DS Cooling

OK, time for a collective head scratching please people.

I'm currently fighting with Moby Dick over cooling. I want it to run cool, it wants to operate as hot as possible. Before we go to arbitration I thought I'd bounce the situation off the Brains Trust and see what (if anything) I'm doing wrong.

The standard D Special has an engine driven fan that would look at home on a Cessna. This fan operates in a moulded shroud such that all of the air coming through the radiator core passes through the shroud on its way to the egress via the engine.

My bright thought was to replace the engine driven fan with a 12 inch electric fan that fits snugly into the round part of the shroud. I was then able to remove the engine driven beast and gain a few horsepower as well as lose a few decibels of noise. So far so good, however the engine then wanted to run way too hot for my liking. I've got the fan thermo switch set to cycle around the 180F mark which seems to be a preferred running temp.

Driving to Phillip Island last weekend I found that on an average evening the fan was running almost continuously and the temp would rise to around 190F even with the fan running. As soon as I stopped and just ran the fan without the engine running, the temp would drop quite rapidly.

I figured I wasn't getting enough airflow through the radiator, so I removed the ducting from the front. Made no change, and in fact the car ran even hotter all the way home from the Island on the Sunday. Next guess was a lack of coolant flow.

That evening I removed the thermostat and tested it in a saucepan of boiling water. It opened only about 2 or 3 mm so I figured I had found the culprit. On spec I also removed the radiator and had the tanks removed and the core cleaned.

I've put it all back together without the thermostat (ordered but not yet arrived). And guess what? It still runs too bloody hot! I've now restored the mechanical fan and re-installed the front ducting. We'll see how it goes now, but this is annoying.

My basic question is this. How critical is the front ducting for airflow through the radiator at highway speed? I would have thought that with everything clean, and no thermostat, that the temperature whould be well maintained at a lowish level by the airflow alone at 100Kmh. However the fan wanted to run continuously and the temp was still getting too high.

The next plan is to fit two 9 inch fans mounted directly onto the radiator core. (Naturally the one I've already bought is too big to fit flat against the core!) My gut feeling is that these two fans, with the moulded shroud removed, should provide all the cooling a car could ever want, but I have to save up for two new fans first!

Am I missing something really obvious here? (Apart from the statement that Mr Citroen knew the right way so don't change it!)

Any information gratefully received.

Cheers Pottsy (hot under the collar!)

You need the ducting in place, it picks up cooling air from a high pressure area under the nose.

Sounds to me like you may be overlooking the obvious ... that is a partially or fully blocked up radiator.

I would suggest getting the radiator 'rodded' and checked before you cook the motor. At a minimum, this would rule the radiator out as a problem if it is found to be ok.

seeya,
Shane L.

Is the water pump working?

Shane, Thanks for the info on the ducting. I suspected as much but needed confirmation.

As far as the radiator being cleaned is concerned, I quote: "On spec I also removed the radiator and had the tanks removed and the core cleaned. " Yes it's been rodded and so should not be a problem. Apparently the core was new a couple or three years ago anyway, but it cleaned up OK this time. The front of the matrix is a bit manky in places, but I've seen worse that were still working fine.

You're excused for not reading that far, however, it is a long winded post!

Boyracer. Good question, but I'm getting swirling and movement of the water with the radiator cap off, so I guess at this stage I assume it's moving coolant.

Pottsy,

How have you been since the 50th D Run? Hot engines, tell me about it. When I first bought the DSpecial I boiled it every 30 minutes between Hobart and Launceston on the way home, no temperature gauge and down to 80kmph and still the big red light screamed STOP!! My nice new D and 4 hours to go 200 ks, not a good start.

I guess that you may have been here already but I had the radiator recored. It had the original core which had heaps of fins but only two rows but room for another row. So replaced with 3 core, with heaps (that's the techincal term) of fins. Now runs in the bottom third of the normal range and hasn't looked like trouble since.

Keep the white DSpecials going...

