Purging air from remote oil filter and cooler

[Joel Heinke]

And to provide some context as to why items can't easily be added around the engine block oil adaptor, here's the "plumbing party" already taking place there.

This picture was taken before the original oil filter was replaced with an adaptor plate (filter is white cylinder). In addition, I plan to add some heat shields onto the header (to protect the coolant and A/C hoses) so things inevitably will get even tighter once that's done. It is because of the jamb packed nature of this area that I'm thinking about using a permanently attached hose to connect to oil adaptor plate for remote oil system air purging purposes.

 

[Neil]

Of course one of the aspects of building your own car is that you can configure it any way you want. It is wise to keep this in mind, however- the more complex the system, the more likely a failure will occur.

 

[Chris Kouba]

Joel-

Are you over-thinking this? Just wire up a switch to energize your starter relay and run your starter motor (without the ignition on). Runs the oil pump at low RPM and will prime your system simply. It's effectively the same thing as disconnecting all the coil wires, etc...

Run your starter for a few seconds, then fire up off the ignition switch.

Chris

 

[Joel Heinke]

Yes, there is a decent probability that I'm over thinking/doing things related to the Miura's Coyote engine lubrication system.

To provide context, my Cobra has been out of service for about 6 months now with a spun crank bearing (most likely cause is sustained high RPM related oil heat/starvation). After the Cobra went down, I've been re-thinking aspects of the Miura build in an attempt to avoid a similar engine breakdown situation. For example, I wasn't initially planning to put an external oil cooler on the Miura, but changed course to add one after having the Cobra inexplicably spin a bearing. In theory, the 5.0L Windsor Cobra engine should have been fine (oil level full, fresh high quality 10w40 synthetic oil, 8 qt Canton road race pan, oil pressure a constant 45+ pounds, coolant temps under 200 degrees, about 20K miles since new on Ford Perf crate engine, driving on straight roadway, rpms between 3,800 to 4,200 for about 20 minutes). The root cause with the Cobra is gearing too low for sustained high speed driving but the reality is that a spun bearing, for whatever reason, is a major pain in the ass to deal with

So am I being over cautious with the Miura, maybe but I'm currently working under a, "better safe than sorry", attitude and am trying to build in a margin of safety.

In doing more research, I did find that the GM service procedures for LS engines (similar oil pump architecture with Coyote) address the "pre-lube during initial startup" situation. They recommend either using a pressurized pre-lube system or removing the spark plugs and rotating the engine with the starter. So I'm good with starter driven engine rotation as being a viable procedure for pre-lube on initial engine startup in an engine with "enclosed" wet sump oiling.

I do have a lingering concern beyond this though. It's that the remote oil system is an "add-on" that itself may have engineering requirements beyond which the OEM engine engineers were concerned with. So in what's likely to be an abundance of caution, I'm trying to avoid missing some engineering aspect of the remote oil system that could come back to bite me down the road. I've looked at the installation instructions for 4 different remote oil filter/cooler kits and find them all to be too high level and thus missing key details I can only conclude that these kits are assuming an experienced professional is installing them. Given this is my first crack at adding an external oil cooler, I'm being cautious and trying to ask the right questions to those with more experience than I.

I do have some detail thoughts/questions but I'll hold them for another post as this one is already too long winded.....

 

[Howard Jones]

First startup newly rebuilt engine with NEW bearings. This is what really high-quality assembly lube is for (I use Comp cams stuff). You know the deal. Run at 2Krpms for 15-20mins or so on the first run-in with 5-20 new oil. Then drain it all, and replace the filter and oil of your choice for first 2000 miles. Drain oil and replace filter again and run normal oil/filter service thereafter.

Now what you ask? Assuming the engine is built correctly and has been run in as above. I would not do anything different than you would do with moms grocery getter, Just start it up, let it idle for a min or two and drive away . Wait until things warm up before you floor it on the onramp.

The one thing I do with my hot rods when they have not been run in several weeks. I Do crank it with Ign off for 30 sec or so twice with a 30 sec off time between each to cool the starter motor. Then start it up and not give it any revs until the oil temp sensor and coolant temp sensor begin to climb off the full cold end of the scale. I keep my foot out of it until the oil gets to 175F at least and the coolant temp is normal.

