Hi just wondering if anyone could help me. I've been having various problems with the whole cooling system on the car and it's really starting to irritate me now.

It started by the temp gauge goes into red the power is reduced (auto) and I would pull over as soon as I can but when I lift the bonnet there is no signs of coolant leaks anywhere.

Top hose feels quite abit stiff to me and the lower hoses are not and they are cold both sides of the thermostat.

I've tried to bleed the system many times now and it's been better and worse different times. And I've always used the correct procedure for doing it. Also I could go for a drive and if it overheats I could lift the bonnet sometimes the radiator is stone cold.

Now a week ago my boss checked over it and assured me it's not the head gasket he has been a Mechanic for over 40years so he must knows what he is on about he said change the thermostat so I did. I ordered one and fitted it and it's been running fantastic temperature has always been half way. Even if I give it a bit of stick.

However last Friday he said on Saturday (today) he said we will take the coolant pipes of the radiator to make sure the radiator isn't blocked as the heater is mostly cold at idle and whenever you accelerate it heats up so when I accelerate the pressure pushes the water round more if there is a blockage.

Now I did clean the rad today and driving home it overheated and there is steam coming from the bleed screw so the water is not pressurising enough to open the thermostat for the hot water to pass through the radiator so is there a modification for the bleed screw as metal screw through plastic is obviously going to wear down after time. And has anybody had problems like mine and been able to sort it? Thanks for reading

Matthew

new thermostat, new rad and new coolant cap, try that, as they will be a bit of age now, mine were, i did alsorts to get to the bottom, rad was not getting hot 1 side, so did the lot and it's been perfect since, 3yrs!
i tried flushing mine to no avail, put a pressure washer in the heater pipe ends and blow it out, 2 pipes at back of the head under the screen,

mattmaclaren said:

the water is not pressurising enough to open the thermostat

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Hi Matt, you have not stated what type of engine you are dealing with, (V8, Tdi, Td5), the cooling system thermostat is solely operated by temperature, not at all by pressure, it is opened by a thermo bulb which MUST be totally immersed in the coolant, it is an IMMERSION device, the same with the temperature senders, i.e. if they are not surrounded by coolant they cannot operate as designed. From what you have been describing you still have an incompletely filled cooling system, (air locks),
you need to try and extend the filler neck of the coolant header overflow tank to well above the highest point of the engine cooling system, this can be done with a cut off 1.5 litre plastic drink bottle, necked into the tank and taped around the joint between the tank and the bottle neck, remove the bleeder plug at the engines highest point and pour/fill the system until coolant without air bubbles flows freely through the bleed point, refit the plug with coolant still discharging to avoid a run back of coolant.
If possible before doing this you should park the vehicle with the front higher than the rear, (nose up), and have your cabin heater valve fully to the hot position, sometimes after starting and running the engine there will be more air moved about the system and unless you have a leaking head gasket this should be moved back by a properly functioning system back to the header tank. Once the engine cools a bit you can remove the pressure cap, check for level loss and re-top up the tank t just above the half way. You can repeat the level loss check once the engine has completely cooled, say, overnight, before driving again.
If the system is definitely free of air locks and totally filled and you still have no obvious movement of coolant around and through the system you may have a failed water pump impellor, a significant radiator blockage or some other restriction within the block/head cooling passages.
Unfortunately the diesels are a fair bit unforgiving of operating the engine with low coolant and you need to be aware that if you have overheated once or more the head gasket could be "cactus".

Check the elbow that takes the top hose to the head, that could be cracked , I've come across this problem in person.

Gazbo said:

Hi Matt, you have not stated what type of engine you are dealing with, (V8, Tdi, Td5)

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Hi sorry it is a Td5 1999 year, Im sure the water pump is working as I took the hose off the top which is the hose behind the water temperature sensor and it's flowing perfect and there is always water pumping back into the header tank

Definitely bleed screw problem as it's letting steam and water pass does anybody near have one at all. Can't drive it now and it's my only vehicle apart from my motorbike which I don't really want to risk in the snow :/

It's no reason for steam to come out at the bleed screw on a well bled system whatsoever, maybe coolant... it seems very like combustion gas leak into the system which can be head gasket or cracked head then the backpressure created by the gasses are stopping the thermostat to open properly and the top hose goes solid