Peter

My 2 cents worth..............A DS is a hot car! Is the original radiator in your car a three row thick unit? My ID21F always ran warm but never boiled. I needed a new rdiator so when I got mine rebuilt it was done with a four row unit so I have all these extra water flow points to let off heat. The car uses its original fan and I maintain the coolant with an annual change. It runs cooler than ever these days.
I've seen alls sorts of extra fans and ducts and gadgets in my 20 years of owning these things all with limited success. I have a feeling that very little air is forced UPwards when you are moving. Its all only sucked up by the fan. More revs = more air.
BTW, my 1963 ID19 now also has a new 4 row radiator and fully overhauled pump and runs real cool.................

It's likely the electric fan just isn't powerful/efficient enough to push sufficient air through the radiator. If it was cooling ok before the change then it stands to reason that the cause of problems is the thing that was changed.

Running without a thermostat can be hazardous on some engines too. The back pressure from the restriction it creates keeps the coolant slightly above atmospheric and raises the boiling point. Without it bubbles can form and create hot spots in the head that cause detonation and damage.

The radiator is a three row unit (I just went and looked)

I'm going to run it tomorrow with the electric fan built into the shroud, and the ducting installed as well. I strongly suspect that the thermostat was already dodgy and was pushed over the edge when I installed the electric fan. (It allowed things to get hotter before cutting in so may have caused the problem)

Anyway, I'll come back with more data once I've tried it out.

Thanks for all your input so far chaps. This is what such a forum is all about.

As far as running without the thermostat. I anticipated it would have arrived by now. I planned on running through a couple of warmup cool down cycles with no thermo just to help flush the system through.

Assuming the new part arrives tomorrow (and it had better!) the whale will have all new coolant to go with the new bottom & heater hoses, the new cap, the new overflow catch bottle, the cleaned radiator and the new thermostat.

If it still overheats I'll begin to believe the theory about the Cessna propeller being needed to suck the air up rather than the air being forced through it. If that's the case it'll be back to the mechanical fan and shroud and a few swear words from me every time I can't hear the music over the noise at cruising speed!

Either that or the two 9 inch fan option, but that may have to await funding.

Cheers, Pottsy.

And yes John, Long Live the White Wonders! (Mine should have the sign writing for the Peugeot Re-Run happening in the next couple of weeks. Can't wait to see the looks on the Lemmings in their more recent whitegoods as I cruise past in a replica rally car from the past!)

pottsy said:

If it still overheats I'll begin to believe the theory about the Cessna propeller being needed to suck the air up rather than the air being forced through it. If that's the case it'll be back to the mechanical fan and shroud and a few swear words from me every time I can't hear the music over the noise at cruising speed!

Click to expand...

Hi Pottsy,
this is an interesting post for me as I have just spent a bit of time on the weekend checking that the electric fan on my 23 is working (yes, even in Tasmania it gets warm enough to need it sometimes). You may be on to something with the above as it rang a bell with something I'd read recently somewhere - (in John Reynolds book Original Citroen DS (Bayview Books 1996) - as it turned out.

On page 32 Reynolds discusses the redesign of the original DS front end which was introduced in September 1962 (not, I stress, the later twin light front). Reynolds says:

'A plasticised fabric tube linking the duct to the main air intake to the radiator completely enclosed the airflow, so that ram effect was eliminated; air flow through the radiator now depended entirely on the action of the fan.'

Also page 83 of the abovementioned text features an underbonnet photograph of a 1969 ID19B (with the last nose, of course). The caption to the photograph reads:

'With the spare wheel removed, the ducting to the radiator can be clearly seen. Note the zip in the fabric shroud which is normally kept closed to maintain fan suction, normal ram effect from the nose being virtually nil. The battery has changed sides'

Now I've been into Ds for 5 minutes compared to most of the guys at AF so I'll gladly defer to their knowledge - but clearly Mr Reynolds is of the opinion that air is sucked through the D radiator by fan rather than ram air effect, is this what you were wondering? Hope this is helpful anyway.

