For the last couple of years about every 3 or 4 months often when towing a trailer (which would probably be equivalent to giving it a thrashing) the car (4x4 saph cos) would overheat - particularly when stopped in traffic after a long run on the open road. There was always plenty of coolant - in fact it would be pushing it out of the top of the header bottle. After quite a while on the side of the road it would suddenly suck all the coolamt back into the engine and I would fill it up and away I would go and it would be alright for another couple of months. I suspected the thermostat was intermittantly not opening so I replaced the stat with a new 82deg one. went away for xmas (summer here in NZ) and the car ran nice and cool all the way up north and when I stopped for gas the same thing happened. After holiday with no probs headed home (3 hour drive) made it home and in the driveway temp rose and what looked like all the coolant it would hold (well heaps anyway) poured out on the driveway. Left the car overnight and the next day the level in the header was still on Max. Started car expecting it to drop away once pumping around but stayed up. Now as it heats up coolant rises in header to overflowing and when I open bleed at thermostat nothing comes out until I open header tank lid then water flows out of screw hole. BUT I have still not been able to put in the amount of coolant that obviously leaked out in the first place and it now has a constant overheating issue. Obviously head gasket is one suspect but why so intermittant up to now and why is the header still full if loosing water this way. Fans not coming on (switch) is another. I do have an override fitted and this did bring temp down initially this morning but further on did not. (remembering I suspect a lack of water in there somewhere) Does the cap cause issues - blocked vent or similar. Sorry for such a long winded story but I am unsure where to start and we don't have the expert tuners here in New Zealand that you enjoy over there. Thanks David

 

Further to above - I just flushed out all the coolant hoses and radiator with no obvious blockages. When I refilled everything and ran the engine I noticed a bit of a grindy dry sounding noise coming from around the water pump pulley area that disappears (becomes quiet) when I open the bleed screw by the thermostat allowing water to escape and comes back again about 30 seconds after locking up the screw. David

 

That noise could be the pump being dry for a second whilst the water is going to all the right places once the system has no air leaks in it after you draining it and filling it up again.
You have left the header tank cap off whilst running the car once you have re-filled it for at least ten minutes to clear the air through the system?
Give the return hose a few squezes too whilst this is being done.

It could be your water pump is on its way out too. They are still available at some place's for the 4x4 system but are pricey. Ł185 I paid for mine from woodford garage in Totnes a few years ago. I'm sure they do overseas postage.

Also I personally wouldnt fill the header to the top, but 3/4 because, in my none mechanical mind lol, your not leaving enough room for the air that Is left in the system to escape to in the header tank.

Just a few ideas but hope this might help.

 

Thanks for the reply. I agree it does sound like the pump running dry but it is all the time unless you bleed water out of the bolt by the thermostat. It then runs nice and quiet but when you tighten off the screw the noise returns after a short time and stays there again. It is as if the pump pumps itself dry. Also does anyone know whether the cap has a vent in it and how to test it. David

 

I had the same problem... And it turned out the rad had blocked in the bottom left corner.

 

RSMat - which of my many symptoms did you have. David

 

If your based in Auckland try giving Phil at Premier Automotive a call. He has a lot of experiance with cossies and classic fords.

 

With you saying the noise goes when the bleed bolt is undone then that means something is blocking the flow and with the bolt open that to me is the water finally finding a route to get out and thus circulating the water through via the pump out the bleed bolt. I would as Mat suggested have a look at the radiator and if so remove it and give it a good blow through and clean out. that sounds like the problem.

With regards to the cap having a vent. I think, (not that I have looked at one really but), the standard yellow cap doesn't look like it has a vent, I think thought the rubber seal in it will give if the temp gets too high???? were as one like mine which is a spec r header tank, its cap does have a vent flap valve thingy in it.

Lets us know how you get on bud.

 

Mines was same as this mate....


For the last couple of years about every 3 or 4 months often when towing a trailer (which would probably be equivalent to giving it a thrashing) the car (4x4 saph cos) would overheat - particularly when stopped in traffic after a long run on the open road. There was always plenty of coolant - in fact it would be pushing it out of the top of the header bottle. After quite a while on the side of the road it would suddenly suck all the coolamt back into the engine and I would fill it up and away I would go and it would be alright for another couple of months.

 

I would reverse flush the system then flush as normal then replace the header cap.I thought the system was self bleeding and the cap releases the pressure automatically,well on 2wd anyway.Different stat housing though on 4x4.I am sure I have seen issues where the cap was no good and caused all sorts of problems.Only fill the header up about half way too.

 

Thanks to all for the replies. I will pull the radiator out to give it a good flushing. Which way does it normally flow on a 4x4. I also have a bottle of "Radiator flush and clean" which you are supposed to put in the system and run for 20mins to an hour then flush out again. Meant to remove sludge and scale but was a little worried that it might loosen up something and then circulate it to a more critical place and get stuck i.e, the pump. May also have to look at a new pump from the U.K. any more sugggestions of the best place for purchase. Bit scared to run it for too long as it sounds like runnning dry. Thanks again David.

 

I think Woodford garage are the only ones of the top of my head, who still have them in stock.
There is likely to be someone on here who will have a used but in good condition one.

Not sure myself what way the water goes round.

The flush stuff would be a good idea but I would just for now, remove the radiator, flush that out until your happy that is clear and then if that doesnt fix it then use the flush stuff. It should break the sludge etc etc enough to not cause damage to the pump.

