in balance. Oil was heated when not using the engine hard and cooled through the coolant system when used vigorously.

[Pan Pan Pan]

Thank you for your replies.
The thing is that the crossflow does get hot, such that in traffic the engine temp climbs quickly to the point that the electric fan cuts in, but the oil cooler and pipes, to and from it, still remain relatively cool.
Once on the move the engine temp very quickly returns to its normal 75 - 80 degrees, so the water pump, and rad are doing their job OK, but given the above I have suspected that the oil cooler is not actually doing anything. hence the question.
I quite like the idea of having a working oil cooler, and the idea that the oil in the oil rad, and its associated pipework increase the oil capacity of the engine, but if it is not working, I hoped that someone might have a view on why.

[the_stoat]

As to why, your oil may not be getting hot enough to open the thermostat. This is why you need to understand how hot the oil is, coolant and oil can be at vastly different temperatures. The oil thermostat may not open until above the temperature that triggers your coolant fan. Take a look and see if it has a model number you can check.

[Megaflow]

You will almost certainly find the reason the cooler is cool, is it is not being used.

I had a x/flow in a Westfield and with a high pressure pump it had a habit of killing oil pressure switches, so I used to carry a spare. The light came on once just as I was pulling onto the drive, so I swapped the switch, it didn’t make a difference. Turns out the oil cooler thermostat had finally opened, but the cooler hadn’t been used in so long the oil inside it had turned to sludge and blocked it.

The whole lot came off and went in the bin.

Oil that is too cold is just as bad as oil that is too hot, that combined with modern oils being good up to 130 degrees continuously, and 135-140 degrees intermittently, means I’d want to know there is a genuine need for a cooler before fitting one.

All of the above is for air to oil coolers. Water to oil coolers actually have the advantage of warming the oil up to the match coolant temperature as the coolant heats faster than the oil.

[gazza285]

Pan Pan Pan said:

The thing is that the crossflow does get hot...

The coolant does, but as I said, it is not an engine known for overheating the oil.

The Crossflow gets hot because it has an iron head, and as iron is a poor conducting of heat, the head retains the heat. However there is little oil in the head, just what is needed to keep the rockers lubricated, so the main body of oil is not really affected by head temperatures like an overhead twin cam would be, with their much larger volumes of oil in the head.

[Pan Pan Pan]

Megaflow said:

You will almost certainly find the reason the cooler is cool, is it is not being used.

I had a x/flow in a Westfield and with a high pressure pump it had a habit of killing oil pressure switches, so I used to carry a spare. The light came on once just as I was pulling onto the drive, so I swapped the switch, it didn’t make a difference. Turns out the oil cooler thermostat had finally opened, but the cooler hadn’t been used in so long the oil inside it had turned to sludge and blocked it.

The whole lot came off and went in the bin.

Oil that is too cold is just as bad as oil that is too hot, that combined with modern oils being good up to 130 degrees continuously, and 135-140 degrees intermittently, means I’d want to know there is a genuine need for a cooler before fitting one.

All of the above is for air to oil coolers. Water to oil coolers actually have the advantage of warming the oil up to the match coolant temperature as the coolant heats faster than the oil.

I may be tempted to go down the same route with my crossflow, and just bin the oil cooler, pipework and sandwich plate. Went for a run this morning, and again the rad was hot, but the oil cooler, and associated pipework was cool, so it doesn't seem to be doing anything except adding weight.
My other car has the benefit an oil temp gauge, next to the water temp gauge. so I am aware of the difference in temps between the two, and the difference, in how quickly the water comes up to temp compared to the oil.
I did quite like the idea of the extra oil capacity a cooler and its pipe work might provide, but that would only happen if the engine oil, was going into / through the system, which seems not to be happening.

[Pan Pan Pan]

gazza285 said:

Pan Pan Pan said:

The thing is that the crossflow does get hot...

The coolant does, but as I said, it is not an engine known for overheating the oil.

The Crossflow gets hot because it has an iron head, and as iron is a poor conducting of heat, the head retains the heat. However there is little oil in the head, just what is needed to keep the rockers lubricated, so the main body of oil is not really affected by head temperatures like an overhead twin cam would be, with their much larger volumes of oil in the head.

Indeed. Having run the 7 across Death Valley, where the operating temp remained normal, despite the massive ambient temperatures, (and err, quite high speed) whilst able to keep moving, as soon as the car gets into traffic, the rad temp rises quickly to the fan cut in speed, which holds it in check for a while, but after that, the temp starts to rise again (even with the electric fan running) and as mentioned above as soon as it is on the move again, the engine temp rapidly drops back to normal, almost regardless of the external ambient temperatures .

[Pan Pan Pan]

gazza285 said:

Pan Pan Pan said:

The thing is that the crossflow does get hot...

The coolant does, but as I said, it is not an engine known for overheating the oil.

The Crossflow gets hot because it has an iron head, and as iron is a poor conducting of heat, the head retains the heat. However there is little oil in the head, just what is needed to keep the rockers lubricated, so the main body of oil is not really affected by head temperatures like an overhead twin cam would be, with their much larger volumes of oil in the head.

