I'm running my carbureted 460 in a 1982 E350-based motorhome (24 ft long and weighing up to 12,500 pounds) with C6 transmission and Gear Vendors Overdrive. I've recently upgraded the cooling system by switching to dual electric fans and eliminated the fan belts by switching to the Poly-Vee pseudo serpentine accessory drive system. After going through the radiator and cooling system, I found that, as manufactured, my motorhome came equipped with a transmission cooler (in the radiator core) and an air-cooled heat exchanger mounted in front of the AC condenser and the primary radiator. The transmission fluid flow is to the radiator core, then to the air-cooled heat exchanger and back to the transmission. Studying the engine, I have the standard 7.5L E350 oil filter adapter with clear provisions for an external oil-to-air engine oil cooler, but none has been plumbed in place.

I've spent more time than I ever anticipated reading various threads about the many real and perceived issues with Ford's OEM oil cooler fitted on a variety of 460's built after 1988 and using a liquid cooled (heated) technology. Most of these threads involved removing the liquid-based oil cooler and either deleting it entirely or replacing it with a remote oil filter w or w/o a remote oil cooler. Now, coming from a multi-decade experience with a water-cooled VW Vanagon running an in-line 4 cylinder for more than 230,000 miles with a liquid-based oil cooler and absolutely no problems, I found myself wondering what the liquid oil cooler failure rate really was and if it just correlated with radiator fluid maintenance. This was certainly my experience through years of participating in VW focussed discussion groups. Then, last weekend, as I wandered through a nearby Pick-n-Pull for my weekly constitutional, I came upon a '94 E350 van with the 7.5L engine and an obvious external engine oil plate cooler mounted beside the trans cooler and ahead of the AC condenser. I stopped to look at the installation details and found a burst hydraulic hose going back to a remote oil filter mount on the engine. The hose was shredded at the burst point and I couldn't tell if the metal damage in the area was due to impact with road debris or all part of a front quarter collision. Nonetheless, it immediately reminded me of the many reservations about having high pressure oil hoses running outside of the engine expressed in the threads on engine oil cooler issues.

I then studied the dimensions of my E350 installation of the 460 with a view towards mounting an oil filter based liquid to oil coolers. It was immediately clear that there was hardly sufficient room for the filter in the current arrangement. Preliminary measurements, however, suggested that with the flexible clocking enabled by the Ford Racing 90-degree oil filter adapter, there was sufficient room to mount a liquid to oil cooler sandwich between the face of the adapter and oil filter. Several oil filter mounted coolers come to mind ranging from the VW TDI units with about 50 cu in of internal volume to the Ford and Dorman replacements for the E350 Super Duty units used with the 6.8L V10s (which has a 90 cc effective volume). A quick check shows that all are dimensionally compatible (gaskets) with the FL-1A filter and can be gasket sealed against the Ford Racing adapter. Plumbing the radiator cooling lines would simply involve tapping into the heater circuit. For an equivalent thermal cooling capacity the effective volume of these liquid to oil coolers would be equal to an air-based oil cooler of 3 to 5 times the size, thus easily the equal of most external coolers. Finally, there would be no external high pressure oil line exposure and the access to gaskets and oil filters would seem to be superior to the cramped space between cross-member and block.

Anyway, thoughts for now and I'm anxious to hear what all I've missed and all the overseen issues. In the meanwhile, I'm going to do a set of 3D mockups...

 

You have really thought this through!!!! I as the son of an old time race engine builder, just don't like external oil lines either....it's one thing on a race car where you are dealing with known track conditions, but for a street vehicle, whole new set of unknowns!

 

I agree! But perhaps a few more points can be made.

First, I think that most FTE participants would agree that Ford usually takes the least overall expensive solution in addressing a problem. Least expensive certainly has to include the engineering cost for developing the solution, the parts and implementation cost in manufacturing the solution and its production line cost impact and finally, the extended warranty claim cost which must include the item repair as well as the components damaged by the solution failure. Looking at my vehicle, I can quickly conclude that Ford engineers never seem to make a choice based on how "high-tech" the solution will be perceived by the buying public.