 

[Joel Heinke]

We had a snow day yesterday, so I had a chance to do more research and distill my remaining/open concerns. These concerns are:

1. Use of oil thermostat or not?
2. Cooler orientation and thus positioning of the in/out ports?

Oil Thermostat:

The remote filter/cooler kit I purchased didn't come with an oil thermostat but early on someone (Howard I think) raised the question as to if an oil thermostat would be used here. My initial thought was to "wait and see" by operating the chassis/engine in "go kart" mode and observing the dynamics and timing on oil system warm up. Now that I've done more research, my perspective has changed and I'm thinking that putting in an oil thermostat will be the right and smart thing to do for this application. An oil thermostat does however add complication to the air pocket purge challenge.​

​

I'm leaning towards using an oil thermostat from Improved Racing. When oil temps are low, it directs 90% of oil back to engine and remaining 10% to oil cooler to "pre-warm" it and avoid a blast of cold oil going to engine on thermostat open. Assuming that air purging from remote oil system will be done with room temperature oil (i.e. not operating level hot) and the cooler holds about 1.5 quarts, if the engine crank process is used to purge air, then it will likely take a lot of cranking to push the air from cooler core. In addition, oil pressure within the engine can't be used to gauge when all the air is purged as the oil thermostat is directing flow to engine and thus oil pressure will result.​

​

As a mitigation to this dynamic, the oil cooler could be "pre-filled" which should reduce the potential 1.5 quarts of air down to mere small pockets if a fill port exists and is located above the cooler core itself. For example, the 1/8" pipe port used for the cooler fan control.​

​

Oil Cooler Port Location:

The cooler I have is 8.5" by 12", is of a stacked plate design (i.e. not just a winding tube with fins around it) and has two male -10 ports on the long side, both facing outward from core. Orienting the oil cooler with long side down and thus these ports facing upward would result in a cooler that in theory would have no air pockets once it was initially filled. The main challenge in doing this is available space (and conflict with shifter cables) and maximizing the air flow to cooler. The cooler fits to the space much better with short side down and less of the core surface area will be near cockpit paneling thus better air flow. So I prefer short side down orientation if possible.​

​

With cooler ports located on the side, it seems that using the bottom port for input would better facilitate air bubble/pocket purging. Air bubbles would rise to the cooler top and should get pushed out of the outlet port. Alternatively, if top port were used as inlet, oil could flow downward through the core leaving residual air bubbles at top. Thus bottom inlet is likely better for air purge.​

​

New air bubbles could be introduced during oil filter change but this could be minimized with pre-fill of oil filter. The oil cooler may be susceptible to oil drain back (it's holding oil above crankshaft level and above engine block oil adaptor plate) when engine off but hopefully the combination oil thermostat and oil filter would prevent it.​

​

So to summarize, the current plan is to use an oil thermostat, orient the cooler with ports on the side, and use the bottom cooler port as the inlet. I think a manual/gravity pre-fill of the remote oil system via a sensor port on the cooler outlet side should purge majority of air from system with exception being high spots in hoses between engine and filter and oil thermostat and engine. Those remaining air pockets should be small and can likely be purged with ignition off engine cranking of a reasonable duration.

So right now, I'm leaning towards the combination of gravity pre-fill and engine cranking for remote oil system air purge.

Am I missing something? Are any of my thought processes off base or out of line with practical experience?

 

[Neil]

We had a snow day yesterday, so I had a chance to do more research and distill my remaining/open concerns. These concerns are:

1. Use of oil thermostat or not?
2. Cooler orientation and thus positioning of the in/out ports?

Oil Thermostat:

The remote filter/cooler kit I purchased didn't come with an oil thermostat but early on someone (Howard I think) raised the question as to if an oil thermostat would be used here. My initial thought was to "wait and see" by operating the chassis/engine in "go kart" mode and observing the dynamics and timing on oil system warm up. Now that I've done more research, my perspective has changed and I'm thinking that putting in an oil thermostat will be the right and smart thing to do for this application. An oil thermostat does however add complication to the air pocket purge challenge.​

