In-head thermostat advice sought

[mangocrazy]

Hi,

I've recently acquired a top water rail from Matt to replace the iffy item on my Spider, and want to do the 'in-head' thermostat mod while I'm at it. I've also acquired a 74 degree thermostat (the car lives in the South of France) and need to plumb it all together. I believe that I need to blank off the outlet that would normally go to the external thermostat and enlarge the hole in the boss that clamps to the head to accept the in-head thermostat. Will I need to relieve the boss to allow for the extra height with the thermostat fitted? And is there anything else I should be aware of - will I need a different radiator hose, for example?

All pointers gratefully received...

Cheers,

Graham

[mangocrazy]

Bumpity-bump...

Having read the topic in 'Engine' where The_Matrix_Master has had a head gasket blow has got me thinking about my Beta. Mine (like his) is an S2 Spyder, and lives in the South of France. As it only gets used in the summer months when we visit, the heater is never on and ambient temps can get over 40 deg C on some days, so it's a concern to me.

I've replaced the standard fan switch on the rad with a 74 degree one, but really need to get a matching 'hot climate' thermostat plumbed in. I'm aware of the mod where you get rid of the outboard thermostat and replace it with one in the head, but it's the mechanics of doing it that I'm unsure of.

I have the standard S2 top water rail that bolts to the head by cylinder 1. Do I need to open out the flange to accomodate the thermostat and, if so, is there a danger of breaking through the metal? Also, I believe that I need to blank off the smaller feed that exits off the rail near to cylinder 4. Is that correct? And do I need any additional or different hoses to make it all work?

If you have (or could point me to) any pictures of this mod that would be very helpful. Or should I be doing what Eric has suggested to The_Matrix_Master and be searching out a VX top rail?

All replies gratefully received,

Graham

[HFStuart]

I think Guy's reply here covers it pretty well.

http://www.guy-croft.com/viewtopic.php?f=13&t=1679

Although that seems to be to  Graham with a car in South France too :-)

I haven't done this on a Beta but I did do it on a Skoda with a T/C.

You do need to relive the top rail best done with a dremmel. Most of the meat comes off the thicker parts. IIRC I found some squre section O rings that sealed the thermostat in place but you could just as well use silicone.

Blanking the spur shown in the picture is easier done just by plugging the hose end (even if it isn't so tidy) and as you'll be getting rid of the thermostat you'll need to modify the bottom rad hose  - I used copper plumbing fittings but you could equally buy a 90 deg elbow and a straight connector.

Stuart

[Thotos]

Car engines are designed to work best at a certain temperature which is quite high compared to ambient temperatures. Water thermostats usually open around the mid to high 80 degree mark and fan cooling thermostats on the radiator switch around 90 degrees. If it all works as it should, the external ambient temperature should not make much difference if it's 20, 30 or even 40 degrees as it's well below the engine's 90 or so degrees. High ambient temperatures of 40 degrees or so will only be an issue if the car's cooling system is not as efficient as it should be. Using lower temperature thermostats will not repair an inherent problem but simply delay (slightly!) the inevitable over-heating.

Having a cooling fan switch of 74 degrees with a water thermostat of above 80 degrees is wrong! The radiator cooling fan switch should have an 'on' temperature at least a couple of degrees higher than the fully-open temperature of the water thermostat.

Changing the thermostat of the twin cam engine to an in-head thermostat is quite straight forward. My Fiat 131 with the same sort of engine has had this done. The 'T-piece' with the water hoses on the head needs to be replaced with a single outlet or should have the end away from the radiator blocked off. See photo of my 131 engine below.



You can just about see that it has a single pipe from the head to the radiator and there isn't another pipe going from the head to the blender thermostat. To the right of the engine you can see that the radiator bottom hose goes straight onto the water pump. A brass pipe was used to 'replace' the external thermostat so the original hoses from the bottom of the radiator and from the water pump were used.

I use a Ford Fiesta thermostat in the head of my twin-cam and there was no modification needed; it's simply a straight fit into the head. This is where older twin cam engines (e.g. Fiat 125) had the thermostat so it's a place designed to take a thermostat.

If you have engine cooling difficulties or even overheating, then I'd suspect the radiator first. Changing thermostats for ones with a lower temperature is not fixing the problem as I've mentioned above. Your engine has been designed to run at the temperature fixed by its thermostat so you should ensure it does that and not try to make it run cooler. Believe me, I drive a Gamma so I have played a lot with cooling systems, radiators and thermostats 

[mangocrazy]

I think Guy's reply here covers it pretty well.

http://www.guy-croft.com/viewtopic.php?f=13&t=1679

Although that seems to be to  Graham with a car in South France too :-)

How embarassing...     I'd completely forgotten about that. The only excuse I have is that it was 3 years ago...