Second, they clearly perceived the need for an engine oil cooler as a necessity, since they went from an optional (external) fitment to making it a standard item for the 460, post '88. This has to be more heat, or they needed to address an engine warranty/reliability problem pointed out by the evil bean counters!

Finally, they had a fully functional engine oil cooler in the external air-to-oil cooler engineered for the pre '88 E350 applications of the 460, so some issues had to push them beyond just specifying the external arrangement as standard.

I think that there were at least three primary driving requirements: 1. More rapid temperature increase of the oil supply to operating temperature (heating when cold or at startup). I have access to a number of VW engineering development papers showing the critical impact of rapidly reaching operating temperature on engine life. This was their main justification for the use of the liquid-based engine oil coolers on every production engine including gasoline, diesel, turbo-diesel and turbo-gas. 2. Applying an effective upper temperature to the engine oil of probably 10F above the coolant temperature (this is a common engineering design objective for the use of liquid heat exchangers mounted at oil filter ports). and 3. The considerably higher thermal capacity per component volume of a liquid-oil heat exchanger as compared to the air-oil alternative. I think the external exposure of high pressure hoses has to figure into their analysis.

Also, two key aspects of the air-oil heat exchangers are that they only cool when the vehicle is moving (must have air flow over cooling fins to dissipate thermal transfer) and, positioned ahead of at least the AC condenser and radiator, they must impede cooling air flow to the engine cooling system.

All in all, it would seem that the key limitations to this approach are: 1. Does the liquid-oil cooler have the required capacity to remove or manage the amount of heat required and 2. Will the darn thing fit in the space available. This last point is the one I'm most obsessed with. This is all based on the proper selection of factory engineered components that can be assembled to fit. No new engineering required except possibly for routing the heater coolant lines!

 

I've decided that it is appropriate to update this thread, as I'm about to implement the sandwich stack oil-to-coolant oil cooler upgrade. There have been several developments based on more study and more internet browsing. As I expressed before, I am really surprised at the level of prejudice concerning the use and effectiveness of liquid-to-liquid heat exchangers. The question is usually asked "Should I remove the OEM oil cooler and install aftermarket?". The advice usually is to remove. The liquid-oil cooler is cited as too small, unreliable -heats rather than cools...

But there are some facts:

1. Every Ford 460 after 1988, all 6.8L V10's and all 5.8L V8's with towing packages (not to mention the Powerstroke Diesels) were equipped with liquid to oil coolers from the factory. In addition, all turbocharged Mopar, most V6 Mopar and all Cummins Diesel equipped vehicles were delivered OEM with liquid-oil coolers. Essentially all VW, Audi, Honda, Toyota and Nissan vehicles are equipped with liquid-to-oil coolers. Against this, there are on the Ford tally, there are less than 500 citations here on the forums of FTE of oil coolers failing giving oil in the coolant. I have found no instances of catastrophic liquid-oil cooler failure leading to major engine damage. A recent assessment by Chrysler of warranty claims for liquid heat exchangers concluded that they were insignificant (essentially unmeasurable in the sample listed as occurrences per 100,000 vehicles). In reading many of the reports here on FTE, I would conclude lack of maintenance was the primary cause of failure. The oncoming high tech engines needed to meet the 54mpg mandates will all have liquid-to-oil coolers because of the need for tight temperature control needed for the xxW-4, -6, -10 and -16 engine oils and the very tight bearing tolerances.

2. The usual size of the stacked sandwich coolers mounted between the block and the oil filter is between 42 and 50 cu.in. Given the far higher thermal transfer efficiency of the liquid-to-oil coolers as compared to the air-oil units, these 50 cu. in coolers are equivalent to the best 19-row stacked plate coolers mounted in front of the radiator/condenser package.

But now for implementation with my 460. My E350 has the factory OEM 90 degree adapter orientating the oil filter to the front of the engine at an angle of about 45 degrees from vertical. With closer inspection and fitting, my favorite staked plate liquid cooler (Uro Parts 038117021E -see figure) will fit with the long axis parallel to the side of the block. This oil cooler was originally specified for the high performance Audi TDi engines and I have personally fitted it to my VW Vanagon TDi experiments. Because of clearance issues with the steering gear, mounting this cooler will require using a shorter oil filter than the FL-1A. Here I have switched to the Motorcraft FL-300 or the Mobil M1-204A. With the shorter filter the whole stack is just 1.4" longer than the FL-1A mounted on the filter adapter.