​

I'm leaning towards using an oil thermostat from Improved Racing. When oil temps are low, it directs 90% of oil back to engine and remaining 10% to oil cooler to "pre-warm" it and avoid a blast of cold oil going to engine on thermostat open. Assuming that air purging from remote oil system will be done with room temperature oil (i.e. not operating level hot) and the cooler holds about 1.5 quarts, if the engine crank process is used to purge air, then it will likely take a lot of cranking to push the air from cooler core. In addition, oil pressure within the engine can't be used to gauge when all the air is purged as the oil thermostat is directing flow to engine and thus oil pressure will result.​

​

As a mitigation to this dynamic, the oil cooler could be "pre-filled" which should reduce the potential 1.5 quarts of air down to mere small pockets if a fill port exists and is located above the cooler core itself. For example, the 1/8" pipe port used for the cooler fan control.​

​

Oil Cooler Port Location:

The cooler I have is 8.5" by 12", is of a stacked plate design (i.e. not just a winding tube with fins around it) and has two male -10 ports on the long side, both facing outward from core. Orienting the oil cooler with long side down and thus these ports facing upward would result in a cooler that in theory would have no air pockets once it was initially filled. The main challenge in doing this is available space (and conflict with shifter cables) and maximizing the air flow to cooler. The cooler fits to the space much better with short side down and less of the core surface area will be near cockpit paneling thus better air flow. So I prefer short side down orientation if possible.​

​

With cooler ports located on the side, it seems that using the bottom port for input would better facilitate air bubble/pocket purging. Air bubbles would rise to the cooler top and should get pushed out of the outlet port. Alternatively, if top port were used as inlet, oil could flow downward through the core leaving residual air bubbles at top. Thus bottom inlet is likely better for air purge.​

​

New air bubbles could be introduced during oil filter change but this could be minimized with pre-fill of oil filter. The oil cooler may be susceptible to oil drain back (it's holding oil above crankshaft level and above engine block oil adaptor plate) when engine off but hopefully the combination oil thermostat and oil filter would prevent it.​

​

So to summarize, the current plan is to use an oil thermostat, orient the cooler with ports on the side, and use the bottom cooler port as the inlet. I think a manual/gravity pre-fill of the remote oil system via a sensor port on the cooler outlet side should purge majority of air from system with exception being high spots in hoses between engine and filter and oil thermostat and engine. Those remaining air pockets should be small and can likely be purged with ignition off engine cranking of a reasonable duration.

So right now, I'm leaning towards the combination of gravity pre-fill and engine cranking for remote oil system air purge.

Am I missing something? Are any of my thought processes off base or out of line with practical experience?

I asked John Horsman about adding a transaxle & engine oil cooler to my red street Mirage; his advice was "don't bother".

 

[Howard Jones]

I think that the standard oil pump in a V8 more than likely will pump something in the range of 4 -10 gals per min depending on revs. At idle 2-3 GPM seems reasonable if not on the low side. I was told this a long time ago so I think I'm pretty close on this but I can't cite any reference off-hand. In any case, if this is correct the pump (turning at 1/2 engine speed because it is driven by the cam) should be able to clear any air in the system really quickly given the volume we are talking about even including the oil cooler and lines. Seconds really. So if you don't give it many revs until you see oil pressure I believe you will be good. In my SLC I have a low oil pressure warning light set to illuminate at 35 PSI. It goes out when I crank it over and before it starts usually.

I once left an oil line (AN-10) off that went to my cooler and it made a 6 foot diameter mess on the floor before I could shut it off and I know the engine never went over 1000 rpms! Just seconds really.

These systems pump a lot of oil per second. 2 Gal (per min)= 256 Ozs. 256/60sec= 4.2 oz per second. If the filter is full and most of the lines are at least 1/2 full then all you will need to fill is the oil passages in the block that are more or less pretty full and the cooler. My big one holds about 2/3s of a quart. So let's call it a quart or so to fill at 4 oz per second. 32/4= 8 seconds. That seems right to me.

BUT..... the bearings still have oil in them from the last time you ran the engine and all the other oil to flow around while the rest of the system purges. This is all guesswork but I think it makes the point that you are going to be OK.