I haven't done this on a Beta but I did do it on a Skoda with a T/C.

You do need to relive the top rail best done with a dremmel. Most of the meat comes off the thicker parts. IIRC I found some squre section O rings that sealed the thermostat in place but you could just as well use silicone.

Blanking the spur shown in the picture is easier done just by plugging the hose end (even if it isn't so tidy) and as you'll be getting rid of the thermostat you'll need to modify the bottom rad hose  - I used copper plumbing fittings but you could equally buy a 90 deg elbow and a straight connector.

Stuart

Copper plumbing fittings sound fine to me. I have plenty of those about. I'm guessing that 22mm would be about right?

[mangocrazy]

Thotos, the reason I went down this path is due to a very strong recommendation from Guy Croft (one that I did actually remember...!) He was adamant that even on mildly-tuned TCs a low-temperature thermostat and corresponding rad fan switch were the way to go. This is one of the threads that I was thinking of:

http://www.guy-croft.com/viewtopic.php?f=13&t=1138

Guy's recommendation is:

The answer (in my exp) for best power and reliability too is 75 deg C engine and 85 deg C oil.

I think I may have confused the low temperature thermostat and fan switch temperatures, by the way. Thermostat temp is 74 deg C (yet to be fitted), rad fan switch cuts in at around 82 deg C (I think).

[Thotos]

Thotos, the reason I went down this path is due to a very strong recommendation from Guy Croft (one that I did actually remember...!) He was adamant that even on mildly-tuned TCs a low-temperature thermostat and corresponding rad fan switch were the way to go.

Sorry, I misunderstood. I thought you were simply lowering the thermostat and fan switch temperatures because your car is to live in the South of France with higher ambient temperatures. As I mentioned above, an engine is designed to run at a certain temperature and a well functioning cooling system should maintain that temperature quite easily regardless of the ambient temperature. Once an engine is modified or tuned, then I'd agree that it most likely requires a lower running temperature.

[75coupe]

I have carried out this mod on my Beta coupe, and is relatively straightforward (depending on your skill level of course!) I have a few pics in the "Tuning and competition" section under "2L uprated engine rebuild". Unless your top water rail is from a VX you may want to add a tube into the rail that connects to the rear of the cylinder head, where the heater pipe usually connects to. As I live in hot climate I disconnected the heater altogether, but you could add another pipe to the top rail to feed the heater as per the VX item in Guy Crofts picture.

You will have to blank off the smaller of the 3 pipes that goes to the original thermostat that comes off the top rail, I just cut it, crimped and welded it, not the prettiest of jobs but functional. You will remove the OE thermostat then you will have to find a 90 degree bend to fit in the bottom hose in its place to connect bottom hose with lower water rail which runs back to waterpump. I found an exhaust bend I had lying around was the right pipe size, but a copper bend could also be used, or something off another car - I used a Nissan hose, but don't ask me what it was off! I actually replaced the original carb type rad with a Ford Focus ST170 radiator and has worked a treat.

You do have to enlarge the top rail with a die grinder or similar to fit the thermostat into it, make sure the little bleed hole in the stat is not obstructed too. I used Loctite 5900 flange sealant for the joint - sparingly, you dont want to fill the stat with sealant!!

[mangocrazy]

Thanks very much, that's very helpful. However, as with most helpful posts, it generates further questions. Sorry...

I would seriously consider bypassing the heater on my car, as we only tend to visit the South of France between April and October and it's very rare to need a heater during those months. It also means one less item in the coolant path to fail and dump fluid where you don't want it, although I suppose on the downside you're reducing the overall coolant volume.

Can you remember approximately what the i.d. of the hose is where the 90 degree elbow is required? One of the problems of being distant from the car is the inability to measure/check things like this. I'm hoping that either a 22mm or 28mm solderless plumbing fitting might be suitable here. If not it may mean getting a 'special' made up.

You've also given me a lead on something else I was fretting about - uprating the radiator. I'm gradually acquiring all the bits I will need to uprate the engine. Currently I've got Eric's Evo head, a pair of DCOE 45s, a GC manifold to suit, and a set of GC Cunningham rods squirrelled away; all I really need now are a set of forged pistons & rings and I've got the full set. But I'm aware I'll need to uprate the rad when I get round to fitting that little lot, and the Focus ST170 rad sounds ideal. Did you have any issues fitting it? And what fan do you use with it? My car is an S2 Beta Spyder, so underbonnet layout should be identical to yours.

I was also interested in the airbox/air ducting you've made up, as that looks an important part of getting reliable power out of the engine. And do I spy some ducting behind the rad to route hot air away from the inlet? Is it possible to route the exhaust air from the radiator under the engine to remove it from the engine bay completely? That's something else I've been thinking about...

