Subie Radiator Bleeding issues

A totally manual version of radiator vent is what tradesmen generally call a "coin vent". Plastic containers full of these (and the keys) sit on the counters at HVAC parts houses starting in about September, through about now.

The thing about a "coin vent" is that it can have a knurled top, so that you can open and bleed it with your fingers or a small pliers. They come in many flavors, but here is one example:

I'm not linking you to anything, because these are available everywhere. If you want something specific, a "Coin Vent" or "Radiator Vent" or "Radiator Auto-Vent" search will turn up a lot of options. The coin vents typically cost less than 5 bucks each.

For the automatic stuff, I'd stick with a name brand- Maid-o-Mist is big here, but Bell & Gossett, Hoffmann, etc. are all safe bets. 

Thanks for this Stan.

IaM-Ray posted:

Those are usually installed at the high point.  Is there a high point in our system?  Maybe near the engine but the flow of the coolant at that area might affect it.  What say you kind Sir,  Stan ?

These would be completely unaffected by flow, as a hyronic heating system has at least as much flow as your engine.

A vent is always in the high point of a system, or at a localized high-point where air can be trapped. It's a good idea to put a vent at every one of these points in a hydronic heating system, and I'd assume if the cooling system on a Subaru is convoluted with any traps, vents in those places would be a good idea. If the heads are where coolant is trapped, I wonder about drilling and tapping the heads for coin vents. 1/8" NPT is pretty stinking little.

My issue as well is on the tubing high points the space is so limited that it is hard to work the petcocks hence my desire to make it so simple that I can do it at home... did I say MYSELF. 

Stan Galat posted:

IaM-Ray posted:

Those are usually installed at the high point.  Is there a high point in our system?  Maybe near the engine but the flow of the coolant at that area might affect it.  What say you kind Sir,  Stan ?

These would be completely unaffected by flow, as a hyronic heating system has at least as much flow as your engine.

A vent is always in the high point of a system, or at a localized high-point where air can be trapped. It's a good idea to put a vent at every one of these points in a hydronic heating system, and I'd assume if the cooling system on a Subaru is convoluted with any traps, vents in those places would be a good idea. If the heads are where coolant is trapped, I wonder about drilling and tapping the heads for coin vents. 1/8" NPT is pretty stinking little.

The heads are not where the air gets trapped in a Soob conversion....in my case at least ...it was always in the hoses to the rad and back or whatever. Or in my case one high spot was the top of the coolant manifold. Other builders won't have this high spot I mention as they have a filler neck with a rad cap on top of it welded onto the top of the coolant manifold. 

I did look as much as I could at a water cooled IM at Carlilse years ago but you cannot see much. The coolant hoses they use are Marine style wire reinforced rubber coolant hoses, very heavy duty and they go in a somewhat convoluted manner from back to front and back again, up and down several times. 

Because I'm not smart enough to emulate that system I just dumbed my system down to something I was capable of dealing with. 

Those are nice little bleeders Stan showed. Not knowing any better, I used several like the ones Ray shows which are just basic radiator drain valves. 

Hope you can find the high spots in the hoses, Ray. You'll need to find every high spot, not just the highest. 

Your right David the hose is a monster wire reinforced marine hose and the pipes going to the front are absolute artwork.  If we find ourselves in Carlisle and were not sitting in the rain, here's hoping we have some sun, I can show you the IM plumbing... The single rad set up is fairly straight forward the dual is a bit more challenging. 

Stan's valves merits a look for sure.

@Stan Galat FWIW, I have 4 high spots on the metal tubes.  One per wheelwell that has that same valve that I showed you but I am not sure of the NPT off hand.  Not sure how high the valve would be in the wheelwell, but I can try to measure how much space I have and see if the valve could be accomodated. 

IaM-Ray posted:

@Stan Galat FWIW, I have 4 high spots on the metal tubes.  One per wheelwell that has that same valve that I showed you but I am not sure of the NPT off hand.  Not sure how high the valve would be in the wheelwell, but I can try to measure how much space I have and see if the valve could be accomodated. 

I just found a spare I had for the Speedster and I'm surprised to see it's 1/4" npt. Install depth requirement is 1".  CTC part 61104, , Ray.