 

[Neil]

I once left an oil line (AN-10) off that went to my cooler and it made a 6 foot diameter mess on the floor before I could shut it off ...

I did something similar, Howard. I cranked the engine over without having remembered to put on my oil filter. Same result.

 

[Ryan L]

Yep, iv'e done silly things like that as well. Drained the sump on one car but not the dry sump oil tank which then emptied its contents all over the floor when the connecting hoses were moved. Was a mates car and we were helping out working late into the night trying to make an event.....

 

[Terry Oxandale]

I think that the standard oil pump in a V8 more than likely will pump something ...

Thanks Howard. I would say "Bingo" with this post. I think this is being way overthought. As a side note, I ran (idled with a blip or two) my motor twice (no haters need to comment please, as I am embarrassed to the end), for at least 2 or more minutes each time, without any oil being pumped into the motor. Yes, I'm using Mobil1, but it was an eye opener in that no discernable damage was done to the bearings when I finally pulled the motor for a completely separate issue. That was 7 years ago, with plenty of track time.

 

[Joel Heinke]

Thanks very much for your insights and feedback!!

Am I overthinking this issue? Probably.

Will I have regrets if this car has no engine lubrication issues? No way.

Would I have had regrets if I had overlooked something and ended up with a spun bearing? Absolutely.

I agree with the sentiment that the vast majority of street cars don't need an oil cooler. I've had some pretty wild street cars, none have had an oil cooler, and they have worked fine. There's two main reasons I decided to put an oil cooler on this car:

1. The Ford factory put an oil cooler on Gen 2 Coyotes in the GT Mustang (the engine used in this car). I don't know the specifics, but Ford usually doesn't add extra cost in their products unless it's necessary.
   
   
2. The front side header passes directly under the oil pan with about 1.5 inches clearance. Yes, I plan on heat shielding the header but still it's going to result in increased oil temperatures in the oil pan.
   
   
   

As this Miura build has progressed, it's become increasingly clear why auto manufactures don't make many car models with mid-engine transverse engines, especially large displacement engines. The very nature of this configuration is complex and thus many issues to overcome. I've learned a lot on this car building journey so far and I'm sure there's many more learning experiences still to come

 

[Howard Jones]

Oil cooler question: If you NEVER run your car on track, run a standing mile type event, Autocross event, do a hard 10-30 min run through a canyon with revs in the top 1/2 of the engine rev range, a few runs at a drag event, or ANYTHING that resembles an event that keeps the engine revs in the top 50% of the rev range for more than 10 mins or so AND you are sure you will abide by this self-imposed rule then......no you don't need a cooler.

It's the (sustained high revs and power production/time) that produces more heat in the oil than can be safely dissipated by simple contact with the rest of the engine and radiated out into the surrounding engine room as well as transferring the additional heat load into the coolant. That in itself can create another problem if you are marginal in coolant system efficiency.

I had a very knowledgeable professional engine builder tell me that about 30-33% of the excess heat generated in an engine is absorbed by the oil system with the other 2/3s in the coolant system.

So I guess you could install an oil temp gauge in the system and see how it goes over time. If you keep oil temps under about 250Fish (IMHO 225F is the point where more control is needed in the form of a cooler) then it will not degrade from the heat, Once oil goes to about 300F it starts to become fluid that does not lubricate and much higher than that and it will never return to a lubricant capable form.

A side note here: If oil temp = coolant temp and coolant temp is at target temp (let's say 200F) then the excess oil heat is being absorbed into the coolant and the coolant system is effective enough for the usage.

I like to keep the oil temp at about 220F and coolant temp at 190-200F in my track car if you need a reference. My street GT40 runs coolant temp at about 170F coolant and about the same for oil temp (that's a little low I think). They both have oil coolers like this.

Setrab Series 1 Oil Cooler, 44 Row, M22 Ports - Pegasus Auto Racing Supplies

This Setrab Series 1 Oil Cooler has a brazed aluminum construction, providing maximum cooling capacity in the smallest possible space with minimal pressure drop.

www.pegasusautoracing.com

Cooler sizing is VERY dependent on ducted airflow. The better the sustained airflow during high engine load periods is, the smaller the cooler area can be. I finally got my SLC right (430hp) with careful attention to ducting and apearanely over sized my Gt40 (350hp).