Considering what happens with my particular crossflow, I don't think the coolant radiator, is at fault, because once on the move, the engine temp quickly comes down to normal, I wondered if it could be the water pump, which is not up to keeping a 145 hp crossflow cool?
Lets face it the crossflow water pump is a crude, long, long way away from state of the art, and it may be, that at idle in traffic, it is not shifting enough coolant through the system, to cool the engine properly.
Increasing the revs whilst sitting in traffic might make the pump work more efficiently, but it would also increase the heat output from the engine. As described, the electric fan cuts in, but after a while, even that does not contain the engine temp, so I am wondering if the head is getting hotter, because not enough coolant is passing through the head. I also wondered if an in line electric coolant pump might help the situation a bit? Again any thoughts would be appreciated.

[AdamIndy]

You’re oil isn’t getting hot enough to open the thermostat as the others have said. I had a similar set up in my 7. It was a Corten miller built 1700 with a proven 140bhp and I struggled to get the oil over 80 degrees without a cooler. That was on long drives, mountain thrashes, hill climbs etc.

Just get an oil temp gauge and get rid of the cooler and save a little weight and complication.

[gazza285]

Pan Pan Pan said:

Considering what happens with my particular crossflow, I don't think the coolant radiator, is at fault, because once on the move, the engine temp quickly comes down to normal, I wondered if it could be the water pump, which is not up to keeping a 145 hp crossflow cool?
Lets face it the crossflow water pump is a crude, long, long way away from state of the art, and it may be, that at idle in traffic, it is not shifting enough coolant through the system, to cool the engine properly.
Increasing the revs whilst sitting in traffic might make the pump work more efficiently, but it would also increase the heat output from the engine. As described, the electric fan cuts in, but after a while, even that does not contain the engine temp, so I am wondering if the head is getting hotter, because not enough coolant is passing through the head. I also wondered if an in line electric coolant pump might help the situation a bit? Again any thoughts would be appreciated.

That’s an airflow problem, either your fan isn’t moving enough air to cool the hot rad, or the hot air is recirculating round the rad. Is the rad and fan ducted at all?

[Pan Pan Pan]

gazza285 said:

Pan Pan Pan said:

Considering what happens with my particular crossflow, I don't think the coolant radiator, is at fault, because once on the move, the engine temp quickly comes down to normal, I wondered if it could be the water pump, which is not up to keeping a 145 hp crossflow cool?
Lets face it the crossflow water pump is a crude, long, long way away from state of the art, and it may be, that at idle in traffic, it is not shifting enough coolant through the system, to cool the engine properly.
Increasing the revs whilst sitting in traffic might make the pump work more efficiently, but it would also increase the heat output from the engine. As described, the electric fan cuts in, but after a while, even that does not contain the engine temp, so I am wondering if the head is getting hotter, because not enough coolant is passing through the head. I also wondered if an in line electric coolant pump might help the situation a bit? Again any thoughts would be appreciated.

That’s an airflow problem, either your fan isn’t moving enough air to cool the hot rad, or the hot air is recirculating round the rad. Is the rad and fan ducted at all?

Yes the fan is ducted, and runs powerfully. but what is odd is that even without the fan running, the engine rapidly comes back to normal; temp once the car is on the move, which seems to indicate the radiator is doing what it is supposed to do, very well.
With louvres in the bonnet and thin aluminium all round with no heat mats/ shields etc, getting rid of heat does not seem to be a problem (on the move) But when sitting, or crawling in traffic at low revs the indicated temp rises quickly, (and after a while, even after the electric fan has cut in) which is why a water pump which is not moving coolant through the head / engine / radiator quickly enough `might' be the culprit.

[gazza285]

I cannot see that being the problem, there were thousands of these engines tuned and running the standard water pump, in fact the only modification usually done was a smaller pump pulley to slow it down.

Have you had the water pump off? The better ones have a cast impeller, cheaper ones are bent plate. I have seen one with the impeller missing the steel plates due to corrosion.

The fan is blowing the right way I presume?

[GreenV8S]

gazza285 said:

in fact the only modification usually done was a smaller pump pulley to slow it down.

A smaller pump pulley would make it run faster, surely.

[gazza285]

GreenV8S said:

gazza285 said:

in fact the only modification usually done was a smaller pump pulley to slow it down.

A smaller pump pulley would make it run faster, surely.

I didn’t explain that well, the smaller pulley goes on the crank...

[Pan Pan Pan]

gazza285 said:

I cannot see that being the problem, there were thousands of these engines tuned and running the standard water pump, in fact the only modification usually done was a smaller pump pulley to slow it down.

Have you had the water pump off? The better ones have a cast impeller, cheaper ones are bent plate. I have seen one with the impeller missing the steel plates due to corrosion.

The fan is blowing the right way I presume?

I changed the water pump a couple of years ago, so no problems with corrosion. and yes the fan is running in the right direction, but the engine still shows the temperature rising quite quickly when sitting or crawling in traffic, and then coming down quickly as soon the car is on the move again.