Now the final problem is that of where to tap the coolant system for the inlet liquid and correspondingly where to dump the outlet fluid. Originally, I had thought to run the heater outlet line to the oil cooler inlet and the cooler outlet into the heater return port in the intake. Realizing that for for much of the motorhome's operating year, the heater inlet valve would be shut off, I then considered changing the heater flow system by routing it through a 4 port bypass valve. I could then direct the heater output flow to the oil cooler as originally planned and the cooler output to the heater return intake manifold port. This was less than optimal as I would be using the very hottest coolant in the input to the cooler and would be dumping water 10F or more hotter into the intake manifold coolant jacket. This did satisfy the requirement for a pressure differential between the oil cooler inlet and outlet, resulting in the necessary directed flow.

Studying the coolant flow diagrams for a variety of liquid oil cooler systems, it became clear that the preferred coolant takeoff site was either at the water pump bypass or at the lower radiator hose inlet to the water pump. This choice was directed at the coolest source of coolant. For the return, the engineering focussed on either the inlet to the water pump (lowest system pressure) or a more general dump into block or intake manifold (away from the thermostat area which had the highest pressure). The problem was two fold, first, one wanted a point of coolest water for best oil heat rejection. Second, for flow, there must be a pressure differential. Simplistically, this suggested a coolant pickup point on the lower radiator hose feeding the water pump inlet and a hot coolant dump point just in front of the water pump inlet (lowest pressure in system). From a hydraulic point of view, this was ridiculous since there would be a negligible pressure differential (no flow differential) between two points along the lower radiator hose.

Then, I turned back to study the cooling system of the Ford 5.8L with oil cooler and found that this was exactly what the OEM solution was. The coolant outlet port for the oil cooler was just 3 inches before the coolant return port!. This lower radiator hose with oil cooler ports adapter is shown in the figure. It turns out that a thin restriction is molded into the adapter at a point just before the return port (closest to the water pump inlet). As a result, the restriction to fluid flow increases pressure at the coolant outlet port and reduces pressure at the return port. This clever solution generates coldest liquid at pressure for the exchanger inlet and mixes the oil heated coolant with the radiator return stream to minimize the heat load on the engine. The restriction reduces the 1.75 inch hose ID to 1.0 inch ID. I have done no calculations, but expect that the flow restriction is less than experienced with the 88 OEM 460 pass through in line radiator approach. Repair and replacement is certainly more serviceable!


So that's it. I'll be reporting the temperatures and flow rates after the install is complete. I know, too many words! Sorry. Hope this helps somebody!

 

Excellent write-up and I agree....just an fyi...Nissan IIRR had a class action lawsuit regarding the radiator failure causing coolant to leak into atf lines and destroying the tranny's..... one thing that I have always done is run anodes in all my vehicle cooling systems....this has saved (IMHO) numerous water pumps, hoses, radiators, etc..... heck my wifes 97 Cougar's radiator lasted 17 years before the plastic cracked.....otherwise, there was nothing wrong with it......the copper core unit in my 65 mustang is 33 years old...spotless inside.

 

Beechkid, couldn't agree more! Electrochemistry can easily overcome corrosion inhibitors and the dissolution battery operating between Cu, Fe and Aluminum is the most likely cause of these liquid-to-oil stacked coolers. The crossproduct of time, temperature and dissolved oxygen can render coolant a caustic etching solution in less than a year of unintended operation. For me, I use the Northern Radiator Caps with the sacrificial Magnesium anode. Easily substitutes for the OEM radiator cap, but the Magnesium anode is fully immersed in the flowing coolant. Good point!

 

Should be: "most likely cause of failure of these liquid-to-oil stacked coolers."

 

Any updates on this cooler project?

 

+1 for using the coolant to cool the oil
It's possible to have the oil too cool in certain circumstances
Reference 1981 Dodge Omni icing up the engine oil and destroying engines
This should never happen to yours unless you take it to Alaska (or somewhere else real cold) with an oil to air cooler
Good luck