By the way, strange question Pottsy, but you don't own a California by any chance?
Cheers,

Hey Pottsy,
If the radiator is clean, inside and out, then maybe it needs to be changed for a 4 core type. Or maybe not.
Also, if the thermostat was dodgey, and you removed it, there should be no restriction to the flow of water. Even though the water seems to be pumping, it could be a faulty pump that isn't pumping enough water...or...at high speed, the bottom hose MIGHT be collapsing because of the vacuum pressure of the water. Make sure the bottom hose has one of those spring things inside it, to stop the hose collapsing from negative pressure. I've seen that happen before.
Check these simple things out, and also....make sure you are not running those incredibly HOT sparkplugs. Those short reach types make everything run too hot. Check which kind should be used...and try a cooler plug.
Cheers...George 1/8th....
CX C-matic 2400.
( plus....ex DS 21 Hydraulique driver)

OK guys, thanks.

Firstly, no, I've never owned a Moke at all, let alone a Californian. Driven a couple though. The closest thing to a go-kart with rego plates! Fun on wheels!

But I digress.

OK, so it seems that airflow may be affected by the nose design. This could possibly explain why the 4 light nose had all that extra ducting under it.

I'm in the process of creating a new under-nose plate to replace the aluminium one that was never on my car since I got it. Perhaps this will assist in the air flow, perhaps not.

George, I'm trying hard not think of the water pump being crook. If it is, I'll create a new blanking plate with the appropriate pipe attachment and run an electric pump.

The bottom hose assembly consists of two short bits with bends in and a crescent shaped metal bit with the t-piece off to the heater. Both of the bends are new, and not noticeably distorting under suction either. I suspect that they're too short to close up in the way you describe. I've experienced that happening way back on a Renault 16, however and the spring thing solved that particular dilemma then.

Incidentally, the two bends for the bottom hose were sourced from a VJ Valiant bottom hose and a Ford F100 bottom hose. It helps having a friendly parts supplier who will take the time to compare the originals with his wall full of stock! Still working on re-creating the top hose out of readily available parts, however.

And I'm running the Bosch 4-electrode plugs (Can't remember the type, but they're the right listing for teh DS) with a new Bosch GT40 oil filled coil.

The saga continues!

Being not so conversant in D Special engines, this might be way off the mark.

Most RWD Peugeotphiles are well aware of a weakness in the cylinder heads in the XM/XC/XN series Peugeot motors. Behind the water pump on the front of the head there is a welsh plug, and it corrodes away and/or dislodges itself. When this happens, less and less of the water pumped by the water pump is circulated through the radiator, and more and more is just pumped around in circles inside the head and water pump.

Could a similar thing be happening on your Citroen?

I've not read all the post (basicly lazey) but these points might be worth considering.

Check your points and timing.
Check that the 'vanes' on the water pump impeller have not corroded through.
Have found that a product from Redline (can't recall name) which is added to the water to promote a better contact between water and metal surfaces and therefore better transfer of heat to be quite good (wont help cool your radiator water but it's sort of close to the topic)

The water pump in my ID19 is rebuilt but am looking towards changing to a Davis Craig electric pump and reworking a 3 core radiator to lie flat over the air inlet point where the spare wheel used to be (rally car so can get away with ungodly mods).

Engines that run too cool (don't reach a reasonable working temp) are less than efficient and have their own set of problems.

Chris.

Demannu (can I cal you Demon for short?)

I'm familiar with the welsh plug behind the 504 water pump. We had a 504 Ti head where the plug had come loose and been rotated by the water pump like a saw blade. The cuts in the head looked like somone had run amuck with an angle grinder!

I'm not au fait enough with the DS head to know whether this is a possibility. I hope not!

As far as checking the impeller blades goes, I'd rather not remove the pump yet until I have some definitive results from the mods. Now that I'm about to put a new thermostat in I may be able to comment soon.