Questions, questions...

[75coupe]

It is around 38mm I think, will have to check, later in week. I used an aluminized exhaust bend ! If you have a spare top rail you could cut the 90 degree bend off that and use it, but be a shame to butcher a rare part!

[andybeta]

mangocrazy here's a pic of my Beta's engine bay, Volumex, but may still be helpful to you.

http://www.lancisti.net/gallery/showimage.php?i=3935&c=217

Rad was made specially - slightly narrower and thicker core. With hindsight I would find one out of a more modern car as other others have done ie Ford ST170 due to cost.

Nothing is written in stone and the Beta set up is pretty straight forward. The std set up is still pretty good just make sure it is working well ie you could fit a more efficient radiator. I would also suggest if you are running the car in ambient temps of mid thirties or forty degree of South of France to make sure the engine oil is being cooled sufficiently as well. Not sure if your Spider engine has an oil cooler? If you are using the car in the UK I would suggest retaining the std cooling system otherwise with an in head thermostat the engine never warms up and will run "cold". This is what I and I know Simon Bray found using the in head thermostat recommended by GC. Unless you are doing lap after lap on a circuit it is over kill IMHO.

[mangocrazy]

Thanks chaps, very helpful. We're visting the house (and car...) next week, so I can check up and do some measuring while I'm down there. I think it might be smart to take lots of photos of the engine bay (and especially the cooling layout) so it can jog my memory when I'm back in the UK and sourcing all the stuff I need.

We're flying over this time, so I can't imagine that top water rails in the hand luggage would be very popular, but in September I'll be going back in the van for building work so I can take down plenty of kit with me.

Sorry to be a pain 75coupe, but is the ST170 rad pretty much plug and play, or does it need a bit of fettling? I assume you retained the radiator fan(s), as well? I've seen a fair few new ST170 rads on eBay for not silly money, so that sounds an excellent route to take.

[75coupe]

The Focus radiator has inlets and outlets in the same location as the carb type rad that will be in your spyder, however it is much wider, so some messing around with hoses is required (more or less same diameter inlet/outlets). It does not mount where the original one does, it sits forward (which you need to clear the DCOE webers), and has 2 round plastic peg type mounts upper and lower which normally secure it in place through rubber grommet type mounts. I drilled holes in the base of the front crossmember to mount the lower mounts, and secured at the top with aluminium angle strips to form a C type section over the top of the core, fitted self adhesive foam inside angle to protect rad, then riveted angle in place either side of engine brace.

The bottom outlet runs very close to the bottom of the alternator, you need a hose with a fairly tight 90 degree bend on it, but it just clears. The small pipe from the expansion tank has to be run all the way around the top of the rad, so a long hose is required here, I used 6mm ID hose for this. There is also a roughly 1/2 to 5/8 size fitting on the side of he rad which will have to be blanked off as it is not used.

So not a direct replacement, but can be made to fit without too much hassle. I was also looking at Renault 5 turbo radiators as well, but think this is a better option.

The fan I used is off a Thermo King Bus Air Conditioner, and is front mounted, so it pushes air through the rad and is a lot more powerful than the original. I used a T piece in the top hose to mount the original electric fan switch as there is no provision on the Focus rad for this, but I am not happy with the operation of the switch at the moment, so I have wired in  an overide switch as well. The fan is hardly aver required though as the rad is very efficient at any speed, and I live in an area where it gets to 40 Degrees C plus!!

[WestonE]

AndyBeta

Please can you let me know who built the radiator for you how much it cost and do they have the design on file? This is for my FI Volumetrico Beta Spyder. As I am getting close to trial fitting the GC engine with 037 SC a change of radiator is essential and that looks like a tidy job. Do you have any feel for its limits regarding engine power i.e. will it handle 285 BHP?

Eric Weston
Tuned Montecarlo & Lunatic Beta Spyder project. 

[Tone]

From: hutch6610   Sent: 11/05/2008 14:09

If you are stuck for a thermostat, you can remove the innards of the original stat so you are just left with the empty shell - assuming its serviceable.

You can then fit a standard thermostat under the water rail where it bolts to the cylinder head - the way Fiat had intended originally.
I have an 84degree (from an Alfasud - at least that's what i removed from an Alfa) and with a little grinding to the opening of the steel pipe with a small grinding stone in a power drill just so the top fits nicely into it.
You then drop the thermostat into the head put a seal on top (or just put silicone sealer around the flange) and bolt down carefully - don't shear them off in the head by over tightening.

This fix works nicely on earlier carb cars and VX's but not well on injection engines because you need a constant flow of water for the coolant sensor.
You would burn a lot of fuel until the stat opens!

Does anyone use this modification on injection Beta? Is it a real problem?