If height is an issue, I'd look pretty hard at that Hoffmann auto-vent-- that seems to be the best of both world. A brass bushing will take you from 1/4" NPT to 1/8" NPT in a jiffy, with about 1/4" of increased height.

After Carlisle I will look into it more fully thanks for all the help you guys.  

BTW I am running Evans coolant which has no water and is a bit heavier than normal coolant.  Have you in your HVAC experience used that stuff in doing radiant heat Stan?   It is a mixture of mostly propylene glycol and some ethylene glycol.  

I did it for the -40 to 350 protection and it being a lifetime coolant. 

David thanks for the info on the part too. 

I'm familar with Evans coolant, and I'd probably run it in a specialty car-- but almost all hydronic systems use water with an anit-corrosion additive. Some in-floor systems will use a polypropylene glycol/water mix for freeze protection, but there is an efficiency loss with it.

It's a valid point to consider, but with a disc type auto-vent, I doubt it'd make a difference.

There are lots of positive elements when considering the switch to Evans coolant, but a few negatives as well.  The overview is that no substance is as efficient as plain water in heat transfer, with a heat transfer coefficient of 1.0. By contrast, Evans comes in at between .6 and .7, depending on the testing source.  We can get water almost anywhere, but a prudent driver would keep at least a small container of Evans with him in the vehicle in case of a cooling system leak.

Admittedly, most of us don't or can't use plain water, since the climates in which we use the car mandate some kind of protection against freezing.  Additionally, our water pumps, radiators, and heat exchangers need lubrication and rust prevention for longevity, so some kind of additive is a good idea.  Adding antifreeze, either ethylene or propylene glycol, in recommended percentages, also decreases the heat transfer coefficient of plain water, not quite as much as Evans, but the decrease can be substantial.

I had a long-term problem with overheating, as many on here will remember.  What that usually means in a Subaru engine is that, when coolant temps rise, small steam pockets form near the cylinder liners due to either insufficient heat transfer at the radiator, insufficient water flow through the system, or a combination of both.  Those small spots of boiling coolant can eventually lead to head gasket failure or worse, cracked heads. 

The use of Evans wouldn't fix the problem for me, it would just mask the symptoms, by not allowing the coolant to boil until it reached 375 degrees F.  I wanted to know why I had those hot spots and prevent them from forming.  I finally figured out my cooling problems,  and presently use distilled water with an additive that lubes the water pump and helps break down surface tension, to improve flow.

I'm not suggesting that Ray's use of Evans is ill-advised by any means.  It's working for him and that's what's important.  I went a different route and my route is working for me (knock on wood, mate).  The more we all know, the better choices we can make.

I always have a gallon with me ‘

I finally installed a second tank as overflow and I am testing it now hopefully it won’t lose any Evans anymore when I turn off the engine and so far so good .  I finally figured out why turbocharged engines have two tanks duh ...,

Jim Kelly posted:

There are lots of positive elements when considering the switch to Evans coolant, but a few negatives as well.  .  I went a different route and my route is working for me (knock on wood, mate).  The more we all know, the better choices we can make.

Exactly . If you could spell out that different route Jim, I think that would be a very nice contribution to the  list and wannabe liquid converters.  Thanks. 

FYI I had a Vanagon Westfalia. Watercooled boxer in back with LONG lines to a front-mounted radiator. The bleeding procedure involved opening a small bypass hose in the back by the header tank, raising the front 12-14 inches, then holding revs around 3000 and bleeding the radiator in front with a small petcock. You were done when coolant pissed out with no more bubbles.

Great.  Well that confirms Carey’s suggestion to lift the front of the car ...

I used one of the spill less funnels when purging the air out of my Special Edition Built system along with having the front of the car raised. The cool spill less funnel (bucket) thing made all the difference keeping the mess that comes with trapped air pushing large amounts of coolant up and out under control. The guy that designed this thing has my appreciation. If you haven't seen one of these, it is basically a bucket that screws on to the top of your radiator fill.

Thanks for all those suggestions guys!  I can start looking into all of it after Carlisle as I just finished my set up and it will have to be sorted out after. 

David,

In my case, it was a series of problems, which started with a poor design by Steve Lawing of SAS.  His aerodynamic chart and calculations for the cooling system looked like something you would expect from a bright high school freshman at the local science fair, not from an experienced builder/engineer/savant, etc.

