Subaru 2.2 Conversion & cooling

[ric smiff]

Fellas, Been away for a while.

Have been running the 2.2 Subaru lump for about a year now and it's great. I do have a bit of a snag with cooling though. There's no thermostat so it runs cold. Not too good for the engine in the long run. I remember some time ago someone was doing a conversion to reverse the coolant manifold. Also Smallcar.com in the states (the biggest T25 subaru conversion specialist over there) was doing a revised coolant system which allows a thermostat to be added without cooking the engine. Anyone have any ideas?

Regards

Ric Smiff

[steve8090]

Ric - if you want to give me a ring at your leisure I can talk you through the ins and outs of cooling a 2.2 correctly without going to smallcar expense of a reverse coolant setup.

[Diamond Hell]

Richard Jones does a reversed manifold in the UK, too. They aren't dear, either. Unfortunately I can't remember the URL, but Clive might.

[scoobyvan]

i agree ,reverse the coolant manifold it also makes it easier to bleed if you use one of richards.put thermostat in and virtually impossible to airlock http://www.rjes.com/ <richards site

[ric smiff]

Steve, Cheers for the offer. I've tried emailing you but no luck. Could you email me your phone number. Cheers.

ric_smiff@btopenworld.com

Ric Smiff

[HarryMann]

was doing a revised coolant system which allows a thermostat to be added without cooking the engine

Ric, can we start at the beginning here?

What is this 'no thermostat' business - unheard of in Subaru, whether in Sub or VW. Certainly nothing to do with 'cooking' the engine... sounds more like a badly designed cooling system.

Reversed coolant mainfold has nothing to do with requirement for a thermostat, which is de-rigeur. RCM simplifies the coolant flow path for an engine mounted back to front, so to speak, with a few other benefits thrown in.

There is a modification that some do on the thermostat housing: a thick spacer block allowing the coolant bypass flow to re-join the flow at the themostat (which is at the bottom of the Subaru engine, not the top, as in most others).

[ric smiff]

Harryman,

Conversion done by TSR Dragracers (AMR Motors) in Cambridge. No thermostat fitted to the engine. Something to do with the returning flow from the heater matrix bringing cooler water back into the thermostat which then remains only partially open and cooks the engine. Only problem is, the engine runs really cold, so I have to blank off part of the radiator to keep the temperature up in the winter.

TSR Dragracers have done quite a few of these and say this is OK. I'm just a little concerned about the long term effects of over cooling the engine.

[HarryMann]

Despite my regard for their experience in Subie conversions for dragracers, I would say this is not OK, and can be improved..

What you say is pretty well what I was referring to.. if a bypass flow off the main cooling manifold at the top of the engine (under the inlet manifold) is fed back into the heater flow before connecting to the thermostat/pump block , this keeps the thermostat open under those conditions. The hose for this normally 5/8" bore and some put a 3/8" restrictor in it to balance the flow
I will send you a schematic that illustrates this.
Have you managed to contact Steve, as his may have a similar arrangement

[scoobyvan]

harry can you send me a copy to.although i have allways used a thermostat with no probs.

[HarryMann]

No problem... wills end you same as Ric, 3 images

send me your email though pmail please, as I need to attach them...

[Beetlecrusher]

HarryMann, I too would appreciate a copy of your schematic diagram as my van has a TSR Subaru conversion. Please check my profile for email address. Also, with the engine running cool all the time, would this affect fuel consumption ?

[HarryMann]

Have you not a thermostat too?

Well, yes, it does affect fuel consumption until it has warmed up, but maybe less than a carbed engine, as the FI is pretty spot on.
In very cold weather, does it run cold on the temp gauge? > risk of condensation if crankcase not breathing well.

I'll send them but think it would be better for you to sraw upa schematic of what you've all got, cooling system-wise..

I cannot attach to an email sent through the forum, as email address is hidden... pmail me with yours please.

[steve8090]

Didn't realise that TSR didn't fit thermostats, thats a bit wrong, if you look at the Yanky following for this motor they all go on about temperatures etc and how hot they run, if you speak to the Subaru Engineers (the older ones not these young 'uns who wouldn't know what a 1/4" BSF spanner is) they tell you that it should run anywhere between 80 degs C and 92 degs C, when I got mine it was almost boiling itself (98 degs C to 102 degs C) so I replaced the water pump, (did the timing belt too whilst it was down)put a 78 deg C thermostat in it, replaced all of the water hoses with Samco silicone, blocked off the bypass (as recommended by the Yanks) and put a new radiator in it, the engine now runs at a steady 82 degs C irrespective of whether I have the heater on or off and the fan cuts in around 92 degs C when in crawling traffic, you do need to get a good flow through the engine as in practice the Subaru motor will work up to its thermostat temp then take a sip of cold and keep on heating so be careful what therrmostat you do put in, an 84 deg C might just be too much with the rad so far away.

[HarryMann]

Good stuff that Steve, but when you say you blocked all the bypasses off, is the sole bypass return now via the heater core, front or rear? This is how the Subarau itself bypasses, through the permanently open heater core circuit.

.. and as you say, the engine does need a good flow and really doesn't like any air pockets or bubbles anywhere in the cyl. head waterways!

So you're saying, start at a low temp thermostat and work up if necessary, gradually.

PS Your calendars are in the post

[steve8090]

Clive, nice one about the calendars, look forward to them.

The thermostat I've used has a built in bypass, you know the ones, they have a little round weight on the and allows the system to bypass itself when in the warm up cycle, once temperature and pressure equalise on both sides of the thermostat it closes allowing normal temp to build up with the thermostat regulating both temperature and pressure.
This system uses the radiator as its bypass and an integral "burp" tank along the main feeder allows for expansion and excess air.

What I did notice with this setup is that you need to bleed it ever so carefully, I have valves on the main feed, radiator and the top of the pump to allow proper bleeding otherwise it just boils and never circulates, this is where the KEP or Smallcar bypass or reverse flow unit comes in very handy as it negates any pressure build up due to air locks, but like I say if you don't want to go to that expense then make sure the coolant ring is in good condition and pursevere (spelling?) to get rid of the last of the air, do not under any circumstances let it boil you will damage the heads, the first time I bled mine it took 3 goes to get it right over about 2 hours but once I'd identified the lock and put in a bleed valve it works a treat.





(edited for spelling)