I don't have experience with a oil thermostat so I can't comment on them but it looks like I might need to use one on my GT40 now that it is a street car only. The oil temps were similar to my SLC when I was tracking it.

I hope this all helps.

 

[Joel Heinke]

Oil cooler question: If you NEVER run your car on track, run a standing mile type event, Autocross event, do a hard 10-30 min run through a canyon with revs in the top 1/2 of the engine rev range, a few runs at a drag event, or ANYTHING that resembles an event that keeps the engine revs in the top 50% of the rev range for more than 10 mins or so AND you are sure you will abide by this self-imposed rule then......no you don't need a cooler.

It's the (sustained high revs and power production/time) that produces more heat in the oil than can be safely dissipated by simple contact with the rest of the engine and radiated out into the surrounding engine room as well as transferring the additional heat load into the coolant. That in itself can create another problem if you are marginal in coolant system efficiency.

I had a very knowledgeable professional engine builder tell me that about 30-33% of the excess heat generated in an engine is absorbed by the oil system with the other 2/3s in the coolant system.

So I guess you could install an oil temp gauge in the system and see how it goes over time. If you keep oil temps under about 250Fish (IMHO 225F is the point where more control is needed in the form of a cooler) then it will not degrade from the heat, Once oil goes to about 300F it starts to become fluid that does not lubricate and much higher than that and it will never return to a lubricant capable form.

A side note here: If oil temp = coolant temp and coolant temp is at target temp (let's say 200F) then the excess oil heat is being absorbed into the coolant and the coolant system is effective enough for the usage.

I like to keep the oil temp at about 220F and coolant temp at 190-200F in my track car if you need a reference. My street GT40 runs coolant temp at about 170F coolant and about the same for oil temp (that's a little low I think). They both have oil coolers like this.

Setrab Series 1 Oil Cooler, 44 Row, M22 Ports - Pegasus Auto Racing Supplies

This Setrab Series 1 Oil Cooler has a brazed aluminum construction, providing maximum cooling capacity in the smallest possible space with minimal pressure drop.

www.pegasusautoracing.com

Cooler sizing is VERY dependent on ducted airflow. The better the sustained airflow during high engine load periods is, the smaller the cooler area can be. I finally got my SLC right (430hp) with careful attention to ducting and apearanely over sized my Gt40 (350hp).

I don't have experience with a oil thermostat so I can't comment on them but it looks like I might need to use one on my GT40 now that it is a street car only. The oil temps were similar to my SLC when I was tracking it.

I hope this all helps.

Howard: yes this information helps and sounds to be spot on.

While I highly doubt this Miura will ever see track time, I do enjoy spirited driving on occasion. The current spun bearing in my Cobra is evidence of that, although that's more attributable to a transmission that's 1:1 in 5th (instead of OD) than to any daredevil type driving. The Miura does have an OD trans and a reasonable final drive ratio such that driving 80 mph won't be above 50% rpm range.

I guess the other factor that tipped me to adding an oil cooler is the A/C. Just one more thing that generates heat and reduces cooling efficiency of the coolant radiator. I'm guessing the Miura is marginal on the need for an oil cooler but I'm looking for a "no regrets" build. I also don't want to have lingering worries when a spirited driving session happens and it inevitably will. So having an oil thermostat should keep the oil temps in the goldilocks zone and if the oil cooler gets bypassed all the time, oh well, the oil cooler is like an insurance policy that never gets used.

 

[Neil]

Howard: yes this information helps and sounds to be spot on.

While I highly doubt this Miura will ever see track time, I do enjoy spirited driving on occasion. The current spun bearing in my Cobra is evidence of that, although that's more attributable to a transmission that's 1:1 in 5th (instead of OD) than to any daredevil type driving. The Miura does have an OD trans and a reasonable final drive ratio such that driving 80 mph won't be above 50% rpm range.