And thanks, I'll re-check the timing etc as well. Car is running fine and not pinging so I don't reckon it can be too far out.

The State of the Nation!

Moby Dick is now running with the following things done to the cooling system:

Radiator de-tanked and cleaned.
Coolant new & really BRIGHT green!
Thermostat new & checked (Nominally 77 deg C, same unit as 504 Pug!)
Bottom hoses & heater hoses replaced.
Front ducting installed.
Fan shroud installed with 12" electric fan filling the round bit. Thermo switch set to cut in about 90C out at about 85C.
Gaps between the shroud and the radiator covered with Gaffer Tape.
New pressure cap (4 lb) and recovery bottle attached.

Water pump is moving coolant around quite well apparently, by observation in the radiator neck at least.

Timing is a nice steady 6 degrees BTDC. Fuel is a blend of Optimax and Ultimate. (It was half full of one when I filled up with the other)

A drive up the freeway at 100Kmh seems to indicate that there is just insufficient airflow at that speed to maintain a working temp of 80-85C. Consequently it slowly gets hotter until the thermo switch actuates. Once the fan cuts in, however, the temp will slowly drop to below cutout, and equally slowly build up again to cut-in temp. Ambient temp today was about 25C max, a pleasant coolish breeze happening through the windows, and a hot engine! Bloody annoying I think you'll agree.

My gut feeling is that no car should be cycling the cooling fan when cruising at 100 Kmh. (Especially with a completely new cooling system!)

Next step is to try fabricating a small "chin spoiler" to re-direct a portion of the 100Kmh wind hitting the nose up and into the radiator duct.

I plan to do this maybe tomorrow after I've created a new skid pan/protector plate for the forward part of the under body, including slots for the brake discs. (My car was missing the original aluminium item with the brake air ducts.) This may in fact improve the airflow situation on its own.

I can't help feeling that this whole situation is a case of the aesthetics getting in the way of the engineering, a rare thing with Citroen but strangely reassuring as well.

If all else fails, as mentioned before, I'll go back to the noisy mongrel bloody propellor!

Cheers, Pottsy. (Time for a beer!)

Cooling Issue

pottsy said:

The State of the Nation!

Moby Dick is now running with the following things done to the cooling system:

Radiator de-tanked and cleaned.
Coolant new & really BRIGHT green!
Thermostat new & checked (Nominally 77 deg C, same unit as 504 Pug!)
Bottom hoses & heater hoses replaced.
Front ducting installed.
Fan shroud installed with 12" electric fan filling the round bit. Thermo switch set to cut in about 90C out at about 85C.
Gaps between the shroud and the radiator covered with Gaffer Tape.
New pressure cap (4 lb) and recovery bottle attached.

Water pump is moving coolant around quite well apparently, by observation in the radiator neck at least.

Timing is a nice steady 6 degrees BTDC. Fuel is a blend of Optimax and Ultimate. (It was half full of one when I filled up with the other)

A drive up the freeway at 100Kmh seems to indicate that there is just insufficient airflow at that speed to maintain a working temp of 80-85C. Consequently it slowly gets hotter until the thermo switch actuates. Once the fan cuts in, however, the temp will slowly drop to below cutout, and equally slowly build up again to cut-in temp. Ambient temp today was about 25C max, a pleasant coolish breeze happening through the windows, and a hot engine! Bloody annoying I think you'll agree.

My gut feeling is that no car should be cycling the cooling fan when cruising at 100 Kmh. (Especially with a completely new cooling system!)

Next step is to try fabricating a small "chin spoiler" to re-direct a portion of the 100Kmh wind hitting the nose up and into the radiator duct.

I plan to do this maybe tomorrow after I've created a new skid pan/protector plate for the forward part of the under body, including slots for the brake discs. (My car was missing the original aluminium item with the brake air ducts.) This may in fact improve the airflow situation on its own.