The radiator was in a bad place originally and couldn't get enough air through it to make it work.  Lawing had riveted a 3" x 5" bent piece of aluminum to a frame member to deflect air to  the rad.  The stock 2008 Legacy rad was completely open with 2 puller fans and no shroud.

I reconfigured the entire cooling system on my mid-engine application.  I moved and redesigned the radiator, fan, and shroud which now sits just underneath the traditional deck lid on our replicas, with twin puller fans and a shroud that forces all the air through the radiator.

I changed the intercooler from air-air to air-water, moved it to the frunk with its own pump and twin heat exchangers.  Not coincidentally, a tuner discovered a clever bit of sabotage.  Someone had placed a brass nipple reducer in a water line: 1/4" npt to 1/8" barb fitting, with just enough room in the hose for some water to bypass.  I took someone's name in vain when I found out about that.

I try to look back on that time as a learning exercise, like making lemonade out of lemons, eh?  I did learn a lot about air and water movement, radiator and fan design, etc.  If that's as bad as my troubles get, I'm a lucky guy.

Jim Kelly posted:

There are lots of positive elements when considering the switch to Evans coolant, but a few negatives as well.  The overview is that no substance is as efficient as plain water in heat transfer, with a heat transfer coefficient of 1.0. By contrast, Evans comes in at between .6 and .7, depending on the testing source.  We can get water almost anywhere, but a prudent driver would keep at least a small container of Evans with him in the vehicle in case of a cooling system leak.

Admittedly, most of us don't or can't use plain water, since the climates in which we use the car mandate some kind of protection against freezing.  Additionally, our water pumps, radiators, and heat exchangers need lubrication and rust prevention for longevity, so some kind of additive is a good idea.  Adding antifreeze, either ethylene or propylene glycol, in recommended percentages, also decreases the heat transfer coefficient of plain water, not quite as much as Evans, but the decrease can be substantial.

 

Bingo.

I did so much research and work on my overheating that I have forgotten some of the process.  I also added an oil cooler and fan, which REALLY helped lower coolant temps.  Sometimes you solve the problem in small increments.  By that, I mean you force all the air through the rad and that lowers coolant temp by 3-4 degrees.  An aluminum dual-pass rad gains 2 degrees.  You install larger fan motors and that drops temp by 2 degrees.  You add intercoolers, another 5 degrees gained, oil cooler gains 6 degrees.

Incremental gains all add up.  For most of the year, ambient air temps may not concern us, depending on our location.  Summer temps in Santa Cruz, CA differ greatly than temps in Prescott, AZ or Redding, CA.  I want to be able to drive in any location at any time of year, so I was OCD about a fix that was bullet-proof.  For my application, the car ran cool until air temps reached the mid-80's, then it would overheat.  I now have that fixed, touch wood.

Vacant real estate is scarce on our cars, so placement of cooling system parts requires experimentation.  Every cooling component manufacturer states that HIS part, whether rad, condenser, heat exchanger, fan, etc.  should be in the maximum stream of cool air.  Easy in theory, hard in execution.

Does the Subaru JE253 out of a 2007 Impreza have an internal oil cooler like the 2.5L in a forester has? I thought I read something saying they had an internal oil cooler? If so that is pretty cool, forgive the pun.

Yes, the EJ253 has a built-in oil cooler that mounts between the block and the oil filter.  The problem is that oil temp is changed by the engine coolant only, not moving air.  That means the cooler actually functions better as an oil heater when the engine is warming up, than a cooler when the t-stat is open and coolant is flowing through the whole system.

An external filter with electric fan and oil t-stat has proven much more effective in keeping oil, and thus coolant, temps down.  Proof is that many of the EJ253 engine owners have removed the stock oil cooler and replaced them with external coolers with fans. 

In addition, a car with marginal overheating will operate at higher cooling temps with the internal cooler, since oil temps are normally 20-30 degrees F more than the coolant temp.  Result: instead of cooling oil, you are only raising coolant temps.  Problem eliminated with quality, external oil cooler.  I installed a Setrab 1-series, 19 row with fan and shroud, the largest I had room for.

Thanks Jim that makes perfect sense.