I guess the other factor that tipped me to adding an oil cooler is the A/C. Just one more thing that generates heat and reduces cooling efficiency of the coolant radiator. I'm guessing the Miura is marginal on the need for an oil cooler but I'm looking for a "no regrets" build. I also don't want to have lingering worries when a spirited driving session happens and it inevitably will. So having an oil thermostat should keep the oil temps in the goldilocks zone and if the oil cooler gets bypassed all the time, oh well, the oil cooler is like an insurance policy that never gets used.

These days a spun bearing is more an indication of improper bearing clearances or lack of lubrication than high oil temperature. Assuming that is a crank main bearing, I'd check the crank/bearing clearances to see if they are within specs and also see if the block needs to be align bored. Lack of oil at high RPM can cause the same problems. Check the oil pump to pan clearances, see that there are baffles in the pan, and check the oil filter & lines for obstruction. Modern oils prevent little things from causing catastrophe but there is a limit to what they can do.

 

[Howard Jones]

It's like this, You're going to spend a boat ton of money, huge total manhours, and pour your heart into that car. Fuck it, put an oil cooler in it. Do it just because it's not a minivan and you're going to drive it hard sometimes, mid-engined cars have a lot of heat sources out of the air stream and tend to heat soak the engine room, it's good practice on a high-performance car and I can tell you want to. Sometimes it's not a matter of "I need it".

 

[Brian Kissel]

Straight and to the point Howard. Better to have it and not need it, than to need it and not have it.

Regards Brian

 

[Brian]

As long as it has a t-stat, go for it.

But underheated oil is no good, unless you plan to change it every 1000 miles or so. It needs to get past 220 to boil the water out. Close to 1/4 of your exhaust is actually water, so 1/4 of the blowby that goes into your crankcase is water looking for something under 200 degrees to condense on. Don't offer your oil up for that job.

 

[Steve Malson]

Joel, how has the MMR external oil cooler worked out for you on the coyote? I have a 5.2 for a GT-R build and I was looking at that kit as an option.

How did your engine priming work out? The ford performance guide for the external oil filter adapter provided some options for priming.

 

[Joel Heinke]

Joel, how has the MMR external oil cooler worked out for you on the coyote? I have a 5.2 for a GT-R build and I was looking at that kit as an option.

How did your engine priming work out? The ford performance guide for the external oil filter adapter provided some options for priming.

I can only halfway answer that question at this point. The installation is complete but I have yet to do an oil fill and/or attempt an engine startup.
As to installation, the MMR external cooler kit appears to have good quality parts and I didn't have any major issues with installation other than figuring out how to fit a 5 lb. gadget into a 4 lb. box. Having almost no space in the engine compartment is more an attribute of the transverse engine placement in the chassis than anything to do with the oil cooler setup though. There is one important component, oil thermostat, that is not included in the MMR kit. I chose to use one from Improved Racing due to it's compact size and good recommendations on it from the Cobra crowd.

As to priming the lubrication system, I can see a way to complete that but haven't attempted it yet. I located the oil temp sensor (also not included in MMR kit) that will control the cooling fan on the output of the oil cooler radiator which is also the vertically highest point of the oil hoses. This sensor port is 1/8" pipe which I think I can get oil through with a small funnel. If so, I should be able to gravity purge the vast majority of air from oil system through this port. The oil filter is also mounted vertically so I can pre-fill the spin on filter before installing it.

For initial engine start, I plan to pull the spark plugs and turn engine over with starter until it builds oil pressure. For subsequent starts following an oil change, I think the gravity purge through the sensor port should be sufficient for any air that might get into hoses during filter change.

I really did think I'd have gotten around to the initial engine startup by now but in reality that's still a ways off. I've been kept busy with getting a major home remodel off the ground and outfitting the workshop with things like 4 post lift, workbenches, and hose/electrical reels, etc. The workshop is in good shape but I anticipate the home remodel will be going on for the next 18 months or so. Even though we're contracting out the actual work, it's amazing how much time the planning, oversight and picking out the finishes/fixtures takes. We're going for a high end "rustic mountain lodge" look so lots of stone, timber beams, etc. that just don't come out of a catalog. Oh well, who am I to complain