I can't help feeling that this whole situation is a case of the aesthetics getting in the way of the engineering, a rare thing with Citroen but strangely reassuring as well.

If all else fails, as mentioned before, I'll go back to the noisy mongrel bloody propellor!

Cheers, Pottsy. (Time for a beer!)

Click to expand...

I don't profess to be a D Special expert, but where is your themo sensor for the electric fan located ?

I had an issue with a Datsun 1600 (that is showing my age... ) where the fan thermo switch was in a top radiator hose and the coolant was not covering the thermo entirely, net effect was that coolant was very hot before the fan turned on and the fan didn't have the capacity to pull the temp because the coolant was so close to boiling.

I moved the thermo to the bottom of of the radiator (like the 504/505) and the fan cycled like a dream at 176f.

Before doing this the symptoms were very similar to ones you are having.

Good luck.

Hey Pottsy,

Just one observation. My car had a 4lb radiator cap in it when I first got the car.

I was advised to swap it for a 7lb one. Can't remember why.

Boyracer said:

Hey Pottsy,

Just one observation. My car had a 4lb radiator cap in it when I first got the car.

I was advised to swap it for a 7lb one. Can't remember why.

Click to expand...

That's a double edged sword. You may find you water pump starts leaking coolant and has a lower lifespan. It's not designed to run higher pressures (though 7psi is hardly a big jump).

Your not causing the engine to run cooler by using this cap, rather raising the boiling point of the coolant.

seeya,
Shane L.

Boyracer said:

Hey Pottsy,

Just one observation. My car had a 4lb radiator cap in it when I first got the car.

I was advised to swap it for a 7lb one. Can't remember why.

Click to expand...

4lb caps are very hard to find, but should be OK on a D special. 7 will work, but your water pump seals have to be good.

The other way to go with a D Special is to use the crossflow setup from a 21/23 - more capacity and a header tank.

I have continuing issues with the 23 Automatic - basically it reaches a point on a warmish/hot day where it just can't get itself cool again in stop/start running - I have the engine driven fan plus a modern 10" electric fan, with an aluminium radiator, and am using straight (no antifreeze) Redline Water Wetter (referred to above). I have the lowest setting switch on the electric fan, plus a manual override. On the open road, even on a hot day it can hold to about midway on the rather vague Citroen gauge.

Bear in mind that the Autos have an extra transmission cooler (a GS oil cooler no less!) mounted in front of the main radiator, plus an engine oil cooler mounted on the side of the engine.

I too am looking at a small 'scoop' or spoiler attached below the front undertray. I know of at least one DS23 IE Hydraulique with one attached which seems to work well. There used to be a guy in WA who made them in fibreglass, but he has stopped, unfortunately.

It seems to me that the issue is getting rid of the hot air - there are really not many ways out of the D engine compartment without heating more things up .

Hmm! Food for thought.

The fan sensor is in the top hose (Standard Davies-Craig install) The hose is certainly full of coolant, however, as I've fitted a catch tank and return valve type sealing radiator cap. Down the track I may solder in a fitting for a 504/505 thermo switch in the bottom of the radiator, but since I'd already bought the Davies-Craig kit I thought I might as well use it.

The 4 lb cap was the one specified in the catalogue for a D-Special. I was amazed it was even listed! (Cat No 536 07. The non return type was No 501 04. Can't recall the brand, will check tomorrow) The one fitted was sort of indeterminate in that the figure on the cap was halfway between being indecipherable and meaningless.

I'd certainly rather run lower pressure than high, for the reasons enumerated by Shane above.

Of interest, or possibly relevance, is the fact that I am monitoring the temperature with my gauge from a home brew fitting in the plug in the bottom of the water pump. I'm basing all my assumptions of overheating on these readings, of course, and have no way of knowing what the actual temp in the top radiator hose really is. It's possible, I suppose, that everything's working fine and I'm just measuring in the wrong spot.

I still think I'll play with a chin spoiler tomorrow.

Cheers All, Pottsy.