 

Thanks again. I haven't got back to looking at the car since due to work commitments. Think I will have to pull the water pump off and see if I can see anything obvious. I guess if I do this I will need a new gasket before refitting. David

 

You will yeah and loktite gasket sealant too. The gasket came with my new pump so it should with your new one too. I think also there are 2 tiny holes in the pumps casing somewere IIRC and if one leaks a bit then it's on it's way out change soon, and if both leak it's time to change now/V soon.

 

If you're going to flush the system and use a cleaning agent i would recommend that you are very carefull with the head gasket.
I did that and it cost me a piston because of headgasket fail

 

I had over heating issues when 1st bought my car, for me it was the radiator which was fucked, if the rad is fuckered the coolant will not circulate around the engine properly and give you the symptoms you are describing, rad fans not kicking in is one of them, if you take the fan switch plug off and bridge out the circuit with a hair clip or paper clip and the fans start to blow that tells you that everything from the car (circuit) is fine, this usually means that the rad is blocked and the coolant is not circulating correctly, fine-ish when you are driving and air is blowing through the engine bay, but when caught in traffic the fans don't blow and the engine over heats,

I'm a little concerned that you are saying coolant is blowing out of the header tank cap, this can indicate head gasket failure

as for the thermostat, 4x4 stats are notoriously unreliable, the way to check if you have problems with the stat is to get the car out on a run, sit at 100mph and if the temp gauge starts to creep up the stat is fuckered, I have always drilled a small 3 mm hole in stats that I have fitted to my car, this way if the stat does jam shut you will have some circulation of the coolant,


Luciano

 

Thanks again for all the replies. I have to admit I have not been back to work on the car for the last couple of weeks due other commitments. I pulled out the radiator and gave it a good flushing (which did expel quite a bit of rusty looking stuff) and also removed the thermostat which I will test in boiling water. next step is to remove all other water hoses as it seems to me to be like a blockage somewhere as it seems to pump the pump dry. Some of the hoses on the inlet side of the engine(that feed to the oil sandwich plate or whatever it is called) look to be pretty hard to get to but like I say I haven't really tried yet. If I don't find anything I guess I will have to remove the pump to have a look at that. David

 

I have used Lodge auto centre in hastings. Call richard they keep nz's largest range of cosworth parts. They def have 2wd pumps because i got one from them
www.lodgeautocentre.co.nz

Kevin

 

any updates on the saph buddy????

 

I feel embarassed to say it but I have not looked at it again since. I am on night shift for the last month and have a bit of a motivation problem when I get up. I reserected my old XR4i so I could get to work and the cossie became lower priority behind a building project at home. I am a bit worried how long you can leave the cooling system open to the air before it corrodes internally so will endevour to get on to it this weekend as I only have 1 more night of ON's and the retaining wall is all but finished. Will let you know what if anything I find. David

 

Dont be embarrassed mate, mine is off the road too and its a pain in the RS to get it finished too lol. Benn ages since mine has seen past 20mph lol. A bit of tape over the openings will be fine making sure no crap gets in the system.

 

I would also go with the rad

 

O.K. Finally got back to work on this today. Pulled the water pump and Thermostat housing off the block. The pump impeller looks a bit manky as it has been rebuilt a couple of times because no one here in New Zealand could supply one. I have since found you can still get them for the 4x4 over there so may look at buying a new one. Having said that I don't think it is bad enough to be causing my problems and I am taking it tomorrow to a water pump specialist to get his opinion. Also taking Radiator to be disassembled and cleaned out.
Anyway the thermostat housing has an O ring which has been not fitted properly (if I knew how to post pictures I would) and I think this would have allowed it to suck in air. Does the water pump get fed directly from the stat housing via the short hose connecting the two. If so I think this could be my problem although why it just started happenning (the pumping dry issue) I am not sure as it has been in there for a number of years. Also is this O ring all there is on the stat housing to block sealing or is there supposed to be a gasket as well. Also need to see if ford here has a pump gasket for refitting. Is this 4x4 gasket the same gasket as off any others. Will keep you posted David

 

use photobucket.com to upload picture onto here and just copy and paste the IRL bits to the post.
I dont think the o ring would be the cause of the problem as you should have had some sort of gasket sealant on there too. like locktite gasket sealant stuff.

You should get a new pump gasket with the pump included in the box.

see where the radiator goes and hope it is that so you havent gotto worry too much about the pump.

Ben.

 

Unfortunately it is dark outside on this side of the world so I can't have a good look at the engine but looking at the thermostat housing I don't think there was any other sealer on there. You could also see on the block how it was bypassing the O ring at the top. I thought it could be sucking in air. Have tried the photo thing but not sure if it will work or not - let me know.

http://s1020.photobucket.com/albums/...t=SAM_3640.jpg

David

 

just copy the img code [IMG]https://passionford.com/forum/ford-sierra-sapphire-rs500-cosworth/http.....photobucket.com etc etc etc etc etc et[IMG]. the last of the 4 options and it should come up like this.

as for that seal i would put a bit of my money saying that Could be the problem with sucking in air. the fitter should be shot lol. once you get the all clear with the rad i would fit it back onand the pump first with a new gasket and sealant around the outer metal bit and see if that helps.
i have seen pumps worse than that but it look fine to me.

good luck bud.

 

Well I am finally back on the road after being parked up since returning from Xmas camping holiday (summer here at Xmas) Temp seems to be running nice and cool for a few days now although for the first day or so it did sit a little higher than it used to but still well in the normal range. Perhaps still a bit of air in the system. So it appears the O ring was causing at least the problem with the pump pumping dry and hopefully my long term problem of occasional overheating will be cured also. Only time will tell but thanks to all who gave suggestions and help. David

 

Glad you have a good result mate.